fix(prompt): preserve buffered input between prompts (#118)

Co-authored-by: cmdr-chara <249489759+cmdr-chara@users.noreply.github.com>

Author: cmdr-chara

src/lib/prompt.test.ts

@@ -39,6 +39,31 @@ describe('promptText', () => {
     expect(await promptText('? ', { input, output })).toBe('ok');
   });
 
+  it('preserves buffered answers for sequential prompts on the same stream', async () => {
+    const input = Readable.from(['first\nsecond\nthird\n']);
+    const output = new CaptureStream();
+
+    await expect(promptText('One: ', { input, output })).resolves.toBe('first');
+    await expect(promptText('Two: ', { input, output })).resolves.toBe('second');
+    await expect(promptText('Three: ', { input, output })).resolves.toBe('third');
+  });
+
+  it('uses buffered tail input at EOF for a following prompt', async () => {
+    const input = Readable.from(['first\nsecond']);
+    const output = new CaptureStream();
+
+    await expect(promptText('One: ', { input, output })).resolves.toBe('first');
+    await expect(promptText('Two: ', { input, output })).resolves.toBe('second');
+  });
+
+  it('preserves buffered CRLF answers for sequential prompts', async () => {
+    const input = Readable.from(['first\r\nsecond\r\n']);
+    const output = new CaptureStream();
+
+    await expect(promptText('One: ', { input, output })).resolves.toBe('first');
+    await expect(promptText('Two: ', { input, output })).resolves.toBe('second');
+  });
+
   it('returns the buffered input on stream end without newline', async () => {
     const input = Readable.from(['eof-no-newline']);
     const output = new CaptureStream();
@@ -70,6 +95,16 @@ describe('promptSecret (non-TTY behavior)', () => {
     expect(await promptSecret('? ', { input, output })).toBe('abd');
   });
 
+  it('preserves buffered secret answers for sequential prompts', async () => {
+    const input = Readable.from(['sk-one\nsk-two\n']);
+    const output = new CaptureStream();
+
+    await expect(promptSecret('First key: ', { input, output })).resolves.toBe('sk-one');
+    await expect(promptSecret('Second key: ', { input, output })).resolves.toBe('sk-two');
+    expect(output.text()).not.toContain('sk-one');
+    expect(output.text()).not.toContain('sk-two');
+  });
+
   it('rejects on Ctrl-C input', async () => {
     const ETX = String.fromCharCode(0x03);
     const input = Readable.from([`abc${ETX}`]);

src/lib/prompt.ts

@@ -11,6 +11,8 @@ interface RawModeCapable {
   resume?: () => unknown;
 }
 
+const pendingPromptInput = new WeakMap<NodeJS.ReadableStream, string>();
+
 export async function promptText(question: string, streams: PromptStreams = {}): Promise<string> {
   const input = streams.input ?? process.stdin;
   const output = streams.output ?? process.stdout;
@@ -41,18 +43,29 @@ function readLine(
   return new Promise<string>((resolve, reject) => {
     let buffer = '';
     let resolved = false;
+    let listening = false;
 
     const onData = (chunk: Buffer | string): void => {
       const str = typeof chunk === 'string' ? chunk : chunk.toString('utf-8');
-      for (const ch of str) {
-        const code = ch.charCodeAt(0);
+      processText(str);
+    };
+
+    const processText = (str: string): void => {
+      for (let i = 0; i < str.length; i += 1) {
+        const code = str.charCodeAt(i);
         // Enter (CR or LF)
         if (code === 13 || code === 10) {
+          let nextIndex = i + 1;
+          if (code === 13 && str.charCodeAt(nextIndex) === 10) {
+            nextIndex += 1;
+          }
+          savePendingInput(str.slice(nextIndex));
           finish();
           return;
         }
         // Ctrl-C
         if (code === 3) {
+          savePendingInput('');
           cleanup();
           output.write('\n');
           if (!resolved) {
@@ -71,7 +84,7 @@ function readLine(
         }
         // Drop other control chars
         if (code < 32) continue;
-        buffer += ch;
+        buffer += str[i];
         if (mask) output.write('*');
       }
     };
@@ -89,9 +102,12 @@ function readLine(
     };
 
     const cleanup = (): void => {
-      input.off('data', onData);
-      input.off('end', onEnd);
-      input.off('error', onError);
+      if (listening) {
+        input.off('data', onData);
+        input.off('end', onEnd);
+        input.off('error', onError);
+        listening = false;
+      }
       const pausable = input as { pause?: () => unknown };
       if (typeof pausable.pause === 'function') pausable.pause();
     };
@@ -105,12 +121,37 @@ function readLine(
       }
     };
 
+    const savePendingInput = (text: string): void => {
+      if (text.length > 0) {
+        pendingPromptInput.set(input, text);
+      } else {
+        pendingPromptInput.delete(input);
+      }
+    };
+
+    const pending = pendingPromptInput.get(input);
+    if (pending !== undefined) {
+      pendingPromptInput.delete(input);
+      processText(pending);
+      if (resolved) return;
+      if (isInputEnded(input)) {
+        finish();
+        return;
+      }
+    }
+
     input.on('data', onData);
     input.on('end', onEnd);
     input.on('error', onError);
+    listening = true;
     const resumable = input as { resume?: () => unknown };
     if (typeof resumable.resume === 'function') resumable.resume();
   });
 }
 
+function isInputEnded(input: NodeJS.ReadableStream): boolean {
+  const state = input as { readableEnded?: boolean; destroyed?: boolean; closed?: boolean };
+  return state.readableEnded === true || state.destroyed === true || state.closed === true;
+}
+
 export type { Writable };