// This file is part of Substrate.

// Copyright (C) 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 scale_info::TypeInfo;
use sp_runtime::{
    traits::{Saturating, Zero},
    DispatchError, RuntimeDebug,
};
use sp_std::prelude::*;
use sp_weights::Weight;

/// Result type of a `bare_call` or `bare_instantiate` call as well as `ContractsApi::call` and
/// `ContractsApi::instantiate`.
///
/// It contains the execution result together with some auxiliary information.
///
/// #Note
///
/// It has been extended to include `events` at the end of the struct while not bumping the
/// `ContractsApi` version. Therefore when SCALE decoding a `ContractResult` its trailing data
/// should be ignored to avoid any potential compatibility issues.
#[derive(Eq, PartialEq, Encode, Decode, RuntimeDebug, TypeInfo)]
pub struct ContractResult<R, Balance, EventRecord> {
    /// How much weight was consumed during execution.
    pub gas_consumed: Weight,
    /// How much weight is required as gas limit in order to execute this call.
    ///
    /// This value should be used to determine the weight 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.
    /// Additionally, any `seal_call` or `seal_instantiate` makes use of pre-charging
    /// when a non-zero `gas_limit` argument is supplied.
    pub gas_required: Weight,
    /// How much balance was paid by the origin into the contract's deposit account in order to
    /// pay for storage.
    ///
    /// The storage deposit is never actually charged from the origin in case of [`Self::result`]
    /// is `Err`. This is because on error all storage changes are rolled back including the
    /// payment of the deposit.
    pub storage_deposit: StorageDeposit<Balance>,
    /// 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.
    pub debug_message: Vec<u8>,
    /// The execution result of the wasm code.
    pub result: R,
    /// The events that were emitted during execution. It is an option as event collection is
    /// optional.
    pub events: Option<Vec<EventRecord>>,
}

/// Result type of a `bare_call` call as well as `ContractsApi::call`.
pub type ContractExecResult<Balance, EventRecord> =
    ContractResult<Result<ExecReturnValue, DispatchError>, Balance, EventRecord>;

/// Result type of a `bare_instantiate` call as well as `ContractsApi::instantiate`.
pub type ContractInstantiateResult<AccountId, Balance, EventRecord> =
    ContractResult<Result<InstantiateReturnValue<AccountId>, DispatchError>, Balance, EventRecord>;

/// Result type of a `bare_code_upload` call.
pub type CodeUploadResult<CodeHash, Balance> =
    Result<CodeUploadReturnValue<CodeHash, Balance>, DispatchError>;

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

/// The possible errors that can happen querying the storage of a contract.
#[derive(Eq, PartialEq, Encode, Decode, RuntimeDebug, TypeInfo)]
pub enum ContractAccessError {
    /// The given address doesn't point to a contract.
    DoesntExist,
    /// Storage key cannot be decoded from the provided input data.
    KeyDecodingFailed,
    /// Storage is migrating. Try again later.
    MigrationInProgress,
}

bitflags! {
    /// Flags used by a contract to customize exit behaviour.
    #[derive(Encode, Decode, TypeInfo)]
    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, TypeInfo)]
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: Vec<u8>,
}

impl ExecReturnValue {
    /// The contract did revert all storage changes.
    pub fn did_revert(&self) -> bool {
        self.flags.contains(ReturnFlags::REVERT)
    }
}

/// The result of a successful contract instantiation.
#[derive(PartialEq, Eq, Encode, Decode, RuntimeDebug, TypeInfo)]
pub struct InstantiateReturnValue<AccountId> {
    /// The output of the called constructor.
    pub result: ExecReturnValue,
    /// The account id of the new contract.
    pub account_id: AccountId,
}

/// The result of successfully uploading a contract.
#[derive(PartialEq, Eq, Encode, Decode, RuntimeDebug, TypeInfo)]
pub struct CodeUploadReturnValue<CodeHash, Balance> {
    /// The key under which the new code is stored.
    pub code_hash: CodeHash,
    /// The deposit that was reserved at the caller. Is zero when the code already existed.
    pub deposit: Balance,
}

/// Reference to an existing code hash or a new wasm module.
#[derive(Eq, PartialEq, Encode, Decode, RuntimeDebug, TypeInfo)]
pub enum Code<Hash> {
    /// A wasm module as raw bytes.
    Upload(Vec<u8>),
    /// The code hash of an on-chain wasm blob.
    Existing(Hash),
}

/// The amount of balance that was either charged or refunded in order to pay for storage.
#[derive(Eq, PartialEq, Ord, PartialOrd, Encode, Decode, RuntimeDebug, Clone, TypeInfo)]
pub enum StorageDeposit<Balance> {
    /// The transaction reduced storage consumption.
    ///
    /// This means that the specified amount of balance was transferred from the involved
    /// deposit accounts to the origin.
    Refund(Balance),
    /// The transaction increased storage consumption.
    ///
    /// This means that the specified amount of balance was transferred from the origin
    /// to the involved deposit accounts.
    Charge(Balance),
}

impl<Balance: Zero> Default for StorageDeposit<Balance> {
    fn default() -> Self {
        Self::Charge(Zero::zero())
    }
}

impl<Balance: Zero + Copy> StorageDeposit<Balance> {
    /// Returns how much balance is charged or `0` in case of a refund.
    pub fn charge_or_zero(&self) -> Balance {
        match self {
            Self::Charge(amount) => *amount,
            Self::Refund(_) => Zero::zero(),
        }
    }

    pub fn is_zero(&self) -> bool {
        match self {
            Self::Charge(amount) => amount.is_zero(),
            Self::Refund(amount) => amount.is_zero(),
        }
    }
}

impl<Balance> StorageDeposit<Balance>
where
    Balance: Saturating + Ord + Copy,
{
    /// This is essentially a saturating signed add.
    pub fn saturating_add(&self, rhs: &Self) -> Self {
        use StorageDeposit::*;
        match (self, rhs) {
            (Charge(lhs), Charge(rhs)) => Charge(lhs.saturating_add(*rhs)),
            (Refund(lhs), Refund(rhs)) => Refund(lhs.saturating_add(*rhs)),
            (Charge(lhs), Refund(rhs)) =>
                if lhs >= rhs {
                    Charge(lhs.saturating_sub(*rhs))
                } else {
                    Refund(rhs.saturating_sub(*lhs))
                },
            (Refund(lhs), Charge(rhs)) =>
                if lhs > rhs {
                    Refund(lhs.saturating_sub(*rhs))
                } else {
                    Charge(rhs.saturating_sub(*lhs))
                },
        }
    }

    /// This is essentially a saturating signed sub.
    pub fn saturating_sub(&self, rhs: &Self) -> Self {
        use StorageDeposit::*;
        match (self, rhs) {
            (Charge(lhs), Refund(rhs)) => Charge(lhs.saturating_add(*rhs)),
            (Refund(lhs), Charge(rhs)) => Refund(lhs.saturating_add(*rhs)),
            (Charge(lhs), Charge(rhs)) =>
                if lhs >= rhs {
                    Charge(lhs.saturating_sub(*rhs))
                } else {
                    Refund(rhs.saturating_sub(*lhs))
                },
            (Refund(lhs), Refund(rhs)) =>
                if lhs > rhs {
                    Refund(lhs.saturating_sub(*rhs))
                } else {
                    Charge(rhs.saturating_sub(*lhs))
                },
        }
    }

    /// If the amount of deposit (this type) is constrained by a `limit` this calculates how
    /// much balance (if any) is still available from this limit.
    ///
    /// # Note
    ///
    /// In case of a refund the return value can be larger than `limit`.
    pub fn available(&self, limit: &Balance) -> Balance {
        use StorageDeposit::*;
        match self {
            Charge(amount) => limit.saturating_sub(*amount),
            Refund(amount) => limit.saturating_add(*amount),
        }
    }
}