// Copyright 2019-2021 Parity Technologies (UK) Ltd.
// This file is part of Parity Bridges Common.

// Parity Bridges Common 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.

// Parity Bridges Common 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 Parity Bridges Common.  If not, see <http://www.gnu.org/licenses/>.

#![cfg_attr(not(feature = "std"), no_std)]

pub mod storage_keys;

use codec::{Decode, Encode};
use frame_support::{weights::Weight, RuntimeDebug};
use scale_info::TypeInfo;
use sp_core::{H256, U256};
use sp_io::hashing::blake2_256;
use sp_std::vec::Vec;

/// Pending token swap state.
#[derive(Encode, Decode, Clone, RuntimeDebug, PartialEq, Eq, TypeInfo)]
pub enum TokenSwapState {
	/// The swap has been started using the `start_claim` call, but we have no proof that it has
	/// happened at the Bridged chain.
	Started,
	/// The swap has happened at the Bridged chain and may be claimed by the Bridged chain party
	/// using the `claim_swap` call.
	Confirmed,
	/// The swap has failed at the Bridged chain and This chain party may cancel it using the
	/// `cancel_swap` call.
	Failed,
}

/// Token swap type.
///
/// Different swap types give a different guarantees regarding possible swap
/// replay protection.
#[derive(Encode, Decode, Clone, RuntimeDebug, PartialEq, Eq, TypeInfo)]
pub enum TokenSwapType<ThisBlockNumber> {
	/// The `target_account_at_bridged_chain` is temporary and only have funds for single swap.
	///
	/// ***WARNING**: if `target_account_at_bridged_chain` still exists after the swap has been
	/// completed (either by claiming or canceling), the `source_account_at_this_chain` will be
	/// able to restart the swap again and repeat the swap until `target_account_at_bridged_chain`
	/// depletes.
	TemporaryTargetAccountAtBridgedChain,
	/// This swap type prevents `source_account_at_this_chain` from restarting the swap after it
	/// has been completed. There are two consequences:
	///
	/// 1) the `source_account_at_this_chain` won't be able to call `start_swap` after given
	/// <ThisBlockNumber>; 2) the `target_account_at_bridged_chain` won't be able to call
	/// `claim_swap` (over the bridge) before    block `<ThisBlockNumber + 1>`.
	///
	/// The second element is the nonce of the swap. You must care about its uniqueness if you're
	/// planning to perform another swap with exactly the same parameters (i.e. same amount, same
	/// accounts, same `ThisBlockNumber`) to avoid collisions.
	LockClaimUntilBlock(ThisBlockNumber, U256),
}

/// An intention to swap `source_balance_at_this_chain` owned by `source_account_at_this_chain`
/// to `target_balance_at_bridged_chain` owned by `target_account_at_bridged_chain`.
///
/// **IMPORTANT NOTE**: this structure is always the same during single token swap. So even
/// when chain changes, the meaning of This and Bridged are still used to point to the same chains.
/// This chain is always the chain where swap has been started. And the Bridged chain is the other
/// chain.
#[derive(Encode, Decode, Clone, RuntimeDebug, PartialEq, Eq, TypeInfo)]
pub struct TokenSwap<ThisBlockNumber, ThisBalance, ThisAccountId, BridgedBalance, BridgedAccountId>
{
	/// The type of the swap.
	pub swap_type: TokenSwapType<ThisBlockNumber>,
	/// This chain balance to be swapped with `target_balance_at_bridged_chain`.
	pub source_balance_at_this_chain: ThisBalance,
	/// Account id of the party acting at This chain and owning the `source_account_at_this_chain`.
	pub source_account_at_this_chain: ThisAccountId,
	/// Bridged chain balance to be swapped with `source_balance_at_this_chain`.
	pub target_balance_at_bridged_chain: BridgedBalance,
	/// Account id of the party acting at the Bridged chain and owning the
	/// `target_balance_at_bridged_chain`.
	pub target_account_at_bridged_chain: BridgedAccountId,
}

impl<ThisBlockNumber, ThisBalance, ThisAccountId, BridgedBalance, BridgedAccountId>
	TokenSwap<ThisBlockNumber, ThisBalance, ThisAccountId, BridgedBalance, BridgedAccountId>
where
	TokenSwap<ThisBlockNumber, ThisBalance, ThisAccountId, BridgedBalance, BridgedAccountId>:
		Encode,
{
	/// Returns hash, used to identify this token swap.
	pub fn hash(&self) -> H256 {
		self.using_encoded(blake2_256).into()
	}
}

/// SCALE-encoded `Currency::transfer` call on the bridged chain.
pub type RawBridgedTransferCall = Vec<u8>;

/// Token swap creation parameters.
#[derive(Encode, Decode, Clone, RuntimeDebug, PartialEq, Eq, TypeInfo)]
pub struct TokenSwapCreation<BridgedAccountPublic, ThisChainBalance, BridgedAccountSignature> {
	/// Public key of the `target_account_at_bridged_chain` account used to verify
	/// `bridged_currency_transfer_signature`.
	pub target_public_at_bridged_chain: BridgedAccountPublic,
	/// Fee that the `source_account_at_this_chain` is ready to pay for the tokens
	/// transfer message delivery and dispatch.
	pub swap_delivery_and_dispatch_fee: ThisChainBalance,
	/// Specification version of the Bridged chain.
	pub bridged_chain_spec_version: u32,
	/// SCALE-encoded tokens transfer call at the Bridged chain.
	pub bridged_currency_transfer: RawBridgedTransferCall,
	/// Dispatch weight of the tokens transfer call at the Bridged chain.
	pub bridged_currency_transfer_weight: Weight,
	/// The signature of the `target_account_at_bridged_chain` for the message
	/// returned by the `pallet_bridge_dispatch::account_ownership_digest()` function call.
	pub bridged_currency_transfer_signature: BridgedAccountSignature,
}