import { Database } from 'bun:sqlite';
import { initializeDatabase, ensureUserExists } from '../../src/db'; // Import ensureUserExists
import { describe, test, expect, beforeEach, afterAll, beforeAll } from 'bun:test';

// Helper function to introduce slight delay for timestamp checks
const sleep = (ms: number) => new Promise(resolve => setTimeout(resolve, ms));

describe('Database', () => {
  let testDb: Database;

  // Create an in-memory database before any tests run
  beforeAll(() => {
    testDb = new Database(':memory:');
    // Enable foreign keys for the test database instance
    testDb.exec('PRAGMA foreign_keys = ON;'); 
  });

  // Close the database connection after all tests have run
  afterAll(() => {
    testDb.close();
  });

  beforeEach(() => {
    // Reset database schema between tests by dropping tables and re-initializing
    testDb.exec('DROP TABLE IF EXISTS task_assignments'); // Drop dependent tables first
    testDb.exec('DROP TABLE IF EXISTS tasks');
    testDb.exec('DROP TABLE IF EXISTS users');
    testDb.exec('DROP TABLE IF EXISTS groups');
    // Initialize schema on the test database instance
    initializeDatabase(testDb);
  });

  describe('Table Creation', () => {
    test('should create all required tables in correct order', () => {
      const tables = testDb
        .query("SELECT name FROM sqlite_master WHERE type='table'")
        .all()
        .map((t: any) => t.name);
      
      // Order matters if foreign keys are involved during creation, though SQLite is flexible
      const expectedTables = ['users', 'groups', 'tasks', 'task_assignments']; 
      const userTables = tables.filter(t => !t.startsWith('sqlite_'));
      // Check if all expected tables exist, order might vary slightly depending on execution
      expect(userTables).toHaveLength(expectedTables.length);
      expectedTables.forEach(table => expect(userTables).toContain(table));
    });
  });

  describe('Table Schemas', () => {
    test('users table should have correct columns', () => {
      const columns = testDb
        .query("PRAGMA table_info(users)")
        .all()
        .map((c: any) => c.name);
      expect(columns).toEqual(['id', 'first_seen', 'last_seen']);
    });

    test('tasks table should have required columns', () => {
      const columns = testDb
        .query("PRAGMA table_info(tasks)")
        .all()
        .map((c: any) => c.name);
      expect(columns).toContain('description');
      expect(columns).toContain('due_date');
      expect(columns).toContain('group_id');
      expect(columns).toContain('created_by');
    });
    
    test('task_assignments table should have correct columns', () => {
      const columns = testDb
        .query("PRAGMA table_info(task_assignments)")
        .all()
        .map((c: any) => c.name);
      expect(columns).toEqual(['task_id', 'user_id', 'assigned_by', 'assigned_at']);
    });

    test('groups table should have active flag default to true', () => {
      testDb.exec(`
        INSERT INTO groups (id, community_id, name)
        VALUES ('test-group', 'test-community', 'Test Group')
      `);
      const group = testDb.query("SELECT active FROM groups WHERE id = 'test-group'").get();
      expect(group.active).toBe(1); // SQLite uses 1 for TRUE
    });
  });

  describe('Foreign Keys', () => {
    test('tasks should reference users via created_by', () => {
      const fkInfo = testDb.query("PRAGMA foreign_key_list(tasks)").all();
      const createdByFk = fkInfo.find(fk => fk.from === 'created_by');
      expect(createdByFk).toBeDefined();
      expect(createdByFk.table).toBe('users');
      expect(createdByFk.to).toBe('id');
    });

    test('tasks should reference groups via group_id', () => {
      const fkInfo = testDb.query("PRAGMA foreign_key_list(tasks)").all();
      const groupIdFk = fkInfo.find(fk => fk.from === 'group_id');
      expect(groupIdFk).toBeDefined();
      expect(groupIdFk.table).toBe('groups');
      expect(groupIdFk.to).toBe('id');
      expect(groupIdFk.on_delete).toBe('SET NULL');
    });

    test('task_assignments should reference tasks via task_id', () => {
      const fkInfo = testDb.query("PRAGMA foreign_key_list(task_assignments)").all();
      const taskIdFk = fkInfo.find(fk => fk.from === 'task_id');
      expect(taskIdFk).toBeDefined();
      expect(taskIdFk.table).toBe('tasks');
      expect(taskIdFk.to).toBe('id');
      expect(taskIdFk.on_delete).toBe('CASCADE');
    });
    
    test('task_assignments should reference users via user_id', () => {
      const fkInfo = testDb.query("PRAGMA foreign_key_list(task_assignments)").all();
      const userIdFk = fkInfo.find(fk => fk.from === 'user_id');
      expect(userIdFk).toBeDefined();
      expect(userIdFk.table).toBe('users');
      expect(userIdFk.to).toBe('id');
      expect(userIdFk.on_delete).toBe('CASCADE');
    });
    
    test('task_assignments should reference users via assigned_by', () => {
      const fkInfo = testDb.query("PRAGMA foreign_key_list(task_assignments)").all();
      const assignedByFk = fkInfo.find(fk => fk.from === 'assigned_by');
      expect(assignedByFk).toBeDefined();
      expect(assignedByFk.table).toBe('users');
      expect(assignedByFk.to).toBe('id');
      expect(assignedByFk.on_delete).toBe('CASCADE');
    });

    test('should prevent inserting task with non-existent user', () => {
       expect(() => {
         testDb.prepare(`
           INSERT INTO tasks (description, created_by) 
           VALUES ('Task for non-existent user', 'nonexistentuser')
         `).run();
       }).toThrow(); // Foreign key constraint failure
    });
    
    test('should prevent inserting assignment with non-existent user', () => {
       // Need a valid user and task first
       testDb.exec(`INSERT INTO users (id) VALUES ('user1')`);
       const taskResult = testDb.prepare(`INSERT INTO tasks (description, created_by) VALUES ('Test Task', 'user1') RETURNING id`).get();
       const taskId = taskResult.id;
       
       expect(() => {
         testDb.prepare(`
           INSERT INTO task_assignments (task_id, user_id, assigned_by) 
           VALUES (?, 'nonexistentuser', 'user1')
         `).run(taskId);
       }).toThrow(); // Foreign key constraint failure on user_id
       
       expect(() => {
         testDb.prepare(`
           INSERT INTO task_assignments (task_id, user_id, assigned_by) 
           VALUES (?, 'user1', 'nonexistentassigner')
         `).run(taskId);
       }).toThrow(); // Foreign key constraint failure on assigned_by
    });
  });

  describe('ensureUserExists', () => {
    const rawUserId = '1234567890@s.whatsapp.net';
    const normalizedId = '1234567890';

    test('should create a new user if they do not exist', () => {
      const resultId = ensureUserExists(rawUserId, testDb);
      expect(resultId).toBe(normalizedId);

      const user = testDb.query("SELECT * FROM users WHERE id = ?").get(normalizedId);
      expect(user).toBeDefined();
      expect(user.id).toBe(normalizedId);
      expect(user.first_seen).toBeDefined();
      expect(user.last_seen).toBe(user.first_seen); // Initially they are the same
    });

    test('should update last_seen for an existing user', async () => {
      // First call creates the user
      ensureUserExists(rawUserId, testDb);
      const initialUser = testDb.query("SELECT * FROM users WHERE id = ?").get(normalizedId);
      const initialLastSeen = initialUser.last_seen;

      // Wait a bit to ensure timestamp changes
      await sleep(50); 

      // Second call should update last_seen
      const resultId = ensureUserExists(rawUserId, testDb);
      expect(resultId).toBe(normalizedId);

      const updatedUser = testDb.query("SELECT * FROM users WHERE id = ?").get(normalizedId);
      expect(updatedUser.last_seen).toBeDefined();
      expect(updatedUser.last_seen).not.toBe(initialLastSeen); // last_seen should be updated
      expect(updatedUser.first_seen).toBe(initialUser.first_seen); // first_seen should NOT be updated
    });

    test('should return the normalized ID on success', () => {
      const resultId = ensureUserExists('9876543210@s.whatsapp.net', testDb);
      expect(resultId).toBe('9876543210');
    });

    test('should return null for invalid raw user ID', () => {
      const resultId = ensureUserExists('invalid-id!', testDb);
      expect(resultId).toBeNull();
      const userCount = testDb.query("SELECT COUNT(*) as count FROM users").get();
      expect(userCount.count).toBe(0); // No user should be created
    });

    test('should return null for null input', () => {
      const resultId = ensureUserExists(null, testDb);
      expect(resultId).toBeNull();
    });

    test('should return null for undefined input', () => {
      const resultId = ensureUserExists(undefined, testDb);
      expect(resultId).toBeNull();
    });
    
    test('should handle user ID with participant correctly', () => {
      const resultId = ensureUserExists('1122334455:12@s.whatsapp.net', testDb);
      expect(resultId).toBe('1122334455');
      const user = testDb.query("SELECT * FROM users WHERE id = ?").get('1122334455');
      expect(user).toBeDefined();
    });
  });

  // Keep existing Data Operations tests, but ensure users/groups are created first
  describe('Data Operations (with user checks)', () => {
    const user1 = '34650112233';
    const group1 = 'test-group-123';

    beforeEach(() => {
      // Ensure users and groups exist before task operations
      ensureUserExists(`${user1}@s.whatsapp.net`, testDb);
      testDb.exec(`
        INSERT OR IGNORE INTO groups (id, community_id, name)
        VALUES (?, 'test-community', 'Test Group')
      `, [group1]);
    });

    test('should allow inserting group tasks with existing user and group', () => {
      const result = testDb.prepare(`
        INSERT INTO tasks (description, created_by, group_id)
        VALUES ('Test task', ?, ?)
      `).run(user1, group1);
      expect(result.changes).toBe(1);
    });

    test('should allow inserting private tasks with existing user', () => {
      const result = testDb.prepare(`
        INSERT INTO tasks (description, created_by)
        VALUES ('Private task', ?)
      `).run(user1);
      expect(result.changes).toBe(1);
    });
  });
});