// Copyright 2017-2018 Parity Technologies (UK) Ltd.
// This file is part of Substrate.

// Substrate 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.

// Substrate 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 Substrate.  If not, see <http://www.gnu.org/licenses/>.

//! Chain utilities.

use std::{self, io::{Read, Write}};
use futures::Future;

use runtime_primitives::generic::{SignedBlock, BlockId};
use runtime_primitives::traits::{As, Block, Header};
use consensus_common::import_queue::{ImportQueue, IncomingBlock, Link};
use network::message;

use consensus_common::BlockOrigin;
use components::{self, Components, ServiceFactory, FactoryFullConfiguration, FactoryBlockNumber, RuntimeGenesis};
use new_client;
use codec::{Decode, Encode};
use error;
use chain_spec::ChainSpec;

/// Export a range of blocks to a binary stream.
pub fn export_blocks<F, E, W>(config: FactoryFullConfiguration<F>, exit: E, mut output: W, from: FactoryBlockNumber<F>, to: Option<FactoryBlockNumber<F>>, json: bool) -> error::Result<()>
	where
	F: ServiceFactory,
	E: Future<Item=(),Error=()> + Send + 'static,
	W: Write,
{
	let client = new_client::<F>(&config)?;
	let mut block = from;

	let last = match to {
		Some(v) if v == As::sa(0) => As::sa(1),
		Some(v) => v,
		None => client.info()?.chain.best_number,
	};

	if last < block {
		return Err("Invalid block range specified".into());
	}

	let (exit_send, exit_recv) = std::sync::mpsc::channel();
	::std::thread::spawn(move || {
		let _ = exit.wait();
		let _ = exit_send.send(());
	});
	info!("Exporting blocks from #{} to #{}", block, last);
	if !json {
		output.write(&(last - block + As::sa(1)).encode())?;
	}

	loop {
		if exit_recv.try_recv().is_ok() {
			break;
		}
		match client.block(&BlockId::number(block))? {
			Some(block) => {
				if json {
					serde_json::to_writer(&mut output, &block).map_err(|e| format!("Eror writing JSON: {}", e))?;
				} else {
					output.write(&block.encode())?;
				}
			},
			None => break,
		}
		if block.as_() % 10000 == 0 {
			info!("#{}", block);
		}
		if block == last {
			break;
		}
		block += As::sa(1);
	}
	Ok(())
}

/// Import blocks from a binary stream.
pub fn import_blocks<F, E, R>(mut config: FactoryFullConfiguration<F>, exit: E, mut input: R) -> error::Result<()>
	where F: ServiceFactory, E: Future<Item=(),Error=()> + Send + 'static, R: Read,
{
	struct DummyLink;
	impl<B: Block> Link<B> for DummyLink { }

	let client = new_client::<F>(&config)?;
	// FIXME: this shouldn't need a mutable config. https://github.com/paritytech/substrate/issues/1134
	let queue = components::FullComponents::<F>::build_import_queue(&mut config, client.clone())?;
	queue.start(DummyLink)?;

	let (exit_send, exit_recv) = std::sync::mpsc::channel();
	::std::thread::spawn(move || {
		let _ = exit.wait();
		let _ = exit_send.send(());
	});

	let count: u32 = Decode::decode(&mut input).ok_or("Error reading file")?;
	info!("Importing {} blocks", count);
	let mut block_count = 0;
	for b in 0 .. count {
		if exit_recv.try_recv().is_ok() {
			break;
		}
		if let Some(signed) = SignedBlock::<F::Block>::decode(&mut input) {
			let (header, extrinsics) = signed.block.deconstruct();
			let hash = header.hash();
			let block  = message::BlockData::<F::Block> {
				hash: hash,
				justification: signed.justification,
				header: Some(header),
				body: Some(extrinsics),
				receipt: None,
				message_queue: None
			};
			// import queue handles verification and importing it into the client
			queue.import_blocks(BlockOrigin::File, vec![
				IncomingBlock::<F::Block>{
					hash: block.hash,
					header: block.header,
					body: block.body,
					justification: block.justification,
					origin: None,
				}
			]);
		} else {
			warn!("Error reading block data at {}.", b);
			break;
		}

		block_count = b;
		if b % 1000 == 0 {
			info!("#{}", b);
		}
	}
	info!("Imported {} blocks. Best: #{}", block_count, client.info()?.chain.best_number);

	Ok(())
}

/// Revert the chain.
pub fn revert_chain<F>(config: FactoryFullConfiguration<F>, blocks: FactoryBlockNumber<F>) -> error::Result<()>
	where F: ServiceFactory,
{
	let client = new_client::<F>(&config)?;
	let reverted = client.revert(blocks)?;
	let info = client.info()?.chain;
	info!("Reverted {} blocks. Best: #{} ({})", reverted, info.best_number, info.best_hash);
	Ok(())
}

/// Build a chain spec json
pub fn build_spec<G>(spec: ChainSpec<G>, raw: bool) -> error::Result<String>
	where G: RuntimeGenesis,
{
	Ok(spec.to_json(raw)?)
}