// Copyright 2015-2020 Parity Technologies (UK) Ltd.
// This file is part of OpenEthereum.

// OpenEthereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// OpenEthereum is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with OpenEthereum.  If not, see <http://www.gnu.org/licenses/>.

//! Eth PUB-SUB rpc implementation.

use std::{
    collections::BTreeMap,
    sync::{Arc, Weak},
};

use jsonrpc_core::{
    futures::{self, Future, IntoFuture},
    Error, Result,
};
use jsonrpc_pubsub::{
    typed::{Sink, Subscriber},
    SubscriptionId,
};

use v1::{
    helpers::{errors, limit_logs, Subscribers},
    metadata::Metadata,
    traits::EthPubSub,
    types::{pubsub, Header, Log, RichHeader},
};

use ethcore::client::{
    BlockChainClient, BlockId, ChainNotify, ChainRouteType, EngineInfo, NewBlocks,
};
use ethereum_types::H256;
use parity_runtime::Executor;
use parking_lot::RwLock;

use types::{encoded, filter::Filter as EthFilter};

type Client = Sink<pubsub::Result>;

/// Eth PubSub implementation.
pub struct EthPubSubClient<C> {
    handler: Arc<ChainNotificationHandler<C>>,
    heads_subscribers: Arc<RwLock<Subscribers<Client>>>,
    logs_subscribers: Arc<RwLock<Subscribers<(Client, EthFilter)>>>,
    transactions_subscribers: Arc<RwLock<Subscribers<Client>>>,
}

impl<C> EthPubSubClient<C> {
    /// Creates new `EthPubSubClient`.
    pub fn new(client: Arc<C>, executor: Executor) -> Self {
        let heads_subscribers = Arc::new(RwLock::new(Subscribers::default()));
        let logs_subscribers = Arc::new(RwLock::new(Subscribers::default()));
        let transactions_subscribers = Arc::new(RwLock::new(Subscribers::default()));

        EthPubSubClient {
            handler: Arc::new(ChainNotificationHandler {
                client,
                executor,
                heads_subscribers: heads_subscribers.clone(),
                logs_subscribers: logs_subscribers.clone(),
                transactions_subscribers: transactions_subscribers.clone(),
            }),
            heads_subscribers,
            logs_subscribers,
            transactions_subscribers,
        }
    }

    /// Creates new `EthPubSubCient` with deterministic subscription ids.
    #[cfg(test)]
    pub fn new_test(client: Arc<C>, executor: Executor) -> Self {
        let client = Self::new(client, executor);
        *client.heads_subscribers.write() = Subscribers::default();
        *client.logs_subscribers.write() = Subscribers::default();
        *client.transactions_subscribers.write() = Subscribers::default();
        client
    }

    /// Returns a chain notification handler.
    pub fn handler(&self) -> Weak<ChainNotificationHandler<C>> {
        Arc::downgrade(&self.handler)
    }
}

/// PubSub Notification handler.
pub struct ChainNotificationHandler<C> {
    client: Arc<C>,
    executor: Executor,
    heads_subscribers: Arc<RwLock<Subscribers<Client>>>,
    logs_subscribers: Arc<RwLock<Subscribers<(Client, EthFilter)>>>,
    transactions_subscribers: Arc<RwLock<Subscribers<Client>>>,
}

impl<C> ChainNotificationHandler<C>
where
    C: EngineInfo,
{
    fn notify(executor: &Executor, subscriber: &Client, result: pubsub::Result) {
        executor.spawn(
            subscriber
                .notify(Ok(result))
                .map(|_| ())
                .map_err(|e| warn!(target: "rpc", "Unable to send notification: {}", e)),
        );
    }

    fn notify_heads(&self, headers: &[(encoded::Header, BTreeMap<String, String>)]) {
        for subscriber in self.heads_subscribers.read().values() {
            for &(ref header, ref extra_info) in headers {
                Self::notify(
                    &self.executor,
                    subscriber,
                    pubsub::Result::Header(Box::new(RichHeader {
                        inner: Header::new(
                            header,
                            self.client.engine().params().eip1559_transition,
                        ),
                        extra_info: extra_info.clone(),
                    })),
                );
            }
        }
    }

    fn notify_logs<F, T, Ex>(&self, enacted: &[(H256, Ex)], logs: F)
    where
        F: Fn(EthFilter, &Ex) -> T,
        Ex: Send,
        T: IntoFuture<Item = Vec<Log>, Error = Error>,
        T::Future: Send + 'static,
    {
        for &(ref subscriber, ref filter) in self.logs_subscribers.read().values() {
            let logs = futures::future::join_all(
                enacted
                    .iter()
                    .map(|&(hash, ref ex)| {
                        let mut filter = filter.clone();
                        filter.from_block = BlockId::Hash(hash);
                        filter.to_block = filter.from_block;
                        logs(filter, ex).into_future()
                    })
                    .collect::<Vec<_>>(),
            );
            let limit = filter.limit;
            let executor = self.executor.clone();
            let subscriber = subscriber.clone();
            self.executor.spawn(
                logs.map(move |logs| {
                    let logs = logs.into_iter().flat_map(|log| log).collect();

                    for log in limit_logs(logs, limit) {
                        Self::notify(&executor, &subscriber, pubsub::Result::Log(Box::new(log)))
                    }
                })
                .map_err(|e| warn!("Unable to fetch latest logs: {:?}", e)),
            );
        }
    }

    /// Notify all subscribers about new transaction hashes.
    pub fn notify_new_transactions(&self, hashes: &[H256]) {
        for subscriber in self.transactions_subscribers.read().values() {
            for hash in hashes {
                Self::notify(
                    &self.executor,
                    subscriber,
                    pubsub::Result::TransactionHash(*hash),
                );
            }
        }
    }
}

impl<C: BlockChainClient + EngineInfo> ChainNotify for ChainNotificationHandler<C> {
    // t_nb 11.3 RPC. Notify subscriber header/logs about new block
    fn new_blocks(&self, new_blocks: NewBlocks) {
        if self.heads_subscribers.read().is_empty() && self.logs_subscribers.read().is_empty() {
            return;
        }
        const EXTRA_INFO_PROOF: &str = "Object exists in in blockchain (fetched earlier), extra_info is always available if object exists; qed";
        let headers = new_blocks
            .route
            .route()
            .iter()
            .filter_map(|&(hash, ref typ)| match typ {
                ChainRouteType::Retracted => None,
                ChainRouteType::Enacted => self.client.block_header(BlockId::Hash(hash)),
            })
            .map(|header| {
                let hash = header.hash();
                (
                    header,
                    self.client
                        .block_extra_info(BlockId::Hash(hash))
                        .expect(EXTRA_INFO_PROOF),
                )
            })
            .collect::<Vec<_>>();

        // Headers
        self.notify_heads(&headers);

        // We notify logs enacting and retracting as the order in route.
        self.notify_logs(new_blocks.route.route(), |filter, ex| match ex {
            ChainRouteType::Enacted => Ok(self
                .client
                .logs(filter)
                .unwrap_or_default()
                .into_iter()
                .map(Into::into)
                .collect()),
            ChainRouteType::Retracted => Ok(self
                .client
                .logs(filter)
                .unwrap_or_default()
                .into_iter()
                .map(Into::into)
                .map(|mut log: Log| {
                    log.log_type = "removed".into();
                    log.removed = true;
                    log
                })
                .collect()),
        });
    }
}

impl<C: Send + Sync + 'static> EthPubSub for EthPubSubClient<C> {
    type Metadata = Metadata;

    fn subscribe(
        &self,
        _meta: Metadata,
        subscriber: Subscriber<pubsub::Result>,
        kind: pubsub::Kind,
        params: Option<pubsub::Params>,
    ) {
        let error = match (kind, params) {
            (pubsub::Kind::NewHeads, None) => {
                self.heads_subscribers.write().push(subscriber);
                return;
            }
            (pubsub::Kind::NewHeads, _) => {
                errors::invalid_params("newHeads", "Expected no parameters.")
            }
            (pubsub::Kind::Logs, Some(pubsub::Params::Logs(filter))) => match filter.try_into() {
                Ok(filter) => {
                    self.logs_subscribers.write().push(subscriber, filter);
                    return;
                }
                Err(err) => err,
            },
            (pubsub::Kind::Logs, _) => errors::invalid_params("logs", "Expected a filter object."),
            (pubsub::Kind::NewPendingTransactions, None) => {
                self.transactions_subscribers.write().push(subscriber);
                return;
            }
            (pubsub::Kind::NewPendingTransactions, _) => {
                errors::invalid_params("newPendingTransactions", "Expected no parameters.")
            }
            _ => errors::unimplemented(None),
        };

        let _ = subscriber.reject(error);
    }

    fn unsubscribe(&self, _: Option<Self::Metadata>, id: SubscriptionId) -> Result<bool> {
        let res = self.heads_subscribers.write().remove(&id).is_some();
        let res2 = self.logs_subscribers.write().remove(&id).is_some();
        let res3 = self.transactions_subscribers.write().remove(&id).is_some();

        Ok(res || res2 || res3)
    }
}