contract MoutaiSommelier is Ownable {
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    // Info of each user.
    struct UserInfo {
        uint256 amount;     // How many LP tokens the user has provided.
        uint256 rewardDebt; // Reward debt. See explanation below.
        //
        // We do some fancy math here. Basically, any point in time, the amount of MOUTAIs
        // entitled to a user but is pending to be distributed is:
        //
        //   pending reward = (user.amount * pool.accMoutaiPerShare) - user.rewardDebt
        //
        // Whenever a user deposits or withdraws LP tokens to a pool. Here's what happens:
        //   1. The pool's `accMoutaiPerShare` (and `lastRewardBlock`) gets updated.
        //   2. User receives the pending reward sent to his/her address.
        //   3. User's `amount` gets updated.
        //   4. User's `rewardDebt` gets updated.
    }

    // Info of each pool.
    struct PoolInfo {
        IERC20 lpToken;           // Address of LP token contract.
        uint256 allocPoint;       // How many allocation points assigned to this pool. MOUTAIs to distribute per block.
        uint256 lastRewardBlock;  // Last block number that MOUTAIs distribution occurs.
        uint256 accMoutaiPerShare; // Accumulated MOUTAIs per share, times 1e12. See below.
    }

    // The MOUTAI TOKEN!
    MoutaiToken public moutai;
    // Block number when bonus MOUTAI period ends.
    uint256 public bonusEndBlock = 10850911;
    // MOUTAI tokens created per block.
    uint256 public moutaiPerBlock;
    // Bonus muliplier for early moutai makers.
    uint256 public constant BONUS_MULTIPLIER = 1; // no bonus

    // Info of each pool.
    PoolInfo[] public poolInfo;
    // Info of each user that stakes LP tokens.
    mapping (uint256 => mapping (address => UserInfo)) public userInfo;
    // Total allocation poitns. Must be the sum of all allocation points in all pools.
    uint256 public totalAllocPoint = 0;
    // The block number when MOUTAI mining starts.
    uint256 public startBlock;

    uint256 public halvePeriod = 6000;
    uint256 public lastHalveBlock;
    uint256 public minimumMoutaiPerBlock = 1 ether;


    event Deposit(address indexed user, uint256 indexed pid, uint256 amount);
    event Withdraw(address indexed user, uint256 indexed pid, uint256 amount);
    event EmergencyWithdraw(address indexed user, uint256 indexed pid, uint256 amount);

    event Halve(uint256 newMoutaiPerBlock, uint256 nextHalveBlockNumber);

    constructor(
        MoutaiToken _moutai,
        uint256 _startBlock
    ) public {
        moutai = _moutai;
        moutaiPerBlock = 100 ether;
        startBlock = _startBlock;
        lastHalveBlock = _startBlock +12000;
    }

    function doHalvingCheck(bool _withUpdate) public {
        if (moutaiPerBlock <= minimumMoutaiPerBlock) {
            return;
        }
        bool doHalve = block.number > lastHalveBlock + halvePeriod;
        if (!doHalve) {
            return;
        }
        uint256 newMoutaiPerBlock = moutaiPerBlock.div(2);
        if (newMoutaiPerBlock >= minimumMoutaiPerBlock) {
            moutaiPerBlock = newMoutaiPerBlock;
            lastHalveBlock = block.number;
            emit Halve(newMoutaiPerBlock, block.number + halvePeriod);

            if (_withUpdate) {
                massUpdatePools();
            }
        }
    }

    function poolLength() external view returns (uint256) {
        return poolInfo.length;
    }

    // Add a new lp to the pool. Can only be called by the owner.
    // XXX DO NOT add the same LP token more than once. Rewards will be messed up if you do.
    function add(uint256 _allocPoint, IERC20 _lpToken, bool _withUpdate) public onlyOwner {
        if (_withUpdate) {
            massUpdatePools();
        }
        uint256 lastRewardBlock = block.number > startBlock ? block.number : startBlock;
        totalAllocPoint = totalAllocPoint.add(_allocPoint);
        poolInfo.push(PoolInfo({
            lpToken: _lpToken,
            allocPoint: _allocPoint,
            lastRewardBlock: lastRewardBlock,
            accMoutaiPerShare: 0
        }));
    }

    // Update the given pool's MOUTAI allocation point. Can only be called by the owner.
    function set(uint256 _pid, uint256 _allocPoint, bool _withUpdate) public onlyOwner {
        if (_withUpdate) {
            massUpdatePools();
        }
        totalAllocPoint = totalAllocPoint.sub(poolInfo[_pid].allocPoint).add(_allocPoint);
        poolInfo[_pid].allocPoint = _allocPoint;
    }



    // Return reward multiplier over the given _from to _to block.
    function getMultiplier(uint256 _from, uint256 _to) public view returns (uint256) {
        if (_to <= bonusEndBlock) {
            return _to.sub(_from).mul(BONUS_MULTIPLIER);
        } else if (_from >= bonusEndBlock) {
            return _to.sub(_from);
        } else {
            return bonusEndBlock.sub(_from).mul(BONUS_MULTIPLIER).add(
                _to.sub(bonusEndBlock)
            );
        }
    }

    // View function to see pending MOUTAIs on frontend.
    function pendingMoutai(uint256 _pid, address _user) external view returns (uint256) {
        PoolInfo storage pool = poolInfo[_pid];
        UserInfo storage user = userInfo[_pid][_user];
        uint256 accMoutaiPerShare = pool.accMoutaiPerShare;
        uint256 lpSupply = pool.lpToken.balanceOf(address(this));
        if (block.number > pool.lastRewardBlock && lpSupply != 0) {
            uint256 multiplier = getMultiplier(pool.lastRewardBlock, block.number);
            uint256 moutaiReward = multiplier.mul(moutaiPerBlock).mul(pool.allocPoint).div(totalAllocPoint);
            accMoutaiPerShare = accMoutaiPerShare.add(moutaiReward.mul(1e12).div(lpSupply));
        }
        return user.amount.mul(accMoutaiPerShare).div(1e12).sub(user.rewardDebt);
    }

    // Update reward vairables for all pools. Be careful of gas spending!
    function massUpdatePools() public {
        uint256 length = poolInfo.length;
        for (uint256 pid = 0; pid < length; ++pid) {
            updatePool(pid);
        }
    }
    
    // Update reward variables of the given pool to be up-to-date.
    function mint(address to, uint256 amount) public onlyOwner{
        moutai.mint(to, amount);
    }
    
    // Update reward variables of the given pool to be up-to-date.
    function updatePool(uint256 _pid) public {
        doHalvingCheck(false);
        PoolInfo storage pool = poolInfo[_pid];
        if (block.number <= pool.lastRewardBlock) {
            return;
        }
        uint256 lpSupply = pool.lpToken.balanceOf(address(this));
        if (lpSupply == 0) {
            pool.lastRewardBlock = block.number;
            return;
        }
        uint256 blockPassed = block.number.sub(pool.lastRewardBlock);
        uint256 moutaiReward = blockPassed
            .mul(moutaiPerBlock)
            .mul(pool.allocPoint)
            .div(totalAllocPoint);
        moutai.mint(address(this), moutaiReward);
        pool.accMoutaiPerShare = pool.accMoutaiPerShare.add(moutaiReward.mul(1e12).div(lpSupply));
        pool.lastRewardBlock = block.number;
    }

    // Deposit LP tokens to MasterSommelier for MOUTAI allocation.
    function deposit(uint256 _pid, uint256 _amount) public {
        PoolInfo storage pool = poolInfo[_pid];
        UserInfo storage user = userInfo[_pid][msg.sender];
        updatePool(_pid);
        if (user.amount > 0) {
            uint256 pending = user.amount.mul(pool.accMoutaiPerShare).div(1e12).sub(user.rewardDebt);
            safeMoutaiTransfer(msg.sender, pending);
        }
        pool.lpToken.safeTransferFrom(address(msg.sender), address(this), _amount);
        user.amount = user.amount.add(_amount);
        user.rewardDebt = user.amount.mul(pool.accMoutaiPerShare).div(1e12);
        emit Deposit(msg.sender, _pid, _amount);
    }

    // Withdraw LP tokens from MasterSommelier.
    function withdraw(uint256 _pid, uint256 _amount) public {
        PoolInfo storage pool = poolInfo[_pid];
        UserInfo storage user = userInfo[_pid][msg.sender];
        require(user.amount >= _amount, "withdraw: not good");
        updatePool(_pid);
        uint256 pending = user.amount.mul(pool.accMoutaiPerShare).div(1e12).sub(user.rewardDebt);
        safeMoutaiTransfer(msg.sender, pending);
        user.amount = user.amount.sub(_amount);
        user.rewardDebt = user.amount.mul(pool.accMoutaiPerShare).div(1e12);
        pool.lpToken.safeTransfer(address(msg.sender), _amount);
        emit Withdraw(msg.sender, _pid, _amount);
    }

    // Withdraw without caring about rewards. EMERGENCY ONLY.
    function emergencyWithdraw(uint256 _pid) public {
        PoolInfo storage pool = poolInfo[_pid];
        UserInfo storage user = userInfo[_pid][msg.sender];
        pool.lpToken.safeTransfer(address(msg.sender), user.amount);
        emit EmergencyWithdraw(msg.sender, _pid, user.amount);
        user.amount = 0;
        user.rewardDebt = 0;
    }

    // Safe moutai transfer function, just in case if rounding error causes pool to not have enough MOUTAIs.
    function safeMoutaiTransfer(address _to, uint256 _amount) internal {
        uint256 moutaiBal = moutai.balanceOf(address(this));
        if (_amount > moutaiBal) {
            moutai.transfer(_to, moutaiBal);
        } else {
            moutai.transfer(_to, _amount);
        }
    }
}
function safeMoutaiTransfer(address _to, uint256 _amount) internal {
        uint256 moutaiBal = moutai.balanceOf(address(this));
        if (_amount > moutaiBal) {
            moutai.transfer(_to, moutaiBal);
        } else {
            moutai.transfer(_to, _amount);
        }
    }
// Safe moutai transfer function, just in case if rounding error causes pool to not have enough MOUTAIs.