zebra_rpc/

methods.rs

//! Zebra supported RPC methods.
//!
//! Based on the [`zcashd` RPC methods](https://zcash.github.io/rpc/)
//! as used by `lightwalletd.`
//!
//! Some parts of the `zcashd` RPC documentation are outdated.
//! So this implementation follows the `zcashd` server and `lightwalletd` client implementations.

use std::{collections::HashSet, fmt::Debug, sync::Arc};

use chrono::Utc;
use futures::{stream::FuturesOrdered, StreamExt, TryFutureExt};
use hex::{FromHex, ToHex};
use hex_data::HexData;
use indexmap::IndexMap;
use jsonrpsee::core::{async_trait, RpcResult as Result};
use jsonrpsee_proc_macros::rpc;
use jsonrpsee_types::{ErrorCode, ErrorObject};
use tokio::{sync::broadcast, task::JoinHandle};
use tower::{Service, ServiceExt};
use tracing::Instrument;

use zcash_primitives::consensus::Parameters;
use zebra_chain::{
    block::{self, Height, SerializedBlock},
    chain_tip::{ChainTip, NetworkChainTipHeightEstimator},
    parameters::{ConsensusBranchId, Network, NetworkUpgrade},
    serialization::{ZcashDeserialize, ZcashSerialize},
    subtree::NoteCommitmentSubtreeIndex,
    transaction::{self, SerializedTransaction, Transaction, UnminedTx},
    transparent::{self, Address},
    work::{
        difficulty::{CompactDifficulty, ExpandedDifficulty},
        equihash::Solution,
    },
};
use zebra_node_services::mempool;
use zebra_state::{HashOrHeight, OutputIndex, OutputLocation, TransactionLocation};

use crate::{
    methods::trees::{GetSubtrees, GetTreestate, SubtreeRpcData},
    queue::Queue,
    server::{
        self,
        error::{MapError, OkOrError},
    },
};

pub mod hex_data;

// We don't use a types/ module here, because it is redundant.
pub mod trees;

pub mod types;

#[cfg(feature = "getblocktemplate-rpcs")]
pub mod get_block_template_rpcs;

#[cfg(feature = "getblocktemplate-rpcs")]
pub use get_block_template_rpcs::{GetBlockTemplateRpcImpl, GetBlockTemplateRpcServer};

#[cfg(test)]
mod tests;

#[rpc(server)]
/// RPC method signatures.
pub trait Rpc {
    /// Returns software information from the RPC server, as a [`GetInfo`] JSON struct.
    ///
    /// zcashd reference: [`getinfo`](https://zcash.github.io/rpc/getinfo.html)
    /// method: post
    /// tags: control
    ///
    /// # Notes
    ///
    /// [The zcashd reference](https://zcash.github.io/rpc/getinfo.html) might not show some fields
    /// in Zebra's [`GetInfo`]. Zebra uses the field names and formats from the
    /// [zcashd code](https://github.com/zcash/zcash/blob/v4.6.0-1/src/rpc/misc.cpp#L86-L87).
    ///
    /// Some fields from the zcashd reference are missing from Zebra's [`GetInfo`]. It only contains the fields
    /// [required for lightwalletd support.](https://github.com/zcash/lightwalletd/blob/v0.4.9/common/common.go#L91-L95)
    #[method(name = "getinfo")]
    fn get_info(&self) -> Result<GetInfo>;

    /// Returns blockchain state information, as a [`GetBlockChainInfo`] JSON struct.
    ///
    /// zcashd reference: [`getblockchaininfo`](https://zcash.github.io/rpc/getblockchaininfo.html)
    /// method: post
    /// tags: blockchain
    ///
    /// # Notes
    ///
    /// Some fields from the zcashd reference are missing from Zebra's [`GetBlockChainInfo`]. It only contains the fields
    /// [required for lightwalletd support.](https://github.com/zcash/lightwalletd/blob/v0.4.9/common/common.go#L72-L89)
    #[method(name = "getblockchaininfo")]
    async fn get_blockchain_info(&self) -> Result<GetBlockChainInfo>;

    /// Returns the total balance of a provided `addresses` in an [`AddressBalance`] instance.
    ///
    /// zcashd reference: [`getaddressbalance`](https://zcash.github.io/rpc/getaddressbalance.html)
    /// method: post
    /// tags: address
    ///
    /// # Parameters
    ///
    /// - `address_strings`: (object, example={"addresses": ["tmYXBYJj1K7vhejSec5osXK2QsGa5MTisUQ"]}) A JSON map with a single entry
    ///     - `addresses`: (array of strings) A list of base-58 encoded addresses.
    ///
    /// # Notes
    ///
    /// zcashd also accepts a single string parameter instead of an array of strings, but Zebra
    /// doesn't because lightwalletd always calls this RPC with an array of addresses.
    ///
    /// zcashd also returns the total amount of Zatoshis received by the addresses, but Zebra
    /// doesn't because lightwalletd doesn't use that information.
    ///
    /// The RPC documentation says that the returned object has a string `balance` field, but
    /// zcashd actually [returns an
    /// integer](https://github.com/zcash/lightwalletd/blob/bdaac63f3ee0dbef62bde04f6817a9f90d483b00/common/common.go#L128-L130).
    #[method(name = "getaddressbalance")]
    async fn get_address_balance(&self, address_strings: AddressStrings) -> Result<AddressBalance>;

    /// Sends the raw bytes of a signed transaction to the local node's mempool, if the transaction is valid.
    /// Returns the [`SentTransactionHash`] for the transaction, as a JSON string.
    ///
    /// zcashd reference: [`sendrawtransaction`](https://zcash.github.io/rpc/sendrawtransaction.html)
    /// method: post
    /// tags: transaction
    ///
    /// # Parameters
    ///
    /// - `raw_transaction_hex`: (string, required, example="signedhex") The hex-encoded raw transaction bytes.
    ///
    /// # Notes
    ///
    /// zcashd accepts an optional `allowhighfees` parameter. Zebra doesn't support this parameter,
    /// because lightwalletd doesn't use it.
    #[method(name = "sendrawtransaction")]
    async fn send_raw_transaction(
        &self,
        raw_transaction_hex: String,
    ) -> Result<SentTransactionHash>;

    /// Returns the requested block by hash or height, as a [`GetBlock`] JSON string.
    /// If the block is not in Zebra's state, returns
    /// [error code `-8`.](https://github.com/zcash/zcash/issues/5758) if a height was
    /// passed or -5 if a hash was passed.
    ///
    /// zcashd reference: [`getblock`](https://zcash.github.io/rpc/getblock.html)
    /// method: post
    /// tags: blockchain
    ///
    /// # Parameters
    ///
    /// - `hash_or_height`: (string, required, example="1") The hash or height for the block to be returned.
    /// - `verbosity`: (number, optional, default=1, example=1) 0 for hex encoded data, 1 for a json object, and 2 for json object with transaction data.
    ///
    /// # Notes
    ///
    /// Zebra previously partially supported verbosity=1 by returning only the
    /// fields required by lightwalletd ([`lightwalletd` only reads the `tx`
    /// field of the result](https://github.com/zcash/lightwalletd/blob/dfac02093d85fb31fb9a8475b884dd6abca966c7/common/common.go#L152)).
    /// That verbosity level was migrated to "3"; so while lightwalletd will
    /// still work by using verbosity=1, it will sync faster if it is changed to
    /// use verbosity=3.
    ///
    /// The undocumented `chainwork` field is not returned.
    #[method(name = "getblock")]
    async fn get_block(&self, hash_or_height: String, verbosity: Option<u8>) -> Result<GetBlock>;

    /// Returns the requested block header by hash or height, as a [`GetBlockHeader`] JSON string.
    /// If the block is not in Zebra's state,
    /// returns [error code `-8`.](https://github.com/zcash/zcash/issues/5758)
    /// if a height was passed or -5 if a hash was passed.
    ///
    /// zcashd reference: [`getblockheader`](https://zcash.github.io/rpc/getblockheader.html)
    /// method: post
    /// tags: blockchain
    ///
    /// # Parameters
    ///
    /// - `hash_or_height`: (string, required, example="1") The hash or height for the block to be returned.
    /// - `verbose`: (bool, optional, default=false, example=true) false for hex encoded data, true for a json object
    ///
    /// # Notes
    ///
    /// The undocumented `chainwork` field is not returned.
    #[method(name = "getblockheader")]
    async fn get_block_header(
        &self,
        hash_or_height: String,
        verbose: Option<bool>,
    ) -> Result<GetBlockHeader>;

    /// Returns the hash of the current best blockchain tip block, as a [`GetBlockHash`] JSON string.
    ///
    /// zcashd reference: [`getbestblockhash`](https://zcash.github.io/rpc/getbestblockhash.html)
    /// method: post
    /// tags: blockchain
    #[method(name = "getbestblockhash")]
    fn get_best_block_hash(&self) -> Result<GetBlockHash>;

    /// Returns the height and hash of the current best blockchain tip block, as a [`GetBlockHeightAndHash`] JSON struct.
    ///
    /// zcashd reference: none
    /// method: post
    /// tags: blockchain
    #[method(name = "getbestblockheightandhash")]
    fn get_best_block_height_and_hash(&self) -> Result<GetBlockHeightAndHash>;

    /// Returns all transaction ids in the memory pool, as a JSON array.
    ///
    /// zcashd reference: [`getrawmempool`](https://zcash.github.io/rpc/getrawmempool.html)
    /// method: post
    /// tags: blockchain
    #[method(name = "getrawmempool")]
    async fn get_raw_mempool(&self) -> Result<Vec<String>>;

    /// Returns information about the given block's Sapling & Orchard tree state.
    ///
    /// zcashd reference: [`z_gettreestate`](https://zcash.github.io/rpc/z_gettreestate.html)
    /// method: post
    /// tags: blockchain
    ///
    /// # Parameters
    ///
    /// - `hash | height`: (string, required, example="00000000febc373a1da2bd9f887b105ad79ddc26ac26c2b28652d64e5207c5b5") The block hash or height.
    ///
    /// # Notes
    ///
    /// The zcashd doc reference above says that the parameter "`height` can be
    /// negative where -1 is the last known valid block". On the other hand,
    /// `lightwalletd` only uses positive heights, so Zebra does not support
    /// negative heights.
    #[method(name = "z_gettreestate")]
    async fn z_get_treestate(&self, hash_or_height: String) -> Result<GetTreestate>;

    /// Returns information about a range of Sapling or Orchard subtrees.
    ///
    /// zcashd reference: [`z_getsubtreesbyindex`](https://zcash.github.io/rpc/z_getsubtreesbyindex.html) - TODO: fix link
    /// method: post
    /// tags: blockchain
    ///
    /// # Parameters
    ///
    /// - `pool`: (string, required) The pool from which subtrees should be returned. Either "sapling" or "orchard".
    /// - `start_index`: (number, required) The index of the first 2^16-leaf subtree to return.
    /// - `limit`: (number, optional) The maximum number of subtree values to return.
    ///
    /// # Notes
    ///
    /// While Zebra is doing its initial subtree index rebuild, subtrees will become available
    /// starting at the chain tip. This RPC will return an empty list if the `start_index` subtree
    /// exists, but has not been rebuilt yet. This matches `zcashd`'s behaviour when subtrees aren't
    /// available yet. (But `zcashd` does its rebuild before syncing any blocks.)
    #[method(name = "z_getsubtreesbyindex")]
    async fn z_get_subtrees_by_index(
        &self,
        pool: String,
        start_index: NoteCommitmentSubtreeIndex,
        limit: Option<NoteCommitmentSubtreeIndex>,
    ) -> Result<GetSubtrees>;

    /// Returns the raw transaction data, as a [`GetRawTransaction`] JSON string or structure.
    ///
    /// zcashd reference: [`getrawtransaction`](https://zcash.github.io/rpc/getrawtransaction.html)
    /// method: post
    /// tags: transaction
    ///
    /// # Parameters
    ///
    /// - `txid`: (string, required, example="mytxid") The transaction ID of the transaction to be returned.
    /// - `verbose`: (number, optional, default=0, example=1) If 0, return a string of hex-encoded data, otherwise return a JSON object.
    ///
    /// # Notes
    ///
    /// We don't currently support the `blockhash` parameter since lightwalletd does not
    /// use it.
    ///
    /// In verbose mode, we only expose the `hex` and `height` fields since
    /// lightwalletd uses only those:
    /// <https://github.com/zcash/lightwalletd/blob/631bb16404e3d8b045e74a7c5489db626790b2f6/common/common.go#L119>
    #[method(name = "getrawtransaction")]
    async fn get_raw_transaction(
        &self,
        txid: String,
        verbose: Option<u8>,
    ) -> Result<GetRawTransaction>;

    /// Returns the transaction ids made by the provided transparent addresses.
    ///
    /// zcashd reference: [`getaddresstxids`](https://zcash.github.io/rpc/getaddresstxids.html)
    /// method: post
    /// tags: address
    ///
    /// # Parameters
    ///
    /// - `request`: (object, required, example={\"addresses\": [\"tmYXBYJj1K7vhejSec5osXK2QsGa5MTisUQ\"], \"start\": 1000, \"end\": 2000}) A struct with the following named fields:
    ///     - `addresses`: (json array of string, required) The addresses to get transactions from.
    ///     - `start`: (numeric, required) The lower height to start looking for transactions (inclusive).
    ///     - `end`: (numeric, required) The top height to stop looking for transactions (inclusive).
    ///
    /// # Notes
    ///
    /// Only the multi-argument format is used by lightwalletd and this is what we currently support:
    /// <https://github.com/zcash/lightwalletd/blob/631bb16404e3d8b045e74a7c5489db626790b2f6/common/common.go#L97-L102>
    #[method(name = "getaddresstxids")]
    async fn get_address_tx_ids(&self, request: GetAddressTxIdsRequest) -> Result<Vec<String>>;

    /// Returns all unspent outputs for a list of addresses.
    ///
    /// zcashd reference: [`getaddressutxos`](https://zcash.github.io/rpc/getaddressutxos.html)
    /// method: post
    /// tags: address
    ///
    /// # Parameters
    ///
    /// - `addresses`: (array, required, example={\"addresses\": [\"tmYXBYJj1K7vhejSec5osXK2QsGa5MTisUQ\"]}) The addresses to get outputs from.
    ///
    /// # Notes
    ///
    /// lightwalletd always uses the multi-address request, without chaininfo:
    /// <https://github.com/zcash/lightwalletd/blob/master/frontend/service.go#L402>
    #[method(name = "getaddressutxos")]
    async fn get_address_utxos(
        &self,
        address_strings: AddressStrings,
    ) -> Result<Vec<GetAddressUtxos>>;

    /// Stop the running zebrad process.
    ///
    /// # Notes
    ///
    /// - Works for non windows targets only.
    /// - Works only if the network of the running zebrad process is `Regtest`.
    ///
    /// zcashd reference: [`stop`](https://zcash.github.io/rpc/stop.html)
    /// method: post
    /// tags: control
    #[method(name = "stop")]
    fn stop(&self) -> Result<String>;
}

/// RPC method implementations.
#[derive(Clone)]
pub struct RpcImpl<Mempool, State, Tip>
where
    Mempool: Service<
            mempool::Request,
            Response = mempool::Response,
            Error = zebra_node_services::BoxError,
        > + Clone
        + Send
        + Sync
        + 'static,
    Mempool::Future: Send,
    State: Service<
            zebra_state::ReadRequest,
            Response = zebra_state::ReadResponse,
            Error = zebra_state::BoxError,
        > + Clone
        + Send
        + Sync
        + 'static,
    State::Future: Send,
    Tip: ChainTip + Clone + Send + Sync + 'static,
{
    // Configuration
    //
    /// Zebra's application version, with build metadata.
    build_version: String,

    /// Zebra's RPC user agent.
    user_agent: String,

    /// The configured network for this RPC service.
    network: Network,

    /// Test-only option that makes Zebra say it is at the chain tip,
    /// no matter what the estimated height or local clock is.
    debug_force_finished_sync: bool,

    /// Test-only option that makes RPC responses more like `zcashd`.
    #[allow(dead_code)]
    debug_like_zcashd: bool,

    // Services
    //
    /// A handle to the mempool service.
    mempool: Mempool,

    /// A handle to the state service.
    state: State,

    /// Allows efficient access to the best tip of the blockchain.
    latest_chain_tip: Tip,

    // Tasks
    //
    /// A sender component of a channel used to send transactions to the mempool queue.
    queue_sender: broadcast::Sender<UnminedTx>,
}

impl<Mempool, State, Tip> Debug for RpcImpl<Mempool, State, Tip>
where
    Mempool: Service<
            mempool::Request,
            Response = mempool::Response,
            Error = zebra_node_services::BoxError,
        > + Clone
        + Send
        + Sync
        + 'static,
    Mempool::Future: Send,
    State: Service<
            zebra_state::ReadRequest,
            Response = zebra_state::ReadResponse,
            Error = zebra_state::BoxError,
        > + Clone
        + Send
        + Sync
        + 'static,
    State::Future: Send,
    Tip: ChainTip + Clone + Send + Sync + 'static,
{
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        // Skip fields without Debug impls, and skip channels
        f.debug_struct("RpcImpl")
            .field("build_version", &self.build_version)
            .field("user_agent", &self.user_agent)
            .field("network", &self.network)
            .field("debug_force_finished_sync", &self.debug_force_finished_sync)
            .field("debug_like_zcashd", &self.debug_like_zcashd)
            .finish()
    }
}

impl<Mempool, State, Tip> RpcImpl<Mempool, State, Tip>
where
    Mempool: Service<
            mempool::Request,
            Response = mempool::Response,
            Error = zebra_node_services::BoxError,
        > + Clone
        + Send
        + Sync
        + 'static,
    Mempool::Future: Send,
    State: Service<
            zebra_state::ReadRequest,
            Response = zebra_state::ReadResponse,
            Error = zebra_state::BoxError,
        > + Clone
        + Send
        + Sync
        + 'static,
    State::Future: Send,
    Tip: ChainTip + Clone + Send + Sync + 'static,
{
    /// Create a new instance of the RPC handler.
    //
    // TODO:
    // - put some of the configs or services in their own struct?
    #[allow(clippy::too_many_arguments)]
    pub fn new<VersionString, UserAgentString>(
        build_version: VersionString,
        user_agent: UserAgentString,
        network: Network,
        debug_force_finished_sync: bool,
        debug_like_zcashd: bool,
        mempool: Mempool,
        state: State,
        latest_chain_tip: Tip,
    ) -> (Self, JoinHandle<()>)
    where
        VersionString: ToString + Clone + Send + 'static,
        UserAgentString: ToString + Clone + Send + 'static,
    {
        let (runner, queue_sender) = Queue::start();

        let mut build_version = build_version.to_string();
        let user_agent = user_agent.to_string();

        // Match zcashd's version format, if the version string has anything in it
        if !build_version.is_empty() && !build_version.starts_with('v') {
            build_version.insert(0, 'v');
        }

        let rpc_impl = RpcImpl {
            build_version,
            user_agent,
            network: network.clone(),
            debug_force_finished_sync,
            debug_like_zcashd,
            mempool: mempool.clone(),
            state: state.clone(),
            latest_chain_tip: latest_chain_tip.clone(),
            queue_sender,
        };

        // run the process queue
        let rpc_tx_queue_task_handle = tokio::spawn(
            runner
                .run(mempool, state, latest_chain_tip, network)
                .in_current_span(),
        );

        (rpc_impl, rpc_tx_queue_task_handle)
    }
}

#[async_trait]
impl<Mempool, State, Tip> RpcServer for RpcImpl<Mempool, State, Tip>
where
    Mempool: Service<
            mempool::Request,
            Response = mempool::Response,
            Error = zebra_node_services::BoxError,
        > + Clone
        + Send
        + Sync
        + 'static,
    Mempool::Future: Send,
    State: Service<
            zebra_state::ReadRequest,
            Response = zebra_state::ReadResponse,
            Error = zebra_state::BoxError,
        > + Clone
        + Send
        + Sync
        + 'static,
    State::Future: Send,
    Tip: ChainTip + Clone + Send + Sync + 'static,
{
    fn get_info(&self) -> Result<GetInfo> {
        let response = GetInfo {
            build: self.build_version.clone(),
            subversion: self.user_agent.clone(),
        };

        Ok(response)
    }

    #[allow(clippy::unwrap_in_result)]
    async fn get_blockchain_info(&self) -> Result<GetBlockChainInfo> {
        let network = self.network.clone();
        let debug_force_finished_sync = self.debug_force_finished_sync;
        let mut state = self.state.clone();

        // `chain` field
        let chain = network.bip70_network_name();

        let request = zebra_state::ReadRequest::TipPoolValues;
        let response: zebra_state::ReadResponse = state
            .ready()
            .and_then(|service| service.call(request))
            .await
            .map_misc_error()?;

        let zebra_state::ReadResponse::TipPoolValues {
            tip_height,
            tip_hash,
            value_balance,
        } = response
        else {
            unreachable!("unmatched response to a TipPoolValues request")
        };

        let request = zebra_state::ReadRequest::BlockHeader(tip_hash.into());
        let response: zebra_state::ReadResponse = state
            .ready()
            .and_then(|service| service.call(request))
            .await
            .map_misc_error()?;

        let zebra_state::ReadResponse::BlockHeader { header, .. } = response else {
            unreachable!("unmatched response to a BlockHeader request")
        };

        let tip_block_time = header.time;

        let now = Utc::now();
        let zebra_estimated_height =
            NetworkChainTipHeightEstimator::new(tip_block_time, tip_height, &network)
                .estimate_height_at(now);

        // If we're testing the mempool, force the estimated height to be the actual tip height, otherwise,
        // check if the estimated height is below Zebra's latest tip height, or if the latest tip's block time is
        // later than the current time on the local clock.
        let estimated_height = if tip_block_time > now
            || zebra_estimated_height < tip_height
            || debug_force_finished_sync
        {
            tip_height
        } else {
            zebra_estimated_height
        };

        // `upgrades` object
        //
        // Get the network upgrades in height order, like `zcashd`.
        let mut upgrades = IndexMap::new();
        for (activation_height, network_upgrade) in network.full_activation_list() {
            // Zebra defines network upgrades based on incompatible consensus rule changes,
            // but zcashd defines them based on ZIPs.
            //
            // All the network upgrades with a consensus branch ID are the same in Zebra and zcashd.
            if let Some(branch_id) = network_upgrade.branch_id() {
                // zcashd's RPC seems to ignore Disabled network upgrades, so Zebra does too.
                let status = if tip_height >= activation_height {
                    NetworkUpgradeStatus::Active
                } else {
                    NetworkUpgradeStatus::Pending
                };

                let upgrade = NetworkUpgradeInfo {
                    name: network_upgrade,
                    activation_height,
                    status,
                };
                upgrades.insert(ConsensusBranchIdHex(branch_id), upgrade);
            }
        }

        // `consensus` object
        let next_block_height =
            (tip_height + 1).expect("valid chain tips are a lot less than Height::MAX");
        let consensus = TipConsensusBranch {
            chain_tip: ConsensusBranchIdHex(
                NetworkUpgrade::current(&network, tip_height)
                    .branch_id()
                    .unwrap_or(ConsensusBranchId::RPC_MISSING_ID),
            ),
            next_block: ConsensusBranchIdHex(
                NetworkUpgrade::current(&network, next_block_height)
                    .branch_id()
                    .unwrap_or(ConsensusBranchId::RPC_MISSING_ID),
            ),
        };

        let response = GetBlockChainInfo {
            chain,
            blocks: tip_height,
            best_block_hash: tip_hash,
            estimated_height,
            value_pools: types::ValuePoolBalance::from_value_balance(value_balance),
            upgrades,
            consensus,
        };

        Ok(response)
    }
    async fn get_address_balance(&self, address_strings: AddressStrings) -> Result<AddressBalance> {
        let state = self.state.clone();

        let valid_addresses = address_strings.valid_addresses()?;

        let request = zebra_state::ReadRequest::AddressBalance(valid_addresses);
        let response = state.oneshot(request).await.map_misc_error()?;

        match response {
            zebra_state::ReadResponse::AddressBalance(balance) => Ok(AddressBalance {
                balance: u64::from(balance),
            }),
            _ => unreachable!("Unexpected response from state service: {response:?}"),
        }
    }

    // TODO: use HexData or GetRawTransaction::Bytes to handle the transaction data argument
    async fn send_raw_transaction(
        &self,
        raw_transaction_hex: String,
    ) -> Result<SentTransactionHash> {
        let mempool = self.mempool.clone();
        let queue_sender = self.queue_sender.clone();

        // Reference for the legacy error code:
        // <https://github.com/zcash/zcash/blob/99ad6fdc3a549ab510422820eea5e5ce9f60a5fd/src/rpc/rawtransaction.cpp#L1259-L1260>
        let raw_transaction_bytes = Vec::from_hex(raw_transaction_hex)
            .map_error(server::error::LegacyCode::Deserialization)?;
        let raw_transaction = Transaction::zcash_deserialize(&*raw_transaction_bytes)
            .map_error(server::error::LegacyCode::Deserialization)?;

        let transaction_hash = raw_transaction.hash();

        // send transaction to the rpc queue, ignore any error.
        let unmined_transaction = UnminedTx::from(raw_transaction.clone());
        let _ = queue_sender.send(unmined_transaction);

        let transaction_parameter = mempool::Gossip::Tx(raw_transaction.into());
        let request = mempool::Request::Queue(vec![transaction_parameter]);

        let response = mempool.oneshot(request).await.map_misc_error()?;

        let mut queue_results = match response {
            mempool::Response::Queued(results) => results,
            _ => unreachable!("incorrect response variant from mempool service"),
        };

        assert_eq!(
            queue_results.len(),
            1,
            "mempool service returned more results than expected"
        );

        let queue_result = queue_results
            .pop()
            .expect("there should be exactly one item in Vec")
            .inspect_err(|err| tracing::debug!("sent transaction to mempool: {:?}", &err))
            .map_misc_error()?
            .await
            .map_misc_error()?;

        tracing::debug!("sent transaction to mempool: {:?}", &queue_result);

        queue_result
            .map(|_| SentTransactionHash(transaction_hash))
            // Reference for the legacy error code:
            // <https://github.com/zcash/zcash/blob/99ad6fdc3a549ab510422820eea5e5ce9f60a5fd/src/rpc/rawtransaction.cpp#L1290-L1301>
            // Note that this error code might not exactly match the one returned by zcashd
            // since zcashd's error code selection logic is more granular. We'd need to
            // propagate the error coming from the verifier to be able to return more specific
            // error codes.
            .map_error(server::error::LegacyCode::Verify)
    }

    // # Performance
    //
    // `lightwalletd` calls this RPC with verosity 1 for its initial sync of 2 million blocks, the
    // performance of this RPC with verbosity 1 significantly affects `lightwalletd`s sync time.
    //
    // TODO:
    // - use `height_from_signed_int()` to handle negative heights
    //   (this might be better in the state request, because it needs the state height)
    async fn get_block(&self, hash_or_height: String, verbosity: Option<u8>) -> Result<GetBlock> {
        let mut state = self.state.clone();
        let verbosity = verbosity.unwrap_or(1);
        let network = self.network.clone();
        let original_hash_or_height = hash_or_height.clone();

        // If verbosity requires a call to `get_block_header`, resolve it here
        let get_block_header_future = if matches!(verbosity, 1 | 2) {
            Some(self.get_block_header(original_hash_or_height.clone(), Some(true)))
        } else {
            None
        };

        let hash_or_height: HashOrHeight = hash_or_height
            .parse()
            // Reference for the legacy error code:
            // <https://github.com/zcash/zcash/blob/99ad6fdc3a549ab510422820eea5e5ce9f60a5fd/src/rpc/blockchain.cpp#L629>
            .map_error(server::error::LegacyCode::InvalidParameter)?;

        if verbosity == 0 {
            let request = zebra_state::ReadRequest::Block(hash_or_height);
            let response = state
                .ready()
                .and_then(|service| service.call(request))
                .await
                .map_misc_error()?;

            match response {
                zebra_state::ReadResponse::Block(Some(block)) => Ok(GetBlock::Raw(block.into())),
                zebra_state::ReadResponse::Block(None) => {
                    Err("Block not found").map_error(server::error::LegacyCode::InvalidParameter)
                }
                _ => unreachable!("unmatched response to a block request"),
            }
        } else if let Some(get_block_header_future) = get_block_header_future {
            let get_block_header_result: Result<GetBlockHeader> = get_block_header_future.await;

            let GetBlockHeader::Object(block_header) = get_block_header_result? else {
                panic!("must return Object")
            };

            let GetBlockHeaderObject {
                hash,
                confirmations,
                height,
                version,
                merkle_root,
                final_sapling_root,
                sapling_tree_size,
                time,
                nonce,
                solution,
                bits,
                difficulty,
                previous_block_hash,
                next_block_hash,
            } = *block_header;

            let transactions_request = match verbosity {
                1 => zebra_state::ReadRequest::TransactionIdsForBlock(hash_or_height),
                2 => zebra_state::ReadRequest::Block(hash_or_height),
                _other => panic!("get_block_header_fut should be none"),
            };

            // # Concurrency
            //
            // We look up by block hash so the hash, transaction IDs, and confirmations
            // are consistent.
            let hash_or_height = hash.0.into();
            let requests = vec![
                // Get transaction IDs from the transaction index by block hash
                //
                // # Concurrency
                //
                // A block's transaction IDs are never modified, so all possible responses are
                // valid. Clients that query block heights must be able to handle chain forks,
                // including getting transaction IDs from any chain fork.
                transactions_request,
                // Orchard trees
                zebra_state::ReadRequest::OrchardTree(hash_or_height),
            ];

            let mut futs = FuturesOrdered::new();

            for request in requests {
                futs.push_back(state.clone().oneshot(request));
            }

            let tx_ids_response = futs.next().await.expect("`futs` should not be empty");
            let tx: Vec<_> = match tx_ids_response.map_misc_error()? {
                zebra_state::ReadResponse::TransactionIdsForBlock(tx_ids) => tx_ids
                    .ok_or_misc_error("block not found")?
                    .iter()
                    .map(|tx_id| GetBlockTransaction::Hash(*tx_id))
                    .collect(),
                zebra_state::ReadResponse::Block(block) => block
                    .ok_or_misc_error("Block not found")?
                    .transactions
                    .iter()
                    .map(|tx| {
                        GetBlockTransaction::Object(TransactionObject::from_transaction(
                            tx.clone(),
                            Some(height),
                            Some(
                                confirmations
                                    .try_into()
                                    .expect("should be less than max block height, i32::MAX"),
                            ),
                        ))
                    })
                    .collect(),
                _ => unreachable!("unmatched response to a transaction_ids_for_block request"),
            };

            let orchard_tree_response = futs.next().await.expect("`futs` should not be empty");
            let zebra_state::ReadResponse::OrchardTree(orchard_tree) =
                orchard_tree_response.map_misc_error()?
            else {
                unreachable!("unmatched response to a OrchardTree request");
            };

            let nu5_activation = NetworkUpgrade::Nu5.activation_height(&network);

            // This could be `None` if there's a chain reorg between state queries.
            let orchard_tree = orchard_tree.ok_or_misc_error("missing Orchard tree")?;

            let final_orchard_root = match nu5_activation {
                Some(activation_height) if height >= activation_height => {
                    Some(orchard_tree.root().into())
                }
                _other => None,
            };

            let sapling = SaplingTrees {
                size: sapling_tree_size,
            };

            let orchard_tree_size = orchard_tree.count();
            let orchard = OrchardTrees {
                size: orchard_tree_size,
            };

            let trees = GetBlockTrees { sapling, orchard };

            Ok(GetBlock::Object {
                hash,
                confirmations,
                height: Some(height),
                version: Some(version),
                merkle_root: Some(merkle_root),
                time: Some(time),
                nonce: Some(nonce),
                solution: Some(solution),
                bits: Some(bits),
                difficulty: Some(difficulty),
                tx,
                trees,
                size: None,
                final_sapling_root: Some(final_sapling_root),
                final_orchard_root,
                previous_block_hash: Some(previous_block_hash),
                next_block_hash,
            })
        } else {
            Err("invalid verbosity value").map_error(server::error::LegacyCode::InvalidParameter)
        }
    }

    async fn get_block_header(
        &self,
        hash_or_height: String,
        verbose: Option<bool>,
    ) -> Result<GetBlockHeader> {
        let state = self.state.clone();
        let verbose = verbose.unwrap_or(true);
        let network = self.network.clone();

        let hash_or_height: HashOrHeight = hash_or_height
            .parse()
            .map_error(server::error::LegacyCode::InvalidAddressOrKey)?;
        let zebra_state::ReadResponse::BlockHeader {
            header,
            hash,
            height,
            next_block_hash,
        } = state
            .clone()
            .oneshot(zebra_state::ReadRequest::BlockHeader(hash_or_height))
            .await
            .map_err(|_| "block height not in best chain")
            .map_error(
                // ## Compatibility with `zcashd`.
                //
                // Since this function is reused by getblock(), we return the errors
                // expected by it (they differ whether a hash or a height was passed).
                if hash_or_height.hash().is_some() {
                    server::error::LegacyCode::InvalidAddressOrKey
                } else {
                    server::error::LegacyCode::InvalidParameter
                },
            )?
        else {
            panic!("unexpected response to BlockHeader request")
        };

        let response = if !verbose {
            GetBlockHeader::Raw(HexData(header.zcash_serialize_to_vec().map_misc_error()?))
        } else {
            let zebra_state::ReadResponse::SaplingTree(sapling_tree) = state
                .clone()
                .oneshot(zebra_state::ReadRequest::SaplingTree(hash_or_height))
                .await
                .map_misc_error()?
            else {
                panic!("unexpected response to SaplingTree request")
            };

            // This could be `None` if there's a chain reorg between state queries.
            let sapling_tree = sapling_tree.ok_or_misc_error("missing Sapling tree")?;

            let zebra_state::ReadResponse::Depth(depth) = state
                .clone()
                .oneshot(zebra_state::ReadRequest::Depth(hash))
                .await
                .map_misc_error()?
            else {
                panic!("unexpected response to SaplingTree request")
            };

            // From <https://zcash.github.io/rpc/getblock.html>
            // TODO: Deduplicate const definition, consider refactoring this to avoid duplicate logic
            const NOT_IN_BEST_CHAIN_CONFIRMATIONS: i64 = -1;

            // Confirmations are one more than the depth.
            // Depth is limited by height, so it will never overflow an i64.
            let confirmations = depth
                .map(|depth| i64::from(depth) + 1)
                .unwrap_or(NOT_IN_BEST_CHAIN_CONFIRMATIONS);

            let mut nonce = *header.nonce;
            nonce.reverse();

            let sapling_activation = NetworkUpgrade::Sapling.activation_height(&network);
            let sapling_tree_size = sapling_tree.count();
            let final_sapling_root: [u8; 32] =
                if sapling_activation.is_some() && height >= sapling_activation.unwrap() {
                    let mut root: [u8; 32] = sapling_tree.root().into();
                    root.reverse();
                    root
                } else {
                    [0; 32]
                };

            let difficulty = header.difficulty_threshold.relative_to_network(&network);

            let block_header = GetBlockHeaderObject {
                hash: GetBlockHash(hash),
                confirmations,
                height,
                version: header.version,
                merkle_root: header.merkle_root,
                final_sapling_root,
                sapling_tree_size,
                time: header.time.timestamp(),
                nonce,
                solution: header.solution,
                bits: header.difficulty_threshold,
                difficulty,
                previous_block_hash: GetBlockHash(header.previous_block_hash),
                next_block_hash: next_block_hash.map(GetBlockHash),
            };

            GetBlockHeader::Object(Box::new(block_header))
        };

        Ok(response)
    }

    fn get_best_block_hash(&self) -> Result<GetBlockHash> {
        self.latest_chain_tip
            .best_tip_hash()
            .map(GetBlockHash)
            .ok_or_misc_error("No blocks in state")
    }

    fn get_best_block_height_and_hash(&self) -> Result<GetBlockHeightAndHash> {
        self.latest_chain_tip
            .best_tip_height_and_hash()
            .map(|(height, hash)| GetBlockHeightAndHash { height, hash })
            .ok_or_misc_error("No blocks in state")
    }

    async fn get_raw_mempool(&self) -> Result<Vec<String>> {
        #[cfg(feature = "getblocktemplate-rpcs")]
        use zebra_chain::block::MAX_BLOCK_BYTES;

        #[cfg(feature = "getblocktemplate-rpcs")]
        // Determines whether the output of this RPC is sorted like zcashd
        let should_use_zcashd_order = self.debug_like_zcashd;

        let mut mempool = self.mempool.clone();

        #[cfg(feature = "getblocktemplate-rpcs")]
        let request = if should_use_zcashd_order {
            mempool::Request::FullTransactions
        } else {
            mempool::Request::TransactionIds
        };

        #[cfg(not(feature = "getblocktemplate-rpcs"))]
        let request = mempool::Request::TransactionIds;

        // `zcashd` doesn't check if it is synced to the tip here, so we don't either.
        let response = mempool
            .ready()
            .and_then(|service| service.call(request))
            .await
            .map_misc_error()?;

        match response {
            #[cfg(feature = "getblocktemplate-rpcs")]
            mempool::Response::FullTransactions {
                mut transactions,
                transaction_dependencies: _,
                last_seen_tip_hash: _,
            } => {
                // Sort transactions in descending order by fee/size, using hash in serialized byte order as a tie-breaker
                transactions.sort_by_cached_key(|tx| {
                    // zcashd uses modified fee here but Zebra doesn't currently
                    // support prioritizing transactions
                    std::cmp::Reverse((
                        i64::from(tx.miner_fee) as u128 * MAX_BLOCK_BYTES as u128
                            / tx.transaction.size as u128,
                        // transaction hashes are compared in their serialized byte-order.
                        tx.transaction.id.mined_id(),
                    ))
                });

                let tx_ids: Vec<String> = transactions
                    .iter()
                    .map(|unmined_tx| unmined_tx.transaction.id.mined_id().encode_hex())
                    .collect();

                Ok(tx_ids)
            }

            mempool::Response::TransactionIds(unmined_transaction_ids) => {
                let mut tx_ids: Vec<String> = unmined_transaction_ids
                    .iter()
                    .map(|id| id.mined_id().encode_hex())
                    .collect();

                // Sort returned transaction IDs in numeric/string order.
                tx_ids.sort();

                Ok(tx_ids)
            }

            _ => unreachable!("unmatched response to a transactionids request"),
        }
    }

    async fn get_raw_transaction(
        &self,
        txid: String,
        verbose: Option<u8>,
    ) -> Result<GetRawTransaction> {
        let mut state = self.state.clone();
        let mut mempool = self.mempool.clone();
        let verbose = verbose.unwrap_or(0) != 0;

        // Reference for the legacy error code:
        // <https://github.com/zcash/zcash/blob/99ad6fdc3a549ab510422820eea5e5ce9f60a5fd/src/rpc/rawtransaction.cpp#L544>
        let txid = transaction::Hash::from_hex(txid)
            .map_error(server::error::LegacyCode::InvalidAddressOrKey)?;

        // Check the mempool first.
        match mempool
            .ready()
            .and_then(|service| {
                service.call(mempool::Request::TransactionsByMinedId([txid].into()))
            })
            .await
            .map_misc_error()?
        {
            mempool::Response::Transactions(txns) => {
                if let Some(tx) = txns.first() {
                    return Ok(if verbose {
                        GetRawTransaction::Object(TransactionObject::from_transaction(
                            tx.transaction.clone(),
                            None,
                            None,
                        ))
                    } else {
                        let hex = tx.transaction.clone().into();
                        GetRawTransaction::Raw(hex)
                    });
                }
            }

            _ => unreachable!("unmatched response to a `TransactionsByMinedId` request"),
        };

        // If the tx wasn't in the mempool, check the state.
        match state
            .ready()
            .and_then(|service| service.call(zebra_state::ReadRequest::Transaction(txid)))
            .await
            .map_misc_error()?
        {
            zebra_state::ReadResponse::Transaction(Some(tx)) => Ok(if verbose {
                GetRawTransaction::Object(TransactionObject::from_transaction(
                    tx.tx.clone(),
                    Some(tx.height),
                    Some(tx.confirmations),
                ))
            } else {
                let hex = tx.tx.into();
                GetRawTransaction::Raw(hex)
            }),

            zebra_state::ReadResponse::Transaction(None) => {
                Err("No such mempool or main chain transaction")
                    .map_error(server::error::LegacyCode::InvalidAddressOrKey)
            }

            _ => unreachable!("unmatched response to a `Transaction` read request"),
        }
    }

    // TODO:
    // - use `height_from_signed_int()` to handle negative heights
    //   (this might be better in the state request, because it needs the state height)
    async fn z_get_treestate(&self, hash_or_height: String) -> Result<GetTreestate> {
        let mut state = self.state.clone();
        let network = self.network.clone();

        // Reference for the legacy error code:
        // <https://github.com/zcash/zcash/blob/99ad6fdc3a549ab510422820eea5e5ce9f60a5fd/src/rpc/blockchain.cpp#L629>
        let hash_or_height = hash_or_height
            .parse()
            .map_error(server::error::LegacyCode::InvalidParameter)?;

        // Fetch the block referenced by [`hash_or_height`] from the state.
        //
        // # Concurrency
        //
        // For consistency, this lookup must be performed first, then all the other lookups must
        // be based on the hash.
        //
        // TODO: If this RPC is called a lot, just get the block header, rather than the whole block.
        let block = match state
            .ready()
            .and_then(|service| service.call(zebra_state::ReadRequest::Block(hash_or_height)))
            .await
            .map_misc_error()?
        {
            zebra_state::ReadResponse::Block(Some(block)) => block,
            zebra_state::ReadResponse::Block(None) => {
                // Reference for the legacy error code:
                // <https://github.com/zcash/zcash/blob/99ad6fdc3a549ab510422820eea5e5ce9f60a5fd/src/rpc/blockchain.cpp#L629>
                return Err("the requested block is not in the main chain")
                    .map_error(server::error::LegacyCode::InvalidParameter);
            }
            _ => unreachable!("unmatched response to a block request"),
        };

        let hash = hash_or_height
            .hash_or_else(|_| Some(block.hash()))
            .expect("block hash");

        let height = hash_or_height
            .height_or_else(|_| block.coinbase_height())
            .expect("verified blocks have a coinbase height");

        let time = u32::try_from(block.header.time.timestamp())
            .expect("Timestamps of valid blocks always fit into u32.");

        let sapling_nu = zcash_primitives::consensus::NetworkUpgrade::Sapling;
        let sapling = if network.is_nu_active(sapling_nu, height.into()) {
            match state
                .ready()
                .and_then(|service| {
                    service.call(zebra_state::ReadRequest::SaplingTree(hash.into()))
                })
                .await
                .map_misc_error()?
            {
                zebra_state::ReadResponse::SaplingTree(tree) => tree.map(|t| t.to_rpc_bytes()),
                _ => unreachable!("unmatched response to a Sapling tree request"),
            }
        } else {
            None
        };

        let orchard_nu = zcash_primitives::consensus::NetworkUpgrade::Nu5;
        let orchard = if network.is_nu_active(orchard_nu, height.into()) {
            match state
                .ready()
                .and_then(|service| {
                    service.call(zebra_state::ReadRequest::OrchardTree(hash.into()))
                })
                .await
                .map_misc_error()?
            {
                zebra_state::ReadResponse::OrchardTree(tree) => tree.map(|t| t.to_rpc_bytes()),
                _ => unreachable!("unmatched response to an Orchard tree request"),
            }
        } else {
            None
        };

        Ok(GetTreestate::from_parts(
            hash, height, time, sapling, orchard,
        ))
    }

    async fn z_get_subtrees_by_index(
        &self,
        pool: String,
        start_index: NoteCommitmentSubtreeIndex,
        limit: Option<NoteCommitmentSubtreeIndex>,
    ) -> Result<GetSubtrees> {
        let mut state = self.state.clone();

        const POOL_LIST: &[&str] = &["sapling", "orchard"];

        if pool == "sapling" {
            let request = zebra_state::ReadRequest::SaplingSubtrees { start_index, limit };
            let response = state
                .ready()
                .and_then(|service| service.call(request))
                .await
                .map_misc_error()?;

            let subtrees = match response {
                zebra_state::ReadResponse::SaplingSubtrees(subtrees) => subtrees,
                _ => unreachable!("unmatched response to a subtrees request"),
            };

            let subtrees = subtrees
                .values()
                .map(|subtree| SubtreeRpcData {
                    root: subtree.root.encode_hex(),
                    end_height: subtree.end_height,
                })
                .collect();

            Ok(GetSubtrees {
                pool,
                start_index,
                subtrees,
            })
        } else if pool == "orchard" {
            let request = zebra_state::ReadRequest::OrchardSubtrees { start_index, limit };
            let response = state
                .ready()
                .and_then(|service| service.call(request))
                .await
                .map_misc_error()?;

            let subtrees = match response {
                zebra_state::ReadResponse::OrchardSubtrees(subtrees) => subtrees,
                _ => unreachable!("unmatched response to a subtrees request"),
            };

            let subtrees = subtrees
                .values()
                .map(|subtree| SubtreeRpcData {
                    root: subtree.root.encode_hex(),
                    end_height: subtree.end_height,
                })
                .collect();

            Ok(GetSubtrees {
                pool,
                start_index,
                subtrees,
            })
        } else {
            Err(ErrorObject::owned(
                server::error::LegacyCode::Misc.into(),
                format!("invalid pool name, must be one of: {:?}", POOL_LIST).as_str(),
                None::<()>,
            ))
        }
    }

    async fn get_address_tx_ids(&self, request: GetAddressTxIdsRequest) -> Result<Vec<String>> {
        let mut state = self.state.clone();
        let latest_chain_tip = self.latest_chain_tip.clone();

        let start = Height(request.start);
        let end = Height(request.end);

        let chain_height = best_chain_tip_height(&latest_chain_tip)?;

        // height range checks
        check_height_range(start, end, chain_height)?;

        let valid_addresses = AddressStrings {
            addresses: request.addresses,
        }
        .valid_addresses()?;

        let request = zebra_state::ReadRequest::TransactionIdsByAddresses {
            addresses: valid_addresses,
            height_range: start..=end,
        };
        let response = state
            .ready()
            .and_then(|service| service.call(request))
            .await
            .map_misc_error()?;

        let hashes = match response {
            zebra_state::ReadResponse::AddressesTransactionIds(hashes) => {
                let mut last_tx_location = TransactionLocation::from_usize(Height(0), 0);

                hashes
                    .iter()
                    .map(|(tx_loc, tx_id)| {
                        // Check that the returned transactions are in chain order.
                        assert!(
                            *tx_loc > last_tx_location,
                            "Transactions were not in chain order:\n\
                                 {tx_loc:?} {tx_id:?} was after:\n\
                                 {last_tx_location:?}",
                        );

                        last_tx_location = *tx_loc;

                        tx_id.to_string()
                    })
                    .collect()
            }
            _ => unreachable!("unmatched response to a TransactionsByAddresses request"),
        };

        Ok(hashes)
    }

    async fn get_address_utxos(
        &self,
        address_strings: AddressStrings,
    ) -> Result<Vec<GetAddressUtxos>> {
        let mut state = self.state.clone();
        let mut response_utxos = vec![];

        let valid_addresses = address_strings.valid_addresses()?;

        // get utxos data for addresses
        let request = zebra_state::ReadRequest::UtxosByAddresses(valid_addresses);
        let response = state
            .ready()
            .and_then(|service| service.call(request))
            .await
            .map_misc_error()?;
        let utxos = match response {
            zebra_state::ReadResponse::AddressUtxos(utxos) => utxos,
            _ => unreachable!("unmatched response to a UtxosByAddresses request"),
        };

        let mut last_output_location = OutputLocation::from_usize(Height(0), 0, 0);

        for utxo_data in utxos.utxos() {
            let address = utxo_data.0;
            let txid = *utxo_data.1;
            let height = utxo_data.2.height();
            let output_index = utxo_data.2.output_index();
            let script = utxo_data.3.lock_script.clone();
            let satoshis = u64::from(utxo_data.3.value);

            let output_location = *utxo_data.2;
            // Check that the returned UTXOs are in chain order.
            assert!(
                output_location > last_output_location,
                "UTXOs were not in chain order:\n\
                     {output_location:?} {address:?} {txid:?} was after:\n\
                     {last_output_location:?}",
            );

            let entry = GetAddressUtxos {
                address,
                txid,
                output_index,
                script,
                satoshis,
                height,
            };
            response_utxos.push(entry);

            last_output_location = output_location;
        }

        Ok(response_utxos)
    }

    fn stop(&self) -> Result<String> {
        #[cfg(not(target_os = "windows"))]
        if self.network.is_regtest() {
            match nix::sys::signal::raise(nix::sys::signal::SIGINT) {
                Ok(_) => Ok("Zebra server stopping".to_string()),
                Err(error) => Err(ErrorObject::owned(
                    ErrorCode::InternalError.code(),
                    format!("Failed to shut down: {}", error).as_str(),
                    None::<()>,
                )),
            }
        } else {
            Err(ErrorObject::borrowed(
                ErrorCode::MethodNotFound.code(),
                "stop is only available on regtest networks",
                None,
            ))
        }
        #[cfg(target_os = "windows")]
        Err(ErrorObject::borrowed(
            ErrorCode::MethodNotFound.code(),
            "stop is not available in windows targets",
            None,
        ))
    }
}

/// Returns the best chain tip height of `latest_chain_tip`,
/// or an RPC error if there are no blocks in the state.
pub fn best_chain_tip_height<Tip>(latest_chain_tip: &Tip) -> Result<Height>
where
    Tip: ChainTip + Clone + Send + Sync + 'static,
{
    latest_chain_tip
        .best_tip_height()
        .ok_or_misc_error("No blocks in state")
}

/// Response to a `getinfo` RPC request.
///
/// See the notes for the [`Rpc::get_info` method].
#[derive(Clone, Debug, Eq, PartialEq, serde::Serialize, serde::Deserialize)]
pub struct GetInfo {
    /// The node version build number
    build: String,

    /// The server sub-version identifier, used as the network protocol user-agent
    subversion: String,
}

impl Default for GetInfo {
    fn default() -> Self {
        GetInfo {
            build: "some build version".to_string(),
            subversion: "some subversion".to_string(),
        }
    }
}

/// Response to a `getblockchaininfo` RPC request.
///
/// See the notes for the [`Rpc::get_blockchain_info` method].
#[derive(Clone, Debug, Eq, PartialEq, serde::Serialize, serde::Deserialize)]
pub struct GetBlockChainInfo {
    /// Current network name as defined in BIP70 (main, test, regtest)
    chain: String,

    /// The current number of blocks processed in the server, numeric
    blocks: Height,

    /// The hash of the currently best block, in big-endian order, hex-encoded
    #[serde(rename = "bestblockhash", with = "hex")]
    best_block_hash: block::Hash,

    /// If syncing, the estimated height of the chain, else the current best height, numeric.
    ///
    /// In Zebra, this is always the height estimate, so it might be a little inaccurate.
    #[serde(rename = "estimatedheight")]
    estimated_height: Height,

    /// Value pool balances
    #[serde(rename = "valuePools")]
    value_pools: [types::ValuePoolBalance; 5],

    /// Status of network upgrades
    upgrades: IndexMap<ConsensusBranchIdHex, NetworkUpgradeInfo>,

    /// Branch IDs of the current and upcoming consensus rules
    consensus: TipConsensusBranch,
}

impl Default for GetBlockChainInfo {
    fn default() -> Self {
        GetBlockChainInfo {
            chain: "main".to_string(),
            blocks: Height(1),
            best_block_hash: block::Hash([0; 32]),
            estimated_height: Height(1),
            value_pools: types::ValuePoolBalance::zero_pools(),
            upgrades: IndexMap::new(),
            consensus: TipConsensusBranch {
                chain_tip: ConsensusBranchIdHex(ConsensusBranchId::default()),
                next_block: ConsensusBranchIdHex(ConsensusBranchId::default()),
            },
        }
    }
}

/// A wrapper type with a list of transparent address strings.
///
/// This is used for the input parameter of [`RpcServer::get_address_balance`],
/// [`RpcServer::get_address_tx_ids`] and [`RpcServer::get_address_utxos`].
#[derive(Clone, Debug, Eq, PartialEq, Hash, serde::Deserialize)]
pub struct AddressStrings {
    /// A list of transparent address strings.
    addresses: Vec<String>,
}

impl AddressStrings {
    /// Creates a new `AddressStrings` given a vector.
    #[cfg(test)]
    pub fn new(addresses: Vec<String>) -> AddressStrings {
        AddressStrings { addresses }
    }

    /// Given a list of addresses as strings:
    /// - check if provided list have all valid transparent addresses.
    /// - return valid addresses as a set of `Address`.
    pub fn valid_addresses(self) -> Result<HashSet<Address>> {
        // Reference for the legacy error code:
        // <https://github.com/zcash/zcash/blob/99ad6fdc3a549ab510422820eea5e5ce9f60a5fd/src/rpc/misc.cpp#L783-L784>
        let valid_addresses: HashSet<Address> = self
            .addresses
            .into_iter()
            .map(|address| {
                address
                    .parse()
                    .map_error(server::error::LegacyCode::InvalidAddressOrKey)
            })
            .collect::<Result<_>>()?;

        Ok(valid_addresses)
    }
}

/// The transparent balance of a set of addresses.
#[derive(Clone, Copy, Debug, Default, Eq, PartialEq, Hash, serde::Serialize)]
pub struct AddressBalance {
    /// The total transparent balance.
    balance: u64,
}

/// A hex-encoded [`ConsensusBranchId`] string.
#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, serde::Serialize, serde::Deserialize)]
pub struct ConsensusBranchIdHex(#[serde(with = "hex")] ConsensusBranchId);

impl ConsensusBranchIdHex {
    /// Returns a new instance of ['ConsensusBranchIdHex'].
    pub fn new(consensus_branch_id: u32) -> Self {
        ConsensusBranchIdHex(consensus_branch_id.into())
    }

    /// Returns the value of the ['ConsensusBranchId'].
    pub fn inner(&self) -> u32 {
        self.0.into()
    }
}

/// Information about [`NetworkUpgrade`] activation.
#[derive(Copy, Clone, Debug, Eq, PartialEq, serde::Serialize, serde::Deserialize)]
pub struct NetworkUpgradeInfo {
    /// Name of upgrade, string.
    ///
    /// Ignored by lightwalletd, but useful for debugging.
    name: NetworkUpgrade,

    /// Block height of activation, numeric.
    #[serde(rename = "activationheight")]
    activation_height: Height,

    /// Status of upgrade, string.
    status: NetworkUpgradeStatus,
}

impl NetworkUpgradeInfo {
    /// Constructs [`NetworkUpgradeInfo`] from its constituent parts.
    pub fn from_parts(
        name: NetworkUpgrade,
        activation_height: Height,
        status: NetworkUpgradeStatus,
    ) -> Self {
        Self {
            name,
            activation_height,
            status,
        }
    }

    /// Returns the contents of ['NetworkUpgradeInfo'].
    pub fn into_parts(self) -> (NetworkUpgrade, Height, NetworkUpgradeStatus) {
        (self.name, self.activation_height, self.status)
    }
}

/// The activation status of a [`NetworkUpgrade`].
#[derive(Copy, Clone, Debug, Eq, PartialEq, serde::Serialize, serde::Deserialize)]
pub enum NetworkUpgradeStatus {
    /// The network upgrade is currently active.
    ///
    /// Includes all network upgrades that have previously activated,
    /// even if they are not the most recent network upgrade.
    #[serde(rename = "active")]
    Active,

    /// The network upgrade does not have an activation height.
    #[serde(rename = "disabled")]
    Disabled,

    /// The network upgrade has an activation height, but we haven't reached it yet.
    #[serde(rename = "pending")]
    Pending,
}

/// The [`ConsensusBranchId`]s for the tip and the next block.
///
/// These branch IDs are different when the next block is a network upgrade activation block.
#[derive(Copy, Clone, Debug, Eq, PartialEq, serde::Serialize, serde::Deserialize)]
pub struct TipConsensusBranch {
    /// Branch ID used to validate the current chain tip, big-endian, hex-encoded.
    #[serde(rename = "chaintip")]
    chain_tip: ConsensusBranchIdHex,

    /// Branch ID used to validate the next block, big-endian, hex-encoded.
    #[serde(rename = "nextblock")]
    next_block: ConsensusBranchIdHex,
}

impl TipConsensusBranch {
    /// Constructs [`TipConsensusBranch`] from its constituent parts.
    pub fn from_parts(chain_tip: u32, next_block: u32) -> Self {
        Self {
            chain_tip: ConsensusBranchIdHex::new(chain_tip),
            next_block: ConsensusBranchIdHex::new(next_block),
        }
    }

    /// Returns the contents of ['TipConsensusBranch'].
    pub fn into_parts(self) -> (u32, u32) {
        (self.chain_tip.inner(), self.next_block.inner())
    }
}

/// Response to a `sendrawtransaction` RPC request.
///
/// Contains the hex-encoded hash of the sent transaction.
///
/// See the notes for the [`Rpc::send_raw_transaction` method].
#[derive(Copy, Clone, Debug, Eq, PartialEq, serde::Serialize, serde::Deserialize)]
pub struct SentTransactionHash(#[serde(with = "hex")] transaction::Hash);

impl Default for SentTransactionHash {
    fn default() -> Self {
        Self(transaction::Hash::from([0; 32]))
    }
}

/// Response to a `getblock` RPC request.
///
/// See the notes for the [`RpcServer::get_block`] method.
#[derive(Clone, Debug, PartialEq, serde::Serialize)]
#[serde(untagged)]
#[allow(clippy::large_enum_variant)] //TODO: create a struct for the Object and Box it
pub enum GetBlock {
    /// The request block, hex-encoded.
    Raw(#[serde(with = "hex")] SerializedBlock),
    /// The block object.
    Object {
        /// The hash of the requested block.
        hash: GetBlockHash,

        /// The number of confirmations of this block in the best chain,
        /// or -1 if it is not in the best chain.
        confirmations: i64,

        /// The block size. TODO: fill it
        #[serde(skip_serializing_if = "Option::is_none")]
        size: Option<i64>,

        /// The height of the requested block.
        #[serde(skip_serializing_if = "Option::is_none")]
        height: Option<Height>,

        /// The version field of the requested block.
        #[serde(skip_serializing_if = "Option::is_none")]
        version: Option<u32>,

        /// The merkle root of the requested block.
        #[serde(with = "opthex", rename = "merkleroot")]
        #[serde(skip_serializing_if = "Option::is_none")]
        merkle_root: Option<block::merkle::Root>,

        // `blockcommitments` would be here. Undocumented. TODO: decide if we want to support it
        // `authdataroot` would be here. Undocumented. TODO: decide if we want to support it
        //
        /// The root of the Sapling commitment tree after applying this block.
        #[serde(with = "opthex", rename = "finalsaplingroot")]
        #[serde(skip_serializing_if = "Option::is_none")]
        final_sapling_root: Option<[u8; 32]>,

        /// The root of the Orchard commitment tree after applying this block.
        #[serde(with = "opthex", rename = "finalorchardroot")]
        #[serde(skip_serializing_if = "Option::is_none")]
        final_orchard_root: Option<[u8; 32]>,

        // `chainhistoryroot` would be here. Undocumented. TODO: decide if we want to support it
        //
        /// List of transactions in block order, hex-encoded if verbosity=1 or
        /// as objects if verbosity=2.
        tx: Vec<GetBlockTransaction>,

        /// The height of the requested block.
        #[serde(skip_serializing_if = "Option::is_none")]
        time: Option<i64>,

        /// The nonce of the requested block header.
        #[serde(with = "opthex")]
        #[serde(skip_serializing_if = "Option::is_none")]
        nonce: Option<[u8; 32]>,

        /// The Equihash solution in the requested block header.
        /// Note: presence of this field in getblock is not documented in zcashd.
        #[serde(with = "opthex")]
        #[serde(skip_serializing_if = "Option::is_none")]
        solution: Option<Solution>,

        /// The difficulty threshold of the requested block header displayed in compact form.
        #[serde(with = "opthex")]
        #[serde(skip_serializing_if = "Option::is_none")]
        bits: Option<CompactDifficulty>,

        /// Floating point number that represents the difficulty limit for this block as a multiple
        /// of the minimum difficulty for the network.
        #[serde(skip_serializing_if = "Option::is_none")]
        difficulty: Option<f64>,

        // `chainwork` would be here, but we don't plan on supporting it
        // `anchor` would be here. Not planned to be supported.
        // `chainSupply` would be here, TODO: implement
        // `valuePools` would be here, TODO: implement
        //
        /// Information about the note commitment trees.
        trees: GetBlockTrees,

        /// The previous block hash of the requested block header.
        #[serde(rename = "previousblockhash", skip_serializing_if = "Option::is_none")]
        previous_block_hash: Option<GetBlockHash>,

        /// The next block hash after the requested block header.
        #[serde(rename = "nextblockhash", skip_serializing_if = "Option::is_none")]
        next_block_hash: Option<GetBlockHash>,
    },
}

impl Default for GetBlock {
    fn default() -> Self {
        GetBlock::Object {
            hash: GetBlockHash::default(),
            confirmations: 0,
            height: None,
            time: None,
            tx: Vec::new(),
            trees: GetBlockTrees::default(),
            size: None,
            version: None,
            merkle_root: None,
            final_sapling_root: None,
            final_orchard_root: None,
            nonce: None,
            bits: None,
            difficulty: None,
            previous_block_hash: None,
            next_block_hash: None,
            solution: None,
        }
    }
}

#[derive(Clone, Debug, PartialEq, serde::Serialize)]
#[serde(untagged)]
/// The transaction list in a `getblock` call. Can be a list of transaction
/// IDs or the full transaction details depending on verbosity.
pub enum GetBlockTransaction {
    /// The transaction hash, hex-encoded.
    Hash(#[serde(with = "hex")] transaction::Hash),
    /// The block object.
    Object(TransactionObject),
}

/// Response to a `getblockheader` RPC request.
///
/// See the notes for the [`RpcServer::get_block_header`] method.
#[derive(Clone, Debug, PartialEq, serde::Serialize)]
#[serde(untagged)]
pub enum GetBlockHeader {
    /// The request block header, hex-encoded.
    Raw(hex_data::HexData),

    /// The block header object.
    Object(Box<GetBlockHeaderObject>),
}

#[derive(Clone, Debug, PartialEq, serde::Serialize)]
/// Verbose response to a `getblockheader` RPC request.
///
/// See the notes for the [`RpcServer::get_block_header`] method.
pub struct GetBlockHeaderObject {
    /// The hash of the requested block.
    pub hash: GetBlockHash,

    /// The number of confirmations of this block in the best chain,
    /// or -1 if it is not in the best chain.
    pub confirmations: i64,

    /// The height of the requested block.
    pub height: Height,

    /// The version field of the requested block.
    pub version: u32,

    /// The merkle root of the requesteed block.
    #[serde(with = "hex", rename = "merkleroot")]
    pub merkle_root: block::merkle::Root,

    /// The root of the Sapling commitment tree after applying this block.
    #[serde(with = "hex", rename = "finalsaplingroot")]
    pub final_sapling_root: [u8; 32],

    /// The number of Sapling notes in the Sapling note commitment tree
    /// after applying this block. Used by the `getblock` RPC method.
    #[serde(skip)]
    pub sapling_tree_size: u64,

    /// The block time of the requested block header in non-leap seconds since Jan 1 1970 GMT.
    pub time: i64,

    /// The nonce of the requested block header.
    #[serde(with = "hex")]
    pub nonce: [u8; 32],

    /// The Equihash solution in the requested block header.
    #[serde(with = "hex")]
    solution: Solution,

    /// The difficulty threshold of the requested block header displayed in compact form.
    #[serde(with = "hex")]
    pub bits: CompactDifficulty,

    /// Floating point number that represents the difficulty limit for this block as a multiple
    /// of the minimum difficulty for the network.
    pub difficulty: f64,

    /// The previous block hash of the requested block header.
    #[serde(rename = "previousblockhash")]
    pub previous_block_hash: GetBlockHash,

    /// The next block hash after the requested block header.
    #[serde(rename = "nextblockhash", skip_serializing_if = "Option::is_none")]
    pub next_block_hash: Option<GetBlockHash>,
}

impl Default for GetBlockHeader {
    fn default() -> Self {
        GetBlockHeader::Object(Box::default())
    }
}

impl Default for GetBlockHeaderObject {
    fn default() -> Self {
        let difficulty: ExpandedDifficulty = zebra_chain::work::difficulty::U256::one().into();

        GetBlockHeaderObject {
            hash: GetBlockHash::default(),
            confirmations: 0,
            height: Height::MIN,
            version: 4,
            merkle_root: block::merkle::Root([0; 32]),
            final_sapling_root: Default::default(),
            sapling_tree_size: Default::default(),
            time: 0,
            nonce: [0; 32],
            solution: Solution::for_proposal(),
            bits: difficulty.to_compact(),
            difficulty: 1.0,
            previous_block_hash: Default::default(),
            next_block_hash: Default::default(),
        }
    }
}

/// Response to a `getbestblockhash` and `getblockhash` RPC request.
///
/// Contains the hex-encoded hash of the requested block.
///
/// Also see the notes for the [`RpcServer::get_best_block_hash`] and `get_block_hash` methods.
#[derive(Copy, Clone, Debug, Eq, PartialEq, serde::Deserialize, serde::Serialize)]
#[serde(transparent)]
pub struct GetBlockHash(#[serde(with = "hex")] pub block::Hash);

/// Response to a `getbestblockheightandhash` RPC request.
#[derive(Copy, Clone, Debug, Eq, PartialEq, serde::Deserialize, serde::Serialize)]
pub struct GetBlockHeightAndHash {
    /// The best chain tip block height
    pub height: block::Height,
    /// The best chain tip block hash
    pub hash: block::Hash,
}

impl Default for GetBlockHeightAndHash {
    fn default() -> Self {
        Self {
            height: block::Height::MIN,
            hash: block::Hash([0; 32]),
        }
    }
}

impl Default for GetBlockHash {
    fn default() -> Self {
        GetBlockHash(block::Hash([0; 32]))
    }
}

/// Response to a `getrawtransaction` RPC request.
///
/// See the notes for the [`Rpc::get_raw_transaction` method].
#[derive(Clone, Debug, Eq, PartialEq, serde::Serialize)]
#[serde(untagged)]
pub enum GetRawTransaction {
    /// The raw transaction, encoded as hex bytes.
    Raw(#[serde(with = "hex")] SerializedTransaction),
    /// The transaction object.
    Object(TransactionObject),
}

impl Default for GetRawTransaction {
    fn default() -> Self {
        Self::Object(TransactionObject::default())
    }
}

/// A Transaction object as returned by `getrawtransaction` and `getblock` RPC
/// requests.
#[derive(Clone, Debug, Eq, PartialEq, serde::Serialize)]
pub struct TransactionObject {
    /// The raw transaction, encoded as hex bytes.
    #[serde(with = "hex")]
    pub hex: SerializedTransaction,
    /// The height of the block in the best chain that contains the tx or `None` if the tx is in
    /// the mempool.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub height: Option<u32>,
    /// The height diff between the block containing the tx and the best chain tip + 1 or `None`
    /// if the tx is in the mempool.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub confirmations: Option<u32>,
    // TODO: many fields not yet supported
}

impl Default for TransactionObject {
    fn default() -> Self {
        Self {
            hex: SerializedTransaction::from(
                [0u8; zebra_chain::transaction::MIN_TRANSPARENT_TX_SIZE as usize].to_vec(),
            ),
            height: Option::default(),
            confirmations: Option::default(),
        }
    }
}

impl TransactionObject {
    /// Converts `tx` and `height` into a new `GetRawTransaction` in the `verbose` format.
    #[allow(clippy::unwrap_in_result)]
    fn from_transaction(
        tx: Arc<Transaction>,
        height: Option<block::Height>,
        confirmations: Option<u32>,
    ) -> Self {
        Self {
            hex: tx.into(),
            height: height.map(|height| height.0),
            confirmations,
        }
    }
}

/// Response to a `getaddressutxos` RPC request.
///
/// See the notes for the [`Rpc::get_address_utxos` method].
#[derive(Clone, Debug, Eq, PartialEq, serde::Serialize)]
pub struct GetAddressUtxos {
    /// The transparent address, base58check encoded
    address: transparent::Address,

    /// The output txid, in big-endian order, hex-encoded
    #[serde(with = "hex")]
    txid: transaction::Hash,

    /// The transparent output index, numeric
    #[serde(rename = "outputIndex")]
    output_index: OutputIndex,

    /// The transparent output script, hex encoded
    #[serde(with = "hex")]
    script: transparent::Script,

    /// The amount of zatoshis in the transparent output
    satoshis: u64,

    /// The block height, numeric.
    ///
    /// We put this field last, to match the zcashd order.
    height: Height,
}

impl Default for GetAddressUtxos {
    fn default() -> Self {
        Self {
            address: transparent::Address::from_pub_key_hash(
                zebra_chain::parameters::NetworkKind::default(),
                [0u8; 20],
            ),
            txid: transaction::Hash::from([0; 32]),
            output_index: OutputIndex::from_u64(0),
            script: transparent::Script::new(&[0u8; 10]),
            satoshis: u64::default(),
            height: Height(0),
        }
    }
}

/// A struct to use as parameter of the `getaddresstxids`.
///
/// See the notes for the [`Rpc::get_address_tx_ids` method].
#[derive(Clone, Debug, Eq, PartialEq, serde::Deserialize)]
pub struct GetAddressTxIdsRequest {
    // A list of addresses to get transactions from.
    addresses: Vec<String>,
    // The height to start looking for transactions.
    start: u32,
    // The height to end looking for transactions.
    end: u32,
}

/// Information about the sapling and orchard note commitment trees if any.
#[derive(Copy, Clone, Debug, Eq, PartialEq, serde::Deserialize, serde::Serialize)]
pub struct GetBlockTrees {
    #[serde(skip_serializing_if = "SaplingTrees::is_empty")]
    sapling: SaplingTrees,
    #[serde(skip_serializing_if = "OrchardTrees::is_empty")]
    orchard: OrchardTrees,
}

impl Default for GetBlockTrees {
    fn default() -> Self {
        GetBlockTrees {
            sapling: SaplingTrees { size: 0 },
            orchard: OrchardTrees { size: 0 },
        }
    }
}

impl GetBlockTrees {
    /// Constructs a new instance of ['GetBlockTrees'].
    pub fn new(sapling: u64, orchard: u64) -> Self {
        GetBlockTrees {
            sapling: SaplingTrees { size: sapling },
            orchard: OrchardTrees { size: orchard },
        }
    }

    /// Returns sapling data held by ['GetBlockTrees'].
    pub fn sapling(self) -> u64 {
        self.sapling.size
    }

    /// Returns orchard data held by ['GetBlockTrees'].
    pub fn orchard(self) -> u64 {
        self.orchard.size
    }
}

/// Sapling note commitment tree information.
#[derive(Copy, Clone, Debug, Eq, PartialEq, serde::Deserialize, serde::Serialize)]
pub struct SaplingTrees {
    size: u64,
}

impl SaplingTrees {
    fn is_empty(&self) -> bool {
        self.size == 0
    }
}

/// Orchard note commitment tree information.
#[derive(Copy, Clone, Debug, Eq, PartialEq, serde::Deserialize, serde::Serialize)]
pub struct OrchardTrees {
    size: u64,
}

impl OrchardTrees {
    fn is_empty(&self) -> bool {
        self.size == 0
    }
}

/// Check if provided height range is valid for address indexes.
fn check_height_range(start: Height, end: Height, chain_height: Height) -> Result<()> {
    if start == Height(0) || end == Height(0) {
        return Err(ErrorObject::owned(
            ErrorCode::InvalidParams.code(),
            format!("start {start:?} and end {end:?} must both be greater than zero"),
            None::<()>,
        ));
    }
    if start > end {
        return Err(ErrorObject::owned(
            ErrorCode::InvalidParams.code(),
            format!("start {start:?} must be less than or equal to end {end:?}"),
            None::<()>,
        ));
    }
    if start > chain_height || end > chain_height {
        return Err(ErrorObject::owned(
            ErrorCode::InvalidParams.code(),
            format!("start {start:?} and end {end:?} must both be less than or equal to the chain tip {chain_height:?}"),
            None::<()>,
        ));
    }

    Ok(())
}

/// Given a potentially negative index, find the corresponding `Height`.
///
/// This function is used to parse the integer index argument of `get_block_hash`.
/// This is based on zcashd's implementation:
/// <https://github.com/zcash/zcash/blob/c267c3ee26510a974554f227d40a89e3ceb5bb4d/src/rpc/blockchain.cpp#L589-L618>
//
// TODO: also use this function in `get_block` and `z_get_treestate`
#[allow(dead_code)]
pub fn height_from_signed_int(index: i32, tip_height: Height) -> Result<Height> {
    if index >= 0 {
        let height = index.try_into().expect("Positive i32 always fits in u32");
        if height > tip_height.0 {
            return Err(ErrorObject::borrowed(
                ErrorCode::InvalidParams.code(),
                "Provided index is greater than the current tip",
                None,
            ));
        }
        Ok(Height(height))
    } else {
        // `index + 1` can't overflow, because `index` is always negative here.
        let height = i32::try_from(tip_height.0)
            .expect("tip height fits in i32, because Height::MAX fits in i32")
            .checked_add(index + 1);

        let sanitized_height = match height {
            None => {
                return Err(ErrorObject::borrowed(
                    ErrorCode::InvalidParams.code(),
                    "Provided index is not valid",
                    None,
                ))
            }
            Some(h) => {
                if h < 0 {
                    return Err(ErrorObject::borrowed(
                        ErrorCode::InvalidParams.code(),
                        "Provided negative index ends up with a negative height",
                        None,
                    ));
                }
                let h: u32 = h.try_into().expect("Positive i32 always fits in u32");
                if h > tip_height.0 {
                    return Err(ErrorObject::borrowed(
                        ErrorCode::InvalidParams.code(),
                        "Provided index is greater than the current tip",
                        None,
                    ));
                }

                h
            }
        };

        Ok(Height(sanitized_height))
    }
}

/// A helper module to serialize `Option<T: ToHex>` as a hex string.
mod opthex {
    use hex::ToHex;
    use serde::Serializer;

    pub fn serialize<S, T>(data: &Option<T>, serializer: S) -> Result<S::Ok, S::Error>
    where
        S: Serializer,
        T: ToHex,
    {
        match data {
            Some(data) => {
                let s = data.encode_hex::<String>();
                serializer.serialize_str(&s)
            }
            None => serializer.serialize_none(),
        }
    }
}