// 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.

//! Transaction building functions

use uuid::Uuid;

use crate::grin_keychain::{Identifier, Keychain};
use crate::grin_util::Mutex;
use crate::internal::{selection, updater};
use crate::slate::Slate;
use crate::types::{Context, NodeClient, TxLogEntryType, WalletBackend};
use crate::{Error, ErrorKind};

/// static for incrementing test UUIDs
lazy_static! {
	static ref SLATE_COUNTER: Mutex<u8> = { Mutex::new(0) };
}

/// Creates a new slate for a transaction, can be called by anyone involved in
/// the transaction (sender(s), receiver(s))
pub fn new_tx_slate<T: ?Sized, C, K>(
	wallet: &mut T,
	amount: u64,
	num_participants: usize,
	use_test_rng: bool,
) -> Result<Slate, Error>
where
	T: WalletBackend<C, K>,
	C: NodeClient,
	K: Keychain,
{
	let current_height = wallet.w2n_client().get_chain_height()?;
	let mut slate = Slate::blank(num_participants);
	if use_test_rng {
		{
			let sc = SLATE_COUNTER.lock();
			let bytes = [4, 54, 67, 12, 43, 2, 98, 76, 32, 50, 87, 5, 1, 33, 43, *sc];
			slate.id = Uuid::from_slice(&bytes).unwrap();
		}
		*SLATE_COUNTER.lock() += 1;
	}
	slate.amount = amount;
	slate.height = current_height;

	// Set the lock_height explicitly to 0 here.
	// This will generate a Plain kernel (rather than a HeightLocked kernel).
	slate.lock_height = 0;

	Ok(slate)
}

/// Estimates locked amount and fee for the transaction without creating one
pub fn estimate_send_tx<T: ?Sized, C, K>(
	wallet: &mut T,
	amount: u64,
	minimum_confirmations: u64,
	max_outputs: usize,
	num_change_outputs: usize,
	selection_strategy_is_use_all: bool,
	parent_key_id: &Identifier,
) -> Result<
	(
		u64, // total
		u64, // fee
	),
	Error,
>
where
	T: WalletBackend<C, K>,
	C: NodeClient,
	K: Keychain,
{
	// Get lock height
	let current_height = wallet.w2n_client().get_chain_height()?;
	// ensure outputs we're selecting are up to date
	updater::refresh_outputs(wallet, parent_key_id, false)?;

	// Sender selects outputs into a new slate and save our corresponding keys in
	// a transaction context. The secret key in our transaction context will be
	// randomly selected. This returns the public slate, and a closure that locks
	// our inputs and outputs once we're convinced the transaction exchange went
	// according to plan
	// This function is just a big helper to do all of that, in theory
	// this process can be split up in any way
	let (_coins, total, _amount, fee) = selection::select_coins_and_fee(
		wallet,
		amount,
		current_height,
		minimum_confirmations,
		max_outputs,
		num_change_outputs,
		selection_strategy_is_use_all,
		parent_key_id,
	)?;
	Ok((total, fee))
}

/// Add inputs to the slate (effectively becoming the sender)
pub fn add_inputs_to_slate<T: ?Sized, C, K>(
	wallet: &mut T,
	slate: &mut Slate,
	minimum_confirmations: u64,
	max_outputs: usize,
	num_change_outputs: usize,
	selection_strategy_is_use_all: bool,
	parent_key_id: &Identifier,
	participant_id: usize,
	message: Option<String>,
	use_test_rng: bool,
) -> Result<Context, Error>
where
	T: WalletBackend<C, K>,
	C: NodeClient,
	K: Keychain,
{
	// sender should always refresh outputs
	updater::refresh_outputs(wallet, parent_key_id, false)?;

	// Sender selects outputs into a new slate and save our corresponding keys in
	// a transaction context. The secret key in our transaction context will be
	// randomly selected. This returns the public slate, and a closure that locks
	// our inputs and outputs once we're convinced the transaction exchange went
	// according to plan
	// This function is just a big helper to do all of that, in theory
	// this process can be split up in any way
	let mut context = selection::build_send_tx(
		wallet,
		slate,
		minimum_confirmations,
		max_outputs,
		num_change_outputs,
		selection_strategy_is_use_all,
		parent_key_id.clone(),
		use_test_rng,
	)?;

	// Generate a kernel offset and subtract from our context's secret key. Store
	// the offset in the slate's transaction kernel, and adds our public key
	// information to the slate
	let _ = slate.fill_round_1(
		wallet.keychain(),
		&mut context.sec_key,
		&context.sec_nonce,
		participant_id,
		message,
		use_test_rng,
	)?;

	Ok(context)
}

/// Add outputs to the slate, becoming the recipient
pub fn add_output_to_slate<T: ?Sized, C, K>(
	wallet: &mut T,
	slate: &mut Slate,
	parent_key_id: &Identifier,
	participant_id: usize,
	message: Option<String>,
	use_test_rng: bool,
) -> Result<Context, Error>
where
	T: WalletBackend<C, K>,
	C: NodeClient,
	K: Keychain,
{
	// create an output using the amount in the slate
	let (_, mut context) =
		selection::build_recipient_output(wallet, slate, parent_key_id.clone(), use_test_rng)?;

	// fill public keys
	let _ = slate.fill_round_1(
		wallet.keychain(),
		&mut context.sec_key,
		&context.sec_nonce,
		1,
		message,
		use_test_rng,
	)?;

	// perform partial sig
	let _ = slate.fill_round_2(
		wallet.keychain(),
		&context.sec_key,
		&context.sec_nonce,
		participant_id,
	)?;

	Ok(context)
}

/// Complete a transaction as the sender
pub fn complete_tx<T: ?Sized, C, K>(
	wallet: &mut T,
	slate: &mut Slate,
	participant_id: usize,
	context: &Context,
) -> Result<(), Error>
where
	T: WalletBackend<C, K>,
	C: NodeClient,
	K: Keychain,
{
	let _ = slate.fill_round_2(
		wallet.keychain(),
		&context.sec_key,
		&context.sec_nonce,
		participant_id,
	)?;
	// Final transaction can be built by anyone at this stage
	slate.finalize(wallet.keychain())?;
	Ok(())
}

/// Rollback outputs associated with a transaction in the wallet
pub fn cancel_tx<T: ?Sized, C, K>(
	wallet: &mut T,
	parent_key_id: &Identifier,
	tx_id: Option<u32>,
	tx_slate_id: Option<Uuid>,
) -> Result<(), Error>
where
	T: WalletBackend<C, K>,
	C: NodeClient,
	K: Keychain,
{
	let mut tx_id_string = String::new();
	if let Some(tx_id) = tx_id {
		tx_id_string = tx_id.to_string();
	} else if let Some(tx_slate_id) = tx_slate_id {
		tx_id_string = tx_slate_id.to_string();
	}
	let tx_vec = updater::retrieve_txs(wallet, tx_id, tx_slate_id, Some(&parent_key_id), false)?;
	if tx_vec.len() != 1 {
		return Err(ErrorKind::TransactionDoesntExist(tx_id_string))?;
	}
	let tx = tx_vec[0].clone();
	if tx.tx_type != TxLogEntryType::TxSent && tx.tx_type != TxLogEntryType::TxReceived {
		return Err(ErrorKind::TransactionNotCancellable(tx_id_string))?;
	}
	if tx.confirmed == true {
		return Err(ErrorKind::TransactionNotCancellable(tx_id_string))?;
	}
	// get outputs associated with tx
	let res = updater::retrieve_outputs(wallet, false, Some(tx.id), Some(&parent_key_id))?;
	let outputs = res.iter().map(|m| m.output.clone()).collect();
	updater::cancel_tx_and_outputs(wallet, tx, outputs, parent_key_id)?;
	Ok(())
}

/// Update the stored transaction (this update needs to happen when the TX is finalised)
pub fn update_stored_tx<T: ?Sized, C, K>(wallet: &mut T, slate: &Slate) -> Result<(), Error>
where
	T: WalletBackend<C, K>,
	C: NodeClient,
	K: Keychain,
{
	// finalize command
	let tx_vec = updater::retrieve_txs(wallet, None, Some(slate.id), None, false)?;
	let mut tx = None;
	// don't want to assume this is the right tx, in case of self-sending
	for t in tx_vec {
		if t.tx_type == TxLogEntryType::TxSent {
			tx = Some(t.clone());
			break;
		}
	}
	let tx = match tx {
		Some(t) => t,
		None => return Err(ErrorKind::TransactionDoesntExist(slate.id.to_string()))?,
	};
	wallet.store_tx(&format!("{}", tx.tx_slate_id.unwrap()), &slate.tx)?;
	Ok(())
}

/// Update the transaction participant messages
pub fn update_message<T: ?Sized, C, K>(wallet: &mut T, slate: &Slate) -> Result<(), Error>
where
	T: WalletBackend<C, K>,
	C: NodeClient,
	K: Keychain,
{
	let tx_vec = updater::retrieve_txs(wallet, None, Some(slate.id), None, false)?;
	if tx_vec.is_empty() {
		return Err(ErrorKind::TransactionDoesntExist(slate.id.to_string()))?;
	}
	let mut batch = wallet.batch()?;
	for mut tx in tx_vec.into_iter() {
		tx.messages = Some(slate.participant_messages());
		let parent_key = tx.parent_key_id.clone();
		batch.save_tx_log_entry(tx, &parent_key)?;
	}
	batch.commit()?;
	Ok(())
}

#[cfg(test)]
mod test {
	use crate::grin_core::libtx::build;
	use crate::grin_keychain::{ExtKeychain, ExtKeychainPath, Keychain};

	#[test]
	// demonstrate that input.commitment == referenced output.commitment
	// based on the public key and amount begin spent
	fn output_commitment_equals_input_commitment_on_spend() {
		let keychain = ExtKeychain::from_random_seed(false).unwrap();
		let key_id1 = ExtKeychainPath::new(1, 1, 0, 0, 0).to_identifier();

		let tx1 = build::transaction(vec![build::output(105, key_id1.clone())], &keychain).unwrap();
		let tx2 = build::transaction(vec![build::input(105, key_id1.clone())], &keychain).unwrap();

		assert_eq!(tx1.outputs()[0].features, tx2.inputs()[0].features);
		assert_eq!(tx1.outputs()[0].commitment(), tx2.inputs()[0].commitment());
	}
}