saveBlob の実装

src/blob.ts

@@ -0,0 +1,103 @@
+import { createHash } from "crypto";
+import fs from "fs";
+import path from "path";
+import zlib from "zlib";
+
+interface GitBlobObject {
+  type: "blob";
+  size: number;
+  content: string;
+}
+
+/**
+ * .git/object/ 以下に保存された Git Blob オブジェクトを読み込む。
+ * @param hash Git Blob オブジェクトのハッシュ値
+ * @returns GitBlobObject
+ */
+const loadBlob = (hash: string): GitBlobObject => {
+  const cwd = process.cwd();
+  const dirName = hash.slice(0, 2);
+  const fileName = hash.slice(2);
+  const objectPath = path.join(cwd, ".git", "objects", dirName, fileName);
+
+  const rawData = fs.readFileSync(objectPath, "binary");
+  const dataBuffer = Buffer.from(rawData, "binary");
+  const decompressed = zlib.unzipSync(toArrayBuffer(dataBuffer));
+
+  // Parse the Git object structure: "<type> <size>\0<content>"
+  const decompressedString = decompressed.toString("utf-8");
+  const nullIndex = decompressedString.indexOf("\0");
+  if (nullIndex === -1) {
+    throw new Error("Invalid Git object format: Missing null separator.");
+  }
+
+  const header = decompressedString.slice(0, nullIndex);
+  const content = decompressedString.slice(nullIndex + 1);
+
+  const [type, size] = header.split(" ");
+  if (!type || !size || isNaN(Number(size))) {
+    throw new Error("Invalid Git object format: Invalid header.");
+  }
+
+  if (type !== "blob") {
+    throw new Error("Invalid Git object format: Invalid type. (excepted: blob)");
+  }
+
+  return { type, size: Number(size), content };
+};
+
+/**
+ * Git Blob オブジェクトを .git/object/ 以下に保存する。
+ * @param blob GitBlobObject
+ */
+const saveBlob = (blob: GitBlobObject): void => {
+  const blobBuffer = blob2UInt8Array(blob);
+
+  // Compress the blob data
+  const compressed = zlib.deflateSync(blobBuffer);
+
+  // Calculate the hash of the blob
+  const hash = createHash("sha1").update(blobBuffer).digest("hex");
+
+  // Write the compressed blob to the file
+  const cwd = process.cwd();
+  const dirName = hash.slice(0, 2);
+  const fileName = hash.slice(2);
+  const dirPath = path.join(cwd, ".git", "objects", dirName);
+  if (!fs.existsSync(dirPath)) {
+    fs.mkdirSync(dirPath, { recursive: true });
+  }
+  const filePath = path.join(dirPath, fileName);
+  fs.writeFileSync(filePath, new Uint8Array(compressed));
+};
+
+
+
+const blob2UInt8Array = (blob: GitBlobObject): Uint8Array => {
+  const contentBuffer = Buffer.from(blob.content, "utf-8");
+  const header = `${blob.type} ${contentBuffer.length.toString()}\0`;
+  const headerBuffer = Buffer.from(header, "utf-8");
+  const blobBuffer = Buffer.concat([headerBuffer, contentBuffer].map((b) => new Uint8Array(b)));
+  return new Uint8Array(blobBuffer);
+};
+
+const blob2Hash = (blob: GitBlobObject): string => {
+  const blobBuffer = blob2UInt8Array(blob);
+  return createHash("sha1").update(blobBuffer).digest("hex");
+};
+
+const toArrayBuffer = (buffer: Buffer): ArrayBuffer => {
+  const ab = new ArrayBuffer(buffer.length);
+  const view = new Uint8Array(ab);
+  for (let i = 0; i < buffer.length; ++i) {
+    // TODO: buffer[i] === undefined の場合に0を入れているが、データ整合静的にはこれでいいのか？
+    view[i] = buffer[i] ?? 0;
+  }
+  return ab;
+}
+
+// test
+const data: GitBlobObject = { type: "blob", size: 5, content: "Hello\n" };
+saveBlob(data);
+console.log(blob2Hash(data));
+console.log(loadBlob(blob2Hash(data)));

src/mygit.ts

@@ -9,31 +9,23 @@ const __dirname = path.dirname(__filename);
 
 export const mygit = async (argv: Array<string>): Promise<void> => {
   const commandName = argv[2] ?? "";
-
-  const commandsDirPath = path.join(__dirname, "commands");
-  const commandsDir = fs.readdirSync(commandsDirPath)
-    .filter((file) => file.endsWith(".js"));
-
-  for (const file of commandsDir) {
-    if(file.replace(".js", "") !== commandName) {
-      continue;
-    }
-
-    // * ESM Module まわりが any を使わざるを得ないので、ESLint 側の制限を緩めてます
-    const commandsPath = path.join(commandsDirPath, file);
-    // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
-    const commandModule = await import(commandsPath);
-    // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment, @typescript-eslint/no-unsafe-member-access
-    const command: Command = commandModule.default;
-
-    if (typeof command.exec === "function") {
-      command.exec(argv);
-      return;
-    }
+
+  switch (commandName) {
+    case "log":
+      break;
+
+    case "add":
+      break;
+
+    case "commit":
+      break;
+
+    default:
+      console.log("サポートされていない引数です ><");
   }
+}
+
 
-  console.log("サポートされていない引数です ><");
-
-  // Avoid eslint error by adding some async operation.
-  await new Promise((resolve) => setTimeout(resolve, 1000));
+// Avoid eslint error by adding some async operation.
+await new Promise((resolve) => setTimeout(resolve, 1000));
 };