contract PUSDShares is ERC20Custom, AccessControl {
    using SafeMath for uint256;

    /* ========== STATE VARIABLES ========== */

    string public symbol;
    string public name;
    uint8 public constant decimals = 18;
    address public PUSDStablecoinAdd;
    
    uint256 public constant genesis_supply = 30000000e18; // 100M is printed upon genesis
    uint256 public PEGS_DAO_min; // Minimum PEGS required to join DAO groups 

    address public owner_address;
    address public oracle_address;
    address public timelock_address; // Governance timelock address
    PUSDStablecoin private PUSD;

    bool public trackingVotes = true; // Tracking votes (only change if need to disable votes)

    // A checkpoint for marking number of votes from a given block
    struct Checkpoint {
        uint32 fromBlock;
        uint96 votes;
    }

    // A record of votes checkpoints for each account, by index
    mapping (address => mapping (uint32 => Checkpoint)) public checkpoints;

    // The number of checkpoints for each account
    mapping (address => uint32) public numCheckpoints;

    /* ========== MODIFIERS ========== */

    modifier onlyPools() {
       require(PUSD.pusd_pools(msg.sender) == true, "Only pusd pools can mint new PUSD");
        _;
    } 
    
    modifier onlyByOwnerOrGovernance() {
        require(msg.sender == owner_address || msg.sender == timelock_address, "You are not an owner or the governance timelock");
        _;
    }

    /* ========== CONSTRUCTOR ========== */

    constructor(
        string memory _name,
        string memory _symbol, 
        address _oracle_address,
        address _owner_address,
        address _timelock_address
    ) public {
        name = _name;
        symbol = _symbol;
        owner_address = _owner_address;
        oracle_address = _oracle_address;
        timelock_address = _timelock_address;
        _setupRole(DEFAULT_ADMIN_ROLE, _msgSender());
        _mint(owner_address, genesis_supply);

        // Do a checkpoint for the owner
        _writeCheckpoint(owner_address, 0, 0, uint96(genesis_supply));
    }

    /* ========== RESTRICTED FUNCTIONS ========== */

    function setOracle(address new_oracle) external onlyByOwnerOrGovernance {
        oracle_address = new_oracle;
    }

    function setTimelock(address new_timelock) external onlyByOwnerOrGovernance {
        timelock_address = new_timelock;
    }
    
    function setPUSDAddress(address pusd_contract_address) external onlyByOwnerOrGovernance {
        PUSD = PUSDStablecoin(pusd_contract_address);
    }
    
    function setPEGSMinDAO(uint256 min_PEGS) external onlyByOwnerOrGovernance {
        PEGS_DAO_min = min_PEGS;
    }

    function setOwner(address _owner_address) external onlyByOwnerOrGovernance {
        owner_address = _owner_address;
    }

    function mint(address to, uint256 amount) public onlyPools {
        _mint(to, amount);
    }
    
    // This function is what other pusd pools will call to mint new PEGS (similar to the PUSD mint) 
    function pool_mint(address m_address, uint256 m_amount) external onlyPools {        
        if(trackingVotes){
            uint32 srcRepNum = numCheckpoints[address(this)];
            uint96 srcRepOld = srcRepNum > 0 ? checkpoints[address(this)][srcRepNum - 1].votes : 0;
            uint96 srcRepNew = add96(srcRepOld, uint96(m_amount), "pool_mint new votes overflows");
            _writeCheckpoint(address(this), srcRepNum, srcRepOld, srcRepNew); // mint new votes
            trackVotes(address(this), m_address, uint96(m_amount));
        }

        super._mint(m_address, m_amount);
        emit PEGSMinted(address(this), m_address, m_amount);
    }

    // This function is what other pusd pools will call to burn PEGS 
    function pool_burn_from(address b_address, uint256 b_amount) external onlyPools {
        if(trackingVotes){
            trackVotes(b_address, address(this), uint96(b_amount));
            uint32 srcRepNum = numCheckpoints[address(this)];
            uint96 srcRepOld = srcRepNum > 0 ? checkpoints[address(this)][srcRepNum - 1].votes : 0;
            uint96 srcRepNew = sub96(srcRepOld, uint96(b_amount), "pool_burn_from new votes underflows");
            _writeCheckpoint(address(this), srcRepNum, srcRepOld, srcRepNew); // burn votes
        }

        super._burnFrom(b_address, b_amount);
        emit PEGSBurned(b_address, address(this), b_amount);
    }

    function toggleVotes() external onlyByOwnerOrGovernance {
        trackingVotes = !trackingVotes;
    }

    /* ========== OVERRIDDEN PUBLIC FUNCTIONS ========== */

    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
        if(trackingVotes){
            // Transfer votes
            trackVotes(_msgSender(), recipient, uint96(amount));
        }

        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {
        if(trackingVotes){
            // Transfer votes
            trackVotes(sender, recipient, uint96(amount));
        }

        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));

        return true;
    }

    /* ========== PUBLIC FUNCTIONS ========== */

    /**
     * @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 getCurrentVotes(address account) external view returns (uint96) {
        uint32 nCheckpoints = numCheckpoints[account];
        return nCheckpoints > 0 ? 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 getPriorVotes(address account, uint blockNumber) public view returns (uint96) {
        require(blockNumber < block.number, "PEGS::getPriorVotes: not yet determined");

        uint32 nCheckpoints = numCheckpoints[account];
        if (nCheckpoints == 0) {
            return 0;
        }

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

        // Next check implicit zero balance
        if (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 = checkpoints[account][center];
            if (cp.fromBlock == blockNumber) {
                return cp.votes;
            } else if (cp.fromBlock < blockNumber) {
                lower = center;
            } else {
                upper = center - 1;
            }
        }
        return checkpoints[account][lower].votes;
    }

    /* ========== INTERNAL FUNCTIONS ========== */

    // From compound's _moveDelegates
    // Keep track of votes. "Delegates" is a misnomer here
    function trackVotes(address srcRep, address dstRep, uint96 amount) internal {
        if (srcRep != dstRep && amount > 0) {
            if (srcRep != address(0)) {
                uint32 srcRepNum = numCheckpoints[srcRep];
                uint96 srcRepOld = srcRepNum > 0 ? checkpoints[srcRep][srcRepNum - 1].votes : 0;
                uint96 srcRepNew = sub96(srcRepOld, amount, "PEGS::_moveVotes: vote amount underflows");
                _writeCheckpoint(srcRep, srcRepNum, srcRepOld, srcRepNew);
            }

            if (dstRep != address(0)) {
                uint32 dstRepNum = numCheckpoints[dstRep];
                uint96 dstRepOld = dstRepNum > 0 ? checkpoints[dstRep][dstRepNum - 1].votes : 0;
                uint96 dstRepNew = add96(dstRepOld, amount, "PEGS::_moveVotes: vote amount overflows");
                _writeCheckpoint(dstRep, dstRepNum, dstRepOld, dstRepNew);
            }
        }
    }

    function _writeCheckpoint(address voter, uint32 nCheckpoints, uint96 oldVotes, uint96 newVotes) internal {
      uint32 blockNumber = safe32(block.number, "PEGS::_writeCheckpoint: block number exceeds 32 bits");

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

      emit VoterVotesChanged(voter, oldVotes, newVotes);
    }

    function safe32(uint n, string memory errorMessage) internal pure returns (uint32) {
        require(n < 2**32, errorMessage);
        return uint32(n);
    }

    function safe96(uint n, string memory errorMessage) internal pure returns (uint96) {
        require(n < 2**96, errorMessage);
        return uint96(n);
    }

    function add96(uint96 a, uint96 b, string memory errorMessage) internal pure returns (uint96) {
        uint96 c = a + b;
        require(c >= a, errorMessage);
        return c;
    }

    function sub96(uint96 a, uint96 b, string memory errorMessage) internal pure returns (uint96) {
        require(b <= a, errorMessage);
        return a - b;
    }

    function getChainId() internal pure returns (uint) {
        uint256 chainId;
        assembly { chainId := chainid() }
        return chainId;
    }

    /* ========== EVENTS ========== */
    
    /// @notice An event thats emitted when a voters account's vote balance changes
    event VoterVotesChanged(address indexed voter, uint previousBalance, uint newBalance);

    // Track PEGS burned
    event PEGSBurned(address indexed from, address indexed to, uint256 amount);

    // Track PEGS minted
    event PEGSMinted(address indexed from, address indexed to, uint256 amount);

}
function getCurrentVotes(address account) external view returns (uint96) {
    uint32 nCheckpoints = numCheckpoints[account];
    return nCheckpoints > 0 ? checkpoints[account][nCheckpoints - 1].votes : 0;
}

/**
 * @notice Gets the current votes balance for `account`
 * @param account The address to get votes balance
 * @return The number of current votes for `account`
 */