contract VotingPower is PrismProxyImplementation, ReentrancyGuardUpgradeSafe {
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    /// @notice An event that's emitted when a user's staked balance increases
    event Staked(address indexed user, address indexed token, uint256 indexed amount, uint256 votingPower);

    /// @notice An event that's emitted when a user's staked balance decreases
    event Withdrawn(address indexed user, address indexed token, uint256 indexed amount, uint256 votingPower);

    /// @notice An event that's emitted when an account's vote balance changes
    event VotingPowerChanged(address indexed voter, uint256 indexed previousBalance, uint256 indexed newBalance);

    /**
     * @notice Initialize VotingPower contract
     * @dev Should be called via VotingPowerPrism before calling anything else
     * @param _archToken address of ARCH token
     * @param _vestingContract address of Vesting contract
     */
    function initialize(
        address _archToken,
        address _vestingContract
    ) public initializer {
        __ReentrancyGuard_init_unchained();
        AppStorage storage app = VotingPowerStorage.appStorage();
        app.archToken = IArchToken(_archToken);
        app.vesting = IVesting(_vestingContract);
    }

    /**
     * @notice Address of ARCH token
     * @return Address of ARCH token
     */
    function archToken() public view returns (address) {
        AppStorage storage app = VotingPowerStorage.appStorage();
        return address(app.archToken);
    }

    /**
     * @notice Address of vesting contract
     * @return Address of vesting contract
     */
    function vestingContract() public view returns (address) {
        AppStorage storage app = VotingPowerStorage.appStorage();
        return address(app.vesting);
    }

    /**
     * @notice Stake ARCH tokens using offchain approvals to unlock voting power
     * @param amount The amount to stake
     * @param deadline The time at which to expire the signature
     * @param v The recovery byte of the signature
     * @param r Half of the ECDSA signature pair
     * @param s Half of the ECDSA signature pair
     */
    function stakeWithPermit(uint256 amount, uint256 deadline, uint8 v, bytes32 r, bytes32 s) external nonReentrant {
        require(amount > 0, "VP::stakeWithPermit: cannot stake 0");
        AppStorage storage app = VotingPowerStorage.appStorage();
        require(app.archToken.balanceOf(msg.sender) >= amount, "VP::stakeWithPermit: not enough tokens");

        app.archToken.permit(msg.sender, address(this), amount, deadline, v, r, s);

        _stake(msg.sender, address(app.archToken), amount, amount);
    }

    /**
     * @notice Stake ARCH tokens to unlock voting power for `msg.sender`
     * @param amount The amount to stake
     */
    function stake(uint256 amount) external nonReentrant {
        AppStorage storage app = VotingPowerStorage.appStorage();
        require(amount > 0, "VP::stake: cannot stake 0");
        require(app.archToken.balanceOf(msg.sender) >= amount, "VP::stake: not enough tokens");
        require(app.archToken.allowance(msg.sender, address(this)) >= amount, "VP::stake: must approve tokens before staking");

        _stake(msg.sender, address(app.archToken), amount, amount);
    }

    /**
     * @notice Count vesting ARCH tokens toward voting power for `account`
     * @param account The recipient of voting power
     * @param amount The amount of voting power to add
     */
    function addVotingPowerForVestingTokens(address account, uint256 amount) external nonReentrant {
        AppStorage storage app = VotingPowerStorage.appStorage();
        require(amount > 0, "VP::addVPforVT: cannot add 0 voting power");
        require(msg.sender == address(app.vesting), "VP::addVPforVT: only vesting contract");

        _increaseVotingPower(account, amount);
    }

    /**
     * @notice Remove claimed vesting ARCH tokens from voting power for `account`
     * @param account The account with voting power
     * @param amount The amount of voting power to remove
     */
    function removeVotingPowerForClaimedTokens(address account, uint256 amount) external nonReentrant {
        AppStorage storage app = VotingPowerStorage.appStorage();
        require(amount > 0, "VP::removeVPforVT: cannot remove 0 voting power");
        require(msg.sender == address(app.vesting), "VP::removeVPforVT: only vesting contract");

        _decreaseVotingPower(account, amount);
    }

    /**
     * @notice Withdraw staked ARCH tokens, removing voting power for `msg.sender`
     * @param amount The amount to withdraw
     */
    function withdraw(uint256 amount) external nonReentrant {
        require(amount > 0, "VP::withdraw: cannot withdraw 0");
        AppStorage storage app = VotingPowerStorage.appStorage();
        _withdraw(msg.sender, address(app.archToken), amount, amount);
    }

    /**
     * @notice Get total amount of ARCH tokens staked in contract by `staker`
     * @param staker The user with staked ARCH
     * @return total ARCH amount staked
     */
    function getARCHAmountStaked(address staker) public view returns (uint256) {
        return getARCHStake(staker).amount;
    }

    /**
     * @notice Get total amount of tokens staked in contract by `staker`
     * @param staker The user with staked tokens
     * @param stakedToken The staked token
     * @return total amount staked
     */
    function getAmountStaked(address staker, address stakedToken) public view returns (uint256) {
        return getStake(staker, stakedToken).amount;
    }

    /**
     * @notice Get staked amount and voting power from ARCH tokens staked in contract by `staker`
     * @param staker The user with staked ARCH
     * @return total ARCH staked
     */
    function getARCHStake(address staker) public view returns (Stake memory) {
        AppStorage storage app = VotingPowerStorage.appStorage();
        return getStake(staker, address(app.archToken));
    }

    /**
     * @notice Get total staked amount and voting power from `stakedToken` staked in contract by `staker`
     * @param staker The user with staked tokens
     * @param stakedToken The staked token
     * @return total staked
     */
    function getStake(address staker, address stakedToken) public view returns (Stake memory) {
        StakeStorage storage ss = VotingPowerStorage.stakeStorage();
        return ss.stakes[staker][stakedToken];
    }

    /**
     * @notice Gets the current votes balance for `account`
     * @param account The address to get votes balance
     * @return The number of current votes for `account`
     */
    function balanceOf(address account) public view returns (uint256) {
        CheckpointStorage storage cs = VotingPowerStorage.checkpointStorage();
        uint32 nCheckpoints = cs.numCheckpoints[account];
        return nCheckpoints > 0 ? cs.checkpoints[account][nCheckpoints - 1].votes : 0;
    }

    /**
     * @notice Determine the prior number of votes for an account as of a block number
     * @dev Block number must be a finalized block or else this function will revert to prevent misinformation.
     * @param account The address of the account to check
     * @param blockNumber The block number to get the vote balance at
     * @return The number of votes the account had as of the given block
     */
    function balanceOfAt(address account, uint256 blockNumber) public view returns (uint256) {
        require(blockNumber < block.number, "VP::balanceOfAt: not yet determined");
        
        CheckpointStorage storage cs = VotingPowerStorage.checkpointStorage();
        uint32 nCheckpoints = cs.numCheckpoints[account];
        if (nCheckpoints == 0) {
            return 0;
        }

        // First check most recent balance
        if (cs.checkpoints[account][nCheckpoints - 1].fromBlock <= blockNumber) {
            return cs.checkpoints[account][nCheckpoints - 1].votes;
        }

        // Next check implicit zero balance
        if (cs.checkpoints[account][0].fromBlock > blockNumber) {
            return 0;
        }

        uint32 lower = 0;
        uint32 upper = nCheckpoints - 1;
        while (upper > lower) {
            uint32 center = upper - (upper - lower) / 2; // ceil, avoiding overflow
            Checkpoint memory cp = cs.checkpoints[account][center];
            if (cp.fromBlock == blockNumber) {
                return cp.votes;
            } else if (cp.fromBlock < blockNumber) {
                lower = center;
            } else {
                upper = center - 1;
            }
        }
        return cs.checkpoints[account][lower].votes;
    }

    /**
     * @notice Internal implementation of stake
     * @param voter The user that is staking tokens
     * @param token The token to stake
     * @param tokenAmount The amount of token to stake
     * @param votingPower The amount of voting power stake translates into
     */
    function _stake(address voter, address token, uint256 tokenAmount, uint256 votingPower) internal {
        IERC20(token).safeTransferFrom(voter, address(this), tokenAmount);

        StakeStorage storage ss = VotingPowerStorage.stakeStorage();
        ss.stakes[voter][token].amount = ss.stakes[voter][token].amount.add(tokenAmount);
        ss.stakes[voter][token].votingPower = ss.stakes[voter][token].votingPower.add(votingPower);

        emit Staked(voter, token, tokenAmount, votingPower);

        _increaseVotingPower(voter, votingPower);
    }

    /**
     * @notice Internal implementation of withdraw
     * @param voter The user with tokens staked
     * @param token The token that is staked
     * @param tokenAmount The amount of token to withdraw
     * @param votingPower The amount of voting power stake translates into
     */
    function _withdraw(address voter, address token, uint256 tokenAmount, uint256 votingPower) internal {
        StakeStorage storage ss = VotingPowerStorage.stakeStorage();
        require(ss.stakes[voter][token].amount >= tokenAmount, "VP::_withdraw: not enough tokens staked");
        require(ss.stakes[voter][token].votingPower >= votingPower, "VP::_withdraw: not enough voting power");
        ss.stakes[voter][token].amount = ss.stakes[voter][token].amount.sub(tokenAmount);
        ss.stakes[voter][token].votingPower = ss.stakes[voter][token].votingPower.sub(votingPower);
        
        IERC20(token).safeTransfer(voter, tokenAmount);

        emit Withdrawn(voter, token, tokenAmount, votingPower);
        
        _decreaseVotingPower(voter, votingPower);
    }

    /**
     * @notice Increase voting power of voter
     * @param voter The voter whose voting power is increasing 
     * @param amount The amount of voting power to increase by
     */
    function _increaseVotingPower(address voter, uint256 amount) internal {
        CheckpointStorage storage cs = VotingPowerStorage.checkpointStorage();
        uint32 checkpointNum = cs.numCheckpoints[voter];
        uint256 votingPowerOld = checkpointNum > 0 ? cs.checkpoints[voter][checkpointNum - 1].votes : 0;
        uint256 votingPowerNew = votingPowerOld.add(amount);
        _writeCheckpoint(voter, checkpointNum, votingPowerOld, votingPowerNew);
    }

    /**
     * @notice Decrease voting power of voter
     * @param voter The voter whose voting power is decreasing 
     * @param amount The amount of voting power to decrease by
     */
    function _decreaseVotingPower(address voter, uint256 amount) internal {
        CheckpointStorage storage cs = VotingPowerStorage.checkpointStorage();
        uint32 checkpointNum = cs.numCheckpoints[voter];
        uint256 votingPowerOld = checkpointNum > 0 ? cs.checkpoints[voter][checkpointNum - 1].votes : 0;
        uint256 votingPowerNew = votingPowerOld.sub(amount);
        _writeCheckpoint(voter, checkpointNum, votingPowerOld, votingPowerNew);
    }

    /**
     * @notice Create checkpoint of voting power for voter at current block number
     * @param voter The voter whose voting power is changing
     * @param nCheckpoints The current checkpoint number for voter
     * @param oldVotes The previous voting power of this voter
     * @param newVotes The new voting power of this voter
     */
    function _writeCheckpoint(address voter, uint32 nCheckpoints, uint256 oldVotes, uint256 newVotes) internal {
      uint32 blockNumber = _safe32(block.number, "VP::_writeCheckpoint: block number exceeds 32 bits");

      CheckpointStorage storage cs = VotingPowerStorage.checkpointStorage();
      if (nCheckpoints > 0 && cs.checkpoints[voter][nCheckpoints - 1].fromBlock == blockNumber) {
          cs.checkpoints[voter][nCheckpoints - 1].votes = newVotes;
      } else {
          cs.checkpoints[voter][nCheckpoints] = Checkpoint(blockNumber, newVotes);
          cs.numCheckpoints[voter] = nCheckpoints + 1;
      }

      emit VotingPowerChanged(voter, oldVotes, newVotes);
    }

    /**
     * @notice Converts uint256 to uint32 safely
     * @param n Number
     * @param errorMessage Error message to use if number cannot be converted
     * @return uint32 number
     */
    function _safe32(uint256 n, string memory errorMessage) internal pure returns (uint32) {
        require(n < 2**32, errorMessage);
        return uint32(n);
    }
}
/**
 * @title VotingPower
 * @dev Implementation contract for voting power prism proxy
 * Calls should not be made directly to this contract, instead make calls to the VotingPowerPrism proxy contract
 * The exception to this is the `become` function specified in PrismProxyImplementation
 * This function is called once and is used by this contract to accept its role as the implementation for the prism proxy
 */
function addVotingPowerForVestingTokens(address account, uint256 amount) external nonReentrant {
        AppStorage storage app = VotingPowerStorage.appStorage();
        require(amount > 0, "VP::addVPforVT: cannot add 0 voting power");
        require(msg.sender == address(app.vesting), "VP::addVPforVT: only vesting contract");

        _increaseVotingPower(account, amount);
    }
/**
 * @notice Count vesting ARCH tokens toward voting power for `account`
 * @param account The recipient of voting power
 * @param amount The amount of voting power to add
 */