pragma solidity ^0.4.11;

contract SafeMath {

    function safeMul(uint256 a, uint256 b) internal constant returns (uint256 ) {
        uint256 c = a * b;
        assert(a == 0 || c / a == b);
        return c;
    }

    function safeDiv(uint256 a, uint256 b) internal constant returns (uint256 ) {
        assert(b > 0);
        uint256 c = a / b;
        assert(a == b * c + a % b);
        return c;
    }

    function safeSub(uint256 a, uint256 b) internal constant returns (uint256 ) {
        assert(b <= a);
        return a - b;
    }

    function safeAdd(uint256 a, uint256 b) internal constant returns (uint256 ) {
        uint256 c = a + b;
        assert(c >= a);
        return c;
    }
}

contract ERC20 {

    /* This is a slight change to the ERC20 base standard.
    function totalSupply() constant returns (uint256 supply);
    is replaced with:
    uint256 public totalSupply;
    This automatically creates a getter function for the totalSupply.
    This is moved to the base contract since public getter functions are not
    currently recognised as an implementation of the matching abstract
    function by the compiler.
    */
    /// total amount of tokens
    uint256 public totalSupply;

    /// @param _owner The address from which the balance will be retrieved
    /// @return The balance
    function balanceOf(address _owner) public constant returns (uint256 balance);

    /// @notice send `_value` token to `_to` from `msg.sender`
    /// @param _to The address of the recipient
    /// @param _value The amount of token to be transferred
    /// @return Whether the transfer was successful or not
    function transfer(address _to, uint256 _value) public returns (bool success);

    /// @notice send `_value` token to `_to` from `_from` on the condition it is approved by `_from`
    /// @param _from The address of the sender
    /// @param _to The address of the recipient
    /// @param _value The amount of token to be transferred
    /// @return Whether the transfer was successful or not
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success);

    /// @notice `msg.sender` approves `_spender` to spend `_value` tokens
    /// @param _spender The address of the account able to transfer the tokens
    /// @param _value The amount of tokens to be approved for transfer
    /// @return Whether the approval was successful or not
    function approve(address _spender, uint256 _value) public returns (bool success);

    /// @param _owner The address of the account owning tokens
    /// @param _spender The address of the account able to transfer the tokens
    /// @return Amount of remaining tokens allowed to spent
    function allowance(address _owner, address _spender) public constant returns (uint256 remaining);

    event Transfer(address indexed _from, address indexed _to, uint256 _value);
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);
}

contract StandardToken is ERC20, SafeMath {

    mapping(address => uint256) balances;
    mapping(address => mapping(address => uint256)) allowed;

    /// @dev Returns number of tokens owned by given address.
    /// @param _owner Address of token owner.
    function balanceOf(address _owner) public constant returns (uint256 balance) {
        return balances[_owner];
    }

    /// @dev Transfers sender's tokens to a given address. Returns success.
    /// @param _to Address of token receiver.
    /// @param _value Number of tokens to transfer.
    function transfer(address _to, uint256 _value) public returns (bool) {
        if (balances[msg.sender] >= _value && _value > 0) {
            balances[msg.sender] = safeSub(balances[msg.sender], _value);
            balances[_to] = safeAdd(balances[_to], _value);
            Transfer(msg.sender, _to, _value);
            return true;
        } else return false;
    }

    /// @dev Allows allowed third party to transfer tokens from one address to another. Returns success.
    /// @param _from Address from where tokens are withdrawn.
    /// @param _to Address to where tokens are sent.
    /// @param _value Number of tokens to transfer.
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
        if (balances[_from] >= _value && allowed[_from][msg.sender] >= _value && _value > 0) {
            balances[_to] = safeAdd(balances[_to], _value);
            balances[_from] = safeSub(balances[_from], _value);
            allowed[_from][msg.sender] = safeSub(allowed[_from][msg.sender], _value);
            Transfer(_from, _to, _value);
            return true;
        } else return false;
    }

    /// @dev Sets approved amount of tokens for spender. Returns success.
    /// @param _spender Address of allowed account.
    /// @param _value Number of approved tokens.
    function approve(address _spender, uint256 _value) public returns (bool) {
        allowed[msg.sender][_spender] = _value;
        Approval(msg.sender, _spender, _value);
        return true;
    }

    /// @dev Returns number of allowed tokens for given address.
    /// @param _owner Address of token owner.
    /// @param _spender Address of token spender.
    function allowance(address _owner, address _spender) public constant returns (uint256 remaining) {
        return allowed[_owner][_spender];
    }
}

contract MultiOwnable {

    mapping (address => bool) ownerMap;
    address[] public owners;

    event OwnerAdded(address indexed _newOwner);
    event OwnerRemoved(address indexed _oldOwner);

    modifier onlyOwner() {
        require(isOwner(msg.sender));
        _;
    }

    function MultiOwnable() {
        // Add default owner
        address owner = msg.sender;
        ownerMap[owner] = true;
        owners.push(owner);
    }

    function ownerCount() public constant returns (uint256) {
        return owners.length;
    }

    function isOwner(address owner) public constant returns (bool) {
        return ownerMap[owner];
    }

    function addOwner(address owner) onlyOwner public returns (bool) {
        if (!isOwner(owner) && owner != 0) {
            ownerMap[owner] = true;
            owners.push(owner);

            OwnerAdded(owner);
            return true;
        } else return false;
    }

    function removeOwner(address owner) onlyOwner public returns (bool) {
        if (isOwner(owner)) {
            ownerMap[owner] = false;
            for (uint i = 0; i < owners.length - 1; i++) {
                if (owners[i] == owner) {
                    owners[i] = owners[owners.length - 1];
                    break;
                }
            }
            owners.length -= 1;

            OwnerRemoved(owner);
            return true;
        } else return false;
    }
}

contract TokenSpender {
    function receiveApproval(address _from, uint256 _value);
}

contract CommonBsToken is StandardToken, MultiOwnable {

    string public name;
    string public symbol;
    uint256 public totalSupply;
    uint8 public decimals = 18;
    string public version = 'v0.1';

    address public creator;
    address public seller;     // The main account that holds all tokens at the beginning.

    uint256 public saleLimit;  // (e18) How many tokens can be sold in total through all tiers or tokensales.
    uint256 public tokensSold; // (e18) Number of tokens sold through all tiers or tokensales.
    uint256 public totalSales; // Total number of sale (including external sales) made through all tiers or tokensales.

    bool public locked;

    event Sell(address indexed _seller, address indexed _buyer, uint256 _value);
    event SellerChanged(address indexed _oldSeller, address indexed _newSeller);

    event Lock();
    event Unlock();

    event Burn(address indexed _burner, uint256 _value);

    modifier onlyUnlocked() {
        if (!isOwner(msg.sender) && locked) throw;
        _;
    }

    function CommonBsToken(
        address _seller,
        string _name,
        string _symbol,
        uint256 _totalSupplyNoDecimals,
        uint256 _saleLimitNoDecimals
    ) MultiOwnable() {

        // Lock the transfer function during the presale/crowdsale to prevent speculations.
        locked = true;

        creator = msg.sender;
        seller = _seller;

        name = _name;
        symbol = _symbol;
        totalSupply = _totalSupplyNoDecimals * 1e18;
        saleLimit = _saleLimitNoDecimals * 1e18;

        balances[seller] = totalSupply;
        Transfer(0x0, seller, totalSupply);
    }

    function changeSeller(address newSeller) onlyOwner public returns (bool) {
        require(newSeller != 0x0 && seller != newSeller);

        address oldSeller = seller;
        uint256 unsoldTokens = balances[oldSeller];
        balances[oldSeller] = 0;
        balances[newSeller] = safeAdd(balances[newSeller], unsoldTokens);
        Transfer(oldSeller, newSeller, unsoldTokens);

        seller = newSeller;
        SellerChanged(oldSeller, newSeller);
        return true;
    }

    function sellNoDecimals(address _to, uint256 _value) public returns (bool) {
        return sell(_to, _value * 1e18);
    }

    function sell(address _to, uint256 _value) onlyOwner public returns (bool) {

        // Check that we are not out of limit and still can sell tokens:
        if (saleLimit > 0) require(safeSub(saleLimit, safeAdd(tokensSold, _value)) >= 0);

        require(_to != address(0));
        require(_value > 0);
        require(_value <= balances[seller]);

        balances[seller] = safeSub(balances[seller], _value);
        balances[_to] = safeAdd(balances[_to], _value);
        Transfer(seller, _to, _value);

        tokensSold = safeAdd(tokensSold, _value);
        totalSales = safeAdd(totalSales, 1);
        Sell(seller, _to, _value);

        return true;
    }

    function transfer(address _to, uint256 _value) onlyUnlocked public returns (bool) {
        return super.transfer(_to, _value);
    }

    function transferFrom(address _from, address _to, uint256 _value) onlyUnlocked public returns (bool) {
        return super.transferFrom(_from, _to, _value);
    }

    function lock() onlyOwner public {
        locked = true;
        Lock();
    }

    function unlock() onlyOwner public {
        locked = false;
        Unlock();
    }

    function burn(uint256 _value) public returns (bool) {
        require(_value > 0);
        require(_value <= balances[msg.sender]);

        balances[msg.sender] = safeSub(balances[msg.sender], _value) ;
        totalSupply = safeSub(totalSupply, _value);
        Transfer(msg.sender, 0x0, _value);
        Burn(msg.sender, _value);

        return true;
    }

    /* Approve and then communicate the approved contract in a single tx */
    function approveAndCall(address _spender, uint256 _value) public {
        TokenSpender spender = TokenSpender(_spender);
        if (approve(_spender, _value)) {
            spender.receiveApproval(msg.sender, _value);
        }
    }
}

contract XToken is CommonBsToken {

    function XToken() public CommonBsToken(
        0xE3E9F66E5Ebe9E961662da34FF9aEA95c6795fd0,     // TODO address _seller (main holder of all tokens)
        'X full',
        'X short',
        100 * 1e6, // Max token supply.
        40 * 1e6   // Sale limit - max tokens that can be sold through all tiers of tokensale.
    ) { }
}