// File: contracts/lina_swap/sls_token.sol



//SPDX-License-Identifier: UNLICENSED

pragma solidity ^0.8.0;

import "./interfaces/IERC20.sol";
import "./ownership/Ownable.sol";
import "./utils/SafeMath.sol";

contract SLSToken is IERC20, Ownable {
    using SafeMath for uint256;

    string public name;
    string public symbol;
    uint8 public decimals;
    uint256 public totalSupply;

    mapping (address => uint256) internal _balances;
    mapping (address => mapping (address => uint256)) internal _allowed;

    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);

    constructor () {
        symbol = 'SLS';
        name = 'SLS Connect Token';
        decimals = 18;
        totalSupply = 900 * 10**6 * 10**18;
        _balances[msg.sender] = totalSupply;
    }

    function transfer(
        address _to, 
        uint256 _value
    ) external override returns (bool) {
        require(_to != address(0), 'SLSToken: to address is not valid');
        require(_value <= _balances[msg.sender], 'SLSToken: insufficient balance');

        _balances[msg.sender] = _balances[msg.sender].sub(_value);
        _balances[_to] =  _balances[_to].add(_value);
        
        emit Transfer(msg.sender, _to, _value);
        
        return true;
    }

   function balanceOf(
       address _owner
    ) external override view returns (uint256 balance) {
        return _balances[_owner];
    }

    function approve(
       address _spender, 
       uint256 _value
    ) external override returns (bool) {
        _allowed[msg.sender][_spender] = _value;
        
        emit Approval(msg.sender, _spender, _value);
        
        return true;
   }

   function transferFrom(
        address _from, 
        address _to, 
        uint256 _value
    ) external override returns (bool) {
        require(_from != address(0), 'SLSToken: from address is not valid');
        require(_to != address(0), 'SLSToken: to address is not valid');
        require(_value <= _balances[_from], 'SLSToken: insufficient balance');
        require(_value <= _allowed[_from][msg.sender], 'SLSToken: transfer from value not allowed');

        _allowed[_from][msg.sender] = _allowed[_from][msg.sender].sub(_value);
        _balances[_from] = _balances[_from].sub(_value);
        _balances[_to] = _balances[_to].add(_value);
        
        emit Transfer(_from, _to, _value);
        
        return true;
   }

    function allowance(
        address _owner, 
        address _spender
    ) external override view returns (uint256) {
        return _allowed[_owner][_spender];
    }

    function increaseApproval(
        address _spender, 
        uint256 _addedValue
    ) external returns (bool) {
        _allowed[msg.sender][_spender] = _allowed[msg.sender][_spender].add(_addedValue);

        emit Approval(msg.sender, _spender, _allowed[msg.sender][_spender]);
        
        return true;
    }

    function decreaseApproval(
        address _spender, 
        uint256 _subtractedValue
    ) external returns (bool) {
        uint256 oldValue = _allowed[msg.sender][_spender];
        
        if (_subtractedValue > oldValue) {
            _allowed[msg.sender][_spender] = 0;
        } else {
            _allowed[msg.sender][_spender] = oldValue.sub(_subtractedValue);
        }
        
        emit Approval(msg.sender, _spender, _allowed[msg.sender][_spender]);
        
        return true;
   }

    function burn(
        uint256 _amount
    ) external returns (bool) {
        require(_balances[msg.sender] >= _amount, 'SLSToken: insufficient balance');

        _balances[msg.sender] = _balances[msg.sender].sub(_amount);
        totalSupply = totalSupply.sub(_amount);

        emit Transfer(msg.sender, address(0), _amount);

        return true;
    }

    function burnFrom(
        address _from,
        uint256 _amount
    ) external returns (bool) {
        require(_from != address(0), 'SLSToken: from address is not valid');
        require(_balances[_from] >= _amount, 'SLSToken: insufficient balance');
        require(_amount <= _allowed[_from][msg.sender], 'SLSToken: burn from value not allowed');
        
        _allowed[_from][msg.sender] = _allowed[_from][msg.sender].sub(_amount);
        _balances[_from] = _balances[_from].sub(_amount);
        totalSupply = totalSupply.sub(_amount);

        emit Transfer(_from, address(0), _amount);

        return true;
    }

}
// File: contracts/lina_swap/interfaces/IERC20.sol



//SPDX-License-Identifier: UNLICENSED

pragma solidity ^0.8.0;

interface IERC20 {
    function balanceOf(address who) external view returns (uint256);
    function transfer(address to, uint256 value) external returns (bool);
    function allowance(address owner, address spender) external view returns (uint256);
    function transferFrom(address from, address to, uint256 value) external returns (bool);
    function approve(address spender, uint256 value) external returns (bool);
}
// File: contracts/lina_swap/ownership/Ownable.sol



//SPDX-License-Identifier: UNLICENSED

pragma solidity ^0.8.0;

contract Ownable {

  address private owner;

  event NewOwner(address oldOwner, address newOwner);

  constructor() {
    owner = msg.sender;
  }

  modifier onlyOwner() {
    require(isOwner(), "Ownable: caller is not the owner");
    _;
  }

  function contractOwner() external view returns (address) {
    return owner;
  }

  function isOwner() public view returns (bool) {
    return msg.sender == owner;
  }

  function transferOwnership(address _newOwner) external onlyOwner {
    require(_newOwner != address(0), 'Ownable: address is not valid');
    owner = _newOwner;
    emit NewOwner(msg.sender, _newOwner);
  } 
}
// File: contracts/lina_swap/utils/SafeMath.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

// CAUTION
// This version of SafeMath should only be used with Solidity 0.8 or later,
// because it relies on the compiler's built in overflow checks.

/**
 * @dev Wrappers over Solidity's arithmetic operations.
 *
 * NOTE: `SafeMath` is no longer needed starting with Solidity 0.8. The compiler
 * now has built in overflow checking.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            uint256 c = a + b;
            if (c < a) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b > a) return (false, 0);
            return (true, a - b);
        }
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            // 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 (true, 0);
            uint256 c = a * b;
            if (c / a != b) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a / b);
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a % b);
        }
    }

    /**
     * @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) {
        return a + b;
    }

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

    /**
     * @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) {
        return a * b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator.
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting 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 a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b <= a, errorMessage);
            return a - b;
        }
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting 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) {
        unchecked {
            require(b > 0, errorMessage);
            return a / b;
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * 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) {
        unchecked {
            require(b > 0, errorMessage);
            return a % b;
        }
    }
}