pragma solidity 0.5.17;

import "./EnsRegistry.sol";
import "./EnsResolver.sol";

/**
 * ENS Reverse registrar test contract.
 */
contract EnsReverseRegistrar {

   // namehash('addr.reverse')
    bytes32 constant ADDR_REVERSE_NODE = 0x91d1777781884d03a6757a803996e38de2a42967fb37eeaca72729271025a9e2;

    EnsRegistry public ens;
    EnsResolver public defaultResolver;

    /**
     * @dev Constructor
     * @param ensAddr The address of the ENS registry.
     * @param resolverAddr The address of the default reverse resolver.
     */
    constructor(address ensAddr, address resolverAddr) public {
        ens = EnsRegistry(ensAddr);
        defaultResolver = EnsResolver(resolverAddr);
    }

    /**
     * @dev Transfers ownership of the reverse ENS record associated with the
     *      calling account.
     * @param owner The address to set as the owner of the reverse record in ENS.
     * @return The ENS node hash of the reverse record.
     */
    function claim(address owner) public returns (bytes32) {
        return claimWithResolver(owner, address(0));
    }

    /**
     * @dev Transfers ownership of the reverse ENS record associated with the
     *      calling account.
     * @param owner The address to set as the owner of the reverse record in ENS.
     * @param resolver The address of the resolver to set; 0 to leave unchanged.
     * @return The ENS node hash of the reverse record.
     */
    function claimWithResolver(address owner, address resolver) public returns (bytes32) {
        bytes32 label = sha3HexAddress(msg.sender);
        bytes32 node = keccak256(abi.encodePacked(ADDR_REVERSE_NODE, label));
        address currentOwner = ens.owner(node);

        // Update the resolver if required
        if(resolver != address(0) && resolver != address(ens.resolver(node))) {
            // Transfer the name to us first if it's not already
            if(currentOwner != address(this)) {
                ens.setSubnodeOwner(ADDR_REVERSE_NODE, label, address(this));
                currentOwner = address(this);
            }
            ens.setResolver(node, resolver);
        }

        // Update the owner if required
        if(currentOwner != owner) {
            ens.setSubnodeOwner(ADDR_REVERSE_NODE, label, owner);
        }

        return node;
    }

    /**
     * @dev Sets the `name()` record for the reverse ENS record associated with
     * the calling account. First updates the resolver to the default reverse
     * resolver if necessary.
     * @param name The name to set for this address.
     * @return The ENS node hash of the reverse record.
     */
    function setName(string memory name) public returns (bytes32 node) {
        node = claimWithResolver(address(this), address(defaultResolver));
        defaultResolver.setName(node, name);
        return node;
    }

    /**
     * @dev Returns the node hash for a given account's reverse records.
     * @param addr The address to hash
     * @return The ENS node hash.
     */
    function node(address addr) public returns (bytes32 ret) {
        return keccak256(abi.encodePacked(ADDR_REVERSE_NODE, sha3HexAddress(addr)));
    }

    /**
     * @dev An optimised function to compute the sha3 of the lower-case
     *      hexadecimal representation of an Ethereum address.
     * @param addr The address to hash
     * @return The SHA3 hash of the lower-case hexadecimal encoding of the
     *         input address.
     */
    function sha3HexAddress(address addr) private pure returns (bytes32 ret) {
        assembly {
            let lookup := 0x3031323334353637383961626364656600000000000000000000000000000000
            let i := 40

            for { } gt(i, 0) { } {
                i := sub(i, 1)
                mstore8(i, byte(and(addr, 0xf), lookup))
                addr := div(addr, 0x10)
                i := sub(i, 1)
                mstore8(i, byte(and(addr, 0xf), lookup))
                addr := div(addr, 0x10)
            }
            ret := keccak256(0, 40)
        }
    }
}