ERC1155Proxy.js

/*
  Copyright 2018 ZeroEx Intl.
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at
    http://www.apache.org/licenses/LICENSE-2.0
  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
*/

/** 
* TO DO : 
*    + Add support for batchTransferFrom
*    + Add support for safeBatchTransferFrom
*    + Convert to assembly code
*/

pragma solidity 0.4.24;

import "../../utils/LibBytes/LibBytes.sol";
import "./MixinAuthorizable.sol";
import "multi-token-standard/contracts/token/IERC1155.sol";

contract ERC1155Proxy is MixinAuthorizable
{   
  using LibBytes for bytes;

  // assetData index constants
  uint256 constant internal TOKEN_ADDRESS_INDEX = 16; // To use with readAddress()
  uint256 constant internal TOKEN_ID_INDEX      = 36; // To use with readUint256()
  // uint8 constant internal TOKEN_AMOUNT_INDEX  = 0x68; // To use with readUint256()

  // Id of this proxy.
  bytes4 constant internal PROXY_ID = bytes4(keccak256("ERC1155Token(address,uint256)"));

  /// @dev Transfers assets. Either succeeds or throws.
  /// @param assetData Byte array encoded for the respective asset proxy.
  /// @param from Address to transfer asset from.
  /// @param to Address to transfer asset to.
  /// @param amount Amount of asset to transfer.
  function transferFrom(
    bytes assetData,
    address from,
    address to,
    uint256 amount
  )
    external
  {

      // Asset data itself is encoded as follows:
      //
      // | Area     | Offset | Length  | Contents                            |
      // |----------|--------|---------|-------------------------------------|
      // | Header   | 0      | 4       | Proxy ID                            |
      // | Params   |        | 2 * 32  | Function parameters:                |
      // |          | 4      | 12 + 20 |   1. Token address                  |
      // |          | 36     | 32      |   2. Token Id                       |
      // |          |        |         |                                     |

      // Token address
      address token = assetData.readAddress(TOKEN_ADDRESS_INDEX); 

      // Token Id
      uint256 tokenId = assetData.readUint256(TOKEN_ID_INDEX);

      // Transfer token in ERC155 contract
      IERC1155(token).safeTransferFrom(from, to, tokenId, amount, '');
  }    

  /// @dev Gets the proxy id associated with the proxy address.
  /// @return Proxy id.
  function getProxyId()
    external
    pure
    returns (bytes4)
  {
    return PROXY_ID;
  }

}