contract Token is ERC20, Ownable {
    
    using SafeMath for uint;
    
    // Public variables of the token
    string public name;
    string public symbol;
    uint8 public decimals; // How many decimals to show.
    string public version = "v0.1";
    uint public initialSupply;
    uint public totalSupply;
    bool public locked;           
    mapping(address => uint) balances;
    mapping(address => mapping(address => uint)) allowed;
    address public migrationMaster;
    address public migrationAgent;
    address public crowdSaleAddress;
    uint256 public totalMigrated;

    // Lock transfer for contributors during the ICO 
    modifier onlyUnlocked() {
        if (msg.sender != crowdSaleAddress && locked) 
            revert();
        _;
    }

    modifier onlyAuthorized() {
        if (msg.sender != owner && msg.sender != crowdSaleAddress) 
            revert();
        _;
    }

    // The SOCX Token created with the time at which the crowdsale ends
    function Token(address _crowdSaleAddress, address _migrationMaster) public {
        // Lock the transfCrowdsaleer function during the crowdsale
        locked = true; // Lock the transfer of tokens during the crowdsale
        initialSupply = 90000000e8;
        totalSupply = initialSupply;
        name = "SocialX"; // Set the name for display purposes
        symbol = "SOCX"; // Set the symbol for display purposes
        decimals = 8; // Amount of decimals for display purposes
        crowdSaleAddress = _crowdSaleAddress;              
        balances[crowdSaleAddress] = totalSupply;
        migrationMaster = _migrationMaster;
    }

    function unlock() public onlyAuthorized {
        locked = false;
    }

    function lock() public onlyAuthorized {
        locked = true;
    }

    event Migrate(address indexed _from, address indexed _to, uint256 _value);

    // Token migration support:

    /// @notice Migrate tokens to the new token contract.
    /// @dev Required state: Operational Migration
    /// @param _value The amount of token to be migrated
    function migrate(uint256 _value) external onlyUnlocked() {
        // Abort if not in Operational Migration state.
        
        if (migrationAgent == 0) 
            revert();
        
        // Validate input value.
        if (_value == 0) 
            revert();
        if (_value > balances[msg.sender]) 
            revert();

        balances[msg.sender] -= _value;
        totalSupply -= _value;
        totalMigrated += _value;
        MigrationAgent(migrationAgent).migrateFrom(msg.sender, _value);
        Migrate(msg.sender, migrationAgent, _value);
    }

    /// @notice Set address of migration target contract and enable migration
    /// process.
    /// @dev Required state: Operational Normal
    /// @dev State transition: -> Operational Migration
    /// @param _agent The address of the MigrationAgent contract
    function setMigrationAgent(address _agent) external onlyUnlocked() {
        // Abort if not in Operational Normal state.
        
        require(migrationAgent == 0);
        require(msg.sender == migrationMaster);
        migrationAgent = _agent;
    }

    function resetCrowdSaleAddress(address _newCrowdSaleAddress) external onlyAuthorized() {
        crowdSaleAddress = _newCrowdSaleAddress;
    }
    
    function setMigrationMaster(address _master) external {       
        require(msg.sender == migrationMaster);
        require(_master != 0);
        migrationMaster = _master;
    }

   // @notice burn tokens in case campaign failed
    // @param _member {address} of member
    // @param _value {uint} amount of tokens to burn
    // @return  {bool} true if successful
    function burn( address _member, uint256 _value) public onlyAuthorized returns(bool) {
        balances[_member] = balances[_member].sub(_value);
        totalSupply = totalSupply.sub(_value);
        Transfer(_member, 0x0, _value);
        return true;
    }

    // @notice transfer tokens to given address 
    // @param _to {address} address or recipient
    // @param _value {uint} amount to transfer
    // @return  {bool} true if successful  
    function transfer(address _to, uint _value) public onlyUnlocked returns(bool) {
        balances[msg.sender] = balances[msg.sender].sub(_value);
        balances[_to] = balances[_to].add(_value);
        Transfer(msg.sender, _to, _value);
        return true;
    }

    // @notice transfer tokens from given address to another address
    // @param _from {address} from whom tokens are transferred 
    // @param _to {address} to whom tokens are transferred
    // @parm _value {uint} amount of tokens to transfer
    // @return  {bool} true if successful   
    function transferFrom(address _from, address _to, uint256 _value) public onlyUnlocked returns(bool success) {
        require(balances[_from] >= _value); // Check if the sender has enough                            
        require(_value <= allowed[_from][msg.sender]); // Check if allowed is greater or equal        
        balances[_from] = balances[_from].sub(_value); // Subtract from the sender
        balances[_to] = balances[_to].add(_value); // Add the same to the recipient
        allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
        Transfer(_from, _to, _value);
        return true;
    }

    // @notice to query balance of account
    // @return _owner {address} address of user to query balance 
    function balanceOf(address _owner) public view returns(uint balance) {
        return balances[_owner];
    }

    /**
    * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
    *
    * Beware that changing an allowance with this method brings the risk that someone may use both the old
    * and the new allowance by unfortunate transaction ordering. One possible solution to mitigate this
    * race condition is to first reduce the spender's allowance to 0 and set the desired value afterwards:
    * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
    * @param _spender The address which will spend the funds.
    * @param _value The amount of tokens to be spent.
    */
    function approve(address _spender, uint _value) public returns(bool) {
        allowed[msg.sender][_spender] = _value;
        Approval(msg.sender, _spender, _value);
        return true;
    }

    // @notice to query of allowance of one user to the other
    // @param _owner {address} of the owner of the account
    // @param _spender {address} of the spender of the account
    // @return remaining {uint} amount of remaining allowance
    function allowance(address _owner, address _spender) public view returns(uint remaining) {
        return allowed[_owner][_spender];
    }

    /**
    * approve should be called when allowed[_spender] == 0. To increment
    * allowed value is better to use this function to avoid 2 calls (and wait until
    * the first transaction is mined)
    * From MonolithDAO Token.sol
    */
    function increaseApproval (address _spender, uint _addedValue) public returns (bool success) {
        allowed[msg.sender][_spender] = allowed[msg.sender][_spender].add(_addedValue);
        Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
        return true;
    }

    function decreaseApproval (address _spender, uint _subtractedValue) public returns (bool success) {
        uint oldValue = allowed[msg.sender][_spender];
        if (_subtractedValue > oldValue) {
            allowed[msg.sender][_spender] = 0;
        } else {
            allowed[msg.sender][_spender] = oldValue.sub(_subtractedValue);
        }
        Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
        return true;
    }

}
// The SOCX token
function setMigrationAgent(address _agent) external onlyUnlocked() {
    // Abort if not in Operational Normal state.
        
    require(migrationAgent == 0);
    require(msg.sender == migrationMaster);
    migrationAgent = _agent;
}

/// @notice Set address of migration target contract and enable migration
/// process.
/// @dev Required state: Operational Normal
/// @dev State transition: -> Operational Migration
/// @param _agent The address of the MigrationAgent contract