use std::{net::SocketAddr, sync::Arc, time::Duration};

use anyhow::{Context as _, Result, anyhow};
#[cfg(not(feature = "standalone"))]
use borsh::BorshDeserialize;
use bytesize::ByteSize;
use common::transaction::NSSATransaction;
#[cfg(not(feature = "standalone"))]
use futures::StreamExt as _;
use futures::never::Never;
use jsonrpsee::server::ServerHandle;
#[cfg(not(feature = "standalone"))]
use log::warn;
use log::{error, info};
#[cfg(not(feature = "standalone"))]
use logos_blockchain_core::mantle::ops::channel::MsgId;
#[cfg(not(feature = "standalone"))]
use logos_blockchain_zone_sdk::{
    CommonHttpClient, Slot, ZoneMessage, adapter::NodeHttpClient, indexer::ZoneIndexer,
};
use mempool::MemPoolHandle;
#[cfg(not(feature = "standalone"))]
use sequencer_core::SequencerCore;
#[cfg(feature = "standalone")]
use sequencer_core::SequencerCoreWithMockClients as SequencerCore;
pub use sequencer_core::config::*;
use sequencer_service_rpc::RpcServer as _;
use tokio::{sync::Mutex, task::JoinHandle};

pub mod service;

const REQUEST_BODY_MAX_SIZE: ByteSize = ByteSize::mib(10);

#[cfg(not(feature = "standalone"))]
#[derive(Clone, Debug, BorshDeserialize)]
struct DepositMetadata {
    recipient_id: nssa::AccountId,
}

#[cfg(not(feature = "standalone"))]
impl DepositMetadata {
    fn decode(bytes: &[u8]) -> Result<Self, std::io::Error> {
        Self::try_from_slice(bytes)
    }
}

/// Handle to manage the sequencer and its tasks.
///
/// Implements `Drop` to ensure all tasks are aborted and the RPC server is stopped when dropped.
pub struct SequencerHandle {
    addr: SocketAddr,
    /// Option because of `Drop` which forbids to simply move out of `self` in `stopped()`.
    server_handle: Option<ServerHandle>,
    main_loop_handle: JoinHandle<Result<Never>>,
    bedrock_deposit_loop_handle: Option<JoinHandle<Result<Never>>>,
}

impl SequencerHandle {
    const fn new(
        addr: SocketAddr,
        server_handle: ServerHandle,
        main_loop_handle: JoinHandle<Result<Never>>,
        bedrock_deposit_loop_handle: Option<JoinHandle<Result<Never>>>,
    ) -> Self {
        Self {
            addr,
            server_handle: Some(server_handle),
            main_loop_handle,
            bedrock_deposit_loop_handle,
        }
    }

    /// Wait for any of the sequencer tasks to fail and return the error.
    #[expect(
        clippy::integer_division_remainder_used,
        reason = "Generated by select! macro, can't be easily rewritten to avoid this lint"
    )]
    pub async fn failed(mut self) -> Result<Never> {
        let Self {
            addr: _,
            server_handle,
            main_loop_handle,
            bedrock_deposit_loop_handle,
        } = &mut self;

        let server_handle = server_handle.take().expect("Server handle is set");
        let deposit_opt_fut =
            futures::future::OptionFuture::from(bedrock_deposit_loop_handle.take());
        tokio::select! {
            () = server_handle.stopped() => {
                Err(anyhow!("RPC Server stopped"))
            }
            res = main_loop_handle => {
                res
                    .context("Main loop task panicked")?
                    .context("Main loop exited unexpectedly")
            }
            Some(res) = deposit_opt_fut => {
                res
                    .context("Bedrock deposit loop task panicked")?
                    .context("Bedrock deposit loop exited unexpectedly")
            }
        }
    }

    /// Check if all Sequencer tasks are still running.
    ///
    /// Return `false` if any of the tasks has failed and `true` otherwise.
    /// Error of the failed task can be retrieved by awaiting on [`Self::failed()`].
    #[must_use]
    pub fn is_healthy(&self) -> bool {
        let Self {
            addr: _,
            server_handle,
            main_loop_handle,
            bedrock_deposit_loop_handle,
        } = self;

        let stopped = server_handle.as_ref().is_none_or(ServerHandle::is_stopped)
            || main_loop_handle.is_finished()
            || bedrock_deposit_loop_handle
                .as_ref()
                .is_some_and(JoinHandle::is_finished);
        !stopped
    }

    #[must_use]
    pub const fn addr(&self) -> SocketAddr {
        self.addr
    }
}

impl Drop for SequencerHandle {
    fn drop(&mut self) {
        let Self {
            addr: _,
            server_handle,
            main_loop_handle,
            bedrock_deposit_loop_handle,
        } = self;

        main_loop_handle.abort();
        if let Some(handle) = bedrock_deposit_loop_handle {
            handle.abort();
        }

        let Some(handle) = server_handle else {
            return;
        };

        if let Err(err) = handle.stop() {
            error!("An error occurred while stopping Sequencer RPC server: {err}");
        }
    }
}

pub async fn run(config: SequencerConfig, port: u16) -> Result<SequencerHandle> {
    let block_timeout = config.block_create_timeout;
    let max_block_size = config.max_block_size;
    #[cfg(not(feature = "standalone"))]
    let bedrock_config = config.bedrock_config.clone();

    let (sequencer_core, mempool_handle) = SequencerCore::start_from_config(config).await;

    info!("Sequencer core set up");

    let seq_core_wrapped = Arc::new(Mutex::new(sequencer_core));
    let mempool_handle_for_server = mempool_handle.clone();

    let (server_handle, addr) = run_server(
        Arc::clone(&seq_core_wrapped),
        mempool_handle_for_server,
        port,
        max_block_size.as_u64(),
    )
    .await?;
    info!("RPC server started");

    info!("Starting main sequencer loop");
    let main_loop_handle = tokio::spawn(main_loop(seq_core_wrapped, block_timeout));

    #[cfg(not(feature = "standalone"))]
    let bedrock_deposit_loop_handle = {
        info!("Starting Bedrock deposit listener loop");
        Some(tokio::spawn(bedrock_deposit_loop(
            bedrock_config,
            mempool_handle,
        )))
    };
    #[cfg(feature = "standalone")]
    let bedrock_deposit_loop_handle = {
        let _ = mempool_handle;
        None
    };

    Ok(SequencerHandle::new(
        addr,
        server_handle,
        main_loop_handle,
        bedrock_deposit_loop_handle,
    ))
}

async fn run_server(
    sequencer: Arc<Mutex<SequencerCore>>,
    mempool_handle: MemPoolHandle<NSSATransaction>,
    port: u16,
    max_block_size: u64,
) -> Result<(ServerHandle, SocketAddr)> {
    let server = jsonrpsee::server::ServerBuilder::with_config(
        jsonrpsee::server::ServerConfigBuilder::new()
            .max_request_body_size(
                u32::try_from(REQUEST_BODY_MAX_SIZE.as_u64())
                    .expect("REQUEST_BODY_MAX_SIZE should be less than u32::MAX"),
            )
            .build(),
    )
    .build(SocketAddr::from(([0, 0, 0, 0], port)))
    .await
    .context("Failed to build RPC server")?;

    let addr = server
        .local_addr()
        .context("Failed to get local address of RPC server")?;

    info!("Starting Sequencer Service RPC server on {addr}");

    let service = service::SequencerService::new(sequencer, mempool_handle, max_block_size);
    let handle = server.start(service.into_rpc());
    Ok((handle, addr))
}

async fn main_loop(seq_core: Arc<Mutex<SequencerCore>>, block_timeout: Duration) -> Result<Never> {
    loop {
        tokio::time::sleep(block_timeout).await;

        info!("Collecting transactions from mempool, block creation");

        let id = {
            let mut state = seq_core.lock().await;

            state.produce_new_block().await?
        };

        info!("Block with id {id} created");

        info!("Waiting for new transactions");
    }
}

#[cfg(not(feature = "standalone"))]
async fn bedrock_deposit_loop(
    bedrock_config: BedrockConfig,
    mempool_handle: MemPoolHandle<NSSATransaction>,
) -> Result<Never> {
    let basic_auth = bedrock_config.auth.map(Into::into);
    let node = NodeHttpClient::new(CommonHttpClient::new(basic_auth), bedrock_config.node_url);
    let zone_indexer = ZoneIndexer::new(bedrock_config.channel_id, node);

    let mut cursor: Option<(MsgId, Slot)> = None;
    let poll_interval = Duration::from_secs(1);

    loop {
        let stream = match zone_indexer.next_messages(cursor).await {
            Ok(stream) => stream,
            Err(err) => {
                error!("Failed to start Bedrock deposit stream: {err}");
                tokio::time::sleep(poll_interval).await;
                continue;
            }
        };

        let mut stream = std::pin::pin!(stream);
        while let Some((msg, slot)) = stream.next().await {
            match msg {
                ZoneMessage::Block(block) => {
                    cursor = Some((block.id, slot));
                    info!("Observed Bedrock channel block id {:?}", block.id);
                }
                ZoneMessage::Deposit(deposit) => {
                    let metadata = match DepositMetadata::decode(&deposit.metadata) {
                        Ok(metadata) => metadata,
                        Err(err) => {
                            warn!("Skipping Bedrock Deposit with invalid metadata: {err}");
                            continue;
                        }
                    };

                    let tx = match build_bridge_deposit_tx(&metadata) {
                        Ok(tx) => tx,
                        Err(err) => {
                            warn!("Skipping Bedrock Deposit due to tx build failure: {err:#}");
                            continue;
                        }
                    };

                    info!(
                        "Observed Bedrock Deposit for recipient {recipient_id}, pushing to mempool",
                        recipient_id = metadata.recipient_id
                    );
                    mempool_handle
                        .push(tx)
                        .await
                        .context("Mempool is closed while pushing Bedrock Deposit transaction")?;
                }
                ZoneMessage::Withdraw(_) => {}
            }
        }

        tokio::time::sleep(poll_interval).await;
    }
}

#[cfg(not(feature = "standalone"))]
fn build_bridge_deposit_tx(metadata: &DepositMetadata) -> Result<NSSATransaction> {
    // TODO: Remove this constant once we have a way to get the deposit amount from Bedrock deposit
    // inputs.
    const TEMPORARY_BRIDGE_DEPOSIT_AMOUNT: u128 = 1;

    let bridge_program_id = nssa::program::Program::bridge().id();
    let vault_program_id = nssa::program::Program::vault().id();
    let recipient_vault_id =
        vault_core::compute_vault_account_id(vault_program_id, metadata.recipient_id);

    let message = nssa::public_transaction::Message::try_new(
        bridge_program_id,
        vec![nssa::system_bridge_account_id(), recipient_vault_id],
        vec![],
        bridge_core::Instruction::Deposit {
            vault_program_id,
            recipient_id: metadata.recipient_id,
            amount: TEMPORARY_BRIDGE_DEPOSIT_AMOUNT,
        },
    )
    .context("Failed to build bridge deposit message")?;

    let witness_set = nssa::public_transaction::WitnessSet::from_raw_parts(vec![]);
    Ok(NSSATransaction::Public(nssa::PublicTransaction::new(
        message,
        witness_set,
    )))
}