1. // SPDX-License-Identifier: MIT
2. pragma solidity ^0.8.0;
3. import "@openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol";
4. import "@openzeppelin/contracts/access/Ownable.sol";
5.  
6.  
7. contract IsotopicAsset is ERC721Enumerable, Ownable {
8.   using Strings for uint256;
9.  
10.   string public baseURI;  
11.   string public baseExtension = ".json";
12.  
13.   bool public paused;
14.  
15.   mapping(address => uint256) public whitelisted;
16.   mapping(address => uint256) public balance;
17.  
18.  
19.   event BaseURIChanged(string indexed _oldBaseURI, string indexed _newBaseURI);
20.   event BaseExtensionChanged(string indexed _oldBaseExtension, string indexed _newBaseExtension);
21.   event PausedChanged(bool indexed _oldPaused, bool indexed _newPaused);
22.  
23.   constructor(  
24.     string memory _name,
25.     string memory _symbol,
26.     string memory _initBaseURI,
27.     bool _paused
28.   ) ERC721(_name, _symbol) {
29.     setBaseURI(_initBaseURI);
30.     paused = _paused;
31.   }
32.  
33.   function _baseURI() internal view virtual override returns (string memory) {
34.     return baseURI;
35.   }
36.  
37.  
38.   function mint(address _to, uint256 _mintAmount) public {  
39.     uint256 supply = totalSupply();
40.     require(!paused);
41.     require(_mintAmount > 0);
42.  
43.     if (msg.sender != owner()) {
44.         require(whitelisted[msg.sender] >= _mintAmount, "only whitelist addresses can mint");
45.     }
46.  
47.     for (uint256 i = 1; i <= _mintAmount; i++) {
48.       _safeMint(_to, supply + i);
49.     }
50.  
51.     if (msg.sender != owner()){
52.         whitelisted[msg.sender] -= _mintAmount;
53.     }
54.  
55.     balance[_to] += _mintAmount;
56.   }
57.  
58.  
59.   function walletOfOwner(address _owner) public view returns (uint256[] memory)
60.   {
61.     uint256 ownerTokenCount = balanceOf(_owner);
62.     uint256[] memory tokenIds = new uint256[](ownerTokenCount);
63.     for (uint256 i; i < ownerTokenCount; i++) {
64.       tokenIds[i] = tokenOfOwnerByIndex(_owner, i);
65.     }
66.     return tokenIds;
67.   }
68.  
69.   function tokenURI(uint256 tokenId) public view virtual override returns (string memory)
70.   {
71.     require(
72.       _exists(tokenId),
73.       "ERC721Metadata: URI query for nonexistent token"
74.     );
75.  
76.     string memory currentBaseURI = _baseURI();
77.     return bytes(currentBaseURI).length > 0 ? string(abi.encodePacked(currentBaseURI, baseExtension)) : "";
78.   }
79.  
80.   function setBaseURI(string memory _newBaseURI) public onlyOwner {
81.     string memory oldBaseURI = baseURI;
82.     baseURI = _newBaseURI;
83.     emit BaseURIChanged(oldBaseURI, _newBaseURI);
84.   }
85.  
86.   function setBaseExtension(string memory _newBaseExtension) public onlyOwner {
87.     string memory oldBaseExtension = baseExtension;
88.     baseExtension = _newBaseExtension;
89.     emit BaseExtensionChanged(oldBaseExtension, _newBaseExtension);
90.   }
91.  
92.   function pause(bool _state) public onlyOwner {  
93.     bool oldPaused = paused;
94.     paused = _state;
95.     emit PausedChanged(oldPaused, _state);
96.   }
97.  
98.  function setUserWhitelistAmount(address _user, uint256 _amount) public onlyOwner {
99.     whitelisted[_user] = _amount;
100.   }
101.  
102.   function increaseUserWhitelistAmount(address _user, uint256 _amount) public onlyOwner {
103.     whitelisted[_user] += _amount;
104.   }
105.  
106.   function getUserWhitelistAmount(address _user) public view returns (uint256){
107.     return whitelisted[_user];
108.   }
109.  
110.   function transferWhitelists(address _to, uint256 _amount) public {
111.     require(whitelisted[msg.sender] >= _amount, "Cannot transfer more whitelists than available.");
112.     whitelisted[_to] += _amount;
113.     whitelisted[msg.sender] -= _amount;
114.   }
115. }