NFTSbt.sol add batchMint method

.gitignore

@@ -6,4 +6,7 @@ node_modules
 contract_whole
 openzeppelin
 .key
-.addr
+.addr
+.selfaddr
+.selfkey
+.env

contracts/tokens/erc721/NFTSbt.sol

@@ -15,6 +15,8 @@ contract NFTSbt is AccessControl, ERC721Enumerable {
 
   Counters.Counter private _tokenIdCounter;
 
+  uint256 public maxBatchSize = 500;
+
   constructor(
     string memory _name,
     string memory _symbol,
@@ -73,6 +75,28 @@ contract NFTSbt is AccessControl, ERC721Enumerable {
     return IMetaData(_metaAddress).getMetaData(address(this), tokenId);
   }
 
+  function batchMint(
+    address to,
+    uint256 count
+  ) external onlyRole(MINTER_ROLE) returns (uint256[] memory) {
+    require(count > 0, "tokenIds too small");
+    require(count <= maxBatchSize, "tokenIds too many");
+    if (supplyLimit > 0) {
+      require(
+        (totalSupply() + count) <= supplyLimit,
+        "Exceed the total supply"
+      );
+    }
+    uint256[] memory tokenIds = new uint256[](count);
+    for (uint256 i = 0; i < count; i++) {
+      _tokenIdCounter.increment();
+      uint256 tokenId = _tokenIdCounter.current();
+      _safeMint(to, tokenId);
+      tokenIds[i] = tokenId;
+    }
+    return tokenIds;
+  }
+
   function mint(address to) external onlyRole(MINTER_ROLE) returns (uint256) {
     require(to != address(0), "Cannot mint to zero address");
     if (supplyLimit > 0) {