// SPDX-License-Identifier: GPL-3.0-or-later
// This program 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.

// This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.8.0;

import '@mimic-fi/helpers/contracts/math/FixedPoint.sol';
import '@mimic-fi/helpers/contracts/utils/Denominations.sol';
import '@mimic-fi/v3-authorizer/contracts/Authorized.sol';
import '@mimic-fi/v3-price-oracle/contracts/interfaces/IPriceOracle.sol';
import '@mimic-fi/v3-smart-vault/contracts/interfaces/ISmartVault.sol';

import '../interfaces/base/IBaseTask.sol';

/**
 * @title BaseTask
 * @dev Base task implementation with a Smart Vault reference and using the Authorizer
 */
abstract contract BaseTask is IBaseTask, Authorized {
    // Smart Vault reference
    address public override smartVault;

    // Optional balance connector id for the previous task in the workflow
    bytes32 internal previousBalanceConnectorId;

    // Optional balance connector id for the next task in the workflow
    bytes32 internal nextBalanceConnectorId;

    /**
     * @dev Base task config. Only used in the initializer.
     * @param smartVault Address of the smart vault this task will reference, it cannot be changed once set
     * @param previousBalanceConnectorId Balance connector id for the previous task in the workflow
     * @param nextBalanceConnectorId Balance connector id for the next task in the workflow
     */
    struct BaseConfig {
        address smartVault;
        bytes32 previousBalanceConnectorId;
        bytes32 nextBalanceConnectorId;
    }

    /**
     * @dev Initializes the base task. It does call upper contracts initializers.
     * @param config Base task config
     */
    function __BaseTask_init(BaseConfig memory config) internal onlyInitializing {
        __Authorized_init(ISmartVault(config.smartVault).authorizer());
        __BaseTask_init_unchained(config);
    }

    /**
     * @dev Initializes the base task. It does not call upper contracts initializers.
     * @param config Base task config
     */
    function __BaseTask_init_unchained(BaseConfig memory config) internal onlyInitializing {
        smartVault = config.smartVault;
        _setBalanceConnectors(config.previousBalanceConnectorId, config.nextBalanceConnectorId);
    }

    /**
     * @dev Tells the address from where the token amounts to execute this task are fetched.
     * Since by default tasks are supposed to use balance connectors, the tokens source has to be the smart vault.
     * In case a task does not need to rely on a previous balance connector, it must override this function to specify
     * where it is getting its tokens from.
     */
    function getTokensSource() external view virtual override returns (address) {
        return smartVault;
    }

    /**
     * @dev Tells the amount a task should use for a token. By default tasks are expected to use balance connectors.
     * In case a task relies on an external tokens source, it must override how the task amount is calculated.
     * @param token Address of the token being queried
     */
    function getTaskAmount(address token) public view virtual override returns (uint256) {
        return ISmartVault(smartVault).getBalanceConnector(previousBalanceConnectorId, token);
    }

    /**
     * @dev Tells the previous and next balance connectors id of the previous task in the workflow
     */
    function getBalanceConnectors() external view returns (bytes32 previous, bytes32 next) {
        previous = previousBalanceConnectorId;
        next = nextBalanceConnectorId;
    }

    /**
     * @dev Sets the balance connectors
     * @param previous Balance connector id of the previous task in the workflow
     * @param next Balance connector id of the next task in the workflow
     */
    function setBalanceConnectors(bytes32 previous, bytes32 next) external override authP(authParams(previous, next)) {
        _setBalanceConnectors(previous, next);
    }

    /**
     * @dev Tells the wrapped native token address if the given address is the native token
     * @param token Address of the token to be checked
     */
    function _wrappedIfNative(address token) internal view returns (address) {
        return Denominations.isNativeToken(token) ? _wrappedNativeToken() : token;
    }

    /**
     * @dev Tells whether a token is the native or the wrapped native token
     * @param token Address of the token to be checked
     */
    function _isWrappedOrNative(address token) internal view returns (bool) {
        return Denominations.isNativeToken(token) || token == _wrappedNativeToken();
    }

    /**
     * @dev Tells the wrapped native token address
     */
    function _wrappedNativeToken() internal view returns (address) {
        return ISmartVault(smartVault).wrappedNativeToken();
    }

    /**
     * @dev Fetches a base/quote price from the smart vault's price oracle
     * @param base Token to rate
     * @param quote Token used for the price rate
     */
    function _getPrice(address base, address quote) internal view virtual returns (uint256) {
        address priceOracle = ISmartVault(smartVault).priceOracle();
        if (priceOracle == address(0)) revert TaskSmartVaultPriceOracleNotSet(smartVault);
        bytes memory extraCallData = _decodeExtraCallData();
        return
            extraCallData.length == 0
                ? IPriceOracle(priceOracle).getPrice(_wrappedIfNative(base), _wrappedIfNative(quote))
                : IPriceOracle(priceOracle).getPrice(_wrappedIfNative(base), _wrappedIfNative(quote), extraCallData);
    }

    /**
     * @dev Before base task hook
     */
    function _beforeBaseTask(address token, uint256 amount) internal virtual {
        _decreaseBalanceConnector(token, amount);
    }

    /**
     * @dev After base task hook
     */
    function _afterBaseTask(address, uint256) internal virtual {
        emit Executed();
    }

    /**
     * @dev Decreases the previous balance connector in the smart vault if defined
     * @param token Address of the token to update the previous balance connector of
     * @param amount Amount to be updated
     */
    function _decreaseBalanceConnector(address token, uint256 amount) internal {
        if (previousBalanceConnectorId != bytes32(0)) {
            ISmartVault(smartVault).updateBalanceConnector(previousBalanceConnectorId, token, amount, false);
        }
    }

    /**
     * @dev Increases the next balance connector in the smart vault if defined
     * @param token Address of the token to update the next balance connector of
     * @param amount Amount to be updated
     */
    function _increaseBalanceConnector(address token, uint256 amount) internal {
        if (nextBalanceConnectorId != bytes32(0)) {
            ISmartVault(smartVault).updateBalanceConnector(nextBalanceConnectorId, token, amount, true);
        }
    }

    /**
     * @dev Sets the balance connectors
     * @param previous Balance connector id of the previous task in the workflow
     * @param next Balance connector id of the next task in the workflow
     */
    function _setBalanceConnectors(bytes32 previous, bytes32 next) internal virtual {
        if (previous == next && previous != bytes32(0)) revert TaskSameBalanceConnectors(previous);
        previousBalanceConnectorId = previous;
        nextBalanceConnectorId = next;
        emit BalanceConnectorsSet(previous, next);
    }

    /**
     * @dev Decodes any potential extra calldata stored in the calldata space. Tasks relying on the extra calldata
     * pattern, assume that the last word of the calldata stores the extra calldata length so it can be decoded. Note
     * that tasks relying on this pattern must contemplate this function may return bogus data if no extra calldata
     * was given.
     */
    function _decodeExtraCallData() private pure returns (bytes memory data) {
        uint256 length = uint256(_decodeLastCallDataWord());
        if (msg.data.length < length) return new bytes(0);
        data = new bytes(length);
        assembly {
            calldatacopy(add(data, 0x20), sub(sub(calldatasize(), length), 0x20), length)
        }
    }

    /**
     * @dev Returns the last calldata word. This function returns zero if the calldata is not long enough.
     */
    function _decodeLastCallDataWord() private pure returns (bytes32 result) {
        if (msg.data.length < 36) return bytes32(0);
        assembly {
            result := calldataload(sub(calldatasize(), 0x20))
        }
    }
}