// SPDX-License-Identifier: MIT
/*
 * MIT License
 * ===========
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 */

pragma solidity 0.7.6;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "./IPendleBaseToken.sol";
import "./IPendleForge.sol";

interface IPendleYieldToken is IERC20, IPendleBaseToken {
    /**
     * @notice Emitted when burning OT or XYT tokens.
     * @param user The address performing the burn.
     * @param amount The amount to be burned.
     **/
    event Burn(address indexed user, uint256 amount);

    /**
     * @notice Emitted when minting OT or XYT tokens.
     * @param user The address performing the mint.
     * @param amount The amount to be minted.
     **/
    event Mint(address indexed user, uint256 amount);

    /**
     * @notice Burns OT or XYT tokens from user, reducing the total supply.
     * @param user The address performing the burn.
     * @param amount The amount to be burned.
     **/
    function burn(address user, uint256 amount) external;

    /**
     * @notice Mints new OT or XYT tokens for user, increasing the total supply.
     * @param user The address to send the minted tokens.
     * @param amount The amount to be minted.
     **/
    function mint(address user, uint256 amount) external;

    /**
     * @notice Gets the forge address of the PendleForge contract for this yield token.
     * @return Retuns the forge address.
     **/
    function forge() external view returns (IPendleForge);

    /**
     * @notice Returns the address of the underlying asset.
     * @return Returns the underlying asset address.
     **/
    function underlyingAsset() external view returns (address);

    /**
     * @notice Returns the address of the underlying yield token.
     * @return Returns the underlying yield token address.
     **/
    function underlyingYieldToken() external view returns (address);

    /**
     * @notice let the router approve itself to spend OT/XYT/LP from any wallet
     * @param user user to approve
     **/
    function approveRouter(address user) external;
}