// This file is part of Substrate.

// Copyright (C) 2020-2021 Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: Apache-2.0

// 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.

//! A crate that hosts a common definitions that are relevant for the pallet-contracts.

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

use bitflags::bitflags;
use codec::{Decode, Encode};
use sp_core::Bytes;
use sp_runtime::{DispatchError, RuntimeDebug};
use sp_std::prelude::*;

#[cfg(feature = "std")]
use serde::{Serialize, Deserialize};

/// Result type of a `bare_call` or `bare_instantiate` call.
///
/// It contains the execution result together with some auxiliary information.
#[derive(Eq, PartialEq, Encode, Decode, RuntimeDebug)]
#[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "std", serde(rename_all = "camelCase"))]
pub struct ContractResult<T> {
	/// How much gas was consumed during execution.
	pub gas_consumed: u64,
	/// How much gas is required as gas limit in order to execute this call.
	///
	/// This value should be used to determine the gas limit for on-chain execution.
	///
	/// # Note
	///
	/// This can only different from [`Self::gas_consumed`] when weight pre charging
	/// is used. Currently, only `seal_call_runtime` makes use of pre charging.
	pub gas_required: u64,
	/// An optional debug message. This message is only filled when explicitly requested
	/// by the code that calls into the contract. Otherwise it is empty.
	///
	/// The contained bytes are valid UTF-8. This is not declared as `String` because
	/// this type is not allowed within the runtime.
	///
	/// Clients should not make any assumptions about the format of the buffer.
	/// They should just display it as-is. It is **not** only a collection of log lines
	/// provided by a contract but a formatted buffer with different sections.
	///
	/// # Note
	///
	/// The debug message is never generated during on-chain execution. It is reserved for
	/// RPC calls.
	#[cfg_attr(feature = "std", serde(with = "as_string"))]
	pub debug_message: Vec<u8>,
	/// The execution result of the wasm code.
	pub result: T,
}

/// Result type of a `bare_call` call.
pub type ContractExecResult = ContractResult<Result<ExecReturnValue, DispatchError>>;

/// Result type of a `bare_instantiate` call.
pub type ContractInstantiateResult<AccountId, BlockNumber> =
	ContractResult<Result<InstantiateReturnValue<AccountId, BlockNumber>, DispatchError>>;

/// Result type of a `get_storage` call.
pub type GetStorageResult = Result<Option<Vec<u8>>, ContractAccessError>;

/// Result type of a `rent_projection` call.
pub type RentProjectionResult<BlockNumber> =
	Result<RentProjection<BlockNumber>, ContractAccessError>;

/// The possible errors that can happen querying the storage of a contract.
#[derive(Eq, PartialEq, Encode, Decode, RuntimeDebug)]
pub enum ContractAccessError {
	/// The given address doesn't point to a contract.
	DoesntExist,
	/// The specified contract is a tombstone and thus cannot have any storage.
	IsTombstone,
}

#[derive(Eq, PartialEq, Encode, Decode, RuntimeDebug)]
#[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "std", serde(rename_all = "camelCase"))]
pub enum RentProjection<BlockNumber> {
	/// Eviction is projected to happen at the specified block number.
	EvictionAt(BlockNumber),
	/// No eviction is scheduled.
	///
	/// E.g. Contract accumulated enough funds to offset the rent storage costs.
	NoEviction,
}

bitflags! {
	/// Flags used by a contract to customize exit behaviour.
	#[derive(Encode, Decode)]
	#[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
	#[cfg_attr(feature = "std", serde(rename_all = "camelCase", transparent))]
	pub struct ReturnFlags: u32 {
		/// If this bit is set all changes made by the contract execution are rolled back.
		const REVERT = 0x0000_0001;
	}
}

/// Output of a contract call or instantiation which ran to completion.
#[derive(PartialEq, Eq, Encode, Decode, RuntimeDebug)]
#[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "std", serde(rename_all = "camelCase"))]
pub struct ExecReturnValue {
	/// Flags passed along by `seal_return`. Empty when `seal_return` was never called.
	pub flags: ReturnFlags,
	/// Buffer passed along by `seal_return`. Empty when `seal_return` was never called.
	pub data: Bytes,
}

impl ExecReturnValue {
	/// We understand the absense of a revert flag as success.
	pub fn is_success(&self) -> bool {
		!self.flags.contains(ReturnFlags::REVERT)
	}
}

/// The result of a successful contract instantiation.
#[derive(PartialEq, Eq, Encode, Decode, RuntimeDebug)]
#[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "std", serde(rename_all = "camelCase"))]
pub struct InstantiateReturnValue<AccountId, BlockNumber> {
	/// The output of the called constructor.
	pub result: ExecReturnValue,
	/// The account id of the new contract.
	pub account_id: AccountId,
	/// Information about when and if the new project will be evicted.
	///
	/// # Note
	///
	/// `None` if `bare_instantiate` was called with
	/// `compute_projection` set to false. From the perspective of an RPC this means that
	/// the runtime API did not request this value and this feature is therefore unsupported.
	pub rent_projection: Option<RentProjection<BlockNumber>>,
}

/// Reference to an existing code hash or a new wasm module.
#[derive(Eq, PartialEq, Encode, Decode, RuntimeDebug)]
#[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "std", serde(rename_all = "camelCase"))]
pub enum Code<Hash> {
	/// A wasm module as raw bytes.
	Upload(Bytes),
	/// The code hash of an on-chain wasm blob.
	Existing(Hash),
}

#[cfg(feature = "std")]
mod as_string {
	use super::*;
	use serde::{Serializer, Deserializer, ser::Error};

	pub fn serialize<S: Serializer>(bytes: &Vec<u8>, serializer: S) -> Result<S::Ok, S::Error> {
		std::str::from_utf8(bytes)
			.map_err(|e| S::Error::custom(format!("Debug buffer contains invalid UTF8: {}", e)))?
			.serialize(serializer)
	}

	pub fn deserialize<'de, D: Deserializer<'de>>(deserializer: D) -> Result<Vec<u8>, D::Error> {
		Ok(String::deserialize(deserializer)?.into_bytes())
	}
}