// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.8.0 <0.9.0;

import { IERC20 } from "@openzeppelin/contracts/token/ERC20/IERC20.sol";

// See https://github.com/curvefi/curve-burners/blob/main/contracts/burners/CowSwapBurner.vy#L44:L56
struct GPv2Order {
    IERC20 sellToken;
    IERC20 buyToken;
    address receiver;
    uint256 sellAmount;
    uint256 buyAmount;
    uint32 validTo;
    bytes32 appData;
    uint256 feeAmount;
    bytes32 kind;
    bool partiallyFillable;
    bytes32 sellTokenBalance;
    bytes32 buyTokenBalance;
}

/**
 * @notice Conditional Order Interface - verify a Cow order.
 * @author CoW Protocol Developers + mfw78 <mfw78@rndlabs.xyz>
 */
interface ICowConditionalOrder {
    /**
     * @notice This struct is used to uniquely identify a conditional order for an owner.
     * @dev H(handler || salt || staticData) **MUST** be unique for an owner.
     * @param handler The contract implementing the conditional order logic
     * @param salt Allows for multiple conditional orders of the same type and data (currently unused)
     * @param staticData Data available to ALL discrete orders created by the conditional order
     */
    struct ConditionalOrderParams {
        ICowConditionalOrder handler;
        bytes32 salt;
        bytes staticData;
    }

    /**
     * @notice This error is returned by the `getTradeableOrder` function if the order conditions are not met.
     * @param reason Text explaining the reason the order is invalid
     */
    error OrderNotValid(string reason);

    // Errors specific to polling (interpreted by the off-chain Watchtower).

    /**
     * @notice Polling should be retried at the next block.
     * @param reason Text description of the reason it should be retried
     */
    error PollTryNextBlock(string reason);

    /**
     * @notice Polling should be retried at a specific block number.
     * @param blockNumber The block number when polling should resume
     * @param reason Text description of the reason it should be retried
     */
    error PollTryAtBlock(uint256 blockNumber, string reason);

    /**
     * @notice Polling should be retried at a specific epoch (unix timestamp).
     * @param timestamp The unix timestamp when polling should resume
     * @param reason Text description of the reason it should be retried
     */
    error PollTryAtEpoch(uint256 timestamp, string reason);

    /**
     * @notice The conditional order should not be polled again (i.e., deleted).
     * @param reason Text description of the reason it should be deleted
     */
    error PollNever(string reason);

    /**
     * @notice Verify that a given discrete order is valid.
     * @dev Used in combination with `isValidSafeSignature` to verify that the order is signed by the Safe.
     * **MUST** revert if any order conditions are not met. The `order` parameter is ignored / not validated by the
     * `ICowConditionalOrderGenerator` implementation. This parameter is included to allow more granular control over
     * the order verification logic, and to allow a watchtower / user to propose a discrete order without it being
     * generated by on-chain logic. See https://docs.cow.fi/cow-protocol/reference/contracts/periphery/composable-cow.
     *
     * @param owner The owner of the order (usually a contract)
     * @param sender The `msg.sender` calling `isValidSignature`
     * @param _hash `EIP712` order digest
     * @param domainSeparator `EIP712` domain separator
     * @param ctx See docs.cow.fi/cow-protocol/reference/contracts/periphery/composable-cow#execution-context
     * @param staticInput Conditional order type-specific data known at time of creation for all discrete orders
     * @param offchainInput Type-specific data NOT known at time of creation for a specific discrete order (or zero)
     * @param order The proposed discrete order's `GPv2Order` data struct
     */
    function verify(
        address owner,
        address sender,
        bytes32 _hash,
        bytes32 domainSeparator,
        bytes32 ctx,
        bytes calldata staticInput,
        bytes calldata offchainInput,
        GPv2Order calldata order
    ) external view;
}