feat: introduce useRewindLogic hook for conversation history navigation

packages/cli/src/ui/hooks/useRewind.test.ts

@@ -0,0 +1,134 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+import { act } from 'react';
+import { renderHook } from '../../test-utils/render.js';
+import { useRewind } from './useRewind.js';
+import * as rewindFileOps from '../utils/rewindFileOps.js';
+import type { FileChangeStats } from '../utils/rewindFileOps.js';
+import type {
+  ConversationRecord,
+  MessageRecord,
+} from '@google/gemini-cli-core';
+
+// Mock the dependency
+vi.mock('../utils/rewindFileOps.js', () => ({
+  calculateTurnStats: vi.fn(),
+  calculateRewindImpact: vi.fn(),
+}));
+
+describe('useRewindLogic', () => {
+  const mockUserMessage: MessageRecord = {
+    id: 'msg-1',
+    type: 'user',
+    content: 'Hello',
+    timestamp: new Date(1000).toISOString(),
+  };
+
+  const mockModelMessage: MessageRecord = {
+    id: 'msg-2',
+    type: 'gemini',
+    content: 'Hi there',
+    timestamp: new Date(1001).toISOString(),
+  };
+
+  const mockConversation: ConversationRecord = {
+    sessionId: 'conv-1',
+    projectHash: 'hash-1',
+    startTime: new Date(1000).toISOString(),
+    lastUpdated: new Date(1001).toISOString(),
+    messages: [mockUserMessage, mockModelMessage],
+  };
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it('should initialize with no selection', () => {
+    const { result } = renderHook(() => useRewind(mockConversation));
+
+    expect(result.current.selectedMessageId).toBeNull();
+    expect(result.current.confirmationStats).toBeNull();
+  });
+
+  it('should update state when a message is selected', () => {
+    const mockStats: FileChangeStats = {
+      fileCount: 1,
+      addedLines: 5,
+      removedLines: 0,
+    };
+    vi.mocked(rewindFileOps.calculateRewindImpact).mockReturnValue(mockStats);
+
+    const { result } = renderHook(() => useRewind(mockConversation));
+
+    act(() => {
+      result.current.selectMessage('msg-1');
+    });
+
+    expect(result.current.selectedMessageId).toBe('msg-1');
+    expect(result.current.confirmationStats).toEqual(mockStats);
+    expect(rewindFileOps.calculateRewindImpact).toHaveBeenCalledWith(
+      mockConversation,
+      mockUserMessage,
+    );
+  });
+
+  it('should not update state if selected message is not found', () => {
+    const { result } = renderHook(() => useRewind(mockConversation));
+
+    act(() => {
+      result.current.selectMessage('non-existent-id');
+    });
+
+    expect(result.current.selectedMessageId).toBeNull();
+    expect(result.current.confirmationStats).toBeNull();
+  });
+
+  it('should clear selection correctly', () => {
+    const mockStats: FileChangeStats = {
+      fileCount: 1,
+      addedLines: 5,
+      removedLines: 0,
+    };
+    vi.mocked(rewindFileOps.calculateRewindImpact).mockReturnValue(mockStats);
+
+    const { result } = renderHook(() => useRewind(mockConversation));
+
+    // Select first
+    act(() => {
+      result.current.selectMessage('msg-1');
+    });
+    expect(result.current.selectedMessageId).toBe('msg-1');
+
+    // Then clear
+    act(() => {
+      result.current.clearSelection();
+    });
+
+    expect(result.current.selectedMessageId).toBeNull();
+    expect(result.current.confirmationStats).toBeNull();
+  });
+
+  it('should proxy getStats call to utility function', () => {
+    const mockStats: FileChangeStats = {
+      fileCount: 2,
+      addedLines: 10,
+      removedLines: 2,
+    };
+    vi.mocked(rewindFileOps.calculateTurnStats).mockReturnValue(mockStats);
+
+    const { result } = renderHook(() => useRewind(mockConversation));
+
+    const stats = result.current.getStats(mockUserMessage);
+
+    expect(stats).toEqual(mockStats);
+    expect(rewindFileOps.calculateTurnStats).toHaveBeenCalledWith(
+      mockConversation,
+      mockUserMessage,
+    );
+  });
+});

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

@@ -0,0 +1,54 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { useState, useCallback } from 'react';
+import type {
+  ConversationRecord,
+  MessageRecord,
+} from '@google/gemini-cli-core';
+import {
+  calculateTurnStats,
+  calculateRewindImpact,
+  type FileChangeStats,
+} from '../utils/rewindFileOps.js';
+
+export function useRewind(conversation: ConversationRecord) {
+  const [selectedMessageId, setSelectedMessageId] = useState<string | null>(
+    null,
+  );
+  const [confirmationStats, setConfirmationStats] =
+    useState<FileChangeStats | null>(null);
+
+  const getStats = useCallback(
+    (userMessage: MessageRecord) =>
+      calculateTurnStats(conversation, userMessage),
+    [conversation],
+  );
+
+  const selectMessage = useCallback(
+    (messageId: string) => {
+      const msg = conversation.messages.find((m) => m.id === messageId);
+      if (msg) {
+        setSelectedMessageId(messageId);
+        setConfirmationStats(calculateRewindImpact(conversation, msg));
+      }
+    },
+    [conversation],
+  );
+
+  const clearSelection = useCallback(() => {
+    setSelectedMessageId(null);
+    setConfirmationStats(null);
+  }, []);
+
+  return {
+    selectedMessageId,
+    getStats,
+    confirmationStats,
+    selectMessage,
+    clearSelection,
+  };
+}