/*
  Copyright 2017 Loopring Project Ltd (Loopring Foundation).
  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.
*/
pragma solidity 0.4.19;
/*
  Copyright 2017 Loopring Project Ltd (Loopring Foundation).
  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.
*/
/*
  Copyright 2017 Loopring Project Ltd (Loopring Foundation).
  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.
*/
/// @title Ownable
/// @dev The Ownable contract has an owner address, and provides basic
///      authorization control functions, this simplifies the implementation of
///      "user permissions".
contract Ownable {
    address public owner;
    event OwnershipTransferred(
        address indexed previousOwner,
        address indexed newOwner
    );
    /// @dev The Ownable constructor sets the original `owner` of the contract
    ///      to the sender.
    function Ownable() public {
        owner = msg.sender;
    }
    /// @dev Throws if called by any account other than the owner.
    modifier onlyOwner() {
        require(msg.sender == owner);
        _;
    }
    /// @dev Allows the current owner to transfer control of the contract to a
    ///      newOwner.
    /// @param newOwner The address to transfer ownership to.
    function transferOwnership(address newOwner) onlyOwner public {
        require(newOwner != 0x0);
        OwnershipTransferred(owner, newOwner);
        owner = newOwner;
    }
}
/// @title Claimable
/// @dev Extension for the Ownable contract, where the ownership needs
///      to be claimed. This allows the new owner to accept the transfer.
contract Claimable is Ownable {
    address public pendingOwner;
    /// @dev Modifier throws if called by any account other than the pendingOwner.
    modifier onlyPendingOwner() {
        require(msg.sender == pendingOwner);
        _;
    }
    /// @dev Allows the current owner to set the pendingOwner address.
    /// @param newOwner The address to transfer ownership to.
    function transferOwnership(address newOwner) onlyOwner public {
        require(newOwner != 0x0 && newOwner != owner);
        pendingOwner = newOwner;
    }
    /// @dev Allows the pendingOwner address to finalize the transfer.
    function claimOwnership() onlyPendingOwner public {
        OwnershipTransferred(owner, pendingOwner);
        owner = pendingOwner;
        pendingOwner = 0x0;
    }
}
/// @title Token Register Contract
/// @dev This contract maintains a list of tokens the Protocol supports.
/// @author Kongliang Zhong - <kongliang@loopring.org>,
/// @author Daniel Wang - <daniel@loopring.org>.
contract TokenRegistry is Claimable {
    address[] public addresses;
    mapping (address => TokenInfo) addressMap;
    mapping (string => address) symbolMap;
    ////////////////////////////////////////////////////////////////////////////
    /// Structs                                                              ///
    ////////////////////////////////////////////////////////////////////////////
    struct TokenInfo {
        uint   pos;      // 0 mens unregistered; if > 0, pos + 1 is the
                         // token's position in `addresses`.
        string symbol;   // Symbol of the token
    }
    ////////////////////////////////////////////////////////////////////////////
    /// Events                                                               ///
    ////////////////////////////////////////////////////////////////////////////
    event TokenRegistered(address addr, string symbol);
    event TokenUnregistered(address addr, string symbol);
    ////////////////////////////////////////////////////////////////////////////
    /// Public Functions                                                     ///
    ////////////////////////////////////////////////////////////////////////////
    /// @dev Disable default function.
    function () payable public {
        revert();
    }
    function registerToken(
        address addr,
        string  symbol
        )
        external
        onlyOwner
    {
        require(0x0 != addr);
        require(bytes(symbol).length > 0);
        require(0x0 == symbolMap[symbol]);
        require(0 == addressMap[addr].pos);
        addresses.push(addr);
        symbolMap[symbol] = addr;
        addressMap[addr] = TokenInfo(addresses.length, symbol);
        TokenRegistered(addr, symbol);
    }
    function unregisterToken(
        address addr,
        string  symbol
        )
        external
        onlyOwner
    {
        require(addr != 0x0);
        require(symbolMap[symbol] == addr);
        delete symbolMap[symbol];
        uint pos = addressMap[addr].pos;
        require(pos != 0);
        delete addressMap[addr];
        // We will replace the token we need to unregister with the last token
        // Only the pos of the last token will need to be updated
        address lastToken = addresses[addresses.length - 1];
        // Don't do anything if the last token is the one we want to delete
        if (addr != lastToken) {
            // Swap with the last token and update the pos
            addresses[pos - 1] = lastToken;
            addressMap[lastToken].pos = pos;
        }
        addresses.length--;
        TokenUnregistered(addr, symbol);
    }
    function areAllTokensRegistered(address[] addressList)
        external
        view
        returns (bool)
    {
        for (uint i = 0; i < addressList.length; i++) {
            if (addressMap[addressList[i]].pos == 0) {
                return false;
            }
        }
        return true;
    }
    function getAddressBySymbol(string symbol)
        external
        view
        returns (address)
    {
        return symbolMap[symbol];
    }
    function isTokenRegisteredBySymbol(string symbol)
        public
        view
        returns (bool)
    {
        return symbolMap[symbol] != 0x0;
    }
    function isTokenRegistered(address addr)
        public
        view
        returns (bool)
    {
        return addressMap[addr].pos != 0;
    }
    function getTokens(
        uint start,
        uint count
        )
        public
        view
        returns (address[] addressList)
    {
        uint num = addresses.length;
        if (start >= num) {
            return;
        }
        uint end = start + count;
        if (end > num) {
            end = num;
        }
        if (start == num) {
            return;
        }
        addressList = new address[](end - start);
        for (uint i = start; i < end; i++) {
            addressList[i - start] = addresses[i];
        }
    }
}