/**
 * @license
 * Copyright 2025 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

/** @vitest-environment jsdom */

import { describe, it, expect, beforeEach, vi, afterEach } from 'vitest';
import { renderHook, waitFor, act } from '@testing-library/react';
import { useAtCompletion } from './useAtCompletion.js';
import { Config, FileSearch } from '@google/gemini-cli-core';
import {
  createTmpDir,
  cleanupTmpDir,
  FileSystemStructure,
} from '@google/gemini-cli-test-utils';
import { useState } from 'react';
import { Suggestion } from '../components/SuggestionsDisplay.js';

// Test harness to capture the state from the hook's callbacks.
function useTestHarnessForAtCompletion(
  enabled: boolean,
  pattern: string,
  config: Config | undefined,
  cwd: string,
) {
  const [suggestions, setSuggestions] = useState<Suggestion[]>([]);
  const [isLoadingSuggestions, setIsLoadingSuggestions] = useState(false);

  useAtCompletion({
    enabled,
    pattern,
    config,
    cwd,
    setSuggestions,
    setIsLoadingSuggestions,
  });

  return { suggestions, isLoadingSuggestions };
}

describe('useAtCompletion', () => {
  let testRootDir: string;
  let mockConfig: Config;

  beforeEach(() => {
    mockConfig = {
      getFileFilteringOptions: vi.fn(() => ({
        respectGitIgnore: true,
        respectGeminiIgnore: true,
      })),
    } as unknown as Config;
    vi.clearAllMocks();
  });

  afterEach(async () => {
    if (testRootDir) {
      await cleanupTmpDir(testRootDir);
    }
    vi.restoreAllMocks();
  });

  describe('File Search Logic', () => {
    it('should perform a recursive search for an empty pattern', async () => {
      const structure: FileSystemStructure = {
        'file.txt': '',
        src: {
          'index.js': '',
          components: ['Button.tsx', 'Button with spaces.tsx'],
        },
      };
      testRootDir = await createTmpDir(structure);

      const { result } = renderHook(() =>
        useTestHarnessForAtCompletion(true, '', mockConfig, testRootDir),
      );

      await waitFor(() => {
        expect(result.current.suggestions.length).toBeGreaterThan(0);
      });

      expect(result.current.suggestions.map((s) => s.value)).toEqual([
        'src/',
        'src/components/',
        'file.txt',
        'src/components/Button\\ with\\ spaces.tsx',
        'src/components/Button.tsx',
        'src/index.js',
      ]);
    });

    it('should correctly filter the recursive list based on a pattern', async () => {
      const structure: FileSystemStructure = {
        'file.txt': '',
        src: {
          'index.js': '',
          components: {
            'Button.tsx': '',
          },
        },
      };
      testRootDir = await createTmpDir(structure);

      const { result } = renderHook(() =>
        useTestHarnessForAtCompletion(true, 'src/', mockConfig, testRootDir),
      );

      await waitFor(() => {
        expect(result.current.suggestions.length).toBeGreaterThan(0);
      });

      expect(result.current.suggestions.map((s) => s.value)).toEqual([
        'src/',
        'src/components/',
        'src/components/Button.tsx',
        'src/index.js',
      ]);
    });

    it('should append a trailing slash to directory paths in suggestions', async () => {
      const structure: FileSystemStructure = {
        'file.txt': '',
        dir: {},
      };
      testRootDir = await createTmpDir(structure);

      const { result } = renderHook(() =>
        useTestHarnessForAtCompletion(true, '', mockConfig, testRootDir),
      );

      await waitFor(() => {
        expect(result.current.suggestions.length).toBeGreaterThan(0);
      });

      expect(result.current.suggestions.map((s) => s.value)).toEqual([
        'dir/',
        'file.txt',
      ]);
    });
  });

  describe('UI State and Loading Behavior', () => {
    it('should be in a loading state during initial file system crawl', async () => {
      testRootDir = await createTmpDir({});
      const { result } = renderHook(() =>
        useTestHarnessForAtCompletion(true, '', mockConfig, testRootDir),
      );

      // It's initially true because the effect runs synchronously.
      expect(result.current.isLoadingSuggestions).toBe(true);

      // Wait for the loading to complete.
      await waitFor(() => {
        expect(result.current.isLoadingSuggestions).toBe(false);
      });
    });

    it('should NOT show a loading indicator for subsequent searches that complete under 100ms', async () => {
      const structure: FileSystemStructure = { 'a.txt': '', 'b.txt': '' };
      testRootDir = await createTmpDir(structure);

      const { result, rerender } = renderHook(
        ({ pattern }) =>
          useTestHarnessForAtCompletion(true, pattern, mockConfig, testRootDir),
        { initialProps: { pattern: 'a' } },
      );

      await waitFor(() => {
        expect(result.current.suggestions.map((s) => s.value)).toEqual([
          'a.txt',
        ]);
      });
      expect(result.current.isLoadingSuggestions).toBe(false);

      rerender({ pattern: 'b' });

      // Wait for the final result
      await waitFor(() => {
        expect(result.current.suggestions.map((s) => s.value)).toEqual([
          'b.txt',
        ]);
      });

      expect(result.current.isLoadingSuggestions).toBe(false);
    });

    it('should show a loading indicator and clear old suggestions for subsequent searches that take longer than 100ms', async () => {
      const structure: FileSystemStructure = { 'a.txt': '', 'b.txt': '' };
      testRootDir = await createTmpDir(structure);

      // Spy on the search method to introduce an artificial delay
      const originalSearch = FileSearch.prototype.search;
      vi.spyOn(FileSearch.prototype, 'search').mockImplementation(
        async function (...args) {
          await new Promise((resolve) => setTimeout(resolve, 200));
          return originalSearch.apply(this, args);
        },
      );

      const { result, rerender } = renderHook(
        ({ pattern }) =>
          useTestHarnessForAtCompletion(true, pattern, mockConfig, testRootDir),
        { initialProps: { pattern: 'a' } },
      );

      // Wait for the initial (slow) search to complete
      await waitFor(() => {
        expect(result.current.suggestions.map((s) => s.value)).toEqual([
          'a.txt',
        ]);
      });

      // Now, rerender to trigger the second search
      rerender({ pattern: 'b' });

      // Wait for the loading indicator to appear
      await waitFor(() => {
        expect(result.current.isLoadingSuggestions).toBe(true);
      });

      // Suggestions should be cleared while loading
      expect(result.current.suggestions).toEqual([]);

      // Wait for the final (slow) search to complete
      await waitFor(
        () => {
          expect(result.current.suggestions.map((s) => s.value)).toEqual([
            'b.txt',
          ]);
        },
        { timeout: 1000 },
      ); // Increase timeout for the slow search

      expect(result.current.isLoadingSuggestions).toBe(false);
    });

    it('should abort the previous search when a new one starts', async () => {
      const structure: FileSystemStructure = { 'a.txt': '', 'b.txt': '' };
      testRootDir = await createTmpDir(structure);

      const abortSpy = vi.spyOn(AbortController.prototype, 'abort');
      const searchSpy = vi
        .spyOn(FileSearch.prototype, 'search')
        .mockImplementation(async (...args) => {
          const delay = args[0] === 'a' ? 500 : 50;
          await new Promise((resolve) => setTimeout(resolve, delay));
          // eslint-disable-next-line @typescript-eslint/no-explicit-any
          return [args[0] as any];
        });

      const { result, rerender } = renderHook(
        ({ pattern }) =>
          useTestHarnessForAtCompletion(true, pattern, mockConfig, testRootDir),
        { initialProps: { pattern: 'a' } },
      );

      // Wait for the hook to be ready (initialization is complete)
      await waitFor(() => {
        expect(searchSpy).toHaveBeenCalledWith('a', expect.any(Object));
      });

      // Now that the first search is in-flight, trigger the second one.
      act(() => {
        rerender({ pattern: 'b' });
      });

      // The abort should have been called for the first search.
      expect(abortSpy).toHaveBeenCalledTimes(1);

      // Wait for the final result, which should be from the second, faster search.
      await waitFor(
        () => {
          expect(result.current.suggestions.map((s) => s.value)).toEqual(['b']);
        },
        { timeout: 1000 },
      );

      // The search spy should have been called for both patterns.
      expect(searchSpy).toHaveBeenCalledWith('b', expect.any(Object));

      vi.restoreAllMocks();
    });
  });

  describe('Filtering and Configuration', () => {
    it('should respect .gitignore files', async () => {
      const gitignoreContent = ['dist/', '*.log'].join('\n');
      const structure: FileSystemStructure = {
        '.git': {},
        '.gitignore': gitignoreContent,
        dist: {},
        'test.log': '',
        src: {},
      };
      testRootDir = await createTmpDir(structure);

      const { result } = renderHook(() =>
        useTestHarnessForAtCompletion(true, '', mockConfig, testRootDir),
      );

      await waitFor(() => {
        expect(result.current.suggestions.length).toBeGreaterThan(0);
      });

      expect(result.current.suggestions.map((s) => s.value)).toEqual([
        'src/',
        '.gitignore',
      ]);
    });

    it('should work correctly when config is undefined', async () => {
      const structure: FileSystemStructure = {
        node_modules: {},
        src: {},
      };
      testRootDir = await createTmpDir(structure);

      const { result } = renderHook(() =>
        useTestHarnessForAtCompletion(true, '', undefined, testRootDir),
      );

      await waitFor(() => {
        expect(result.current.suggestions.length).toBeGreaterThan(0);
      });

      expect(result.current.suggestions.map((s) => s.value)).toEqual([
        'node_modules/',
        'src/',
      ]);
    });

    it('should reset and re-initialize when the cwd changes', async () => {
      const structure1: FileSystemStructure = { 'file1.txt': '' };
      const rootDir1 = await createTmpDir(structure1);
      const structure2: FileSystemStructure = { 'file2.txt': '' };
      const rootDir2 = await createTmpDir(structure2);

      const { result, rerender } = renderHook(
        ({ cwd, pattern }) =>
          useTestHarnessForAtCompletion(true, pattern, mockConfig, cwd),
        {
          initialProps: {
            cwd: rootDir1,
            pattern: 'file',
          },
        },
      );

      // Wait for initial suggestions from the first directory
      await waitFor(() => {
        expect(result.current.suggestions.map((s) => s.value)).toEqual([
          'file1.txt',
        ]);
      });

      // Change the CWD
      act(() => {
        rerender({ cwd: rootDir2, pattern: 'file' });
      });

      // After CWD changes, suggestions should be cleared and it should load again.
      await waitFor(() => {
        expect(result.current.isLoadingSuggestions).toBe(true);
        expect(result.current.suggestions).toEqual([]);
      });

      // Wait for the new suggestions from the second directory
      await waitFor(() => {
        expect(result.current.suggestions.map((s) => s.value)).toEqual([
          'file2.txt',
        ]);
      });
      expect(result.current.isLoadingSuggestions).toBe(false);

      await cleanupTmpDir(rootDir1);
      await cleanupTmpDir(rootDir2);
    });
  });
});