// File: contracts/PalToken.sol



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//██████╔╝███████║██║     ███████║██║  ██║██║██╔██╗ ██║
//██╔═══╝ ██╔══██║██║     ██╔══██║██║  ██║██║██║╚██╗██║
//██║     ██║  ██║███████╗██║  ██║██████╔╝██║██║ ╚████║
//╚═╝     ╚═╝  ╚═╝╚══════╝╚═╝  ╚═╝╚═════╝ ╚═╝╚═╝  ╚═══╝
                                                     

pragma solidity ^0.7.6;
//SPDX-License-Identifier: MIT

import "./utils/SafeMath.sol";
import "./utils/IERC20.sol";
import "./utils/Admin.sol";
import {Errors} from  "./utils/Errors.sol";

/** @title palToken ERC20 contract  */
/// @author Paladin
contract PalToken is IERC20, Admin {
    using SafeMath for uint;

    //ERC20 Variables & Mappings :

    /** @notice ERC20 token Name */
    string public name;
    /** @notice ERC20 token Symbol */
    string public symbol;
    /** @notice ERC20 token Decimals */
    uint public decimals;

    // ERC20 total Supply
    uint private _totalSupply;


    //don't want to initiate the contract twice
    bool private initialized;


    /** @notice PalPool contract that can Mint/Burn this token */
    address public palPool;


    /** @dev Balances for this ERC20 token */
    mapping(address => uint) internal balances;
    /** @dev Allowances for this ERC20 token, sorted by user */
    mapping(address => mapping (address => uint)) internal transferAllowances;


    /** @dev Modifier so only the PalPool linked to this contract can Mint/Burn tokens */
    modifier onlyPool() {
        require(msg.sender == palPool);

        _;
    }


    //Functions : 


    constructor (string memory name_, string memory symbol_) {
        admin = msg.sender;

        name = name_;
        symbol = symbol_;
        decimals = 18;
        initialized = false;
    }


    function initiate(address _palPool) external adminOnly returns (bool){
        require(!initialized);

        initialized = true;
        palPool = _palPool;

        return true;
    }


    function totalSupply() external override view returns (uint256){
        return _totalSupply;
    }


    function transfer(address dest, uint amount) external override returns(bool){
        return _transfer(msg.sender, dest, amount);
    }


    function transferFrom(address src, address dest, uint amount) external override returns(bool){
        require(transferAllowances[src][msg.sender] >= amount, Errors.ALLOWANCE_TOO_LOW);

        transferAllowances[src][msg.sender] = transferAllowances[src][msg.sender].sub(amount);

        _transfer(src, dest, amount);

        return true;
    }


    function _transfer(address src, address dest, uint amount) internal returns(bool){
        //Check if the transfer is possible
        require(balances[src] >= amount, Errors.BALANCE_TOO_LOW);
        require(dest != src, Errors.SELF_TRANSFER);
        require(src != address(0) && dest != address(0), Errors.ZERO_ADDRESS);

        //Update balances
        balances[src] = balances[src].sub(amount);
        balances[dest] = balances[dest].add(amount);

        //emit the Transfer Event
        emit Transfer(src,dest,amount);
        return true;
    }

    function approve(address spender, uint amount) external override returns(bool){
        return _approve(msg.sender, spender, amount);
    }

    function increaseAllowance(address spender, uint256 addedValue) external returns (bool) {
        return _approve(msg.sender, spender, transferAllowances[msg.sender][spender].add(addedValue));
    }

    function decreaseAllowance(address spender, uint256 subtractedValue) external returns (bool) {
        uint256 currentAllowance = transferAllowances[msg.sender][spender];
        require(currentAllowance >= subtractedValue, "decreased allowance below zero");
        return _approve(msg.sender, spender, currentAllowance.sub(subtractedValue));
    }


    function _approve(address owner, address spender, uint amount) internal returns(bool){
        require(spender != address(0), Errors.ZERO_ADDRESS);

        //Update allowance and emit the Approval event
        transferAllowances[owner][spender] = amount;

        emit Approval(owner, spender, amount);

        return true;
    }


    function allowance(address owner, address spender) external view override returns(uint){
        return transferAllowances[owner][spender];
    }


    function balanceOf(address owner) external view override returns(uint){
        return balances[owner];
    }


    function mint(address _user, uint _toMint) external onlyPool returns(bool){
        require(_user != address(0), Errors.ZERO_ADDRESS);

        _totalSupply = _totalSupply.add(_toMint);
        balances[_user] = balances[_user].add(_toMint);

        emit Transfer(address(0),_user,_toMint);

        return true;
    }


    function burn(address _user, uint _toBurn) external onlyPool returns(bool){
        require(_user != address(0), Errors.ZERO_ADDRESS);
        require(balances[_user] >= _toBurn, Errors.INSUFFICIENT_BALANCE);

        _totalSupply = _totalSupply.sub(_toBurn);
        balances[_user] = balances[_user].sub(_toBurn);

        emit Transfer(_user,address(0),_toBurn);

        return true;
    }

}
// File: contracts/utils/SafeMath.sol



pragma solidity ^0.7.6;
//SPDX-License-Identifier: MIT

// From https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/math/Math.sol
// Subject to the MIT license.

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting with custom message on overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, errorMessage);

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on underflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot underflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction underflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on underflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot underflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     * - Multiplication cannot 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-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b, string memory errorMessage) 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-contracts/pull/522
        if (a == 0) {
            return 0;
        }

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

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers.
     * Reverts on division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers.
     * Reverts with custom message on division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}
// File: contracts/utils/IERC20.sol



// SPDX-License-Identifier: agpl-3.0
pragma solidity ^0.7.6;

/**
 * @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);
}
// File: contracts/utils/Admin.sol



pragma solidity ^0.7.6;
//SPDX-License-Identifier: MIT


/** @title Admin contract  */
/// @author Paladin
contract Admin {

    /** @notice (Admin) Event when the contract admin is updated */
    event NewAdmin(address oldAdmin, address newAdmin);

    /** @dev Admin address for this contract */
    address payable internal admin;
    
    modifier adminOnly() {
        //allows only the admin of this contract to call the function
        require(msg.sender == admin, '1');
        _;
    }

        /**
    * @notice Set a new Admin
    * @dev Changes the address for the admin parameter
    * @param _newAdmin address of the new Controller Admin
    */
    function setNewAdmin(address payable _newAdmin) external adminOnly {
        address _oldAdmin = admin;
        admin = _newAdmin;

        emit NewAdmin(_oldAdmin, _newAdmin);
    }
}
// File: contracts/utils/Errors.sol



//██████╗  █████╗ ██╗      █████╗ ██████╗ ██╗███╗   ██╗
//██╔══██╗██╔══██╗██║     ██╔══██╗██╔══██╗██║████╗  ██║
//██████╔╝███████║██║     ███████║██║  ██║██║██╔██╗ ██║
//██╔═══╝ ██╔══██║██║     ██╔══██║██║  ██║██║██║╚██╗██║
//██║     ██║  ██║███████╗██║  ██║██████╔╝██║██║ ╚████║
//╚═╝     ╚═╝  ╚═╝╚══════╝╚═╝  ╚═╝╚═════╝ ╚═╝╚═╝  ╚═══╝
                                                     

pragma solidity ^0.7.6;
//SPDX-License-Identifier: MIT

library Errors {
    // Admin error
    string public constant CALLER_NOT_ADMIN = '1'; // 'The caller must be the admin'
    string public constant CALLER_NOT_CONTROLLER = '29'; // 'The caller must be the admin or the controller'
    string public constant CALLER_NOT_ALLOWED_POOL = '30';  // 'The caller must be a palPool listed in the controller'
    string public constant CALLER_NOT_MINTER = '31';

    // ERC20 type errors
    string public constant FAIL_TRANSFER = '2';
    string public constant FAIL_TRANSFER_FROM = '3';
    string public constant BALANCE_TOO_LOW = '4';
    string public constant ALLOWANCE_TOO_LOW = '5';
    string public constant SELF_TRANSFER = '6';

    // PalPool errors
    string public constant INSUFFICIENT_CASH = '9';
    string public constant INSUFFICIENT_BALANCE = '10';
    string public constant FAIL_DEPOSIT = '11';
    string public constant FAIL_LOAN_INITIATE = '12';
    string public constant FAIL_BORROW = '13';
    string public constant ZERO_BORROW = '27';
    string public constant BORROW_INSUFFICIENT_FEES = '23';
    string public constant LOAN_CLOSED = '14';
    string public constant NOT_LOAN_OWNER = '15';
    string public constant LOAN_OWNER = '16';
    string public constant FAIL_LOAN_EXPAND = '17';
    string public constant NOT_KILLABLE = '18';
    string public constant RESERVE_FUNDS_INSUFFICIENT = '19';
    string public constant FAIL_MINT = '20';
    string public constant FAIL_BURN = '21';
    string public constant FAIL_WITHDRAW = '24';
    string public constant FAIL_CLOSE_BORROW = '25';
    string public constant FAIL_KILL_BORROW = '26';
    string public constant ZERO_ADDRESS = '22';
    string public constant INVALID_PARAMETERS = '28'; 
    string public constant FAIL_LOAN_DELEGATEE_CHANGE = '32';
    string public constant FAIL_LOAN_TOKEN_BURN = '33';
    string public constant FEES_ACCRUED_INSUFFICIENT = '34';

}