1 files changed, 240 insertions, 0 deletions
diff --git a/std/node/_stream/end-of-stream.ts b/std/node/_stream/end-of-stream.ts
new file mode 100644
index 000000000..c42bb0e1c
--- /dev/null
+++ b/std/node/_stream/end-of-stream.ts
@@ -0,0 +1,240 @@
+// Copyright Node.js contributors. All rights reserved. MIT License.
+import { once } from "../_utils.ts";
+import type Readable from "./readable.ts";
+import type Stream from "./stream.ts";
+import type { ReadableState } from "./readable.ts";
+import type Writable from "./writable.ts";
+import type { WritableState } from "./writable.ts";
+import {
+  ERR_INVALID_ARG_TYPE,
+  ERR_STREAM_PREMATURE_CLOSE,
+  NodeErrorAbstraction,
+} from "../_errors.ts";
+
+type StreamImplementations = Readable | Stream | Writable;
+
+// TODO(Soremwar)
+// Bring back once requests are implemented
+// function isRequest(stream: Stream) {
+//   return stream.setHeader && typeof stream.abort === "function";
+// }
+
+// deno-lint-ignore no-explicit-any
+function isReadable(stream: any) {
+  return typeof stream.readable === "boolean" ||
+    typeof stream.readableEnded === "boolean" ||
+    !!stream._readableState;
+}
+
+// deno-lint-ignore no-explicit-any
+function isWritable(stream: any) {
+  return typeof stream.writable === "boolean" ||
+    typeof stream.writableEnded === "boolean" ||
+    !!stream._writableState;
+}
+
+function isWritableFinished(stream: Writable) {
+  if (stream.writableFinished) return true;
+  const wState = stream._writableState;
+  if (!wState || wState.errored) return false;
+  return wState.finished || (wState.ended && wState.length === 0);
+}
+
+function nop() {}
+
+function isReadableEnded(stream: Readable) {
+  if (stream.readableEnded) return true;
+  const rState = stream._readableState;
+  if (!rState || rState.errored) return false;
+  return rState.endEmitted || (rState.ended && rState.length === 0);
+}
+
+interface FinishedOptions {
+  error?: boolean;
+  readable?: boolean;
+  writable?: boolean;
+}
+
+/**
+ * Appends an ending callback triggered when a stream is no longer readable,
+ * writable or has experienced an error or a premature close event
+*/
+export default function eos(
+  stream: StreamImplementations,
+  options: FinishedOptions | null,
+  callback: (err?: NodeErrorAbstraction | null) => void,
+): () => void;
+export default function eos(
+  stream: StreamImplementations,
+  callback: (err?: NodeErrorAbstraction | null) => void,
+): () => void;
+export default function eos(
+  stream: StreamImplementations,
+  x: FinishedOptions | ((err?: NodeErrorAbstraction | null) => void) | null,
+  y?: (err?: NodeErrorAbstraction | null) => void,
+) {
+  let opts: FinishedOptions;
+  let callback: (err?: NodeErrorAbstraction | null) => void;
+
+  if (!y) {
+    if (typeof x !== "function") {
+      throw new ERR_INVALID_ARG_TYPE("callback", "function", x);
+    }
+    opts = {};
+    callback = x;
+  } else {
+    if (!x || Array.isArray(x) || typeof x !== "object") {
+      throw new ERR_INVALID_ARG_TYPE("opts", "object", x);
+    }
+    opts = x;
+
+    if (typeof y !== "function") {
+      throw new ERR_INVALID_ARG_TYPE("callback", "function", y);
+    }
+    callback = y;
+  }
+
+  callback = once(callback);
+
+  const readable = opts.readable ?? isReadable(stream);
+  const writable = opts.writable ?? isWritable(stream);
+
+  // deno-lint-ignore no-explicit-any
+  const wState: WritableState | undefined = (stream as any)._writableState;
+  // deno-lint-ignore no-explicit-any
+  const rState: ReadableState | undefined = (stream as any)._readableState;
+  const validState = wState || rState;
+
+  const onlegacyfinish = () => {
+    if (!(stream as Writable).writable) {
+      onfinish();
+    }
+  };
+
+  let willEmitClose = (
+    validState?.autoDestroy &&
+    validState?.emitClose &&
+    validState?.closed === false &&
+    isReadable(stream) === readable &&
+    isWritable(stream) === writable
+  );
+
+  let writableFinished = (stream as Writable).writableFinished ||
+    wState?.finished;
+  const onfinish = () => {
+    writableFinished = true;
+    // deno-lint-ignore no-explicit-any
+    if ((stream as any).destroyed) {
+      willEmitClose = false;
+    }
+
+    if (willEmitClose && (!(stream as Readable).readable || readable)) {
+      return;
+    }
+    if (!readable || readableEnded) {
+      callback.call(stream);
+    }
+  };
+
+  let readableEnded = (stream as Readable).readableEnded || rState?.endEmitted;
+  const onend = () => {
+    readableEnded = true;
+    // deno-lint-ignore no-explicit-any
+    if ((stream as any).destroyed) {
+      willEmitClose = false;
+    }
+
+    if (willEmitClose && (!(stream as Writable).writable || writable)) {
+      return;
+    }
+    if (!writable || writableFinished) {
+      callback.call(stream);
+    }
+  };
+
+  const onerror = (err: NodeErrorAbstraction) => {
+    callback.call(stream, err);
+  };
+
+  const onclose = () => {
+    if (readable && !readableEnded) {
+      if (!isReadableEnded(stream as Readable)) {
+        return callback.call(stream, new ERR_STREAM_PREMATURE_CLOSE());
+      }
+    }
+    if (writable && !writableFinished) {
+      if (!isWritableFinished(stream as Writable)) {
+        return callback.call(stream, new ERR_STREAM_PREMATURE_CLOSE());
+      }
+    }
+    callback.call(stream);
+  };
+
+  // TODO(Soremwar)
+  // Bring back once requests are implemented
+  // const onrequest = () => {
+  //   stream.req.on("finish", onfinish);
+  // };
+
+  // TODO(Soremwar)
+  // Bring back once requests are implemented
+  // if (isRequest(stream)) {
+  //   stream.on("complete", onfinish);
+  //   stream.on("abort", onclose);
+  //   if (stream.req) {
+  //     onrequest();
+  //   } else {
+  //     stream.on("request", onrequest);
+  //   }
+  // } else
+  if (writable && !wState) {
+    stream.on("end", onlegacyfinish);
+    stream.on("close", onlegacyfinish);
+  }
+
+  // TODO(Soremwar)
+  // Bring back once requests are implemented
+  // if (typeof stream.aborted === "boolean") {
+  //   stream.on("aborted", onclose);
+  // }
+
+  stream.on("end", onend);
+  stream.on("finish", onfinish);
+  if (opts.error !== false) stream.on("error", onerror);
+  stream.on("close", onclose);
+
+  const closed = (
+    wState?.closed ||
+    rState?.closed ||
+    wState?.errorEmitted ||
+    rState?.errorEmitted ||
+    // TODO(Soremwar)
+    // Bring back once requests are implemented
+    // (rState && stream.req && stream.aborted) ||
+    (
+      (!writable || wState?.finished) &&
+      (!readable || rState?.endEmitted)
+    )
+  );
+
+  if (closed) {
+    queueMicrotask(callback);
+  }
+
+  return function () {
+    callback = nop;
+    stream.removeListener("aborted", onclose);
+    stream.removeListener("complete", onfinish);
+    stream.removeListener("abort", onclose);
+    // TODO(Soremwar)
+    // Bring back once requests are implemented
+    // stream.removeListener("request", onrequest);
+    // if (stream.req) stream.req.removeListener("finish", onfinish);
+    stream.removeListener("end", onlegacyfinish);
+    stream.removeListener("close", onlegacyfinish);
+    stream.removeListener("finish", onfinish);
+    stream.removeListener("end", onend);
+    stream.removeListener("error", onerror);
+    stream.removeListener("close", onclose);
+  };
+}