// Copyright 2018 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.

//! Client functions, implementations of the WalletClient trait
//! specific to the FileWallet

use failure::ResultExt;
use libwallet::types::*;
use std::collections::HashMap;
use std::io;

use futures::{Future, Stream};
use hyper::header::ContentType;
use hyper::{self, Method, Request};
use serde_json;
use tokio_core::reactor;

use api;
use error::{Error, ErrorKind};
use libwallet;
use libtx::slate::Slate;
use util::secp::pedersen;
use util::{self, LOGGER};

#[derive(Clone)]
pub struct HTTPWalletClient {
	node_url: String,
}

impl HTTPWalletClient {
	/// Create a new client that will communicate with the given grin node
	pub fn new(node_url:&str) -> HTTPWalletClient {
		HTTPWalletClient {
			node_url: node_url.to_owned(),
		}
	}
}

impl WalletClient for HTTPWalletClient {
	fn node_url(&self) -> &str {
		&self.node_url
	}

	/// Call the wallet API to create a coinbase output for the given block_fees.
	/// Will retry based on default "retry forever with backoff" behavior.
	fn create_coinbase(&self, dest: &str, block_fees: &BlockFees) -> Result<CbData, libwallet::Error> {
		let url = format!("{}/v1/wallet/foreign/build_coinbase", dest);
		match single_create_coinbase(&url, &block_fees) {
			Err(e) => {
				error!(
					LOGGER,
					"Failed to get coinbase from {}. Run grin wallet listen?", url
				);
				error!(LOGGER, "Underlying Error: {}", e.cause().unwrap());
				error!(LOGGER, "Backtrace: {}", e.backtrace().unwrap());
				Err(libwallet::ErrorKind::ClientCallback("Failed to get coinbase"))?
			}
			Ok(res) => Ok(res),
		}
	}

	/// Send the slate to a listening wallet instance
	fn send_tx_slate(&self, dest: &str, slate: &Slate) -> Result<Slate, libwallet::Error> {
		if &dest[..4] != "http" {
			let err_str = format!(
				"dest formatted as {} but send -d expected stdout or http://IP:port",
				dest
			);
			error!(LOGGER, "{}", err_str,);
			Err(libwallet::ErrorKind::Uri)?
		}
		let url = format!("{}/v1/wallet/foreign/receive_tx", dest);
		debug!(LOGGER, "Posting transaction slate to {}", url);

		let mut core = reactor::Core::new()
			.context(libwallet::ErrorKind::ClientCallback("Sending transaction: Initialise API"))?;
		let client = hyper::Client::new(&core.handle());

		let url_pool = url.to_owned();

		let mut req = Request::new(
			Method::Post,
			url_pool.parse::<hyper::Uri>()
			.context(libwallet::ErrorKind::ClientCallback("Sending transaction: parsing URL"))?
		);
		req.headers_mut().set(ContentType::json());
		let json = serde_json::to_string(&slate)
			.context(libwallet::ErrorKind::ClientCallback("Sending transaction: parsing response"))?;
		req.set_body(json);

		let work = client.request(req).and_then(|res| {
			res.body().concat2().and_then(move |body| {
				let slate: Slate =
					serde_json::from_slice(&body).map_err(|e| io::Error::new(io::ErrorKind::Other, e))?;
				Ok(slate)
			})
		});
		let res = core.run(work)
			.context(libwallet::ErrorKind::ClientCallback("Sending transaction: posting request"))?;
		Ok(res)
	}


	/// Posts a transaction to a grin node
	fn post_tx(&self, tx: &TxWrapper, fluff: bool) -> Result<(), libwallet::Error> {
		let url;
		let dest = self.node_url();
		if fluff {
			url = format!("{}/v1/pool/push?fluff", dest);
		} else {
			url = format!("{}/v1/pool/push", dest);
		}
		api::client::post(url.as_str(), tx)
			.context(libwallet::ErrorKind::ClientCallback("Posting transaction to node"))?;
		Ok(())
	}

	/// Return the chain tip from a given node
	fn get_chain_height(&self) -> Result<u64, libwallet::Error> {
		let addr = self.node_url();
		let url = format!("{}/v1/chain", addr);
		let res = api::client::get::<api::Tip>(url.as_str())
			.context(libwallet::ErrorKind::ClientCallback("Getting chain height from node"))?;
		Ok(res.height)
	}

	/// Retrieve outputs from node
	fn get_outputs_from_node(
		&self,
		wallet_outputs: Vec<pedersen::Commitment>,
	) -> Result<HashMap<pedersen::Commitment, String>, libwallet::Error> {
		let addr = self.node_url();
		// build the necessary query params -
		// ?id=xxx&id=yyy&id=zzz
		let query_params: Vec<String> = wallet_outputs
			.iter()
			.map(|commit| format!("id={}", util::to_hex(commit.as_ref().to_vec())))
			.collect();

		// build a map of api outputs by commit so we can look them up efficiently
		let mut api_outputs: HashMap<pedersen::Commitment, String> = HashMap::new();

		for query_chunk in query_params.chunks(1000) {
			let url = format!("{}/v1/chain/outputs/byids?{}", addr, query_chunk.join("&"),);

			match api::client::get::<Vec<api::Output>>(url.as_str()) {
				Ok(outputs) => for out in outputs {
					api_outputs.insert(out.commit.commit(), util::to_hex(out.commit.to_vec()));
				},
				Err(e) => {
					// if we got anything other than 200 back from server, don't attempt to refresh
					// the wallet data after
					return Err(libwallet::ErrorKind::ClientCallback("Error from server"))?;
				}
			}
		}
		Ok(api_outputs)
	}

	fn get_outputs_by_pmmr_index(
		&self,
		start_height: u64,
		max_outputs: u64,
	) -> Result<
		(
			u64,
			u64,
			Vec<(pedersen::Commitment, pedersen::RangeProof, bool)>,
		),
		libwallet::Error,
	> {
		let addr = self.node_url();
		let query_param = format!("start_index={}&max={}", start_height, max_outputs);

		let url = format!("{}/v1/txhashset/outputs?{}", addr, query_param,);

		let mut api_outputs: Vec<(pedersen::Commitment, pedersen::RangeProof, bool)> = Vec::new();

		match api::client::get::<api::OutputListing>(url.as_str()) {
			Ok(o) => {
				for out in o.outputs {
					let is_coinbase = match out.output_type {
						api::OutputType::Coinbase => true,
						api::OutputType::Transaction => false,
					};
					api_outputs.push((out.commit, out.range_proof().unwrap(), is_coinbase));
				}

				Ok((o.highest_index, o.last_retrieved_index, api_outputs))
			}
			Err(e) => {
				// if we got anything other than 200 back from server, bye
				error!(
					LOGGER,
					"get_outputs_by_pmmr_index: unable to contact API {}. Error: {}", addr, e
				);
				Err(libwallet::ErrorKind::ClientCallback("unable to contact api"))?
			}
		}
	}
}
/// Call the wallet API to create a coinbase output for the given block_fees.
/// Will retry based on default "retry forever with backoff" behavior.
pub fn create_coinbase(dest: &str, block_fees: &BlockFees) -> Result<CbData, Error> {
	let url = format!("{}/v1/wallet/foreign/build_coinbase", dest);
	match single_create_coinbase(&url, &block_fees) {
		Err(e) => {
			error!(
				LOGGER,
				"Failed to get coinbase from {}. Run grin wallet listen?", url
			);
			error!(LOGGER, "Underlying Error: {}", e.cause().unwrap());
			error!(LOGGER, "Backtrace: {}", e.backtrace().unwrap());
			Err(e)?
		}
		Ok(res) => Ok(res),
	}
}

/// Makes a single request to the wallet API to create a new coinbase output.
fn single_create_coinbase(url: &str, block_fees: &BlockFees) -> Result<CbData, Error> {
	let mut core =
		reactor::Core::new().context(ErrorKind::GenericError("Could not create reactor"))?;
	let client = hyper::Client::new(&core.handle());

	let mut req = Request::new(
		Method::Post,
		url.parse::<hyper::Uri>().context(ErrorKind::Uri)?,
	);
	req.headers_mut().set(ContentType::json());
	let json = serde_json::to_string(&block_fees).context(ErrorKind::Format)?;
	trace!(LOGGER, "Sending coinbase request: {:?}", json);
	req.set_body(json);

	let work = client.request(req).and_then(|res| {
		res.body().concat2().and_then(move |body| {
			trace!(LOGGER, "Returned Body: {:?}", body);
			let coinbase: CbData =
				serde_json::from_slice(&body).map_err(|e| io::Error::new(io::ErrorKind::Other, e))?;
			Ok(coinbase)
		})
	});

	let res = core.run(work)
		.context(ErrorKind::GenericError("Could not run core"))?;
	Ok(res)
}