// SPDX-License-Identifier: Apache-2.0
pragma solidity >=0.5.0 <0.9.0;
pragma experimental ABIEncoderV2;

import "../common/HederaResponseCodes.sol";
import "./IHederaAccountService.sol";

abstract contract HederaAccountService {
    address constant HASPrecompileAddress = address(0x16a);

    /// Returns the amount of hbars that the spender has been authorized to spend on behalf of the owner.
    /// @param owner The account that has authorized the spender
    /// @param spender The account that has been authorized by the owner
    /// @return responseCode The response code for the status of the request. SUCCESS is 22.
    /// @return amount The amount of hbar that the spender has been authorized to spend on behalf of the owner.
    function hbarAllowance(address owner, address spender) internal returns (int64 responseCode, int256 amount)
    {
        (bool success, bytes memory result) = HASPrecompileAddress.call(
            abi.encodeWithSelector(IHederaAccountService.hbarAllowance.selector,
                owner, spender));
        (responseCode, amount) = success ? abi.decode(result, (int32, int256)) : (HederaResponseCodes.UNKNOWN, (int256)(0));
    }


    /// Allows spender to withdraw hbars from the owner account multiple times, up to the value amount. If this function is called
    /// again it overwrites the current allowance with the new amount.
    /// @param owner The owner of the hbars
    /// @param spender the account address authorized to spend
    /// @param amount the amount of hbars authorized to spend.
    /// @return responseCode The response code for the status of the request. SUCCESS is 22.
    function hbarApprove(address owner, address spender, int256 amount) internal returns (int64 responseCode)
    {
        (bool success, bytes memory result) = HASPrecompileAddress.call(
            abi.encodeWithSelector(IHederaAccountService.hbarApprove.selector,
                owner, spender, amount));
        responseCode = success ? abi.decode(result, (int32)) : HederaResponseCodes.UNKNOWN;
    }

    /// Returns the EVM address alias for a given Hedera account.
    /// @param accountNumAlias The Hedera account number alias to lookup. Must satisfy all of the following:
    ///                         - Must be in long-zero format (0x000...0<account_num>)
    ///                         - Must reference an existing Hedera account
    ///                         - Referenced account must have an associated EVM address alias
    /// @return responseCode The response code indicating the status of the request:
    ///                         - SUCCESS (22) if successful
    ///                         - INVALID_ACCOUNT_ID (15) if any validation of the accountNumAlias fails
    ///                         - UNKNOWN (21) if the precompile call fails
    /// @return evmAddressAlias The EVM address alias associated with the Hedera account, or address(0) if the request fails
    function getEvmAddressAlias(address accountNumAlias) internal returns (int64 responseCode, address evmAddressAlias)
    {
        (bool success, bytes memory result) = HASPrecompileAddress.call(
            abi.encodeWithSelector(IHederaAccountService.getEvmAddressAlias.selector, accountNumAlias));
        (responseCode, evmAddressAlias) = success ? abi.decode(result, (int32, address)) : (HederaResponseCodes.UNKNOWN, address(0));
    }

    /// Returns the Hedera Account ID (as account num alias) for the given EVM address alias
    /// @param evmAddressAlias The EVM address alias to get the Hedera account for. Must satisfy all of the following:
    ///                         - Must be in EVM format (not a long-zero address)
    ///                         - Must reference an existing Hedera account
    ///                         - Referenced account must have an associated account num alias (long-zero format)
    /// @return responseCode The response code indicating the status of the request:
    ///                         - SUCCESS (22) if successful
    ///                         - INVALID_SOLIDITY_ADDRESS (29) if any validation of the evmAddressAlias fails
    ///                         - UNKNOWN (21) if the precompile call fails
    /// @return accountNumAlias The Hedera account's num alias in long-zero format, or address(0) if the request fails
    function getHederaAccountNumAlias(address evmAddressAlias) internal returns (int64 responseCode, address accountNumAlias) {
        (bool success, bytes memory result) = HASPrecompileAddress.call(
            abi.encodeWithSelector(IHederaAccountService.getHederaAccountNumAlias.selector, evmAddressAlias));
        (responseCode, accountNumAlias) = success ? abi.decode(result, (int32, address)) : (HederaResponseCodes.UNKNOWN, address(0));
    }

    /// Returns true iff a Hedera account num alias or EVM address alias.
    /// @param addr Some 20-byte address.
    /// @return responseCode The response code for the status of the request. SUCCESS is 22.
    /// @return response true iff addr is a Hedera account num alias or an EVM address alias (and false otherwise).
    function isValidAlias(address addr) internal returns (int64 responseCode, bool response) {
        (bool success, bytes memory result) = HASPrecompileAddress.call(
            abi.encodeWithSelector(IHederaAccountService.isValidAlias.selector, addr));
        (responseCode, response) = success ? (HederaResponseCodes.SUCCESS, abi.decode(result, (bool))) : (HederaResponseCodes.UNKNOWN, false);
    }

    /// Determines if the signature is valid for the given message hash and account.
    /// It is assumed that the signature is composed of a single EDCSA or ED25519 key.
    /// @param account The account to check the signature against
    /// @param messageHash The hash of the message to check the signature against
    /// @param signature The signature to check
    /// @return responseCode The response code for the status of the request. SUCCESS is 22.
    /// @return authorized True if the signature is valid, false otherwise
    function isAuthorizedRaw(address account, bytes memory messageHash, bytes memory signature) internal returns (int64 responseCode, bool authorized) {
        (bool success, bytes memory result) = HASPrecompileAddress.call(
            abi.encodeWithSelector(IHederaAccountService.isAuthorizedRaw.selector,
                account, messageHash, signature));
        (responseCode, authorized) = success ? (HederaResponseCodes.SUCCESS, abi.decode(result, (bool))) : (HederaResponseCodes.UNKNOWN, false);
    }

    /// Determines if the signature is valid for the given message and account.
    /// It is assumed that the signature is composed of a possibly complex cryptographic key.
    /// @param account The account to check the signature against.
    /// @param message The message to check the signature against.
    /// @param signature The signature to check encoded as bytes.
    /// @return responseCode The response code for the status of the request.  SUCCESS is 22.
    /// @return authorized True if the signature is valid, false otherwise.
    function isAuthorized(address account, bytes memory message, bytes memory signature) internal returns (int64 responseCode, bool authorized) {
        (bool success, bytes memory result) = HASPrecompileAddress.call(
            abi.encodeWithSelector(IHederaAccountService.isAuthorized.selector,
                account, message, signature));
        (responseCode, authorized) = success ? abi.decode(result, (int32, bool)) : (HederaResponseCodes.UNKNOWN, false);
    }
}