repl: make history navigation work with big inputs

Fixes: #59938

Author: puskin

lib/internal/readline/interface.js

@@ -513,11 +513,30 @@ class Interface extends InterfaceConstructor {
 
     if (this[kIsMultiline]) {
       const lines = StringPrototypeSplit(this.line, '\n');
-      // Write first line with normal prompt
-      this[kWriteToOutput](this[kPrompt] + lines[0]);
+      const terminalRows = this.output?.rows;
+      let startLine = 0;
+      let endLine = lineRows;
+
+      const isTallerThanTerminalHeight = terminalRows && (lineRows >= terminalRows);
+
+      if (isTallerThanTerminalHeight) {
+        const firstVisibleLineIdx = lineRows - terminalRows;
+
+        if (cursorPos.rows > firstVisibleLineIdx) {
+          startLine = firstVisibleLineIdx;
+        } else {
+          startLine = cursorPos.rows;
+          endLine = cursorPos.rows + terminalRows - 1;
+        }
+      }
+
+      if (startLine === 0) {
+        this[kWriteToOutput](this[kPrompt] + lines[0]);
+        startLine++;
+      }
 
       // For continuation lines, add the "|" prefix
-      for (let i = 1; i < lines.length; i++) {
+      for (let i = startLine; i <= endLine; i++) {
         this[kWriteToOutput](`\n${kMultilinePrompt.description}` + lines[i]);
       }
     } else {
@@ -1156,10 +1175,16 @@ class Interface extends InterfaceConstructor {
 
   [kMoveUpOrHistoryPrev]() {
     const cursorPos = this.getCursorPos();
-    if (this[kIsMultiline] && cursorPos.rows > 0) {
-      const splitLines = StringPrototypeSplit(this.line, '\n');
-      this[kMultilineMove](-1, splitLines, cursorPos);
-      return;
+    if (this[kIsMultiline]) {
+      if (cursorPos.rows > 0) {
+        const splitLines = StringPrototypeSplit(this.line, '\n');
+        this[kMultilineMove](-1, splitLines, cursorPos);
+        return;
+      } else if (cursorPos.rows === 0 && this.historyIndex === -1) {
+        // Pressing up when at the first line of a new multiline input, should do nothing
+        // we don't want the user to lose what he has written so far.
+        return;
+      }
     }
     this[kPreviousCursorCols] = -1;
     this[kHistoryPrev]();

test/parallel/test-repl-multiline-navigation-while-adding.js

@@ -310,3 +310,43 @@ tmpdir.refresh();
     checkResults
   );
 }
+
+{
+  const historyPath = tmpdir.resolve(`.${Math.floor(Math.random() * 10000)}`);
+  // Make sure the cursor is at the right places when navigating an input which is
+  // bigger than the terminal height
+  const checkResults = common.mustSucceed((r) => {
+    r.write('let fff = `I am a');
+    r.input.run([{ name: 'enter' }]);
+    r.write('1111111111111');
+    r.input.run([{ name: 'enter' }]);
+    r.write('22222222222222');
+    r.input.run([{ name: 'enter' }]);
+    r.write('333333333333333');
+    r.input.run([{ name: 'enter' }]);
+    r.write('4444444444`');
+
+    // Make sure that if we press up while adding a new multiline input,
+    // and the cursor is at the first line, we don't lose what we have written so far.
+    for (let i = 0; i < 5; i++) {
+      r.input.run([{ name: 'up' }]);
+    }
+
+    assert.strictEqual(r.line, 'let fff = `I am a\r1111111111111\r22222222222222\r333333333333333\r4444444444`');
+    assert.strictEqual(r.history.length, 1);
+  });
+
+  repl.createInternalRepl(
+    { NODE_REPL_HISTORY: historyPath },
+    {
+      terminal: true,
+      input: new ActionStream(),
+      output: Object.assign(new stream.Writable({
+        write(chunk, _, next) {
+          next();
+        }
+      }), { rows: 3 }),
+    },
+    checkResults
+  );
+}