// SPDX-License-Identifier: MIT

pragma solidity 0.6.12;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: 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
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}


contract TwoWeeksNotice {
    
    struct StakeState {
        uint64 balance;
        uint64 unlockPeriod; // time it takes from requesting withdraw to being able to withdraw
        uint64 lockedUntil; // 0 if withdraw is not requested
        uint64 since;
        uint128 accumulated; // token-days staked
        uint128 accumulatedStrict; // token-days staked sans withdraw periods
    }
    
    event StakeUpdate(address indexed from, uint64 balance);
    event WithdrawRequest(address indexed from, uint64 until);
    
    mapping(address => StakeState) private _states;
    
    IERC20 private token;
    
    constructor (IERC20 _token) public {
        token = _token;
    }

    function getStakeState(address account) external view returns (uint64, uint64, uint64, uint64) {
        StakeState storage ss = _states[account];
        return (ss.balance, ss.unlockPeriod, ss.lockedUntil, ss.since);
    }
    
    function getAccumulated(address account) external view returns (uint128, uint128) {
        StakeState storage ss = _states[account];
        return (ss.accumulated, ss.accumulatedStrict);
    }

    function estimateAccumulated(address account) external view returns (uint128, uint128) {
        StakeState storage ss = _states[account];
        uint128 sum = ss.accumulated;
        uint128 sumStrict = ss.accumulatedStrict;
        if (ss.balance > 0) {
            uint256 until = block.timestamp;
            if (ss.lockedUntil > 0 && ss.lockedUntil < block.timestamp) {
                until = ss.lockedUntil;
            }
            if (until > ss.since) {
                uint128 delta = uint128( (uint256(ss.balance) * (until - ss.since))/86400 );
                sum += delta;
                if (ss.lockedUntil == 0) {
                    sumStrict += delta;
                }
            }
        }
        return (sum, sumStrict);
    }
    
    
    function updateAccumulated(StakeState storage ss) private {
        if (ss.balance > 0) {
            uint256 until = block.timestamp;
            if (ss.lockedUntil > 0 && ss.lockedUntil < block.timestamp) {
                until = ss.lockedUntil;
            }
            if (until > ss.since) {
                uint128 delta = uint128( (uint256(ss.balance) * (until - ss.since))/86400 );
                ss.accumulated += delta;
                if (ss.lockedUntil == 0) {
                    ss.accumulatedStrict += delta;
                }
            }
        }
    }

    function stake(uint64 amount, uint64 unlockPeriod) external {
        StakeState storage ss = _states[msg.sender];
        require(amount > 0, "amount must be positive");
        require(ss.balance <= amount, "cannot decrease balance");
        require(unlockPeriod <= 1000 days, "unlockPeriod cannot be higher than 1000 days");
        require(ss.unlockPeriod <= unlockPeriod, "cannot decrease unlock period");
        require(unlockPeriod >= 2 weeks, "unlock period can't be less than 2 weeks");
        
        updateAccumulated(ss);
        
        uint128 delta = amount - ss.balance;
        if (delta > 0) {
            require(token.transferFrom(msg.sender, address(this), delta), "transfer unsuccessful");
        }

        ss.balance = amount;
        ss.unlockPeriod = unlockPeriod;
        ss.lockedUntil = 0;
        ss.since = uint64(block.timestamp);
        emit StakeUpdate(msg.sender, amount);
    }
    
    function requestWithdraw() external {
         StakeState storage ss = _states[msg.sender];
         require(ss.balance > 0);
         updateAccumulated(ss);
         ss.since = uint64(block.timestamp);
         ss.lockedUntil = uint64(block.timestamp + ss.unlockPeriod);
    }

    function withdraw(address to) external {
        StakeState storage ss = _states[msg.sender];
        require(ss.balance > 0, "must have tokens to withdraw");
        require(ss.lockedUntil != 0, "unlock not requested");
        require(ss.lockedUntil < block.timestamp, "still locked");
        updateAccumulated(ss);
        uint128 balance = ss.balance;
        ss.balance = 0;
        ss.unlockPeriod = 0;
        ss.lockedUntil = 0;
        ss.since = 0;
        require(token.transfer(to, balance), "transfer unsuccessful");
        emit StakeUpdate(msg.sender, 0);
    }
}

/**
 *Submitted for verification at Etherscan.io on 2019-05-27
*/

// Copyright (C) Chromapolis Devcenter OU 2019


// File: openzeppelin-solidity/contracts/token/ERC20/IERC20.sol

pragma solidity ^0.5.2;

/**
 * @title ERC20 interface
 * @dev see https://eips.ethereum.org/EIPS/eip-20
 */
interface IERC20 {
    function transfer(address to, uint256 value) external returns (bool);

    function approve(address spender, uint256 value) external returns (bool);

    function transferFrom(address from, address to, uint256 value) external returns (bool);

    function totalSupply() external view returns (uint256);

    function balanceOf(address who) external view returns (uint256);

    function allowance(address owner, address spender) external view returns (uint256);

    event Transfer(address indexed from, address indexed to, uint256 value);

    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// File: openzeppelin-solidity/contracts/math/SafeMath.sol

pragma solidity ^0.5.2;

/**
 * @title SafeMath
 * @dev Unsigned math operations with safety checks that revert on error
 */
library SafeMath {
    /**
     * @dev Multiplies two unsigned integers, reverts on overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b);

        return c;
    }

    /**
     * @dev Integer division of two unsigned integers truncating the quotient, reverts on division by zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Subtracts two unsigned integers, reverts on overflow (i.e. if subtrahend is greater than minuend).
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Adds two unsigned integers, reverts on overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a);

        return c;
    }

    /**
     * @dev Divides two unsigned integers and returns the remainder (unsigned integer modulo),
     * reverts when dividing by zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b != 0);
        return a % b;
    }
}

// File: openzeppelin-solidity/contracts/token/ERC20/ERC20.sol

pragma solidity ^0.5.2;



/**
 * @title Standard ERC20 token
 *
 * @dev Implementation of the basic standard token.
 * https://eips.ethereum.org/EIPS/eip-20
 * Originally based on code by FirstBlood:
 * https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
 *
 * This implementation emits additional Approval events, allowing applications to reconstruct the allowance status for
 * all accounts just by listening to said events. Note that this isn't required by the specification, and other
 * compliant implementations may not do it.
 */
contract ERC20 is IERC20 {
    using SafeMath for uint256;

    mapping (address => uint256) private _balances;

    mapping (address => mapping (address => uint256)) private _allowed;

    uint256 private _totalSupply;

    /**
     * @dev Total number of tokens in existence
     */
    function totalSupply() public view returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev Gets the balance of the specified address.
     * @param owner The address to query the balance of.
     * @return A uint256 representing the amount owned by the passed address.
     */
    function balanceOf(address owner) public view returns (uint256) {
        return _balances[owner];
    }

    /**
     * @dev Function to check the amount of tokens that an owner allowed to a spender.
     * @param owner address The address which owns the funds.
     * @param spender address The address which will spend the funds.
     * @return A uint256 specifying the amount of tokens still available for the spender.
     */
    function allowance(address owner, address spender) public view returns (uint256) {
        return _allowed[owner][spender];
    }

    /**
     * @dev Transfer token to a specified address
     * @param to The address to transfer to.
     * @param value The amount to be transferred.
     */
    function transfer(address to, uint256 value) public returns (bool) {
        _transfer(msg.sender, to, value);
        return true;
    }

    /**
     * @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, uint256 value) public returns (bool) {
        _approve(msg.sender, spender, value);
        return true;
    }

    /**
     * @dev Transfer tokens from one address to another.
     * Note that while this function emits an Approval event, this is not required as per the specification,
     * and other compliant implementations may not emit the event.
     * @param from address The address which you want to send tokens from
     * @param to address The address which you want to transfer to
     * @param value uint256 the amount of tokens to be transferred
     */
    function transferFrom(address from, address to, uint256 value) public returns (bool) {
        _transfer(from, to, value);
        _approve(from, msg.sender, _allowed[from][msg.sender].sub(value));
        return true;
    }

    /**
     * @dev Increase the amount of tokens that an owner allowed to a spender.
     * approve should be called when _allowed[msg.sender][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
     * Emits an Approval event.
     * @param spender The address which will spend the funds.
     * @param addedValue The amount of tokens to increase the allowance by.
     */
    function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
        _approve(msg.sender, spender, _allowed[msg.sender][spender].add(addedValue));
        return true;
    }

    /**
     * @dev Decrease the amount of tokens that an owner allowed to a spender.
     * approve should be called when _allowed[msg.sender][spender] == 0. To decrement
     * allowed value is better to use this function to avoid 2 calls (and wait until
     * the first transaction is mined)
     * From MonolithDAO Token.sol
     * Emits an Approval event.
     * @param spender The address which will spend the funds.
     * @param subtractedValue The amount of tokens to decrease the allowance by.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
        _approve(msg.sender, spender, _allowed[msg.sender][spender].sub(subtractedValue));
        return true;
    }

    /**
     * @dev Transfer token for a specified addresses
     * @param from The address to transfer from.
     * @param to The address to transfer to.
     * @param value The amount to be transferred.
     */
    function _transfer(address from, address to, uint256 value) internal {
        require(to != address(0));

        _balances[from] = _balances[from].sub(value);
        _balances[to] = _balances[to].add(value);
        emit Transfer(from, to, value);
    }

    /**
     * @dev Internal function that mints an amount of the token and assigns it to
     * an account. This encapsulates the modification of balances such that the
     * proper events are emitted.
     * @param account The account that will receive the created tokens.
     * @param value The amount that will be created.
     */
    function _mint(address account, uint256 value) internal {
        require(account != address(0));

        _totalSupply = _totalSupply.add(value);
        _balances[account] = _balances[account].add(value);
        emit Transfer(address(0), account, value);
    }

    /**
     * @dev Internal function that burns an amount of the token of a given
     * account.
     * @param account The account whose tokens will be burnt.
     * @param value The amount that will be burnt.
     */
    function _burn(address account, uint256 value) internal {
        require(account != address(0));

        _totalSupply = _totalSupply.sub(value);
        _balances[account] = _balances[account].sub(value);
        emit Transfer(account, address(0), value);
    }

    /**
     * @dev Approve an address to spend another addresses' tokens.
     * @param owner The address that owns the tokens.
     * @param spender The address that will spend the tokens.
     * @param value The number of tokens that can be spent.
     */
    function _approve(address owner, address spender, uint256 value) internal {
        require(spender != address(0));
        require(owner != address(0));

        _allowed[owner][spender] = value;
        emit Approval(owner, spender, value);
    }

    /**
     * @dev Internal function that burns an amount of the token of a given
     * account, deducting from the sender's allowance for said account. Uses the
     * internal burn function.
     * Emits an Approval event (reflecting the reduced allowance).
     * @param account The account whose tokens will be burnt.
     * @param value The amount that will be burnt.
     */
    function _burnFrom(address account, uint256 value) internal {
        _burn(account, value);
        _approve(account, msg.sender, _allowed[account][msg.sender].sub(value));
    }
}

// File: openzeppelin-solidity/contracts/token/ERC20/ERC20Detailed.sol

pragma solidity ^0.5.2;


/**
 * @title ERC20Detailed token
 * @dev The decimals are only for visualization purposes.
 * All the operations are done using the smallest and indivisible token unit,
 * just as on Ethereum all the operations are done in wei.
 */
contract ERC20Detailed is IERC20 {
    string private _name;
    string private _symbol;
    uint8 private _decimals;

    constructor (string memory name, string memory symbol, uint8 decimals) public {
        _name = name;
        _symbol = symbol;
        _decimals = decimals;
    }

    /**
     * @return the name of the token.
     */
    function name() public view returns (string memory) {
        return _name;
    }

    /**
     * @return the symbol of the token.
     */
    function symbol() public view returns (string memory) {
        return _symbol;
    }

    /**
     * @return the number of decimals of the token.
     */
    function decimals() public view returns (uint8) {
        return _decimals;
    }
}

// File: contracts/token/ERC20/Chromia.sol

// Copyright (C) Chromapolis Devcenter OU 2019

pragma solidity 0.5.8;



contract Chromia is ERC20, ERC20Detailed {
    uint8 public constant DECIMALS = 6;
    address private _minter;
    // one billion tokens with 6 decimals
    uint256 private _cap = 1000000000 * 1000000;

    event MinterSet(address indexed account);
    event TransferToChromia(address indexed from, bytes32 indexed to, uint256 value);
    event TransferFromChromia(address indexed to, bytes32 indexed refID, uint256 value);

    /**
     * @dev Constructor that gives msg.sender all of existing tokens.
     * @param minter the multi-sig contract address
     */
    constructor(address minter, uint256 initialBalance) public ERC20Detailed("Chroma", "CHR", DECIMALS) {
        _mint(msg.sender, initialBalance);
        _setMinter(minter);
    }

    modifier onlyMinter() {
        require(isMinter(msg.sender), "caller is not a minter");
        _;
    }
    
    function cap() public view returns (uint256) {
        return _cap;
    }

    /**
     * @dev Burns a specific amount of tokens and emit transfer event for Chromia
     * @param to The address to transfer to in Chromia.
     * @param value The amount of token to be burned.
     */
    function transferToChromia(bytes32 to, uint256 value) public {
        _burn(msg.sender, value);
        emit TransferToChromia(msg.sender, to, value);
    }

    /**
     * @dev Function to mint tokens
     * @param to The address that will receive the minted tokens.
     * @param value The amount of tokens to mint.
     * @return A boolean that indicates if the operation was successful.
     */
    function transferFromChromia(address to, uint256 value, bytes32 refID) public onlyMinter returns (bool) {
        _mint(to, value);
        emit TransferFromChromia(to, refID, value);
        return true;
    }
    
    function _mint(address account, uint256 value) internal {
        require(totalSupply().add(value) <= cap(), "ERC20Capped: cap exceeded");
        super._mint(account, value);
    }

    function isMinter(address account) public view returns (bool) {
        return _minter == account;
    }

    function _setMinter(address account) internal {
        _minter = account;
        emit MinterSet(account);
    }
    
    function changeMinter(address newMinter) public onlyMinter {
        _setMinter(newMinter);
    }
}