pragma solidity ^0.6.0;

// SPDX-License-Identifier: MIT

/**
 * @title SafeMath
 * @dev Math operations with safety checks that throw on error
 *
*/

library SafeMath {
  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    if (a == 0) {
      return 0;
    }
    uint256 c = a * b;
    assert(c / a == b);
    return c;
  }

  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    // assert(b > 0); // Solidity automatically throws when dividing by 0
    uint256 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold
    return c;
  }

  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    assert(b <= a);
    return a - b;
  }

  function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    assert(c >= a);
    return c;
  }

  function ceil(uint a, uint m) internal pure returns (uint r) {
    return (a + m - 1) / m * m;
  }
}

// ----------------------------------------------------------------------------
// Owned contract
// ----------------------------------------------------------------------------
contract Owned {
    address payable public owner;

    event OwnershipTransferred(address indexed _from, address indexed _to);

    constructor() public {
        owner = msg.sender;
    }

    modifier onlyOwner {
        require(msg.sender == owner);
        _;
    }

    function transferOwnership(address payable _newOwner) public onlyOwner {
        owner = _newOwner;
        emit OwnershipTransferred(msg.sender, _newOwner);
    }
}


// ----------------------------------------------------------------------------
// ERC Token Standard #20 Interface
// ----------------------------------------------------------------------------
interface IToken {
    function transfer(address to, uint256 tokens) external returns (bool success);
    function burnTokens(uint256 _amount) external;
    function balanceOf(address tokenOwner) external view returns (uint256 balance);
}


contract UNQTpresale is Owned {
    using SafeMath for uint256;
    
    bool public isPresaleOpen;
    
    //@dev ERC20 token address and decimals
    address public tokenAddress;
    uint256 public tokenDecimals = 18;
    
    //@dev amount of tokens per ether 1000 indicates 1 token per eth
    uint256 public tokenRatePerEth = 1000_00;
    //@dev decimal for tokenRatePerEth,
    //2 means if you want 100 tokens per eth then set the rate as 100 + number of rateDecimals i.e => 10000
    uint256 public rateDecimals = 2;
    
    //@dev max and min token buy limit per account
    uint256 public minEthLimit = 1 finney; // 0.00100000 ETH
    uint256 public maxEthLimit = 5 ether;
    
    mapping(address => uint256) public usersInvestments;
    
    constructor() public {
        owner = msg.sender;
    }
    
    function startPresale() external onlyOwner{
        require(!isPresaleOpen, "Presale is open");
        
        isPresaleOpen = true;
    }
    
    function closePresale() external onlyOwner{
        require(isPresaleOpen, "Presale is not open yet.");
        
        isPresaleOpen = false;
    }
    
    function setTokenAddress(address token) external onlyOwner {
        require(tokenAddress == address(0), "Token address is already set.");
        require(token != address(0), "Token address zero not allowed.");
        
        tokenAddress = token;
    }
    
    function setTokenDecimals(uint256 decimals) external onlyOwner {
       tokenDecimals = decimals;
    }
    
    function setMinEthLimit(uint256 amount) external onlyOwner {
        minEthLimit = amount;    
    }
    
    function setMaxEthLimit(uint256 amount) external onlyOwner {
        maxEthLimit = amount;    
    }
    
    function setTokenRatePerEth(uint256 rate) external onlyOwner {
        tokenRatePerEth = rate;
    }
    
    function setRateDecimals(uint256 decimals) external onlyOwner {
        rateDecimals = decimals;
    }
    
    receive() external payable{
        require(isPresaleOpen, "Presale is not open.");
        require(
                usersInvestments[msg.sender].add(msg.value) <= maxEthLimit
                && usersInvestments[msg.sender].add(msg.value) >= minEthLimit,
                "Installment Invalid."
            );
        
        //@dev calculate the amount of tokens to transfer for the given eth
        uint256 tokenAmount = getTokensPerEth(msg.value);
        
        require(IToken(tokenAddress).transfer(msg.sender, tokenAmount), "Insufficient balance of presale contract!");
        
        usersInvestments[msg.sender] = usersInvestments[msg.sender].add(msg.value);
        
        //@dev send received funds to the owner
        owner.transfer(msg.value);
    }
    
    function getTokensPerEth(uint256 amount) internal view returns(uint256) {
        return amount.mul(tokenRatePerEth).div(
            10**(uint256(18).sub(tokenDecimals).add(rateDecimals))
            );
    }
    
    function burnUnsoldTokens() external onlyOwner {
        require(!isPresaleOpen, "You cannot burn tokens untitl the presale is closed.");
        
        IToken(tokenAddress).burnTokens(IToken(tokenAddress).balanceOf(address(this)));   
    }
    
    function getUnsoldTokens() external onlyOwner {
        require(!isPresaleOpen, "You cannot get tokens until the presale is closed.");
        
        IToken(tokenAddress).transfer(owner, IToken(tokenAddress).balanceOf(address(this)) );
    }
}

pragma solidity 0.8.3;

// SPDX-License-Identifier: MIT

// ----------------------------------------------------------------------------
// Safe maths
// ----------------------------------------------------------------------------

contract SafeMath {
    function safeAdd(uint a, uint b) public pure returns (uint c) {
        c = a + b;
        require(c >= a);
    }
    function safeSub(uint a, uint b) public pure returns (uint c) {
        require(b <= a);
        c = a - b;
    }
    function safeMul(uint a, uint b) public pure returns (uint c) {
        c = a * b;
        require(a == 0 || c / a == b);
    }
    function safeDiv(uint a, uint b) public pure returns (uint c) {
        require(b > 0);
        c = a / b;
    }
}


// ----------------------------------------------------------------------------
// ERC Token Standard #20 Interface
// https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20-token-standard.md
// ----------------------------------------------------------------------------

interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    function balanceOf(address account) external view returns (uint256);

    function transfer(address recipient, uint256 amount) external returns (bool);

    function allowance(address owner, address spender) external view returns (uint256);
    
    function approve(address spender, uint256 amount) external returns (bool);

    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

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

    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// ----------------------------------------------------------------------------
// Contract function to receive approval and execute function in one call
//
// Borrowed from MiniMeToken
// ----------------------------------------------------------------------------
abstract contract ApproveAndCallFallBack {
    function receiveApproval(address from, uint256 tokens, address token, bytes memory data) virtual public;
}


// ----------------------------------------------------------------------------
// Owned contract
// ----------------------------------------------------------------------------
contract Owned {
    address public owner;
    address public newOwner;

    event OwnershipTransferred(address indexed _from, address indexed _to);

    constructor()  {
        owner = 0xC7781bf45EE2C64AA6E330Bd0e35522C1d7BA6b3;
    }

    modifier onlyOwner {
        require(msg.sender == owner);
        _;
    }

    function transferOwnership(address _newOwner) public onlyOwner {
        newOwner = _newOwner;
    }
    function acceptOwnership() public {
        require(msg.sender == newOwner);
        emit OwnershipTransferred(owner, newOwner);
        owner = newOwner;
        newOwner = address(0);
    }
}


// ----------------------------------------------------------------------------
// ERC20 Token, with the addition of symbol, name and decimals and assisted
// token transfers
// ----------------------------------------------------------------------------

contract UniqueUtilityToken is IERC20, Owned, SafeMath {
    string public symbol;
    string public  name;
    uint8 public decimals;
    uint public _totalSupply;

    mapping(address => uint) balances;
    mapping(address => mapping(address => uint)) allowed;


    // ------------------------------------------------------------------------
    // Constructor
    // ------------------------------------------------------------------------
    
 constructor() {
        name = "Unique Utility Token";
        symbol = "UNQT";
        decimals = 18;
        _totalSupply = 100000000e18;         // 100,000,000 UNQT
        address owner = owner;
        balances[owner] = _totalSupply;
        emit Transfer(address(0), owner, _totalSupply);
    }


    // ------------------------------------------------------------------------
    // Total supply
    // ------------------------------------------------------------------------
    function totalSupply() public view override returns (uint) {
        return _totalSupply;
    }


    // ------------------------------------------------------------------------
    // Get the token balance for account tokenOwner
    // ------------------------------------------------------------------------
    function balanceOf(address tokenOwner) public view override returns (uint balance) {
        return balances[tokenOwner];
    }


    // ------------------------------------------------------------------------
    // Transfer the balance from token owner's account to to account
    // - Owner's account must have sufficient balance to transfer
    // - 0 value transfers are allowed
    // ------------------------------------------------------------------------
    function transfer(address to, uint tokens) public override returns (bool success) {
        balances[msg.sender] = safeSub(balances[msg.sender], tokens);
        balances[to] = safeAdd(balances[to], tokens);
        Transfer(msg.sender, to, tokens);
        return true;
    }


    // ------------------------------------------------------------------------
    // Token owner can approve for spender to transferFrom(...) tokens
    // from the token owner's account
    //
    // https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20-token-standard.md
    // recommends that there are no checks for the approval double-spend attack
    // as this should be implemented in user interfaces 
    // ------------------------------------------------------------------------
    function approve(address spender, uint tokens) public virtual override returns (bool success) {
        allowed[msg.sender][spender] = tokens;
        Approval(msg.sender, spender, tokens);
        return true;
    }

    // ------------------------------------------------------------------------
    // Transfer tokens from the from account to the to account
    // 
    // The calling account must already have sufficient tokens approve(...)-d
    // for spending from the from account and
    // - From account must have sufficient balance to transfer
    // - Spender must have sufficient allowance to transfer
    // - 0 value transfers are allowed
    // ------------------------------------------------------------------------
    function transferFrom(address from, address to, uint tokens) public virtual override returns (bool success) {
        balances[from] = safeSub(balances[from], tokens);
        allowed[from][msg.sender] = safeSub(allowed[from][msg.sender], tokens);
        balances[to] = safeAdd(balances[to], tokens);
        Transfer(from, to, tokens);
        return true;
    }


    // ------------------------------------------------------------------------
    // Returns the amount of tokens approved by the owner that can be
    // transferred to the spender's account
    // ------------------------------------------------------------------------
    function allowance(address tokenOwner, address spender) public view virtual override  returns (uint remaining) {
        return allowed[tokenOwner][spender];
    }


    // ------------------------------------------------------------------------
    // Token owner can approve for spender to transferFrom(...) tokens
    // from the token owner's account. The spender contract function
    // receiveApproval(...) is then executed
    // ------------------------------------------------------------------------
    function approveAndCall(address spender, uint tokens, bytes memory data) public returns (bool success) {
        allowed[msg.sender][spender] = tokens;
        Approval(msg.sender, spender, tokens);
        ApproveAndCallFallBack(spender).receiveApproval(msg.sender, tokens, address(this), data);
        return true;
    }


    // ------------------------------------------------------------------------
    // Don't accept ETH
    // ------------------------------------------------------------------------
    receive () external payable {
        revert();
    }


    // ------------------------------------------------------------------------
    // Owner can transfer out any accidentally sent ERC20 tokens
    // ------------------------------------------------------------------------
    function transferAnyERC20Token(address tokenAddress, uint tokens) public onlyOwner returns (bool success) {
        return IERC20(tokenAddress).transfer(owner, tokens);
    }
}