const fc = require('fast-check');

/**
 * Property-Based Tests for Notification System
 * Feature: overseas-appointment-backend
 * 
 * These tests verify notification properties using property-based testing
 * to ensure correctness across a wide range of inputs.
 */

// Mock notification database
class MockNotificationDatabase {
  constructor() {
    this.notifications = [];
    this.appointments = [];
  }

  clear() {
    this.notifications = [];
    this.appointments = [];
  }

  createNotification(notificationData) {
    // Use a counter to ensure unique timestamps for ordering
    const timestamp = new Date(Date.now() + this.notifications.length);
    
    const notification = {
      id: Math.random().toString(36).substring(7),
      userId: notificationData.userId,
      type: notificationData.type,
      titleZh: notificationData.titleZh,
      titleEn: notificationData.titleEn,
      titlePt: notificationData.titlePt,
      contentZh: notificationData.contentZh,
      contentEn: notificationData.contentEn,
      contentPt: notificationData.contentPt,
      isRead: false,
      readAt: null,
      createdAt: timestamp,
      updatedAt: timestamp,
    };
    this.notifications.push(notification);
    return notification;
  }

  createAppointment(appointmentData) {
    const appointment = {
      id: Math.random().toString(36).substring(7),
      appointmentNo: appointmentData.appointmentNo,
      userId: appointmentData.userId,
      serviceId: appointmentData.serviceId,
      status: 'pending',
      createdAt: new Date(),
    };
    this.appointments.push(appointment);
    
    // Automatically create notification
    this.createNotification({
      userId: appointmentData.userId,
      type: 'service',
      titleZh: '预约创建成功',
      titleEn: 'Appointment Created',
      titlePt: 'Agendamento Criado',
      contentZh: `您的预约 ${appointmentData.appointmentNo} 已创建成功`,
      contentEn: `Your appointment ${appointmentData.appointmentNo} has been created successfully`,
      contentPt: `Seu agendamento ${appointmentData.appointmentNo} foi criado com sucesso`,
    });
    
    return appointment;
  }

  getNotifications(userId, options = {}) {
    let filtered = this.notifications.filter(n => n.userId === userId);
    
    // Apply type filter
    if (options.type) {
      filtered = filtered.filter(n => n.type === options.type);
    }
    
    // Sort by creation time descending
    filtered.sort((a, b) => b.createdAt - a.createdAt);
    
    // Apply pagination
    const page = options.page || 1;
    const limit = options.limit || 10;
    const offset = (page - 1) * limit;
    const paginated = filtered.slice(offset, offset + limit);
    
    return {
      data: paginated,
      pagination: {
        page,
        limit,
        total: filtered.length,
        totalPages: Math.ceil(filtered.length / limit),
      },
    };
  }

  countNotifications(userId) {
    return this.notifications.filter(n => n.userId === userId).length;
  }

  countAppointments(userId) {
    return this.appointments.filter(a => a.userId === userId).length;
  }
}

describe('Notification Property Tests', () => {
  const testUserId = 'test-user-123';

  // Create a fresh mock database for each property test
  const createMockDb = () => new MockNotificationDatabase();

  /**
   * Feature: overseas-appointment-backend, Property 12: Appointment creation triggers notification
   * Validates: Requirements 3.3
   * 
   * For any successfully created appointment, a corresponding notification 
   * should be created for the user.
   */
  describe('Property 12: Appointment creation triggers notification', () => {
    test('Creating an appointment creates a notification', () => {
      fc.assert(
        fc.property(
          fc.hexaString({ minLength: 10, maxLength: 20 }),
          (appointmentNo) => {
            const mockDb = createMockDb();
            
            // Count notifications before
            const notificationsBefore = mockDb.countNotifications(testUserId);

            // Create appointment (which automatically creates notification)
            mockDb.createAppointment({
              appointmentNo,
              userId: testUserId,
              serviceId: 'service-123',
            });

            // Count notifications after
            const notificationsAfter = mockDb.countNotifications(testUserId);

            // Verify a notification was created
            expect(notificationsAfter).toBe(notificationsBefore + 1);

            // Verify the notification exists and has correct properties
            const result = mockDb.getNotifications(testUserId, { page: 1, limit: 1 });
            const notification = result.data[0];

            expect(notification).toBeDefined();
            expect(notification.userId).toBe(testUserId);
            expect(notification.type).toBe('service');
            expect(notification.isRead).toBe(false);
          }
        ),
        { numRuns: 100 }
      );
    });

    test('Notification contains appointment information', () => {
      fc.assert(
        fc.property(
          fc.hexaString({ minLength: 10, maxLength: 20 }),
          (appointmentNo) => {
            const mockDb = createMockDb();
            
            // Create appointment
            mockDb.createAppointment({
              appointmentNo,
              userId: testUserId,
              serviceId: 'service-123',
            });

            // Get the notification
            const result = mockDb.getNotifications(testUserId, { page: 1, limit: 1 });
            const notification = result.data[0];

            // Verify notification contains appointment number
            expect(notification.contentZh).toContain(appointmentNo);
            expect(notification.contentEn).toContain(appointmentNo);
            expect(notification.contentPt).toContain(appointmentNo);
          }
        ),
        { numRuns: 100 }
      );
    });

    test('Multiple appointments create multiple notifications', () => {
      fc.assert(
        fc.property(
          fc.array(fc.hexaString({ minLength: 10, maxLength: 20 }), { minLength: 2, maxLength: 10 }),
          (appointmentNos) => {
            const mockDb = createMockDb();
            
            const notificationsBefore = mockDb.countNotifications(testUserId);

            // Create multiple appointments
            for (const appointmentNo of appointmentNos) {
              mockDb.createAppointment({
                appointmentNo,
                userId: testUserId,
                serviceId: 'service-123',
              });
            }

            const notificationsAfter = mockDb.countNotifications(testUserId);

            // Verify one notification per appointment
            expect(notificationsAfter).toBe(notificationsBefore + appointmentNos.length);
          }
        ),
        { numRuns: 100 }
      );
    });

    test('Notification is created with correct initial state', () => {
      fc.assert(
        fc.property(
          fc.hexaString({ minLength: 10, maxLength: 20 }),
          (appointmentNo) => {
            const mockDb = createMockDb();
            
            mockDb.createAppointment({
              appointmentNo,
              userId: testUserId,
              serviceId: 'service-123',
            });

            const result = mockDb.getNotifications(testUserId, { page: 1, limit: 1 });
            const notification = result.data[0];

            // Verify initial state
            expect(notification.isRead).toBe(false);
            expect(notification.readAt).toBeNull();
            expect(notification.type).toBe('service');
          }
        ),
        { numRuns: 100 }
      );
    });
  });

  /**
   * Feature: overseas-appointment-backend, Property 25: Notification type support
   * Validates: Requirements 6.1
   * 
   * For any notification type (system, activity, service), the system should 
   * correctly create and categorize notifications.
   */
  describe('Property 25: Notification type support', () => {
    test('All notification types are supported', () => {
      fc.assert(
        fc.property(
          fc.constantFrom('system', 'activity', 'service'),
          (notificationType) => {
            // Verify type is in the valid list
            const validTypes = ['system', 'activity', 'service'];
            expect(validTypes).toContain(notificationType);
          }
        ),
        { numRuns: 100 }
      );
    });

    test('Notifications can be created with any valid type', () => {
      fc.assert(
        fc.property(
          fc.constantFrom('system', 'activity', 'service'),
          fc.string({ minLength: 1, maxLength: 100 }),
          fc.string({ minLength: 1, maxLength: 500 }),
          (type, title, content) => {
            const mockDb = createMockDb();
            
            const notification = mockDb.createNotification({
              userId: testUserId,
              type,
              titleZh: title,
              titleEn: title,
              titlePt: title,
              contentZh: content,
              contentEn: content,
              contentPt: content,
            });

            expect(notification.type).toBe(type);
            expect(['system', 'activity', 'service']).toContain(notification.type);
          }
        ),
        { numRuns: 100 }
      );
    });

    test('Notification type is preserved after creation', () => {
      fc.assert(
        fc.property(
          fc.constantFrom('system', 'activity', 'service'),
          (type) => {
            const mockDb = createMockDb();
            
            const notification = mockDb.createNotification({
              userId: testUserId,
              type,
              titleZh: '测试标题',
              titleEn: 'Test Title',
              titlePt: 'Título de Teste',
              contentZh: '测试内容',
              contentEn: 'Test Content',
              contentPt: 'Conteúdo de Teste',
            });

            // Verify type is preserved
            expect(notification.type).toBe(type);
            
            // Retrieve and verify
            const result = mockDb.getNotifications(testUserId, { page: 1, limit: 100 });
            const retrieved = result.data.find(n => n.id === notification.id);
            
            expect(retrieved.type).toBe(type);
            expect(retrieved.type).toBe(notification.type);
          }
        ),
        { numRuns: 100 }
      );
    });

    test('Different notification types can coexist', () => {
      fc.assert(
        fc.property(
          fc.array(fc.constantFrom('system', 'activity', 'service'), { minLength: 2, maxLength: 10 }),
          (types) => {
            const mockDb = createMockDb();
            
            // Create notifications with different types
            for (const type of types) {
              mockDb.createNotification({
                userId: testUserId,
                type,
                titleZh: `标题-${type}`,
                titleEn: `Title-${type}`,
                titlePt: `Título-${type}`,
                contentZh: `内容-${type}`,
                contentEn: `Content-${type}`,
                contentPt: `Conteúdo-${type}`,
              });
            }

            // Verify all types are present
            const uniqueTypes = new Set(types);
            for (const type of uniqueTypes) {
              const result = mockDb.getNotifications(testUserId, { type, page: 1, limit: 100 });
              expect(result.data.length).toBeGreaterThan(0);
              
              // Verify all returned notifications have the correct type
              for (const notification of result.data) {
                expect(notification.type).toBe(type);
              }
            }
          }
        ),
        { numRuns: 100 }
      );
    });
  });

  /**
   * Feature: overseas-appointment-backend, Property 29: Notification query filtering
   * Validates: Requirements 6.5
   * 
   * For any notification type filter and pagination parameters, the query 
   * should return only notifications of that type with correct pagination.
   */
  describe('Property 29: Notification query filtering', () => {
    test('Filtering by type returns only notifications of that type', () => {
      fc.assert(
        fc.property(
          fc.constantFrom('system', 'activity', 'service'),
          fc.integer({ min: 2, max: 5 }),
          (filterType, count) => {
            const mockDb = createMockDb();
            
            // Create notifications of different types
            const types = ['system', 'activity', 'service'];
            for (const type of types) {
              for (let i = 0; i < count; i++) {
                mockDb.createNotification({
                  userId: testUserId,
                  type,
                  titleZh: `标题-${type}-${i}`,
                  titleEn: `Title-${type}-${i}`,
                  titlePt: `Título-${type}-${i}`,
                  contentZh: `内容-${type}-${i}`,
                  contentEn: `Content-${type}-${i}`,
                  contentPt: `Conteúdo-${type}-${i}`,
                });
              }
            }

            // Query with type filter
            const result = mockDb.getNotifications(testUserId, {
              type: filterType,
              page: 1,
              limit: 100,
            });

            // Verify all returned notifications have the correct type
            expect(result.data.length).toBe(count);
            for (const notification of result.data) {
              expect(notification.type).toBe(filterType);
            }
          }
        ),
        { numRuns: 100 }
      );
    });

    test('Pagination limits the number of results', () => {
      fc.assert(
        fc.property(
          fc.integer({ min: 1, max: 10 }),
          fc.integer({ min: 5, max: 20 }),
          (limit, totalCount) => {
            const mockDb = createMockDb();
            
            // Create notifications
            for (let i = 0; i < totalCount; i++) {
              mockDb.createNotification({
                userId: testUserId,
                type: 'system',
                titleZh: `标题-${i}`,
                titleEn: `Title-${i}`,
                titlePt: `Título-${i}`,
                contentZh: `内容-${i}`,
                contentEn: `Content-${i}`,
                contentPt: `Conteúdo-${i}`,
              });
            }

            // Query with limit
            const result = mockDb.getNotifications(testUserId, {
              page: 1,
              limit,
            });

            // Verify result count respects limit
            expect(result.data.length).toBeLessThanOrEqual(limit);
            expect(result.data.length).toBe(Math.min(limit, totalCount));
          }
        ),
        { numRuns: 100 }
      );
    });

    test('Pagination metadata is correct', () => {
      fc.assert(
        fc.property(
          fc.record({
            page: fc.integer({ min: 1, max: 5 }),
            limit: fc.integer({ min: 2, max: 10 }),
            totalCount: fc.integer({ min: 5, max: 30 }),
          }),
          ({ page, limit, totalCount }) => {
            const mockDb = createMockDb();
            
            // Create notifications
            for (let i = 0; i < totalCount; i++) {
              mockDb.createNotification({
                userId: testUserId,
                type: 'system',
                titleZh: `标题-${i}`,
                titleEn: `Title-${i}`,
                titlePt: `Título-${i}`,
                contentZh: `内容-${i}`,
                contentEn: `Content-${i}`,
                contentPt: `Conteúdo-${i}`,
              });
            }

            // Query with pagination
            const result = mockDb.getNotifications(testUserId, {
              page,
              limit,
            });

            // Verify pagination metadata
            expect(result.pagination.page).toBe(page);
            expect(result.pagination.limit).toBe(limit);
            expect(result.pagination.total).toBe(totalCount);
            expect(result.pagination.totalPages).toBe(Math.ceil(totalCount / limit));
          }
        ),
        { numRuns: 100 }
      );
    });

    test('Combining type filter and pagination works correctly', () => {
      fc.assert(
        fc.property(
          fc.constantFrom('system', 'activity', 'service'),
          fc.integer({ min: 1, max: 5 }),
          fc.integer({ min: 3, max: 10 }),
          (filterType, limit, countPerType) => {
            const mockDb = createMockDb();
            
            // Create notifications of different types
            const types = ['system', 'activity', 'service'];
            for (const type of types) {
              for (let i = 0; i < countPerType; i++) {
                mockDb.createNotification({
                  userId: testUserId,
                  type,
                  titleZh: `标题-${type}-${i}`,
                  titleEn: `Title-${type}-${i}`,
                  titlePt: `Título-${type}-${i}`,
                  contentZh: `内容-${type}-${i}`,
                  contentEn: `Content-${type}-${i}`,
                  contentPt: `Conteúdo-${type}-${i}`,
                });
              }
            }

            // Query with both filter and pagination
            const result = mockDb.getNotifications(testUserId, {
              type: filterType,
              page: 1,
              limit,
            });

            // Verify results
            expect(result.data.length).toBeLessThanOrEqual(limit);
            expect(result.data.length).toBe(Math.min(limit, countPerType));
            expect(result.pagination.total).toBe(countPerType);
            
            // Verify all have correct type
            for (const notification of result.data) {
              expect(notification.type).toBe(filterType);
            }
          }
        ),
        { numRuns: 100 }
      );
    });

    test('Notifications are ordered by creation time descending', () => {
      fc.assert(
        fc.property(
          fc.integer({ min: 3, max: 10 }),
          (count) => {
            const mockDb = createMockDb();
            
            // Create notifications
            const createdIds = [];
            for (let i = 0; i < count; i++) {
              const notification = mockDb.createNotification({
                userId: testUserId,
                type: 'system',
                titleZh: `标题-${i}`,
                titleEn: `Title-${i}`,
                titlePt: `Título-${i}`,
                contentZh: `内容-${i}`,
                contentEn: `Content-${i}`,
                contentPt: `Conteúdo-${i}`,
              });
              createdIds.push(notification.id);
            }

            // Query notifications
            const result = mockDb.getNotifications(testUserId, {
              page: 1,
              limit: 100,
            });

            // Verify order (newest first)
            for (let i = 0; i < result.data.length - 1; i++) {
              const current = new Date(result.data[i].createdAt);
              const next = new Date(result.data[i + 1].createdAt);
              expect(current.getTime()).toBeGreaterThanOrEqual(next.getTime());
            }

            // Verify the last created is first in results
            expect(result.data[0].id).toBe(createdIds[createdIds.length - 1]);
          }
        ),
        { numRuns: 100 }
      );
    });
  });
});
