// SPDX-License-Identifier: MIT
pragma solidity 0.8.6;

import "../interfaces/v1_2/KeeperRegistryInterface1_2.sol";
import "../../interfaces/TypeAndVersionInterface.sol";
import "../../shared/interfaces/LinkTokenInterface.sol";
import "../../shared/access/ConfirmedOwner.sol";
import "../../shared/interfaces/IERC677Receiver.sol";

/**
 * @notice Contract to accept requests for upkeep registrations
 * @dev There are 2 registration workflows in this contract
 * Flow 1. auto approve OFF / manual registration - UI calls `register` function on this contract, this contract owner at a later time then manually
 *  calls `approve` to register upkeep and emit events to inform UI and others interested.
 * Flow 2. auto approve ON / real time registration - UI calls `register` function as before, which calls the `registerUpkeep` function directly on
 *  keeper registry and then emits approved event to finish the flow automatically without manual intervention.
 * The idea is to have same interface(functions,events) for UI or anyone using this contract irrespective of auto approve being enabled or not.
 * they can just listen to `RegistrationRequested` & `RegistrationApproved` events and know the status on registrations.
 */
contract KeeperRegistrar is TypeAndVersionInterface, ConfirmedOwner, IERC677Receiver {
  /**
   * DISABLED: No auto approvals, all new upkeeps should be approved manually.
   * ENABLED_SENDER_ALLOWLIST: Auto approvals for allowed senders subject to max allowed. Manual for rest.
   * ENABLED_ALL: Auto approvals for all new upkeeps subject to max allowed.
   */
  enum AutoApproveType {
    DISABLED,
    ENABLED_SENDER_ALLOWLIST,
    ENABLED_ALL
  }

  bytes4 private constant REGISTER_REQUEST_SELECTOR = this.register.selector;

  mapping(bytes32 => PendingRequest) private s_pendingRequests;

  LinkTokenInterface public immutable LINK;

  /**
   * @notice versions:
   * - KeeperRegistrar 1.1.0: Add functionality for sender allowlist in auto approve
   *                        : Remove rate limit and add max allowed for auto approve
   * - KeeperRegistrar 1.0.0: initial release
   */
  string public constant override typeAndVersion = "KeeperRegistrar 1.1.0";

  struct Config {
    AutoApproveType autoApproveConfigType;
    uint32 autoApproveMaxAllowed;
    uint32 approvedCount;
    KeeperRegistryBaseInterface keeperRegistry;
    uint96 minLINKJuels;
  }

  struct PendingRequest {
    address admin;
    uint96 balance;
  }

  Config private s_config;
  // Only applicable if s_config.configType is ENABLED_SENDER_ALLOWLIST
  mapping(address => bool) private s_autoApproveAllowedSenders;

  event RegistrationRequested(
    bytes32 indexed hash,
    string name,
    bytes encryptedEmail,
    address indexed upkeepContract,
    uint32 gasLimit,
    address adminAddress,
    bytes checkData,
    uint96 amount,
    uint8 indexed source
  );

  event RegistrationApproved(bytes32 indexed hash, string displayName, uint256 indexed upkeepId);

  event RegistrationRejected(bytes32 indexed hash);

  event AutoApproveAllowedSenderSet(address indexed senderAddress, bool allowed);

  event ConfigChanged(
    AutoApproveType autoApproveConfigType,
    uint32 autoApproveMaxAllowed,
    address keeperRegistry,
    uint96 minLINKJuels
  );

  error InvalidAdminAddress();
  error RequestNotFound();
  error HashMismatch();
  error OnlyAdminOrOwner();
  error InsufficientPayment();
  error RegistrationRequestFailed();
  error OnlyLink();
  error AmountMismatch();
  error SenderMismatch();
  error FunctionNotPermitted();
  error LinkTransferFailed(address to);
  error InvalidDataLength();

  /*
   * @param LINKAddress Address of Link token
   * @param autoApproveConfigType setting for auto-approve registrations
   * @param autoApproveMaxAllowed max number of registrations that can be auto approved
   * @param keeperRegistry keeper registry address
   * @param minLINKJuels minimum LINK that new registrations should fund their upkeep with
   */
  constructor(
    address LINKAddress,
    AutoApproveType autoApproveConfigType,
    uint16 autoApproveMaxAllowed,
    address keeperRegistry,
    uint96 minLINKJuels
  ) ConfirmedOwner(msg.sender) {
    LINK = LinkTokenInterface(LINKAddress);
    setRegistrationConfig(autoApproveConfigType, autoApproveMaxAllowed, keeperRegistry, minLINKJuels);
  }

  //EXTERNAL

  /**
   * @notice register can only be called through transferAndCall on LINK contract
   * @param name string of the upkeep to be registered
   * @param encryptedEmail email address of upkeep contact
   * @param upkeepContract address to perform upkeep on
   * @param gasLimit amount of gas to provide the target contract when performing upkeep
   * @param adminAddress address to cancel upkeep and withdraw remaining funds
   * @param checkData data passed to the contract when checking for upkeep
   * @param amount quantity of LINK upkeep is funded with (specified in Juels)
   * @param source application sending this request
   * @param sender address of the sender making the request
   */
  function register(
    string memory name,
    bytes calldata encryptedEmail,
    address upkeepContract,
    uint32 gasLimit,
    address adminAddress,
    bytes calldata checkData,
    uint96 amount,
    uint8 source,
    address sender
  ) external onlyLINK {
    if (adminAddress == address(0)) {
      revert InvalidAdminAddress();
    }
    bytes32 hash = keccak256(abi.encode(upkeepContract, gasLimit, adminAddress, checkData));

    emit RegistrationRequested(
      hash,
      name,
      encryptedEmail,
      upkeepContract,
      gasLimit,
      adminAddress,
      checkData,
      amount,
      source
    );

    Config memory config = s_config;
    if (_shouldAutoApprove(config, sender)) {
      s_config.approvedCount = config.approvedCount + 1;

      _approve(name, upkeepContract, gasLimit, adminAddress, checkData, amount, hash);
    } else {
      uint96 newBalance = s_pendingRequests[hash].balance + amount;
      s_pendingRequests[hash] = PendingRequest({admin: adminAddress, balance: newBalance});
    }
  }

  /**
   * @dev register upkeep on KeeperRegistry contract and emit RegistrationApproved event
   */
  function approve(
    string memory name,
    address upkeepContract,
    uint32 gasLimit,
    address adminAddress,
    bytes calldata checkData,
    bytes32 hash
  ) external onlyOwner {
    PendingRequest memory request = s_pendingRequests[hash];
    if (request.admin == address(0)) {
      revert RequestNotFound();
    }
    bytes32 expectedHash = keccak256(abi.encode(upkeepContract, gasLimit, adminAddress, checkData));
    if (hash != expectedHash) {
      revert HashMismatch();
    }
    delete s_pendingRequests[hash];
    _approve(name, upkeepContract, gasLimit, adminAddress, checkData, request.balance, hash);
  }

  /**
   * @notice cancel will remove a registration request and return the refunds to the msg.sender
   * @param hash the request hash
   */
  function cancel(bytes32 hash) external {
    PendingRequest memory request = s_pendingRequests[hash];
    if (!(msg.sender == request.admin || msg.sender == owner())) {
      revert OnlyAdminOrOwner();
    }
    if (request.admin == address(0)) {
      revert RequestNotFound();
    }
    delete s_pendingRequests[hash];
    bool success = LINK.transfer(msg.sender, request.balance);
    if (!success) {
      revert LinkTransferFailed(msg.sender);
    }
    emit RegistrationRejected(hash);
  }

  /**
   * @notice owner calls this function to set if registration requests should be sent directly to the Keeper Registry
   * @param autoApproveConfigType setting for auto-approve registrations
   *                   note: autoApproveAllowedSenders list persists across config changes irrespective of type
   * @param autoApproveMaxAllowed max number of registrations that can be auto approved
   * @param keeperRegistry new keeper registry address
   * @param minLINKJuels minimum LINK that new registrations should fund their upkeep with
   */
  function setRegistrationConfig(
    AutoApproveType autoApproveConfigType,
    uint16 autoApproveMaxAllowed,
    address keeperRegistry,
    uint96 minLINKJuels
  ) public onlyOwner {
    uint32 approvedCount = s_config.approvedCount;
    s_config = Config({
      autoApproveConfigType: autoApproveConfigType,
      autoApproveMaxAllowed: autoApproveMaxAllowed,
      approvedCount: approvedCount,
      minLINKJuels: minLINKJuels,
      keeperRegistry: KeeperRegistryBaseInterface(keeperRegistry)
    });

    emit ConfigChanged(autoApproveConfigType, autoApproveMaxAllowed, keeperRegistry, minLINKJuels);
  }

  /**
   * @notice owner calls this function to set allowlist status for senderAddress
   * @param senderAddress senderAddress to set the allowlist status for
   * @param allowed true if senderAddress needs to be added to allowlist, false if needs to be removed
   */
  function setAutoApproveAllowedSender(address senderAddress, bool allowed) external onlyOwner {
    s_autoApproveAllowedSenders[senderAddress] = allowed;

    emit AutoApproveAllowedSenderSet(senderAddress, allowed);
  }

  /**
   * @notice read the allowlist status of senderAddress
   * @param senderAddress address to read the allowlist status for
   */
  function getAutoApproveAllowedSender(address senderAddress) external view returns (bool) {
    return s_autoApproveAllowedSenders[senderAddress];
  }

  /**
   * @notice read the current registration configuration
   */
  function getRegistrationConfig()
    external
    view
    returns (
      AutoApproveType autoApproveConfigType,
      uint32 autoApproveMaxAllowed,
      uint32 approvedCount,
      address keeperRegistry,
      uint256 minLINKJuels
    )
  {
    Config memory config = s_config;
    return (
      config.autoApproveConfigType,
      config.autoApproveMaxAllowed,
      config.approvedCount,
      address(config.keeperRegistry),
      config.minLINKJuels
    );
  }

  /**
   * @notice gets the admin address and the current balance of a registration request
   */
  function getPendingRequest(bytes32 hash) external view returns (address, uint96) {
    PendingRequest memory request = s_pendingRequests[hash];
    return (request.admin, request.balance);
  }

  /**
   * @notice Called when LINK is sent to the contract via `transferAndCall`
   * @param sender Address of the sender transfering LINK
   * @param amount Amount of LINK sent (specified in Juels)
   * @param data Payload of the transaction
   */
  function onTokenTransfer(
    address sender,
    uint256 amount,
    bytes calldata data
  )
    external
    override
    onlyLINK
    permittedFunctionsForLINK(data)
    isActualAmount(amount, data)
    isActualSender(sender, data)
  {
    if (data.length < 292) revert InvalidDataLength();
    if (amount < s_config.minLINKJuels) {
      revert InsufficientPayment();
    }
    (bool success, ) = address(this).delegatecall(data);
    // calls register
    if (!success) {
      revert RegistrationRequestFailed();
    }
  }

  //PRIVATE

  /**
   * @dev register upkeep on KeeperRegistry contract and emit RegistrationApproved event
   */
  function _approve(
    string memory name,
    address upkeepContract,
    uint32 gasLimit,
    address adminAddress,
    bytes calldata checkData,
    uint96 amount,
    bytes32 hash
  ) private {
    KeeperRegistryBaseInterface keeperRegistry = s_config.keeperRegistry;

    // register upkeep
    uint256 upkeepId = keeperRegistry.registerUpkeep(upkeepContract, gasLimit, adminAddress, checkData);
    // fund upkeep
    bool success = LINK.transferAndCall(address(keeperRegistry), amount, abi.encode(upkeepId));
    if (!success) {
      revert LinkTransferFailed(address(keeperRegistry));
    }

    emit RegistrationApproved(hash, name, upkeepId);
  }

  /**
   * @dev verify sender allowlist if needed and check max limit
   */
  function _shouldAutoApprove(Config memory config, address sender) private returns (bool) {
    if (config.autoApproveConfigType == AutoApproveType.DISABLED) {
      return false;
    }
    if (
      config.autoApproveConfigType == AutoApproveType.ENABLED_SENDER_ALLOWLIST && (!s_autoApproveAllowedSenders[sender])
    ) {
      return false;
    }
    if (config.approvedCount < config.autoApproveMaxAllowed) {
      return true;
    }
    return false;
  }

  //MODIFIERS

  /**
   * @dev Reverts if not sent from the LINK token
   */
  modifier onlyLINK() {
    if (msg.sender != address(LINK)) {
      revert OnlyLink();
    }
    _;
  }

  /**
   * @dev Reverts if the given data does not begin with the `register` function selector
   * @param _data The data payload of the request
   */
  modifier permittedFunctionsForLINK(bytes memory _data) {
    bytes4 funcSelector;
    assembly {
      // solhint-disable-next-line avoid-low-level-calls
      funcSelector := mload(add(_data, 32)) // First 32 bytes contain length of data
    }
    if (funcSelector != REGISTER_REQUEST_SELECTOR) {
      revert FunctionNotPermitted();
    }
    _;
  }

  /**
   * @dev Reverts if the actual amount passed does not match the expected amount
   * @param expected amount that should match the actual amount
   * @param data bytes
   */
  modifier isActualAmount(uint256 expected, bytes memory data) {
    uint256 actual;
    assembly {
      actual := mload(add(data, 228))
    }
    if (expected != actual) {
      revert AmountMismatch();
    }
    _;
  }

  /**
   * @dev Reverts if the actual sender address does not match the expected sender address
   * @param expected address that should match the actual sender address
   * @param data bytes
   */
  modifier isActualSender(address expected, bytes memory data) {
    address actual;
    assembly {
      actual := mload(add(data, 292))
    }
    if (expected != actual) {
      revert SenderMismatch();
    }
    _;
  }
}