// 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 keychain::{Keychain, Identifier};
use util::{LOGGER, from_hex};
use util::secp::pedersen;
use api;
use core::core::{Output, SwitchCommitHash};
use core::core::transaction::{COINBASE_OUTPUT, DEFAULT_OUTPUT, SWITCH_COMMIT_HASH_SIZE};
use types::{WalletConfig, WalletData, OutputData, OutputStatus, Error};
use byteorder::{BigEndian, ByteOrder};

pub fn get_chain_height(config: &WalletConfig) -> Result<u64, Error> {
	let url = format!("{}/v1/chain", config.check_node_api_http_addr);

	match api::client::get::<api::Tip>(url.as_str()) {
		Ok(tip) => Ok(tip.height),
		Err(e) => {
			// if we got anything other than 200 back from server, bye
			error!(LOGGER, "Restore failed... unable to contact node: {}", e);
			Err(Error::Node(e))
		}
	}
}

fn output_with_range_proof(config: &WalletConfig, commit_id: &str) -> Result<api::Output, Error> {
	let url =
		format!(
		"{}/v1/chain/utxos/byids?id={}&include_rp&include_switch",
		config.check_node_api_http_addr,
		commit_id,
	);

	match api::client::get::<Vec<api::Output>>(url.as_str()) {
		Ok(outputs) => {
			if let Some(output) = outputs.first() {
				Ok(output.clone())
			} else {
				Err(Error::Node(api::Error::NotFound))
			}
		}
		Err(e) => {
			// if we got anything other than 200 back from server, don't attempt to refresh
			// the wallet
			// data after
			Err(Error::Node(e))
		}
	}
}

fn retrieve_amount_and_coinbase_status(
	config: &WalletConfig,
	keychain: &Keychain,
	key_id: Identifier,
	commit_id: &str,
) -> Result<(u64, bool), Error> {
	let output = output_with_range_proof(config, commit_id)?;
	let core_output = Output {
		features: match output.output_type {
			api::OutputType::Coinbase => COINBASE_OUTPUT,
			api::OutputType::Transaction => DEFAULT_OUTPUT,
		},
		proof: output.proof.expect("output with proof"),
		switch_commit_hash: output.switch_commit_hash.expect("output with switch_commit_hash"),
		commit: output.commit,
	};
	if let Some(amount) = core_output.recover_value(keychain, &key_id) {
		let is_coinbase = match output.output_type {
			api::OutputType::Coinbase => true,
			api::OutputType::Transaction => false,
		};
		Ok((amount, is_coinbase))
	} else {
		Err(Error::GenericError(format!("cannot recover value")))
	}
}

pub fn utxos_batch_block(
	config: &WalletConfig,
	start_height: u64,
	end_height: u64,
) -> Result<Vec<api::BlockOutputs>, Error> {
	// build the necessary query param -
	// ?height=x
	let query_param = format!("start_height={}&end_height={}", start_height, end_height);

	let url =
		format!(
		"{}/v1/chain/utxos/atheight?{}",
		config.check_node_api_http_addr,
		query_param,
	);

	match api::client::get::<Vec<api::BlockOutputs>>(url.as_str()) {
		Ok(outputs) => Ok(outputs),
		Err(e) => {
			// if we got anything other than 200 back from server, bye
			error!(LOGGER, "Restore failed... unable to contact node: {}", e);
			Err(Error::Node(e))
		}
	}
}

fn find_utxos_with_key(
	config: &WalletConfig,
	keychain: &Keychain,
	switch_commit_cache: &Vec<[u8; SWITCH_COMMIT_HASH_SIZE]>,
	block_outputs: api::BlockOutputs,
	key_iterations: &mut usize,
	padding: &mut usize,
) -> Vec<(pedersen::Commitment, Identifier, u32, u64, u64, bool)> {
	let mut wallet_outputs: Vec<(pedersen::Commitment, Identifier, u32, u64, u64, bool)> =
		Vec::new();

	info!(
		LOGGER,
		"Scanning block {}, {} outputs, over {} key derivations",
		block_outputs.header.height,
		block_outputs.outputs.len(),
		*key_iterations,
	);

	for output in block_outputs.outputs {
		for i in 0..*key_iterations {
			if switch_commit_cache[i as usize] == output.switch_commit_hash {
				info!(
					LOGGER,
					"Output found: {:?}, key_index: {:?}",
					output.switch_commit_hash,
					i,
				);

				// add it to result set here
				let commit_id = from_hex(output.commit.clone()).unwrap();
				let key_id = keychain.derive_key_id(i as u32).unwrap();
				let res = retrieve_amount_and_coinbase_status(
					config,
					keychain,
					key_id.clone(),
					&output.commit,
				);

				if let Ok((amount, is_coinbase)) = res {
					info!(LOGGER, "Amount: {}", amount);

					let commit = keychain
						.commit_with_key_index(BigEndian::read_u64(&commit_id), i as u32)
						.expect("commit with key index");

					wallet_outputs.push((
						commit,
						key_id.clone(),
						i as u32,
						amount,
						output.height,
						is_coinbase,
					));

					// probably don't have to look for indexes greater than this now
					*key_iterations = i + *padding;
					if *key_iterations > switch_commit_cache.len() {
						*key_iterations = switch_commit_cache.len();
					}
					info!(LOGGER, "Setting max key index to: {}", *key_iterations);
					break;
				} else {
					info!(
						LOGGER,
						"Unable to retrieve the amount (needs investigating)",
					);

				}
			}
		}
	}
	debug!(
		LOGGER,
		"Found {} wallet_outputs for block {}",
		wallet_outputs.len(),
		block_outputs.header.height,
	);

	wallet_outputs
}

pub fn restore(
	config: &WalletConfig,
	keychain: &Keychain,
	key_derivations: u32,
) -> Result<(), Error> {
	// Don't proceed if wallet.dat has anything in it
	let is_empty = WalletData::read_wallet(&config.data_file_dir, |wallet_data| {
		wallet_data.outputs.len() == 0
	})?;
	if !is_empty {
		error!(
			LOGGER,
			"Not restoring. Please back up and remove existing wallet.dat first."
		);
		return Ok(());
	}

	// Get height of chain from node (we'll check again when done)
	let chain_height = get_chain_height(config)?;
	info!(
		LOGGER,
		"Starting restore: Chain height is {}.",
		chain_height
	);

	let mut switch_commit_cache: Vec<[u8; SWITCH_COMMIT_HASH_SIZE]> = vec![];
	info!(
		LOGGER,
		"Building key derivation cache ({}) ...",
		key_derivations,
	);
	for i in 0..key_derivations {
		let switch_commit = keychain.switch_commit_from_index(i as u32).unwrap();
		let switch_commit_hash = SwitchCommitHash::from_switch_commit(switch_commit);
		switch_commit_cache.push(switch_commit_hash.hash);
	}
	debug!(LOGGER, "... done");

	let batch_size = 100;
	// this will start here, then lower as outputs are found, moving backwards on
	// the chain
	let mut key_iterations = key_derivations as usize;
	// set to a percentage of the key_derivation value
	let mut padding = (key_iterations as f64 * 0.25) as usize;
	let mut h = chain_height;
	while {
		let end_batch = h;
		if h >= batch_size {
			h -= batch_size;
		} else {
			h = 0;
		}
		let mut blocks = utxos_batch_block(config, h + 1, end_batch)?;
		blocks.reverse();

		let _ = WalletData::with_wallet(&config.data_file_dir, |wallet_data| {
			for block in blocks {
				let result_vec = find_utxos_with_key(
					config,
					keychain,
					&switch_commit_cache,
					block,
					&mut key_iterations,
					&mut padding,
				);
				if result_vec.len() > 0 {
					for output in result_vec.clone() {
						let root_key_id = keychain.root_key_id();
						// Just plonk it in for now, and refresh actual values via wallet info
						// command later
						wallet_data.add_output(OutputData {
							root_key_id: root_key_id.clone(),
							key_id: output.1.clone(),
							n_child: output.2,
							value: output.3,
							status: OutputStatus::Unconfirmed,
							height: output.4,
							lock_height: 0,
							is_coinbase: output.5,
						});
					};
				}
			}
		});
		h > 0
	}
	{}
	Ok(())
}