// This file is part of Astar.

// Copyright (C) Stake Technologies Pte.Ltd.
// SPDX-License-Identifier: GPL-3.0-or-later

// Astar 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.

// Astar 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 Astar. If not, see <http://www.gnu.org/licenses/>.

// Copyright 2019-2022 PureStake Inc.
// Copyright 2022      Stake Technologies
// This file is part of AssetsERC20 package, originally developed by Purestake Inc.
// AssetsERC20 package used in Astar Network in terms of GPLv3.
//
// AssetsERC20 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.

// AssetsERC20 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 AssetsERC20.  If not, see <http://www.gnu.org/licenses/>.

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

use fp_evm::{ExitError, PrecompileHandle};
use frame_support::{
    dispatch::{GetDispatchInfo, PostDispatchInfo},
    traits::{
        fungibles::{
            approvals::Inspect as ApprovalInspect, metadata::Inspect as MetadataInspect, Inspect,
        },
        OriginTrait,
    },
    DefaultNoBound,
};
use pallet_evm::AddressMapping;
use precompile_utils::prelude::*;
use sp_runtime::traits::{Bounded, Dispatchable, StaticLookup};

use sp_core::{Get, MaxEncodedLen, H160, U256};
use sp_std::{
    convert::{TryFrom, TryInto},
    marker::PhantomData,
};

#[cfg(test)]
mod mock;
#[cfg(test)]
mod tests;

/// Solidity selector of the Transfer log, which is the Keccak of the Log signature.
pub const SELECTOR_LOG_TRANSFER: [u8; 32] = keccak256!("Transfer(address,address,uint256)");

/// Solidity selector of the Approval log, which is the Keccak of the Log signature.
pub const SELECTOR_LOG_APPROVAL: [u8; 32] = keccak256!("Approval(address,address,uint256)");

/// Alias for the Balance type for the provided Runtime and Instance.
pub type BalanceOf<Runtime, Instance = ()> = <Runtime as pallet_assets::Config<Instance>>::Balance;

/// Alias for the Asset Id type for the provided Runtime and Instance.
pub type AssetIdOf<Runtime, Instance = ()> = <Runtime as pallet_assets::Config<Instance>>::AssetId;

/// This trait ensure we can convert EVM address to AssetIds
/// We will require Runtime to have this trait implemented
pub trait AddressToAssetId<AssetId> {
    // Get assetId from address
    fn address_to_asset_id(address: H160) -> Option<AssetId>;

    // Get address from AssetId
    fn asset_id_to_address(asset_id: AssetId) -> H160;
}

/// The following distribution has been decided for the precompiles
/// 0-1023: Ethereum Mainnet Precompiles
/// 1024-2047 Precompiles that are not in Ethereum Mainnet but are neither Astar specific
/// 2048-4095 Astar specific precompiles
/// Asset precompiles can only fall between
///     0xFFFFFFFF00000000000000000000000000000000 - 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
/// The precompile for AssetId X, where X is a u128 (i.e.16 bytes), if 0XFFFFFFFF + Bytes(AssetId)
/// In order to route the address to Erc20AssetsPrecompile<R>, we first check whether the AssetId
/// exists in pallet-assets
/// We cannot do this right now, so instead we check whether the total supply is zero. If so, we
/// do not route to the precompiles

/// This means that every address that starts with 0xFFFFFFFF will go through an additional db read,
/// but the probability for this to happen is 2^-32 for random addresses
#[derive(Clone, DefaultNoBound)]
pub struct Erc20AssetsPrecompileSet<Runtime, Instance: 'static = ()>(
    PhantomData<(Runtime, Instance)>,
);

impl<Runtime, Instance> Erc20AssetsPrecompileSet<Runtime, Instance> {
    pub fn new() -> Self {
        Self(PhantomData)
    }
}

#[precompile_utils::precompile]
#[precompile::precompile_set]
#[precompile::test_concrete_types(mock::Runtime, ())]
impl<Runtime, Instance> Erc20AssetsPrecompileSet<Runtime, Instance>
where
    Instance: 'static,
    Runtime: pallet_assets::Config<Instance> + pallet_evm::Config + frame_system::Config,
    Runtime::RuntimeCall: Dispatchable<PostInfo = PostDispatchInfo> + GetDispatchInfo,
    Runtime::RuntimeCall: From<pallet_assets::Call<Runtime, Instance>>,
    <Runtime::RuntimeCall as Dispatchable>::RuntimeOrigin: From<Option<Runtime::AccountId>>,
    BalanceOf<Runtime, Instance>: TryFrom<U256> + Into<U256> + solidity::Codec,
    Runtime: AddressToAssetId<AssetIdOf<Runtime, Instance>>,
    <<Runtime as frame_system::Config>::RuntimeCall as Dispatchable>::RuntimeOrigin: OriginTrait,
    AssetIdOf<Runtime, Instance>: Copy,
{
    /// PrecompileSet discriminant. Allows to knows if the address maps to an asset id,
    /// and if this is the case which one.
    #[precompile::discriminant]
    fn discriminant(address: H160, gas: u64) -> DiscriminantResult<AssetIdOf<Runtime, Instance>> {
        let extra_cost = RuntimeHelper::<Runtime>::db_read_gas_cost();
        if gas < extra_cost {
            return DiscriminantResult::OutOfGas;
        }

        let asset_id = match Runtime::address_to_asset_id(address) {
            Some(asset_id) => asset_id,
            None => return DiscriminantResult::None(extra_cost),
        };

        if pallet_assets::Pallet::<Runtime, Instance>::maybe_total_supply(asset_id).is_some() {
            DiscriminantResult::Some(asset_id, extra_cost)
        } else {
            DiscriminantResult::None(extra_cost)
        }
    }

    #[precompile::public("totalSupply()")]
    #[precompile::view]
    fn total_supply(
        asset_id: AssetIdOf<Runtime, Instance>,
        handle: &mut impl PrecompileHandle,
    ) -> EvmResult<U256> {
        // TODO: benchmark this function so we can measure ref time & PoV correctly
        // Storage item: Asset:
        // Blake2_128(16) + AssetId(16) + AssetDetails((4 * AccountId(32)) + (3 * Balance(16)) + 15)
        handle.record_db_read::<Runtime>(223)?;

        Ok(pallet_assets::Pallet::<Runtime, Instance>::total_issuance(asset_id).into())
    }

    #[precompile::public("balanceOf(address)")]
    #[precompile::view]
    fn balance_of(
        asset_id: AssetIdOf<Runtime, Instance>,
        handle: &mut impl PrecompileHandle,
        who: Address,
    ) -> EvmResult<U256> {
        // TODO: benchmark this function so we can measure ref time & PoV correctly
        // Storage item: Account:
        // Blake2_128(16) + AssetId(16) + Blake2_128(16) + AccountId(32) + AssetAccount(19 + Extra)
        handle.record_db_read::<Runtime>(
            99 + <Runtime as pallet_assets::Config<Instance>>::Extra::max_encoded_len(),
        )?;

        let who: H160 = who.into();

        // Fetch info.
        let amount: U256 = {
            let who: Runtime::AccountId = Runtime::AddressMapping::into_account_id(who);
            pallet_assets::Pallet::<Runtime, Instance>::balance(asset_id, &who).into()
        };

        // Build output.
        Ok(amount)
    }

    #[precompile::public("allowance(address,address)")]
    #[precompile::view]
    fn allowance(
        asset_id: AssetIdOf<Runtime, Instance>,
        handle: &mut impl PrecompileHandle,
        owner: Address,
        spender: Address,
    ) -> EvmResult<U256> {
        // TODO: benchmark this function so we can measure ref time & PoV correctly
        // Storage item: Approvals:
        // Blake2_128(16) + AssetId(16) + (2 * Blake2_128(16) + AccountId(32)) + Approval(32)
        handle.record_db_read::<Runtime>(148)?;

        let owner: H160 = owner.into();
        let spender: H160 = spender.into();

        // Fetch info.
        let amount: U256 = {
            let owner: Runtime::AccountId = Runtime::AddressMapping::into_account_id(owner);
            let spender: Runtime::AccountId = Runtime::AddressMapping::into_account_id(spender);

            // Fetch info.
            pallet_assets::Pallet::<Runtime, Instance>::allowance(asset_id, &owner, &spender).into()
        };

        // Build output.
        Ok(amount)
    }

    #[precompile::public("approve(address,uint256)")]
    fn approve(
        asset_id: AssetIdOf<Runtime, Instance>,
        handle: &mut impl PrecompileHandle,
        spender: Address,
        value: U256,
    ) -> EvmResult<bool> {
        handle.record_log_costs_manual(3, 32)?;

        let spender: H160 = spender.into();

        Self::approve_inner(asset_id, handle, handle.context().caller, spender, value)?;

        log3(
            handle.context().address,
            SELECTOR_LOG_APPROVAL,
            handle.context().caller,
            spender,
            solidity::encode_event_data(value),
        )
        .record(handle)?;

        // Build output.
        Ok(true)
    }

    fn approve_inner(
        asset_id: AssetIdOf<Runtime, Instance>,
        handle: &mut impl PrecompileHandle,
        owner: H160,
        spender: H160,
        value: U256,
    ) -> EvmResult {
        let owner = Runtime::AddressMapping::into_account_id(owner);
        let spender: Runtime::AccountId = Runtime::AddressMapping::into_account_id(spender);
        // Amount saturate if too high.
        let amount: BalanceOf<Runtime, Instance> =
            value.try_into().unwrap_or_else(|_| Bounded::max_value());

        // Storage item: Approvals:
        // Blake2_128(16) + AssetId(16) + (2 * Blake2_128(16) + AccountId(32)) + Approval(32)
        handle.record_db_read::<Runtime>(148)?;

        // If previous approval exists, we need to clean it
        if pallet_assets::Pallet::<Runtime, Instance>::allowance(asset_id, &owner, &spender)
            != 0u32.into()
        {
            RuntimeHelper::<Runtime>::try_dispatch(
                handle,
                Some(owner.clone()).into(),
                pallet_assets::Call::<Runtime, Instance>::cancel_approval {
                    id: asset_id.into(),
                    delegate: Runtime::Lookup::unlookup(spender.clone()),
                },
            )?;
        }
        // Dispatch call (if enough gas).
        RuntimeHelper::<Runtime>::try_dispatch(
            handle,
            Some(owner).into(),
            pallet_assets::Call::<Runtime, Instance>::approve_transfer {
                id: asset_id.into(),
                delegate: Runtime::Lookup::unlookup(spender),
                amount,
            },
        )?;

        Ok(())
    }

    #[precompile::public("transfer(address,uint256)")]
    fn transfer(
        asset_id: AssetIdOf<Runtime, Instance>,
        handle: &mut impl PrecompileHandle,
        to: Address,
        value: U256,
    ) -> EvmResult<bool> {
        handle.record_log_costs_manual(3, 32)?;

        let to: H160 = to.into();
        let value = Self::u256_to_amount(value).in_field("value")?;

        // Build call with origin.
        {
            let origin = Runtime::AddressMapping::into_account_id(handle.context().caller);
            let to = Runtime::AddressMapping::into_account_id(to);

            // Dispatch call (if enough gas).
            RuntimeHelper::<Runtime>::try_dispatch(
                handle,
                Some(origin).into(),
                pallet_assets::Call::<Runtime, Instance>::transfer {
                    id: asset_id.into(),
                    target: Runtime::Lookup::unlookup(to),
                    amount: value,
                },
            )?;
        }

        log3(
            handle.context().address,
            SELECTOR_LOG_TRANSFER,
            handle.context().caller,
            to,
            solidity::encode_event_data(value),
        )
        .record(handle)?;

        Ok(true)
    }

    #[precompile::public("transferFrom(address,address,uint256)")]
    fn transfer_from(
        asset_id: AssetIdOf<Runtime, Instance>,
        handle: &mut impl PrecompileHandle,
        from: Address,
        to: Address,
        value: U256,
    ) -> EvmResult<bool> {
        handle.record_log_costs_manual(3, 32)?;

        let from: H160 = from.into();
        let to: H160 = to.into();
        let value = Self::u256_to_amount(value).in_field("value")?;

        {
            let caller: Runtime::AccountId =
                Runtime::AddressMapping::into_account_id(handle.context().caller);
            let from: Runtime::AccountId = Runtime::AddressMapping::into_account_id(from.clone());
            let to: Runtime::AccountId = Runtime::AddressMapping::into_account_id(to);

            // If caller is "from", it can spend as much as it wants from its own balance.
            if caller != from {
                // Dispatch call (if enough gas).
                RuntimeHelper::<Runtime>::try_dispatch(
                    handle,
                    Some(caller).into(),
                    pallet_assets::Call::<Runtime, Instance>::transfer_approved {
                        id: asset_id.into(),
                        owner: Runtime::Lookup::unlookup(from),
                        destination: Runtime::Lookup::unlookup(to),
                        amount: value,
                    },
                )?;
            } else {
                // Dispatch call (if enough gas).
                RuntimeHelper::<Runtime>::try_dispatch(
                    handle,
                    Some(from).into(),
                    pallet_assets::Call::<Runtime, Instance>::transfer {
                        id: asset_id.into(),
                        target: Runtime::Lookup::unlookup(to),
                        amount: value,
                    },
                )?;
            }
        }

        log3(
            handle.context().address,
            SELECTOR_LOG_TRANSFER,
            from,
            to,
            solidity::encode_event_data(value),
        )
        .record(handle)?;

        // Build output.
        Ok(true)
    }

    #[precompile::public("name()")]
    #[precompile::view]
    fn name(
        asset_id: AssetIdOf<Runtime, Instance>,
        handle: &mut impl PrecompileHandle,
    ) -> EvmResult<UnboundedBytes> {
        // Storage item: Metadata:
        // Blake2_128(16) + AssetId(16) + AssetMetadata[deposit(16) + name(StringLimit)
        // + symbol(StringLimit) + decimals(1) + is_frozen(1)]
        handle.record_db_read::<Runtime>(
            50 + (2 * <Runtime as pallet_assets::Config<Instance>>::StringLimit::get()) as usize,
        )?;

        let name = pallet_assets::Pallet::<Runtime, Instance>::name(asset_id)
            .as_slice()
            .into();

        Ok(name)
    }

    #[precompile::public("symbol()")]
    #[precompile::view]
    fn symbol(
        asset_id: AssetIdOf<Runtime, Instance>,
        handle: &mut impl PrecompileHandle,
    ) -> EvmResult<UnboundedBytes> {
        // Storage item: Metadata:
        // Blake2_128(16) + AssetId(16) + AssetMetadata[deposit(16) + name(StringLimit)
        // + symbol(StringLimit) + decimals(1) + is_frozen(1)]
        handle.record_db_read::<Runtime>(
            50 + (2 * <Runtime as pallet_assets::Config<Instance>>::StringLimit::get()) as usize,
        )?;

        let symbol = pallet_assets::Pallet::<Runtime, Instance>::symbol(asset_id)
            .as_slice()
            .into();

        Ok(symbol)
    }

    #[precompile::public("decimals()")]
    #[precompile::view]
    fn decimals(
        asset_id: AssetIdOf<Runtime, Instance>,
        handle: &mut impl PrecompileHandle,
    ) -> EvmResult<u8> {
        // Storage item: Metadata:
        // Blake2_128(16) + AssetId(16) + AssetMetadata[deposit(16) + name(StringLimit)
        // + symbol(StringLimit) + decimals(1) + is_frozen(1)]
        handle.record_db_read::<Runtime>(
            50 + (2 * <Runtime as pallet_assets::Config<Instance>>::StringLimit::get()) as usize,
        )?;

        Ok(pallet_assets::Pallet::<Runtime, Instance>::decimals(
            asset_id,
        ))
    }

    #[precompile::public("minimumBalance()")]
    #[precompile::view]
    fn minimum_balance(
        asset_id: AssetIdOf<Runtime, Instance>,
        handle: &mut impl PrecompileHandle,
    ) -> EvmResult<U256> {
        // TODO: benchmark this function so we can measure ref time & PoV correctly
        // Storage item: AssetDetails:
        // Blake2_128(16) + AssetDetails((4 * AccountId(32)) + (3 * Balance(16)) + 15)
        handle.record_db_read::<Runtime>(207)?;

        Ok(pallet_assets::Pallet::<Runtime, Instance>::minimum_balance(asset_id).into())
    }

    #[precompile::public("mint(address,uint256)")]
    fn mint(
        asset_id: AssetIdOf<Runtime, Instance>,
        handle: &mut impl PrecompileHandle,
        to: Address,
        value: U256,
    ) -> EvmResult<bool> {
        handle.record_log_costs_manual(3, 32)?;

        let to: H160 = to.into();
        let value = Self::u256_to_amount(value).in_field("value")?;

        // Build call with origin.
        {
            let origin = Runtime::AddressMapping::into_account_id(handle.context().caller);
            let to = Runtime::AddressMapping::into_account_id(to);

            // Dispatch call (if enough gas).
            RuntimeHelper::<Runtime>::try_dispatch(
                handle,
                Some(origin).into(),
                pallet_assets::Call::<Runtime, Instance>::mint {
                    id: asset_id.into(),
                    beneficiary: Runtime::Lookup::unlookup(to),
                    amount: value,
                },
            )?;
        }

        log3(
            handle.context().address,
            SELECTOR_LOG_TRANSFER,
            H160::default(),
            to,
            solidity::encode_event_data(value),
        )
        .record(handle)?;

        Ok(true)
    }

    #[precompile::public("burn(address,uint256)")]
    fn burn(
        asset_id: AssetIdOf<Runtime, Instance>,
        handle: &mut impl PrecompileHandle,
        from: Address,
        value: U256,
    ) -> EvmResult<bool> {
        handle.record_log_costs_manual(3, 32)?;

        let from: H160 = from.into();
        let value = Self::u256_to_amount(value).in_field("value")?;

        // Build call with origin.
        {
            let origin = Runtime::AddressMapping::into_account_id(handle.context().caller);
            let from = Runtime::AddressMapping::into_account_id(from);

            // Dispatch call (if enough gas).
            RuntimeHelper::<Runtime>::try_dispatch(
                handle,
                Some(origin).into(),
                pallet_assets::Call::<Runtime, Instance>::burn {
                    id: asset_id.into(),
                    who: Runtime::Lookup::unlookup(from),
                    amount: value,
                },
            )?;
        }

        log3(
            handle.context().address,
            SELECTOR_LOG_TRANSFER,
            from,
            H160::default(),
            solidity::encode_event_data(value),
        )
        .record(handle)?;

        Ok(true)
    }

    fn u256_to_amount(value: U256) -> MayRevert<BalanceOf<Runtime, Instance>> {
        value
            .try_into()
            .map_err(|_| RevertReason::value_is_too_large("balance type").into())
    }
}