[Init] Initial commit - NetMesh terminal manager

lib/readTextFile.ts

@@ -0,0 +1,48 @@
+type ReadTextFileOptions = {
+  encoding?: string;
+  fallbackEncoding?: string;
+};
+
+export async function readTextFile(
+  file: File,
+  options: ReadTextFileOptions = {},
+): Promise<string> {
+  const buf = await file.arrayBuffer();
+  const bytes = new Uint8Array(buf);
+
+  if (options.encoding) {
+    return new TextDecoder(options.encoding).decode(bytes);
+  }
+
+  let encoding: string = "utf-8";
+  let offset = 0;
+
+  if (bytes.length >= 2 && bytes[0] === 0xff && bytes[1] === 0xfe) {
+    encoding = "utf-16le";
+    offset = 2;
+  } else if (bytes.length >= 2 && bytes[0] === 0xfe && bytes[1] === 0xff) {
+    encoding = "utf-16be";
+    offset = 2;
+  } else if (
+    bytes.length >= 3 &&
+    bytes[0] === 0xef &&
+    bytes[1] === 0xbb &&
+    bytes[2] === 0xbf
+  ) {
+    encoding = "utf-8";
+    offset = 3;
+  }
+
+  const content = bytes.slice(offset);
+  if (offset === 0 && options.fallbackEncoding) {
+    let utf8: string;
+    try {
+      utf8 = new TextDecoder("utf-8", { fatal: true }).decode(content);
+    } catch {
+      return new TextDecoder(options.fallbackEncoding).decode(content);
+    }
+    return utf8;
+  }
+
+  return new TextDecoder(encoding).decode(content);
+}