feat(cli): Improve @ autocompletion for mid-sentence edits (#5321)

packages/cli/src/ui/hooks/useCompletion.ts

@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import { useState, useEffect, useCallback, useMemo } from 'react';
+import { useState, useEffect, useCallback, useMemo, useRef } from 'react';
 import * as fs from 'fs/promises';
 import * as path from 'path';
 import { glob } from 'glob';
@@ -22,7 +22,10 @@ import {
   Suggestion,
 } from '../components/SuggestionsDisplay.js';
 import { CommandContext, SlashCommand } from '../commands/types.js';
-import { TextBuffer } from '../components/shared/text-buffer.js';
+import {
+  logicalPosToOffset,
+  TextBuffer,
+} from '../components/shared/text-buffer.js';
 import { isSlashCommand } from '../utils/commandUtils.js';
 import { toCodePoints } from '../utils/textUtils.js';
 
@@ -57,6 +60,11 @@ export function useCompletion(
   const [isLoadingSuggestions, setIsLoadingSuggestions] =
     useState<boolean>(false);
   const [isPerfectMatch, setIsPerfectMatch] = useState<boolean>(false);
+  const completionStart = useRef(-1);
+  const completionEnd = useRef(-1);
+
+  const cursorRow = buffer.cursor[0];
+  const cursorCol = buffer.cursor[1];
 
   const resetCompletionState = useCallback(() => {
     setSuggestions([]);
@@ -127,17 +135,15 @@ export function useCompletion(
   }, [suggestions.length]);
 
   // Check if cursor is after @ or / without unescaped spaces
-  const isActive = useMemo(() => {
+  const commandIndex = useMemo(() => {
     if (isSlashCommand(buffer.text.trim())) {
-      return true;
+      return 0;
     }
 
     // For other completions like '@', we search backwards from the cursor.
-    const [row, col] = buffer.cursor;
-    const currentLine = buffer.lines[row] || '';
-    const codePoints = toCodePoints(currentLine);
 
-    for (let i = col - 1; i >= 0; i--) {
+    const codePoints = toCodePoints(buffer.lines[cursorRow] || '');
+    for (let i = cursorCol - 1; i >= 0; i--) {
       const char = codePoints[i];
 
       if (char === ' ') {
@@ -147,19 +153,19 @@ export function useCompletion(
           backslashCount++;
         }
         if (backslashCount % 2 === 0) {
-          return false; // Inactive on unescaped space.
+          return -1; // Inactive on unescaped space.
         }
       } else if (char === '@') {
         // Active if we find an '@' before any unescaped space.
-        return true;
+        return i;
       }
     }
 
-    return false;
-  }, [buffer.text, buffer.cursor, buffer.lines]);
+    return -1;
+  }, [buffer.text, cursorRow, cursorCol, buffer.lines]);
 
   useEffect(() => {
-    if (!isActive) {
+    if (commandIndex === -1) {
       resetCompletionState();
       return;
     }
@@ -311,14 +317,29 @@ export function useCompletion(
     }
 
     // Handle At Command Completion
-    const atIndex = buffer.text.lastIndexOf('@');
-    if (atIndex === -1) {
-      resetCompletionState();
-      return;
+    const currentLine = buffer.lines[cursorRow] || '';
+    const codePoints = toCodePoints(currentLine);
+
+    completionEnd.current = codePoints.length;
+    for (let i = cursorCol; i < codePoints.length; i++) {
+      if (codePoints[i] === ' ') {
+        let backslashCount = 0;
+        for (let j = i - 1; j >= 0 && codePoints[j] === '\\'; j--) {
+          backslashCount++;
+        }
+
+        if (backslashCount % 2 === 0) {
+          completionEnd.current = i;
+          break;
+        }
+      }
     }
 
-    const partialPath = buffer.text.substring(atIndex + 1);
+    const pathStart = commandIndex + 1;
+    const partialPath = currentLine.substring(pathStart, completionEnd.current);
     const lastSlashIndex = partialPath.lastIndexOf('/');
+    completionStart.current =
+      lastSlashIndex === -1 ? pathStart : pathStart + lastSlashIndex + 1;
     const baseDirRelative =
       lastSlashIndex === -1
         ? '.'
@@ -601,9 +622,12 @@ export function useCompletion(
     };
   }, [
     buffer.text,
+    cursorRow,
+    cursorCol,
+    buffer.lines,
     dirs,
     cwd,
-    isActive,
+    commandIndex,
     resetCompletionState,
     slashCommands,
     commandContext,
@@ -669,23 +693,19 @@ export function useCompletion(
 
         buffer.setText(newValue);
       } else {
-        const atIndex = query.lastIndexOf('@');
-        if (atIndex === -1) return;
-        const pathPart = query.substring(atIndex + 1);
-        const lastSlashIndexInPath = pathPart.lastIndexOf('/');
-        let autoCompleteStartIndex = atIndex + 1;
-        if (lastSlashIndexInPath !== -1) {
-          autoCompleteStartIndex += lastSlashIndexInPath + 1;
+        if (completionStart.current === -1 || completionEnd.current === -1) {
+          return;
         }
+
         buffer.replaceRangeByOffset(
-          autoCompleteStartIndex,
-          buffer.text.length,
+          logicalPosToOffset(buffer.lines, cursorRow, completionStart.current),
+          logicalPosToOffset(buffer.lines, cursorRow, completionEnd.current),
           suggestion,
         );
       }
       resetCompletionState();
     },
-    [resetCompletionState, buffer, suggestions, slashCommands],
+    [cursorRow, resetCompletionState, buffer, suggestions, slashCommands],
   );
 
   return {