// SPDX-License-Identifier: MIT

pragma solidity 0.8.1;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}
/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor () {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}


/**
 * @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 Genesis_Voting is Ownable {

  struct proposal {
    uint256 votes_for;
    uint256 votes_against;
    uint256 opens;
    uint256 expires;
    bool valid_vote;
  }

  mapping(address => mapping(uint16 => bool)) public user_votes;
  mapping(uint16 => proposal) public proposals;

  address public token_address;
  uint16 public total_proposals;

  constructor(address _token_address) {
    token_address = _token_address;
    emit Token_Address_Changed(_token_address);
  }

  event Proposal_Created(uint16 indexed proposal_id, string url, uint256 opens, uint256 expires);
  event Token_Address_Changed(address token_address);
  event Vote_Cast(uint16 indexed proposal_id, address indexed user, uint256 user_balance);

  function create_proposal(string calldata url, uint256 opens, uint256 expires) public onlyOwner {
    require(opens > block.timestamp, "Proposal cannot start in the past");
    require(expires > opens, "Proposal cannot end before it starts");
    proposals[total_proposals] = proposal(0, 0, opens, expires, false);
    emit Proposal_Created(total_proposals, url, opens, expires);
    total_proposals += 1;
  }

  function get_proposal_result(uint16 proposal_id) public view returns (bool) {
    require(proposals[proposal_id].expires < block.timestamp, "Proposal not finished");
    require(proposals[proposal_id].valid_vote, "Insufficient participation");
    return proposals[proposal_id].votes_for > proposals[proposal_id].votes_against;
  }

  function vote(uint16 proposal_id, bool vote_choice) public {
    uint256 user_balance = IERC20(token_address).balanceOf(msg.sender);
    require(user_balance > 0, "User has no tokens");
    require(proposals[proposal_id].opens < block.timestamp, "Proposal not started");
    require(proposals[proposal_id].expires > block.timestamp, "Proposal invalid or expired");
    require(!user_votes[msg.sender][proposal_id], "User has already voted");
    if(!proposals[proposal_id].valid_vote && proposals[proposal_id].votes_for + proposals[proposal_id].votes_against > 0){
      // someone else already voted
      proposals[proposal_id].valid_vote = true;
    }

    if(vote_choice) {
      proposals[proposal_id].votes_for += user_balance;
    } else {
      proposals[proposal_id].votes_against += user_balance;
    }

    user_votes[msg.sender][proposal_id] = true;
    emit Vote_Cast(proposal_id, msg.sender, user_balance);
  }

  function update_token_address(address _token_address) onlyOwner public {
    token_address = _token_address;
    emit Token_Address_Changed(_token_address);
  }

}


/**
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MMMMMMLOVEMMMMMMMMMMMMMMMMMMMMMM...............MMMMMMMMMMMMM
MMMMMMMMMMHIXELMMMMMMMMMMMM....................MMMMMNNMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMM....................MMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMM88=........................+MMMMMMMMMM
MMMMMMMMMMMMMMMMM....................MMMMM...MMMMMMMMMMMMMMM
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MMMMMMMMMNMM...................... ..MM?..MMM.. .+MMMMMMMMMM
MMMMNDDMM+........................+MM........MM..+MMMMMMMMMM
MMMMZ.............................+MM....................MMM
MMMMZ.............................+MM....................MMM
MMMMZ.............................+MM....................DDD
MMMMZ.............................+MM..ZMMMMMMMMMMMMMMMMMMMM
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MM..............................MMZ....ZMMMMMMMMMMMMMMMMMMMM
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