pragma solidity 0.4.11;

contract RegistryICAPInterface {
    function parse(bytes32 _icap) constant returns(address, bytes32, bool);
    function institutions(bytes32 _institution) constant returns(address);
}

contract EToken2Interface {
    function registryICAP() constant returns(RegistryICAPInterface);
    function baseUnit(bytes32 _symbol) constant returns(uint8);
    function description(bytes32 _symbol) constant returns(string);
    function owner(bytes32 _symbol) constant returns(address);
    function isOwner(address _owner, bytes32 _symbol) constant returns(bool);
    function totalSupply(bytes32 _symbol) constant returns(uint);
    function balanceOf(address _holder, bytes32 _symbol) constant returns(uint);
    function isLocked(bytes32 _symbol) constant returns(bool);
    function issueAsset(bytes32 _symbol, uint _value, string _name, string _description, uint8 _baseUnit, bool _isReissuable) returns(bool);
    function reissueAsset(bytes32 _symbol, uint _value) returns(bool);
    function revokeAsset(bytes32 _symbol, uint _value) returns(bool);
    function setProxy(address _address, bytes32 _symbol) returns(bool);
    function lockAsset(bytes32 _symbol) returns(bool);
    function proxyTransferFromToICAPWithReference(address _from, bytes32 _icap, uint _value, string _reference, address _sender) returns(bool);
    function proxyApprove(address _spender, uint _value, bytes32 _symbol, address _sender) returns(bool);
    function allowance(address _from, address _spender, bytes32 _symbol) constant returns(uint);
    function proxyTransferFromWithReference(address _from, address _to, uint _value, bytes32 _symbol, string _reference, address _sender) returns(bool);
}

contract AssetInterface {
    function _performTransferWithReference(address _to, uint _value, string _reference, address _sender) returns(bool);
    function _performTransferToICAPWithReference(bytes32 _icap, uint _value, string _reference, address _sender) returns(bool);
    function _performApprove(address _spender, uint _value, address _sender) returns(bool);
    function _performTransferFromWithReference(address _from, address _to, uint _value, string _reference, address _sender) returns(bool);
    function _performTransferFromToICAPWithReference(address _from, bytes32 _icap, uint _value, string _reference, address _sender) returns(bool);
    function _performGeneric(bytes _data, address _sender) payable returns(bytes32) {
        throw;
    }
}

contract ERC20Interface {
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed from, address indexed spender, uint256 value);

    function totalSupply() constant returns(uint256 supply);
    function balanceOf(address _owner) constant returns(uint256 balance);
    function transfer(address _to, uint256 _value) returns(bool success);
    function transferFrom(address _from, address _to, uint256 _value) returns(bool success);
    function approve(address _spender, uint256 _value) returns(bool success);
    function allowance(address _owner, address _spender) constant returns(uint256 remaining);

    // function symbol() constant returns(string);
    function decimals() constant returns(uint8);
    // function name() constant returns(string);
}

contract AssetProxyInterface {
    function _forwardApprove(address _spender, uint _value, address _sender) returns(bool);
    function _forwardTransferFromWithReference(address _from, address _to, uint _value, string _reference, address _sender) returns(bool);
    function _forwardTransferFromToICAPWithReference(address _from, bytes32 _icap, uint _value, string _reference, address _sender) returns(bool);
    function balanceOf(address _owner) constant returns(uint);
}

contract Bytes32 {
    function _bytes32(string _input) internal constant returns(bytes32 result) {
        assembly {
            result := mload(add(_input, 32))
        }
    }
}

/**
 * @title EToken2 Asset Proxy.
 *
 * Proxy implements ERC20 interface and acts as a gateway to a single EToken2 asset.
 * Proxy adds etoken2Symbol and caller(sender) when forwarding requests to EToken2.
 * Every request that is made by caller first sent to the specific asset implementation
 * contract, which then calls back to be forwarded onto EToken2.
 *
 * Calls flow: Caller ->
 *             Proxy.func(...) ->
 *             Asset._performFunc(..., Caller.address) ->
 *             Proxy._forwardFunc(..., Caller.address) ->
 *             Platform.proxyFunc(..., symbol, Caller.address)
 *
 * Generic call flow: Caller ->
 *             Proxy.unknownFunc(...) ->
 *             Asset._performGeneric(..., Caller.address) ->
 *             Asset.unknownFunc(...)
 *
 * Asset implementation contract is mutable, but each user have an option to stick with
 * old implementation, through explicit decision made in timely manner, if he doesn't agree
 * with new rules.
 * Each user have a possibility to upgrade to latest asset contract implementation, without the
 * possibility to rollback.
 *
 * Note: all the non constant functions return false instead of throwing in case if state change
 * didn't happen yet.
 */
contract Refereum is ERC20Interface, AssetProxyInterface, Bytes32 {
    // Assigned EToken2, immutable.
    EToken2Interface public etoken2;

    // Assigned symbol, immutable.
    bytes32 public etoken2Symbol;

    // Assigned name, immutable. For UI.
    string public name;
    string public symbol;

    /**
     * Sets EToken2 address, assigns symbol and name.
     *
     * Can be set only once.
     *
     * @param _etoken2 EToken2 contract address.
     * @param _symbol assigned symbol.
     * @param _name assigned name.
     *
     * @return success.
     */
    function init(EToken2Interface _etoken2, string _symbol, string _name) returns(bool) {
        if (address(etoken2) != 0x0) {
            return false;
        }
        etoken2 = _etoken2;
        etoken2Symbol = _bytes32(_symbol);
        name = _name;
        symbol = _symbol;
        return true;
    }

    /**
     * Only EToken2 is allowed to call.
     */
    modifier onlyEToken2() {
        if (msg.sender == address(etoken2)) {
            _;
        }
    }

    /**
     * Only current asset owner is allowed to call.
     */
    modifier onlyAssetOwner() {
        if (etoken2.isOwner(msg.sender, etoken2Symbol)) {
            _;
        }
    }

    /**
     * Returns asset implementation contract for current caller.
     *
     * @return asset implementation contract.
     */
    function _getAsset() internal returns(AssetInterface) {
        return AssetInterface(getVersionFor(msg.sender));
    }

    function recoverTokens(uint _value) onlyAssetOwner() returns(bool) {
        return this.transferWithReference(msg.sender, _value, 'Tokens recovery');
    }

    /**
     * Returns asset total supply.
     *
     * @return asset total supply.
     */
    function totalSupply() constant returns(uint) {
        return etoken2.totalSupply(etoken2Symbol);
    }

    /**
     * Returns asset balance for a particular holder.
     *
     * @param _owner holder address.
     *
     * @return holder balance.
     */
    function balanceOf(address _owner) constant returns(uint) {
        return etoken2.balanceOf(_owner, etoken2Symbol);
    }

    /**
     * Returns asset allowance from one holder to another.
     *
     * @param _from holder that allowed spending.
     * @param _spender holder that is allowed to spend.
     *
     * @return holder to spender allowance.
     */
    function allowance(address _from, address _spender) constant returns(uint) {
        return etoken2.allowance(_from, _spender, etoken2Symbol);
    }

    /**
     * Returns asset decimals.
     *
     * @return asset decimals.
     */
    function decimals() constant returns(uint8) {
        return etoken2.baseUnit(etoken2Symbol);
    }

    /**
     * Transfers asset balance from the caller to specified receiver.
     *
     * @param _to holder address to give to.
     * @param _value amount to transfer.
     *
     * @return success.
     */
    function transfer(address _to, uint _value) returns(bool) {
        return transferWithReference(_to, _value, '');
    }

    /**
     * Transfers asset balance from the caller to specified receiver adding specified comment.
     * Resolves asset implementation contract for the caller and forwards there arguments along with
     * the caller address.
     *
     * @param _to holder address to give to.
     * @param _value amount to transfer.
     * @param _reference transfer comment to be included in a EToken2's Transfer event.
     *
     * @return success.
     */
    function transferWithReference(address _to, uint _value, string _reference) returns(bool) {
        return _getAsset()._performTransferWithReference(_to, _value, _reference, msg.sender);
    }

    /**
     * Transfers asset balance from the caller to specified ICAP.
     *
     * @param _icap recipient ICAP to give to.
     * @param _value amount to transfer.
     *
     * @return success.
     */
    function transferToICAP(bytes32 _icap, uint _value) returns(bool) {
        return transferToICAPWithReference(_icap, _value, '');
    }

    /**
     * Transfers asset balance from the caller to specified ICAP adding specified comment.
     * Resolves asset implementation contract for the caller and forwards there arguments along with
     * the caller address.
     *
     * @param _icap recipient ICAP to give to.
     * @param _value amount to transfer.
     * @param _reference transfer comment to be included in a EToken2's Transfer event.
     *
     * @return success.
     */
    function transferToICAPWithReference(bytes32 _icap, uint _value, string _reference) returns(bool) {
        return _getAsset()._performTransferToICAPWithReference(_icap, _value, _reference, msg.sender);
    }

    /**
     * Prforms allowance transfer of asset balance between holders.
     *
     * @param _from holder address to take from.
     * @param _to holder address to give to.
     * @param _value amount to transfer.
     *
     * @return success.
     */
    function transferFrom(address _from, address _to, uint _value) returns(bool) {
        return transferFromWithReference(_from, _to, _value, '');
    }

    /**
     * Prforms allowance transfer of asset balance between holders adding specified comment.
     * Resolves asset implementation contract for the caller and forwards there arguments along with
     * the caller address.
     *
     * @param _from holder address to take from.
     * @param _to holder address to give to.
     * @param _value amount to transfer.
     * @param _reference transfer comment to be included in a EToken2's Transfer event.
     *
     * @return success.
     */
    function transferFromWithReference(address _from, address _to, uint _value, string _reference) returns(bool) {
        return _getAsset()._performTransferFromWithReference(_from, _to, _value, _reference, msg.sender);
    }

    /**
     * Performs transfer call on the EToken2 by the name of specified sender.
     *
     * Can only be called by asset implementation contract assigned to sender.
     *
     * @param _from holder address to take from.
     * @param _to holder address to give to.
     * @param _value amount to transfer.
     * @param _reference transfer comment to be included in a EToken2's Transfer event.
     * @param _sender initial caller.
     *
     * @return success.
     */
    function _forwardTransferFromWithReference(address _from, address _to, uint _value, string _reference, address _sender) onlyImplementationFor(_sender) returns(bool) {
        return etoken2.proxyTransferFromWithReference(_from, _to, _value, etoken2Symbol, _reference, _sender);
    }

    /**
     * Prforms allowance transfer of asset balance between holders.
     *
     * @param _from holder address to take from.
     * @param _icap recipient ICAP address to give to.
     * @param _value amount to transfer.
     *
     * @return success.
     */
    function transferFromToICAP(address _from, bytes32 _icap, uint _value) returns(bool) {
        return transferFromToICAPWithReference(_from, _icap, _value, '');
    }

    /**
     * Prforms allowance transfer of asset balance between holders adding specified comment.
     * Resolves asset implementation contract for the caller and forwards there arguments along with
     * the caller address.
     *
     * @param _from holder address to take from.
     * @param _icap recipient ICAP address to give to.
     * @param _value amount to transfer.
     * @param _reference transfer comment to be included in a EToken2's Transfer event.
     *
     * @return success.
     */
    function transferFromToICAPWithReference(address _from, bytes32 _icap, uint _value, string _reference) returns(bool) {
        return _getAsset()._performTransferFromToICAPWithReference(_from, _icap, _value, _reference, msg.sender);
    }

    /**
     * Performs allowance transfer to ICAP call on the EToken2 by the name of specified sender.
     *
     * Can only be called by asset implementation contract assigned to sender.
     *
     * @param _from holder address to take from.
     * @param _icap recipient ICAP address to give to.
     * @param _value amount to transfer.
     * @param _reference transfer comment to be included in a EToken2's Transfer event.
     * @param _sender initial caller.
     *
     * @return success.
     */
    function _forwardTransferFromToICAPWithReference(address _from, bytes32 _icap, uint _value, string _reference, address _sender) onlyImplementationFor(_sender) returns(bool) {
        return etoken2.proxyTransferFromToICAPWithReference(_from, _icap, _value, _reference, _sender);
    }

    /**
     * Sets asset spending allowance for a specified spender.
     * Resolves asset implementation contract for the caller and forwards there arguments along with
     * the caller address.
     *
     * @param _spender holder address to set allowance to.
     * @param _value amount to allow.
     *
     * @return success.
     */
    function approve(address _spender, uint _value) returns(bool) {
        return _getAsset()._performApprove(_spender, _value, msg.sender);
    }

    /**
     * Performs allowance setting call on the EToken2 by the name of specified sender.
     *
     * Can only be called by asset implementation contract assigned to sender.
     *
     * @param _spender holder address to set allowance to.
     * @param _value amount to allow.
     * @param _sender initial caller.
     *
     * @return success.
     */
    function _forwardApprove(address _spender, uint _value, address _sender) onlyImplementationFor(_sender) returns(bool) {
        return etoken2.proxyApprove(_spender, _value, etoken2Symbol, _sender);
    }

    /**
     * Emits ERC20 Transfer event on this contract.
     *
     * Can only be, and, called by assigned EToken2 when asset transfer happens.
     */
    function emitTransfer(address _from, address _to, uint _value) onlyEToken2() {
        Transfer(_from, _to, _value);
    }

    /**
     * Emits ERC20 Approval event on this contract.
     *
     * Can only be, and, called by assigned EToken2 when asset allowance set happens.
     */
    function emitApprove(address _from, address _spender, uint _value) onlyEToken2() {
        Approval(_from, _spender, _value);
    }

    /**
     * Resolves asset implementation contract for the caller and forwards there transaction data,
     * along with the value. This allows for proxy interface growth.
     */
    function () payable {
        bytes32 result = _getAsset()._performGeneric.value(msg.value)(msg.data, msg.sender);
        assembly {
            mstore(0, result)
            return(0, 32)
        }
    }

    /**
     * Indicates an upgrade freeze-time start, and the next asset implementation contract.
     */
    event UpgradeProposal(address newVersion);

    // Current asset implementation contract address.
    address latestVersion;

    // Proposed next asset implementation contract address.
    address pendingVersion;

    // Upgrade freeze-time start.
    uint pendingVersionTimestamp;

    // Timespan for users to review the new implementation and make decision.
    uint constant UPGRADE_FREEZE_TIME = 3 days;

    // Asset implementation contract address that user decided to stick with.
    // 0x0 means that user uses latest version.
    mapping(address => address) userOptOutVersion;

    /**
     * Only asset implementation contract assigned to sender is allowed to call.
     */
    modifier onlyImplementationFor(address _sender) {
        if (getVersionFor(_sender) == msg.sender) {
            _;
        }
    }

    /**
     * Returns asset implementation contract address assigned to sender.
     *
     * @param _sender sender address.
     *
     * @return asset implementation contract address.
     */
    function getVersionFor(address _sender) constant returns(address) {
        return userOptOutVersion[_sender] == 0 ? latestVersion : userOptOutVersion[_sender];
    }

    /**
     * Returns current asset implementation contract address.
     *
     * @return asset implementation contract address.
     */
    function getLatestVersion() constant returns(address) {
        return latestVersion;
    }

    /**
     * Returns proposed next asset implementation contract address.
     *
     * @return asset implementation contract address.
     */
    function getPendingVersion() constant returns(address) {
        return pendingVersion;
    }

    /**
     * Returns upgrade freeze-time start.
     *
     * @return freeze-time start.
     */
    function getPendingVersionTimestamp() constant returns(uint) {
        return pendingVersionTimestamp;
    }

    /**
     * Propose next asset implementation contract address.
     *
     * Can only be called by current asset owner.
     *
     * Note: freeze-time should not be applied for the initial setup.
     *
     * @param _newVersion asset implementation contract address.
     *
     * @return success.
     */
    function proposeUpgrade(address _newVersion) onlyAssetOwner() returns(bool) {
        // Should not already be in the upgrading process.
        if (pendingVersion != 0x0) {
            return false;
        }
        // New version address should be other than 0x0.
        if (_newVersion == 0x0) {
            return false;
        }
        // Don't apply freeze-time for the initial setup.
        if (latestVersion == 0x0) {
            latestVersion = _newVersion;
            return true;
        }
        pendingVersion = _newVersion;
        pendingVersionTimestamp = now;
        UpgradeProposal(_newVersion);
        return true;
    }

    /**
     * Cancel the pending upgrade process.
     *
     * Can only be called by current asset owner.
     *
     * @return success.
     */
    function purgeUpgrade() onlyAssetOwner() returns(bool) {
        if (pendingVersion == 0x0) {
            return false;
        }
        delete pendingVersion;
        delete pendingVersionTimestamp;
        return true;
    }

    /**
     * Finalize an upgrade process setting new asset implementation contract address.
     *
     * Can only be called after an upgrade freeze-time.
     *
     * @return success.
     */
    function commitUpgrade() returns(bool) {
        if (pendingVersion == 0x0) {
            return false;
        }
        if (pendingVersionTimestamp + UPGRADE_FREEZE_TIME > now) {
            return false;
        }
        latestVersion = pendingVersion;
        delete pendingVersion;
        delete pendingVersionTimestamp;
        return true;
    }

    /**
     * Disagree with proposed upgrade, and stick with current asset implementation
     * until further explicit agreement to upgrade.
     *
     * @return success.
     */
    function optOut() returns(bool) {
        if (userOptOutVersion[msg.sender] != 0x0) {
            return false;
        }
        userOptOutVersion[msg.sender] = latestVersion;
        return true;
    }

    /**
     * Implicitly agree to upgrade to current and future asset implementation upgrades,
     * until further explicit disagreement.
     *
     * @return success.
     */
    function optIn() returns(bool) {
        delete userOptOutVersion[msg.sender];
        return true;
    }

    // Backwards compatibility.
    function multiAsset() constant returns(EToken2Interface) {
        return etoken2;
    }
}

// This software is a subject to Ambisafe License Agreement.
// No use or distribution is allowed without written permission from Ambisafe.
// https://ambisafe.com/terms.pdf

contract Ambi {
    function getNodeAddress(bytes32 _nodeName) constant returns(address);
    function hasRelation(bytes32 _nodeName, bytes32 _relation, address _to) constant returns(bool);
    function addNode(bytes32 _nodeName, address _nodeAddress) constant returns(bool);
}

contract AmbiEnabled {
    Ambi public ambiC;
    bool public isImmortal;
    bytes32 public name;

    modifier checkAccess(bytes32 _role) {
        if(address(ambiC) != 0x0 && ambiC.hasRelation(name, _role, msg.sender)){
            _
        }
    }
    
    function getAddress(bytes32 _name) constant returns (address) {
        return ambiC.getNodeAddress(_name);
    }

    function setAmbiAddress(address _ambi, bytes32 _name) returns (bool){
        if(address(ambiC) != 0x0){
            return false;
        }
        Ambi ambiContract = Ambi(_ambi);
        if(ambiContract.getNodeAddress(_name)!=address(this)) {
            if (!ambiContract.addNode(_name, address(this))){
                return false;
            }
        }
        name = _name;
        ambiC = ambiContract;
        return true;
    }

    function immortality() checkAccess("owner") returns(bool) {
        isImmortal = true;
        return true;
    }

    function remove() checkAccess("owner") returns(bool) {
        if (isImmortal) {
            return false;
        }
        selfdestruct(msg.sender);
        return true;
    }
}

library StackDepthLib {
    // This will probably work with a value of 390 but no need to cut it
    // that close in the case that the optimizer changes slightly or
    // something causing that number to rise slightly.
    uint constant GAS_PER_DEPTH = 400;

    function checkDepth(address self, uint n) constant returns(bool) {
        if (n == 0) return true;
        return self.call.gas(GAS_PER_DEPTH * n)(0x21835af6, n - 1);
    }

    function __dig(uint n) constant {
        if (n == 0) return;
        if (!address(this).delegatecall(0x21835af6, n - 1)) throw;
    }
}

contract Safe {
    // Should always be placed as first modifier!
    modifier noValue {
        if (msg.value > 0) {
            // Internal Out Of Gas/Throw: revert this transaction too;
            // Call Stack Depth Limit reached: revert this transaction too;
            // Recursive Call: safe, no any changes applied yet, we are inside of modifier.
            _safeSend(msg.sender, msg.value);
        }
        _
    }

    modifier onlyHuman {
        if (_isHuman()) {
            _
        }
    }

    modifier noCallback {
        if (!isCall) {
            _
        }
    }

    modifier immutable(address _address) {
        if (_address == 0) {
            _
        }
    }

    address stackDepthLib;
    function setupStackDepthLib(address _stackDepthLib) immutable(address(stackDepthLib)) returns(bool) {
        stackDepthLib = _stackDepthLib;
        return true;
    }

    modifier requireStackDepth(uint16 _depth) {
        if (stackDepthLib == 0x0) {
            throw;
        }
        if (_depth > 1023) {
            throw;
        }
        if (!stackDepthLib.delegatecall(0x32921690, stackDepthLib, _depth)) {
            throw;
        }
        _
    }

    // Must not be used inside the functions that have noValue() modifier!
    function _safeFalse() internal noValue() returns(bool) {
        return false;
    }

    function _safeSend(address _to, uint _value) internal {
        if (!_unsafeSend(_to, _value)) {
            throw;
        }
    }

    function _unsafeSend(address _to, uint _value) internal returns(bool) {
        return _to.call.value(_value)();
    }

    function _isContract() constant internal returns(bool) {
        return msg.sender != tx.origin;
    }

    function _isHuman() constant internal returns(bool) {
        return !_isContract();
    }

    bool private isCall = false;
    function _setupNoCallback() internal {
        isCall = true;
    }

    function _finishNoCallback() internal {
        isCall = false;
    }
}

/**
 * @title Events History universal contract.
 *
 * Contract serves as an Events storage and version history for a particular contract type.
 * Events appear on this contract address but their definitions provided by other contracts/libraries.
 * Version info is provided for historical and informational purposes.
 *
 * Note: all the non constant functions return false instead of throwing in case if state change
 * didn't happen yet.
 */
contract EventsHistory is AmbiEnabled, Safe {
    // Event emitter signature to address with Event definiton mapping.
    mapping(bytes4 => address) public emitters;

    // Calling contract address to version mapping.
    mapping(address => uint) public versions;

    // Version to info mapping.
    mapping(uint => VersionInfo) public versionInfo;

    // Latest verion number.
    uint public latestVersion;

    struct VersionInfo {
        uint block;        // Block number in which version has been introduced.
        address by;        // Contract owner address who added version.
        address caller;    // Address of this version calling contract.
        string name;       // Version name, informative.
        string changelog;  // Version changelog, informative.
    }

    /**
     * Assign emitter address to a specified emit function signature.
     *
     * Can be set only once for each signature, and only by contract owner.
     * Caller contract should be sure that emitter for a particular signature will never change.
     *
     * @param _eventSignature signature of the event emitting function.
     * @param _emitter address with Event definition.
     *
     * @return success.
     */
    function addEmitter(bytes4 _eventSignature, address _emitter) noValue() checkAccess("admin") returns(bool) {
        if (emitters[_eventSignature] != 0x0) {
            return false;
        }
        emitters[_eventSignature] = _emitter;
        return true;
    }

    /**
     * Introduce new caller contract version specifing version information.
     *
     * Can be set only once for each caller, and only by contract owner.
     * Name and changelog should not be empty.
     *
     * @param _caller address of the new caller.
     * @param _name version name.
     * @param _changelog version changelog.
     *
     * @return success.
     */
    function addVersion(address _caller, string _name, string _changelog) noValue() checkAccess("admin") returns(bool) {
        if (versions[_caller] != 0) {
            return false;
        }
        if (bytes(_name).length == 0) {
            return false;
        }
        if (bytes(_changelog).length == 0) {
            return false;
        }
        uint version = ++latestVersion;
        versions[_caller] = version;
        versionInfo[version] = VersionInfo(block.number, msg.sender, _caller, _name, _changelog);
        return true;
    }

    /**
     * Event emitting fallback.
     *
     * Can be and only called caller with assigned version.
     * Resolves msg.sig to an emitter address, and calls it to emit an event.
     *
     * Throws if emit function signature is not registered, or call failed.
     */
    function () noValue() {
        if (versions[msg.sender] == 0) {
            return;
        }
        // Internal Out Of Gas/Throw: revert this transaction too;
        // Call Stack Depth Limit reached: revert this transaction too;
        // Recursive Call: safe, all changes already made.
        if (!emitters[msg.sig].delegatecall(msg.data)) {
            throw;
        }
    }
}

// This software is a subject to Ambisafe License Agreement.
// No use or distribution is allowed without written permission from Ambisafe.
// https://ambisafe.com/terms.pdf

pragma solidity 0.4.8;

contract Ambi2 {
    function claimFor(address _address, address _owner) returns(bool);
    function hasRole(address _from, bytes32 _role, address _to) constant returns(bool);
    function isOwner(address _node, address _owner) constant returns(bool);
}

contract Ambi2Enabled {
    Ambi2 ambi2;

    modifier onlyRole(bytes32 _role) {
        if (address(ambi2) != 0x0 && ambi2.hasRole(this, _role, msg.sender)) {
            _;
        }
    }

    // Perform only after claiming the node, or claim in the same tx.
    function setupAmbi2(Ambi2 _ambi2) returns(bool) {
        if (address(ambi2) != 0x0) {
            return false;
        }

        ambi2 = _ambi2;
        return true;
    }
}

contract Ambi2EnabledFull is Ambi2Enabled {
    // Setup and claim atomically.
    function setupAmbi2(Ambi2 _ambi2) returns(bool) {
        if (address(ambi2) != 0x0) {
            return false;
        }
        if (!_ambi2.claimFor(this, msg.sender) && !_ambi2.isOwner(this, msg.sender)) {
            return false;
        }

        ambi2 = _ambi2;
        return true;
    }
}

contract RegistryICAPInterface {
    function parse(bytes32 _icap) constant returns(address, bytes32, bool);
    function institutions(bytes32 _institution) constant returns(address);
}

contract Cosigner {
    function consumeOperation(bytes32 _opHash, uint _required) returns(bool);
}

contract Emitter {
    function emitTransfer(address _from, address _to, bytes32 _symbol, uint _value, string _reference);
    function emitTransferToICAP(address _from, address _to, bytes32 _icap, uint _value, string _reference);
    function emitIssue(bytes32 _symbol, uint _value, address _by);
    function emitRevoke(bytes32 _symbol, uint _value, address _by);
    function emitOwnershipChange(address _from, address _to, bytes32 _symbol);
    function emitApprove(address _from, address _spender, bytes32 _symbol, uint _value);
    function emitRecovery(address _from, address _to, address _by);
    function emitError(bytes32 _message);
    function emitChange(bytes32 _symbol);
}

contract Proxy {
    function emitTransfer(address _from, address _to, uint _value);
    function emitApprove(address _from, address _spender, uint _value);
}

/**
 * @title EToken2.
 *
 * The official Ambisafe assets platform powering all kinds of tokens.
 * EToken2 uses EventsHistory contract to keep events, so that in case it needs to be redeployed
 * at some point, all the events keep appearing at the same place.
 *
 * Every asset is meant to be used through a proxy contract. Only one proxy contract have access
 * rights for a particular asset.
 *
 * Features: assets issuance, transfers, allowances, supply adjustments, lost wallet access recovery.
 *           cosignature check, ICAP.
 *
 * Note: all the non constant functions return false instead of throwing in case if state change
 * didn't happen yet.
 */
contract EToken2 is Ambi2EnabledFull {
    mapping(bytes32 => bool) switches;

    function isEnabled(bytes32 _switch) constant returns(bool) {
        return switches[_switch];
    }

    function enableSwitch(bytes32 _switch) onlyRole('issuance') returns(bool) {
        switches[_switch] = true;
        return true;
    }

    modifier checkEnabledSwitch(bytes32 _switch) {
        if (!isEnabled(_switch)) {
            _error('Feature is disabled');
        } else {
            _;
        }
    }

    enum Features { Issue, TransferWithReference, Revoke, ChangeOwnership, Allowances, ICAP }

    // Structure of a particular asset.
    struct Asset {
        uint owner;                       // Asset's owner id.
        uint totalSupply;                 // Asset's total supply.
        string name;                      // Asset's name, for information purposes.
        string description;               // Asset's description, for information purposes.
        bool isReissuable;                // Indicates if asset have dynamic of fixed supply.
        uint8 baseUnit;                   // Proposed number of decimals.
        bool isLocked;                    // Are changes still allowed.
        mapping(uint => Wallet) wallets;  // Holders wallets.
    }

    // Structure of an asset holder wallet for particular asset.
    struct Wallet {
        uint balance;
        mapping(uint => uint) allowance;
    }

    // Structure of an asset holder.
    struct Holder {
        address addr;                    // Current address of the holder.
        Cosigner cosigner;               // Cosigner contract for 2FA and recovery.
        mapping(address => bool) trust;  // Addresses that are trusted with recovery proocedure.
    }

    // Iterable mapping pattern is used for holders.
    uint public holdersCount;
    mapping(uint => Holder) public holders;

    // This is an access address mapping. Many addresses may have access to a single holder.
    mapping(address => uint) holderIndex;

    // Asset symbol to asset mapping.
    mapping(bytes32 => Asset) public assets;

    // Asset symbol to asset proxy mapping.
    mapping(bytes32 => address) public proxies;

    // ICAP registry contract.
    RegistryICAPInterface public registryICAP;

    // Should use interface of the emitter, but address of events history.
    Emitter public eventsHistory;

    /**
     * Emits Error event with specified error message.
     *
     * Should only be used if no state changes happened.
     *
     * @param _message error message.
     */
    function _error(bytes32 _message) internal {
        eventsHistory.emitError(_message);
    }

    /**
     * Sets EventsHstory contract address.
     *
     * Can be set only once, and only by contract owner.
     *
     * @param _eventsHistory EventsHistory contract address.
     *
     * @return success.
     */
    function setupEventsHistory(Emitter _eventsHistory) onlyRole('setup') returns(bool) {
        if (address(eventsHistory) != 0) {
            return false;
        }
        eventsHistory = _eventsHistory;
        return true;
    }

    /**
     * Sets RegistryICAP contract address.
     *
     * Can be set only once, and only by contract owner.
     *
     * @param _registryICAP RegistryICAP contract address.
     *
     * @return success.
     */
    function setupRegistryICAP(RegistryICAPInterface _registryICAP) onlyRole('setup') returns(bool) {
        if (address(registryICAP) != 0) {
            return false;
        }
        registryICAP = _registryICAP;
        return true;
    }

    /**
     * Emits Error if called not by asset owner.
     */
    modifier onlyOwner(bytes32 _symbol) {
        if (_isSignedOwner(_symbol)) {
            _;
        } else {
            _error('Only owner: access denied');
        }
    }

    /**
     * Emits Error if called not by asset proxy.
     */
    modifier onlyProxy(bytes32 _symbol) {
        if (_isProxy(_symbol)) {
            _;
        } else {
            _error('Only proxy: access denied');
        }
    }

    /**
     * Emits Error if _from doesn't trust _to.
     */
    modifier checkTrust(address _from, address _to) {
        if (isTrusted(_from, _to)) {
            _;
        } else {
            _error('Only trusted: access denied');
        }
    }

    function _isSignedOwner(bytes32 _symbol) internal checkSigned(getHolderId(msg.sender), 1) returns(bool) {
        return isOwner(msg.sender, _symbol);
    }

    /**
     * Check asset existance.
     *
     * @param _symbol asset symbol.
     *
     * @return asset existance.
     */
    function isCreated(bytes32 _symbol) constant returns(bool) {
        return assets[_symbol].owner != 0;
    }

    function isLocked(bytes32 _symbol) constant returns(bool) {
        return assets[_symbol].isLocked;
    }

    /**
     * Returns asset decimals.
     *
     * @param _symbol asset symbol.
     *
     * @return asset decimals.
     */
    function baseUnit(bytes32 _symbol) constant returns(uint8) {
        return assets[_symbol].baseUnit;
    }

    /**
     * Returns asset name.
     *
     * @param _symbol asset symbol.
     *
     * @return asset name.
     */
    function name(bytes32 _symbol) constant returns(string) {
        return assets[_symbol].name;
    }

    /**
     * Returns asset description.
     *
     * @param _symbol asset symbol.
     *
     * @return asset description.
     */
    function description(bytes32 _symbol) constant returns(string) {
        return assets[_symbol].description;
    }

    /**
     * Returns asset reissuability.
     *
     * @param _symbol asset symbol.
     *
     * @return asset reissuability.
     */
    function isReissuable(bytes32 _symbol) constant returns(bool) {
        return assets[_symbol].isReissuable;
    }

    /**
     * Returns asset owner address.
     *
     * @param _symbol asset symbol.
     *
     * @return asset owner address.
     */
    function owner(bytes32 _symbol) constant returns(address) {
        return holders[assets[_symbol].owner].addr;
    }

    /**
     * Check if specified address has asset owner rights.
     *
     * @param _owner address to check.
     * @param _symbol asset symbol.
     *
     * @return owner rights availability.
     */
    function isOwner(address _owner, bytes32 _symbol) constant returns(bool) {
        return isCreated(_symbol) && (assets[_symbol].owner == getHolderId(_owner));
    }

    /**
     * Returns asset total supply.
     *
     * @param _symbol asset symbol.
     *
     * @return asset total supply.
     */
    function totalSupply(bytes32 _symbol) constant returns(uint) {
        return assets[_symbol].totalSupply;
    }

    /**
     * Returns asset balance for current address of a particular holder.
     *
     * @param _holder holder address.
     * @param _symbol asset symbol.
     *
     * @return holder balance.
     */
    function balanceOf(address _holder, bytes32 _symbol) constant returns(uint) {
        uint holderId = getHolderId(_holder);
        return holders[holderId].addr == _holder ? _balanceOf(holderId, _symbol) : 0;
    }

    /**
     * Returns asset balance for a particular holder id.
     *
     * @param _holderId holder id.
     * @param _symbol asset symbol.
     *
     * @return holder balance.
     */
    function _balanceOf(uint _holderId, bytes32 _symbol) constant internal returns(uint) {
        return assets[_symbol].wallets[_holderId].balance;
    }

    /**
     * Returns current address for a particular holder id.
     *
     * @param _holderId holder id.
     *
     * @return holder address.
     */
    function _address(uint _holderId) constant internal returns(address) {
        return holders[_holderId].addr;
    }

    function _isProxy(bytes32 _symbol) constant internal returns(bool) {
        return proxies[_symbol] == msg.sender;
    }

    /**
     * Sets Proxy contract address for a particular asset.
     *
     * Can be set only once for each asset, and only by contract owner.
     *
     * @param _address Proxy contract address.
     * @param _symbol asset symbol.
     *
     * @return success.
     */
    function setProxy(address _address, bytes32 _symbol) onlyOwner(_symbol) returns(bool) {
        if (proxies[_symbol] != 0x0 && assets[_symbol].isLocked) {
            return false;
        }
        proxies[_symbol] = _address;
        return true;
    }

    /**
     * Transfers asset balance between holders wallets.
     *
     * @param _fromId holder id to take from.
     * @param _toId holder id to give to.
     * @param _value amount to transfer.
     * @param _symbol asset symbol.
     */
    function _transferDirect(uint _fromId, uint _toId, uint _value, bytes32 _symbol) internal {
        assets[_symbol].wallets[_fromId].balance -= _value;
        assets[_symbol].wallets[_toId].balance += _value;
    }

    /**
     * Transfers asset balance between holders wallets.
     *
     * Performs sanity checks and takes care of allowances adjustment.
     *
     * @param _fromId holder id to take from.
     * @param _toId holder id to give to.
     * @param _value amount to transfer.
     * @param _symbol asset symbol.
     * @param _reference transfer comment to be included in a Transfer event.
     * @param _senderId transfer initiator holder id.
     *
     * @return success.
     */
    function _transfer(uint _fromId, uint _toId, uint _value, bytes32 _symbol, string _reference, uint _senderId) internal checkSigned(_senderId, 1) returns(bool) {
        // Should not allow to send to oneself.
        if (_fromId == _toId) {
            _error('Cannot send to oneself');
            return false;
        }
        // Should have positive value.
        if (_value == 0) {
            _error('Cannot send 0 value');
            return false;
        }
        // Should have enough balance.
        if (_balanceOf(_fromId, _symbol) < _value) {
            _error('Insufficient balance');
            return false;
        }
        // Should allow references.
        if (bytes(_reference).length > 0 && !isEnabled(sha3(_symbol, Features.TransferWithReference))) {
            _error('References feature is disabled');
            return false;
        }
        // Should have enough allowance.
        if (_fromId != _senderId && _allowance(_fromId, _senderId, _symbol) < _value) {
            _error('Not enough allowance');
            return false;
        }
        // Adjust allowance.
        if (_fromId != _senderId) {
            assets[_symbol].wallets[_fromId].allowance[_senderId] -= _value;
        }
        _transferDirect(_fromId, _toId, _value, _symbol);
        // Internal Out Of Gas/Throw: revert this transaction too;
        // Recursive Call: safe, all changes already made.
        eventsHistory.emitTransfer(_address(_fromId), _address(_toId), _symbol, _value, _reference);
        _proxyTransferEvent(_fromId, _toId, _value, _symbol);
        return true;
    }

    // Feature and proxy checks done internally due to unknown symbol when the function is called.
    function _transferToICAP(uint _fromId, bytes32 _icap, uint _value, string _reference, uint _senderId) internal returns(bool) {
        var (to, symbol, success) = registryICAP.parse(_icap);
        if (!success) {
            _error('ICAP is not registered');
            return false;
        }
        if (!isEnabled(sha3(symbol, Features.ICAP))) {
            _error('ICAP feature is disabled');
            return false;
        }
        if (!_isProxy(symbol)) {
            _error('Only proxy: access denied');
            return false;
        }
        uint toId = _createHolderId(to);
        if (!_transfer(_fromId, toId, _value, symbol, _reference, _senderId)) {
            return false;
        }
        // Internal Out Of Gas/Throw: revert this transaction too;
        // Recursive Call: safe, all changes already made.
        eventsHistory.emitTransferToICAP(_address(_fromId), _address(toId), _icap, _value, _reference);
        return true;
    }

    function proxyTransferFromToICAPWithReference(address _from, bytes32 _icap, uint _value, string _reference, address _sender) returns(bool) {
        return _transferToICAP(getHolderId(_from), _icap, _value, _reference, getHolderId(_sender));
    }

    /**
     * Ask asset Proxy contract to emit ERC20 compliant Transfer event.
     *
     * @param _fromId holder id to take from.
     * @param _toId holder id to give to.
     * @param _value amount to transfer.
     * @param _symbol asset symbol.
     */
    function _proxyTransferEvent(uint _fromId, uint _toId, uint _value, bytes32 _symbol) internal {
        if (proxies[_symbol] != 0x0) {
            // Internal Out Of Gas/Throw: revert this transaction too;
            // Recursive Call: safe, all changes already made.
            Proxy(proxies[_symbol]).emitTransfer(_address(_fromId), _address(_toId), _value);
        }
    }

    /**
     * Returns holder id for the specified address.
     *
     * @param _holder holder address.
     *
     * @return holder id.
     */
    function getHolderId(address _holder) constant returns(uint) {
        return holderIndex[_holder];
    }

    /**
     * Returns holder id for the specified address, creates it if needed.
     *
     * @param _holder holder address.
     *
     * @return holder id.
     */
    function _createHolderId(address _holder) internal returns(uint) {
        uint holderId = holderIndex[_holder];
        if (holderId == 0) {
            holderId = ++holdersCount;
            holders[holderId].addr = _holder;
            holderIndex[_holder] = holderId;
        }
        return holderId;
    }

    /**
     * Issues new asset token on the platform.
     *
     * Tokens issued with this call go straight to contract owner.
     * Each symbol can be issued only once, and only by contract owner.
     *
     * _isReissuable is included in checkEnabledSwitch because it should be
     * explicitly allowed before issuing new asset.
     *
     * @param _symbol asset symbol.
     * @param _value amount of tokens to issue immediately.
     * @param _name name of the asset.
     * @param _description description for the asset.
     * @param _baseUnit number of decimals.
     * @param _isReissuable dynamic or fixed supply.
     *
     * @return success.
     */
    function issueAsset(bytes32 _symbol, uint _value, string _name, string _description, uint8 _baseUnit, bool _isReissuable) checkEnabledSwitch(sha3(_symbol, _isReissuable, Features.Issue)) returns(bool) {
        // Should have positive value if supply is going to be fixed.
        if (_value == 0 && !_isReissuable) {
            _error('Cannot issue 0 value fixed asset');
            return false;
        }
        // Should not be issued yet.
        if (isCreated(_symbol)) {
            _error('Asset already issued');
            return false;
        }
        uint holderId = _createHolderId(msg.sender);

        assets[_symbol] = Asset(holderId, _value, _name, _description, _isReissuable, _baseUnit, false);
        assets[_symbol].wallets[holderId].balance = _value;
        // Internal Out Of Gas/Throw: revert this transaction too;
        // Recursive Call: safe, all changes already made.
        eventsHistory.emitIssue(_symbol, _value, _address(holderId));
        return true;
    }

    function changeAsset(bytes32 _symbol, string _name, string _description, uint8 _baseUnit) onlyOwner(_symbol) returns(bool) {
        if (isLocked(_symbol)) {
            _error('Asset is locked');
            return false;
        }
        assets[_symbol].name = _name;
        assets[_symbol].description = _description;
        assets[_symbol].baseUnit = _baseUnit;
        eventsHistory.emitChange(_symbol);
        return true;
    }

    function lockAsset(bytes32 _symbol) onlyOwner(_symbol) returns(bool) {
        if (isLocked(_symbol)) {
            _error('Asset is locked');
            return false;
        }
        assets[_symbol].isLocked = true;
        return true;
    }

    /**
     * Issues additional asset tokens if the asset have dynamic supply.
     *
     * Tokens issued with this call go straight to asset owner.
     * Can only be called by asset owner.
     *
     * @param _symbol asset symbol.
     * @param _value amount of additional tokens to issue.
     *
     * @return success.
     */
    function reissueAsset(bytes32 _symbol, uint _value) onlyOwner(_symbol) returns(bool) {
        // Should have positive value.
        if (_value == 0) {
            _error('Cannot reissue 0 value');
            return false;
        }
        Asset asset = assets[_symbol];
        // Should have dynamic supply.
        if (!asset.isReissuable) {
            _error('Cannot reissue fixed asset');
            return false;
        }
        // Resulting total supply should not overflow.
        if (asset.totalSupply + _value < asset.totalSupply) {
            _error('Total supply overflow');
            return false;
        }
        uint holderId = getHolderId(msg.sender);
        asset.wallets[holderId].balance += _value;
        asset.totalSupply += _value;
        // Internal Out Of Gas/Throw: revert this transaction too;
        // Recursive Call: safe, all changes already made.
        eventsHistory.emitIssue(_symbol, _value, _address(holderId));
        _proxyTransferEvent(0, holderId, _value, _symbol);
        return true;
    }

    /**
     * Destroys specified amount of senders asset tokens.
     *
     * @param _symbol asset symbol.
     * @param _value amount of tokens to destroy.
     *
     * @return success.
     */
    function revokeAsset(bytes32 _symbol, uint _value) checkEnabledSwitch(sha3(_symbol, Features.Revoke)) checkSigned(getHolderId(msg.sender), 1) returns(bool) {
        // Should have positive value.
        if (_value == 0) {
            _error('Cannot revoke 0 value');
            return false;
        }
        Asset asset = assets[_symbol];
        uint holderId = getHolderId(msg.sender);
        // Should have enough tokens.
        if (asset.wallets[holderId].balance < _value) {
            _error('Not enough tokens to revoke');
            return false;
        }
        asset.wallets[holderId].balance -= _value;
        asset.totalSupply -= _value;
        // Internal Out Of Gas/Throw: revert this transaction too;
        // Recursive Call: safe, all changes already made.
        eventsHistory.emitRevoke(_symbol, _value, _address(holderId));
        _proxyTransferEvent(holderId, 0, _value, _symbol);
        return true;
    }

    /**
     * Passes asset ownership to specified address.
     *
     * Only ownership is changed, balances are not touched.
     * Can only be called by asset owner.
     *
     * @param _symbol asset symbol.
     * @param _newOwner address to become a new owner.
     *
     * @return success.
     */
    function changeOwnership(bytes32 _symbol, address _newOwner) checkEnabledSwitch(sha3(_symbol, Features.ChangeOwnership)) onlyOwner(_symbol) returns(bool) {
        Asset asset = assets[_symbol];
        uint newOwnerId = _createHolderId(_newOwner);
        // Should pass ownership to another holder.
        if (asset.owner == newOwnerId) {
            _error('Cannot pass ownership to oneself');
            return false;
        }
        address oldOwner = _address(asset.owner);
        asset.owner = newOwnerId;
        // Internal Out Of Gas/Throw: revert this transaction too;
        // Recursive Call: safe, all changes already made.
        eventsHistory.emitOwnershipChange(oldOwner, _address(newOwnerId), _symbol);
        return true;
    }

    function setCosignerAddress(Cosigner _cosigner) checkSigned(_createHolderId(msg.sender), 1) returns(bool) {
        if (!_checkSigned(_cosigner, getHolderId(msg.sender), 1)) {
            _error('Invalid cosigner');
            return false;
        }
        holders[_createHolderId(msg.sender)].cosigner = _cosigner;
        return true;
    }

    function isCosignerSet(uint _holderId) constant returns(bool) {
        return address(holders[_holderId].cosigner) != 0x0;
    }

    function _checkSigned(Cosigner _cosigner, uint _holderId, uint _required) internal returns(bool) {
        return _cosigner.consumeOperation(sha3(msg.data, _holderId), _required);
    }

    modifier checkSigned(uint _holderId, uint _required) {
        if (!isCosignerSet(_holderId) || _checkSigned(holders[_holderId].cosigner, _holderId, _required)) {
            _;
        } else {
            _error('Cosigner: access denied');
        }
    }

    /**
     * Check if specified holder trusts an address with recovery procedure.
     *
     * @param _from truster.
     * @param _to trustee.
     *
     * @return trust existance.
     */
    function isTrusted(address _from, address _to) constant returns(bool) {
        return holders[getHolderId(_from)].trust[_to];
    }

    /**
     * Trust an address to perform recovery procedure for the caller.
     *
     * @param _to trustee.
     *
     * @return success.
     */
    function trust(address _to) returns(bool) {
        uint fromId = _createHolderId(msg.sender);
        // Should trust to another address.
        if (fromId == getHolderId(_to)) {
            _error('Cannot trust to oneself');
            return false;
        }
        // Should trust to yet untrusted.
        if (isTrusted(msg.sender, _to)) {
            _error('Already trusted');
            return false;
        }
        holders[fromId].trust[_to] = true;
        return true;
    }

    /**
     * Revoke trust to perform recovery procedure from an address.
     *
     * @param _to trustee.
     *
     * @return success.
     */
    function distrust(address _to) checkTrust(msg.sender, _to) returns(bool) {
        holders[getHolderId(msg.sender)].trust[_to] = false;
        return true;
    }

    /**
     * Perform recovery procedure.
     *
     * This function logic is actually more of an grantAccess(uint _holderId, address _to).
     * It grants another address access to recovery subject wallets.
     * Can only be called by trustee of recovery subject.
     * If cosigning is enabled, should have atleast 2 confirmations.
     *
     * @dev Deprecated. Backward compatibility.
     *
     * @param _from holder address to recover from.
     * @param _to address to grant access to.
     *
     * @return success.
     */
    function recover(address _from, address _to) checkTrust(_from, msg.sender) returns(bool) {
        return _grantAccess(getHolderId(_from), _to);
    }

    /**
     * Perform recovery procedure.
     *
     * This function logic is actually more of an grantAccess(uint _holderId, address _to).
     * It grants another address access to subject holder wallets.
     * Can only be called if pre-confirmed by atleast 2 cosign oracles.
     *
     * @param _from holder address to recover from.
     * @param _to address to grant access to.
     *
     * @return success.
     */
    function grantAccess(address _from, address _to) returns(bool) {
        if (!isCosignerSet(getHolderId(_from))) {
            _error('Cosigner not set');
            return false;
        }
        return _grantAccess(getHolderId(_from), _to);
    }

    function _grantAccess(uint _fromId, address _to) internal checkSigned(_fromId, 2) returns(bool) {
        // Should recover to previously unused address.
        if (getHolderId(_to) != 0) {
            _error('Should recover to new address');
            return false;
        }
        // We take current holder address because it might not equal _from.
        // It is possible to recover from any old holder address, but event should have the current one.
        address from = holders[_fromId].addr;
        holders[_fromId].addr = _to;
        holderIndex[_to] = _fromId;
        // Internal Out Of Gas/Throw: revert this transaction too;
        // Recursive Call: safe, all changes already made.
        eventsHistory.emitRecovery(from, _to, msg.sender);
        return true;
    }

    /**
     * Sets asset spending allowance for a specified spender.
     *
     * Note: to revoke allowance, one needs to set allowance to 0.
     *
     * @param _spenderId holder id to set allowance for.
     * @param _value amount to allow.
     * @param _symbol asset symbol.
     * @param _senderId approve initiator holder id.
     *
     * @return success.
     */
    function _approve(uint _spenderId, uint _value, bytes32 _symbol, uint _senderId) internal checkEnabledSwitch(sha3(_symbol, Features.Allowances)) checkSigned(_senderId, 1) returns(bool) {
        // Asset should exist.
        if (!isCreated(_symbol)) {
            _error('Asset is not issued');
            return false;
        }
        // Should allow to another holder.
        if (_senderId == _spenderId) {
            _error('Cannot approve to oneself');
            return false;
        }
        assets[_symbol].wallets[_senderId].allowance[_spenderId] = _value;
        // Internal Out Of Gas/Throw: revert this transaction too;
        // Recursive Call: safe, all changes already made.
        eventsHistory.emitApprove(_address(_senderId), _address(_spenderId), _symbol, _value);
        if (proxies[_symbol] != 0x0) {
            // Internal Out Of Gas/Throw: revert this transaction too;
            // Recursive Call: safe, all changes already made.
            Proxy(proxies[_symbol]).emitApprove(_address(_senderId), _address(_spenderId), _value);
        }
        return true;
    }

    /**
     * Sets asset spending allowance for a specified spender.
     *
     * Can only be called by asset proxy.
     *
     * @param _spender holder address to set allowance to.
     * @param _value amount to allow.
     * @param _symbol asset symbol.
     * @param _sender approve initiator address.
     *
     * @return success.
     */
    function proxyApprove(address _spender, uint _value, bytes32 _symbol, address _sender) onlyProxy(_symbol) returns(bool) {
        return _approve(_createHolderId(_spender), _value, _symbol, _createHolderId(_sender));
    }

    /**
     * Returns asset allowance from one holder to another.
     *
     * @param _from holder that allowed spending.
     * @param _spender holder that is allowed to spend.
     * @param _symbol asset symbol.
     *
     * @return holder to spender allowance.
     */
    function allowance(address _from, address _spender, bytes32 _symbol) constant returns(uint) {
        return _allowance(getHolderId(_from), getHolderId(_spender), _symbol);
    }

    /**
     * Returns asset allowance from one holder to another.
     *
     * @param _fromId holder id that allowed spending.
     * @param _toId holder id that is allowed to spend.
     * @param _symbol asset symbol.
     *
     * @return holder to spender allowance.
     */
    function _allowance(uint _fromId, uint _toId, bytes32 _symbol) constant internal returns(uint) {
        return assets[_symbol].wallets[_fromId].allowance[_toId];
    }

    /**
     * Prforms allowance transfer of asset balance between holders wallets.
     *
     * Can only be called by asset proxy.
     *
     * @param _from holder address to take from.
     * @param _to holder address to give to.
     * @param _value amount to transfer.
     * @param _symbol asset symbol.
     * @param _reference transfer comment to be included in a Transfer event.
     * @param _sender allowance transfer initiator address.
     *
     * @return success.
     */
    function proxyTransferFromWithReference(address _from, address _to, uint _value, bytes32 _symbol, string _reference, address _sender) onlyProxy(_symbol) returns(bool) {
        return _transfer(getHolderId(_from), _createHolderId(_to), _value, _symbol, _reference, getHolderId(_sender));
    }
}

// This software is a subject to Ambisafe License Agreement.
// No use or distribution is allowed without written permission from Ambisafe.
// https://ambisafe.com/terms.pdf

contract EventsHistory {
    function versions(address) constant returns(uint);
}

/**
 * @title MultiAsset Emitter.
 *
 * Contains all the original event emitting function definitions and events.
 * In case of new events needed later, additional emitters can be developed.
 * All the functions is meant to be called using delegatecall.
 */
library MultiAssetEmitter {
    event Transfer(address indexed from, address indexed to, bytes32 indexed symbol, uint value, string reference, uint version);
    event Issue(bytes32 indexed symbol, uint value, address by, uint version);
    event Revoke(bytes32 indexed symbol, uint value, address by, uint version);
    event OwnershipChange(address indexed from, address indexed to, bytes32 indexed symbol, uint version);
    event Approve(address indexed from, address indexed spender, bytes32 indexed symbol, uint value, uint version);
    event Recovery(address indexed from, address indexed to, address by, uint version);
    event TransferToICAP(address indexed from, address indexed to, bytes32 indexed icap, uint value, string reference, uint version);
    event Error(bytes32 message, uint version);
    
    function emitTransfer(address _from, address _to, bytes32 _symbol, uint _value, string _reference) {
        Transfer(_from, _to, _symbol, _value, _reference, _getVersion());
    }

    function emitIssue(bytes32 _symbol, uint _value, address _by) {
        Issue(_symbol, _value, _by, _getVersion());
    }

    function emitRevoke(bytes32 _symbol, uint _value, address _by) {
        Revoke(_symbol, _value, _by, _getVersion());
    }

    function emitOwnershipChange(address _from, address _to, bytes32 _symbol) {
        OwnershipChange(_from, _to, _symbol, _getVersion());
    }

    function emitApprove(address _from, address _spender, bytes32 _symbol, uint _value) {
        Approve(_from, _spender, _symbol, _value, _getVersion());
    }

    function emitRecovery(address _from, address _to, address _by) {
        Recovery(_from, _to, _by, _getVersion());
    }

    function emitTransferToICAP(address _from, address _to, bytes32 _icap, uint _value, string _reference) {
        TransferToICAP(_from, _to, _icap, _value, _reference, _getVersion());
    }

    function emitError(bytes32 _message) {
        Error(_message, _getVersion());
    }

    /**
     * Get version number of the caller.
     *
     * Assuming that the call is made by EventsHistory using delegate call,
     * context was not changed, so the caller is the address that called
     * EventsHistory.
     *
     * @return current context caller version number.
     */
    function _getVersion() constant internal returns(uint) {
        return EventsHistory(address(this)).versions(msg.sender);
    }
}