// Copyright 2017 The Grin Developers
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use std::io::Read;
use std::sync::{Arc, RwLock};
use std::thread;

use iron::prelude::*;
use iron::Handler;
use iron::status;
use urlencoded::UrlEncodedQuery;
use serde::Serialize;
use serde_json;

use chain;
use core::core::Transaction;
use core::ser;
use pool;
use p2p;
use rest::*;
use util::secp::pedersen::Commitment;
use types::*;
use util;
use util::LOGGER;


// Supports retrieval of multiple outputs in a single request -
// GET /v1/chain/utxos?id=xxx,yyy,zzz
// GET /v1/chain/utxos?id=xxx&id=yyy&id=zzz
struct UtxoHandler {
	chain: Arc<chain::Chain>,
}

impl UtxoHandler {
	fn get_utxo(&self, id: &str) -> Result<Output, Error> {
		debug!(LOGGER, "getting utxo: {}", id);
		let c = util::from_hex(String::from(id)).map_err(|_| {
			Error::Argument(format!("Not a valid commitment: {}", id))
		})?;
		let commit = Commitment::from_vec(c);

		let out = self.chain
			.get_unspent(&commit)
			.map_err(|_| Error::NotFound)?;

		let header = self.chain
			.get_block_header_by_output_commit(&commit)
			.map_err(|_| Error::NotFound)?;

		Ok(Output::from_output(&out, &header))
	}
}

impl Handler for UtxoHandler {
	fn handle(&self, req: &mut Request) -> IronResult<Response> {
		let mut commitments: Vec<&str> = vec![];
		if let Ok(params) = req.get_ref::<UrlEncodedQuery>() {
			if let Some(ids) = params.get("id") {
				for id in ids {
					for id in id.split(",") {
						commitments.push(id.clone());
					}
				}
			}
		}

		let mut utxos: Vec<Output> = vec![];
		for commit in commitments {
			if let Ok(out) = self.get_utxo(commit) {
				utxos.push(out);
			}
		}
		json_response(&utxos)
	}
}

// Sum tree handler. Retrieve the roots:
// GET /v1/sumtrees/roots
//
// Last inserted nodes::
// GET /v1/sumtrees/lastutxos (gets last 10)
// GET /v1/sumtrees/lastutxos?n=5
// GET /v1/sumtrees/lastrangeproofs
// GET /v1/sumtrees/lastkernels
struct SumTreeHandler {
	chain: Arc<chain::Chain>,
}

impl SumTreeHandler {
	// gets roots
	fn get_roots(&self) -> SumTrees {
		SumTrees::from_head(self.chain.clone())
	}

	// gets last n utxos inserted in to the tree
	fn get_last_n_utxo(&self, distance: u64) -> Vec<SumTreeNode> {
		SumTreeNode::get_last_n_utxo(self.chain.clone(), distance)
	}

	// gets last n utxos inserted in to the tree
	fn get_last_n_rangeproof(&self, distance: u64) -> Vec<SumTreeNode> {
		SumTreeNode::get_last_n_rangeproof(self.chain.clone(), distance)
	}

	// gets last n utxos inserted in to the tree
	fn get_last_n_kernel(&self, distance: u64) -> Vec<SumTreeNode> {
		SumTreeNode::get_last_n_kernel(self.chain.clone(), distance)
	}
}

impl Handler for SumTreeHandler {
	fn handle(&self, req: &mut Request) -> IronResult<Response> {
		let url = req.url.clone();
		let mut path_elems = url.path();
		if *path_elems.last().unwrap() == "" {
			path_elems.pop();
		}
		// TODO: probably need to set a reasonable max limit here
		let mut last_n = 10;
		if let Ok(params) = req.get_ref::<UrlEncodedQuery>() {
			if let Some(nums) = params.get("n") {
				for num in nums {
					if let Ok(n) = str::parse(num) {
						last_n = n;
					}
				}
			}
		}
		match *path_elems.last().unwrap() {
			"roots" => json_response(&self.get_roots()),
			"lastutxos" => json_response(&self.get_last_n_utxo(last_n)),
			"lastrangeproofs" => json_response(&self.get_last_n_rangeproof(last_n)),
			"lastkernels" => json_response(&self.get_last_n_kernel(last_n)),
			_ => Ok(Response::with((status::BadRequest, ""))),
		}
	}
}

pub struct PeersAllHandler {
	pub peer_store: Arc<p2p::PeerStore>,
}

impl Handler for PeersAllHandler {
	fn handle(&self, _req: &mut Request) -> IronResult<Response> {
		let peers = &self.peer_store.all_peers();
		json_response(&peers)
	}
}

pub struct PeersConnectedHandler {
	pub p2p_server: Arc<p2p::Server>,
}

impl Handler for PeersConnectedHandler {
	fn handle(&self, _req: &mut Request) -> IronResult<Response> {
		let mut peers = vec![];
		for p in &self.p2p_server.all_peers() {
			let peer_info = p.info.clone();
			peers.push(peer_info);
		}
		json_response(&peers)
	}
}

// Chain handler. Get the head details.
// GET /v1/chain
pub struct ChainHandler {
	pub chain: Arc<chain::Chain>,
}

impl ChainHandler {
	fn get_tip(&self) -> Tip {
		Tip::from_tip(self.chain.head().unwrap())
	}
}

impl Handler for ChainHandler {
	fn handle(&self, _req: &mut Request) -> IronResult<Response> {
		json_response(&self.get_tip())
	}
}

// Get basic information about the transaction pool.
struct PoolInfoHandler<T> {
	tx_pool: Arc<RwLock<pool::TransactionPool<T>>>,
}

impl<T> Handler for PoolInfoHandler<T>
where
	T: pool::BlockChain + Send + Sync + 'static,
{
	fn handle(&self, _req: &mut Request) -> IronResult<Response> {
		let pool = self.tx_pool.read().unwrap();
		json_response(&PoolInfo {
			pool_size: pool.pool_size(),
			orphans_size: pool.orphans_size(),
			total_size: pool.total_size(),
		})
	}
}

/// Dummy wrapper for the hex-encoded serialized transaction.
#[derive(Serialize, Deserialize)]
struct TxWrapper {
	tx_hex: String,
}

// Push new transactions to our transaction pool, that should broadcast it
// to the network if valid.
struct PoolPushHandler<T> {
	tx_pool: Arc<RwLock<pool::TransactionPool<T>>>,
}

impl<T> Handler for PoolPushHandler<T>
where
	T: pool::BlockChain + Send + Sync + 'static,
{
	fn handle(&self, req: &mut Request) -> IronResult<Response> {
		let wrapper: TxWrapper = serde_json::from_reader(req.body.by_ref())
			.map_err(|e| IronError::new(e, status::BadRequest))?;

		let tx_bin = util::from_hex(wrapper.tx_hex).map_err(|_| {
			Error::Argument(format!("Invalid hex in transaction wrapper."))
		})?;

		let tx: Transaction = ser::deserialize(&mut &tx_bin[..]).map_err(|_| {
			Error::Argument("Could not deserialize transaction, invalid format.".to_string())
		})?;

		let source = pool::TxSource {
			debug_name: "push-api".to_string(),
			identifier: "?.?.?.?".to_string(),
		};
		info!(
			LOGGER,
			"Pushing transaction with {} inputs and {} outputs to pool.",
			tx.inputs.len(),
			tx.outputs.len()
		);
		self.tx_pool
			.write()
			.unwrap()
			.add_to_memory_pool(source, tx)
			.map_err(|e| {
				Error::Internal(format!("Addition to transaction pool failed: {:?}", e))
			})?;

		Ok(Response::with(status::Ok))
	}
}

// Utility to serialize a struct into JSON and produce a sensible IronResult
// out of it.
fn json_response<T>(s: &T) -> IronResult<Response>
where
	T: Serialize,
{
	match serde_json::to_string_pretty(s) {
		Ok(json) => Ok(Response::with((status::Ok, json))),
		Err(_) => Ok(Response::with((status::InternalServerError, ""))),
	}
}

/// Start all server HTTP handlers. Register all of them with Iron
/// and runs the corresponding HTTP server.
pub fn start_rest_apis<T>(
	addr: String,
	chain: Arc<chain::Chain>,
	tx_pool: Arc<RwLock<pool::TransactionPool<T>>>,
	p2p_server: Arc<p2p::Server>,
	peer_store: Arc<p2p::PeerStore>,
) where
	T: pool::BlockChain + Send + Sync + 'static,
{
	thread::spawn(move || {
		// build handlers and register them under the appropriate endpoint
		let utxo_handler = UtxoHandler {
			chain: chain.clone(),
		};
		let chain_tip_handler = ChainHandler {
			chain: chain.clone(),
		};
		let sumtree_handler = SumTreeHandler {
			chain: chain.clone(),
		};
		let pool_info_handler = PoolInfoHandler {
			tx_pool: tx_pool.clone(),
		};
		let pool_push_handler = PoolPushHandler {
			tx_pool: tx_pool.clone(),
		};
		let peers_all_handler = PeersAllHandler {
			peer_store: peer_store.clone(),
		};
		let peers_connected_handler = PeersConnectedHandler {
			p2p_server: p2p_server.clone(),
		};

		let router = router!(
			chain_tip: get "/chain" => chain_tip_handler,
			chain_utxos: get "/chain/utxos" => utxo_handler,
			sumtree_roots: get "/sumtrees/*" => sumtree_handler,
			pool_info: get "/pool" => pool_info_handler,
			pool_push: post "/pool/push" => pool_push_handler,
			peers_all: get "/peers/all" => peers_all_handler,
			peers_connected: get "/peers/connected" => peers_connected_handler,
		);

		let mut apis = ApiServer::new("/v1".to_string());
		apis.register_handler(router);

		info!(LOGGER, "Starting HTTP API server at {}.", addr);
		apis.start(&addr[..]).unwrap_or_else(|e| {
			error!(LOGGER, "Failed to start API HTTP server: {}.", e);
		});
	});
}