/**
 * Comprehensive Unit Tests for api-helper.ts
 *
 * 테스트 범위:
 * 1. 기본 GET/POST 요청
 * 2. HTTP 에러 처리 (4xx, 5xx)
 * 3. Zod 스키마 검증
 * 4. 타임아웃 처리
 * 5. 재시도 로직 통합
 * 6. 커스텀 헤더 및 옵션
 */
import { describe, it, expect, beforeEach, vi, afterEach } from 'vitest';
import { z } from 'zod';
import { callApi } from '../src/utils/api-helper';

// Mock fetch globally
const mockFetch = vi.fn();
global.fetch = mockFetch as any;

describe('callApi', () => {
  beforeEach(() => {
    vi.clearAllMocks();
    vi.useFakeTimers();
  });

  afterEach(() => {
    vi.restoreAllMocks();
    vi.useRealTimers();
  });

  describe('기본 GET 요청', () => {
    it('should perform GET request with default options', async () => {
      const mockData = { status: 'ok', message: 'success' };
      mockFetch.mockResolvedValueOnce({
        ok: true,
        status: 200,
        json: async () => mockData,
      });

      const promise = callApi('https://api.example.com/health');

      // 재시도 타이머 진행
      await vi.runAllTimersAsync();
      const result = await promise;

      expect(result).toEqual(mockData);
      expect(mockFetch).toHaveBeenCalledWith(
        'https://api.example.com/health',
        expect.objectContaining({
          method: 'GET',
          headers: expect.objectContaining({
            'Accept': 'application/json',
            'Content-Type': 'application/json',
          }),
        })
      );
    });

    it('should parse JSON response correctly', async () => {
      const mockData = {
        id: 123,
        name: 'Test User',
        email: 'test@example.com',
      };
      mockFetch.mockResolvedValueOnce({
        ok: true,
        status: 200,
        json: async () => mockData,
      });

      const promise = callApi<typeof mockData>('https://api.example.com/user/123');
      await vi.runAllTimersAsync();
      const result = await promise;

      expect(result).toEqual(mockData);
      expect(result.id).toBe(123);
      expect(result.name).toBe('Test User');
    });
  });

  describe('POST 요청', () => {
    it('should serialize body to JSON', async () => {
      const mockResponse = { success: true };
      mockFetch.mockResolvedValueOnce({
        ok: true,
        status: 201,
        json: async () => mockResponse,
      });

      const requestBody = { name: 'New Item', value: 42 };
      const promise = callApi('https://api.example.com/items', {
        method: 'POST',
        body: requestBody,
      });

      await vi.runAllTimersAsync();
      await promise;

      expect(mockFetch).toHaveBeenCalledWith(
        'https://api.example.com/items',
        expect.objectContaining({
          method: 'POST',
          body: JSON.stringify(requestBody),
        })
      );
    });

    it('should set Content-Type header for POST', async () => {
      mockFetch.mockResolvedValueOnce({
        ok: true,
        status: 200,
        json: async () => ({}),
      });

      const promise = callApi('https://api.example.com/data', {
        method: 'POST',
        body: { test: 'data' },
      });

      await vi.runAllTimersAsync();
      await promise;

      expect(mockFetch).toHaveBeenCalledWith(
        expect.any(String),
        expect.objectContaining({
          headers: expect.objectContaining({
            'Content-Type': 'application/json',
          }),
        })
      );
    });
  });

  describe('HTTP 에러 처리', () => {
    it('should throw error on 4xx client error', async () => {
      mockFetch.mockResolvedValue({
        ok: false,
        status: 404,
        statusText: 'Not Found',
        json: async () => ({ error: 'Resource not found' }),
      });

      const promise = callApi('https://api.example.com/missing', {
        retries: 0, // 재시도 없음
      });
      const expectPromise = expect(promise).rejects.toThrow();
      await vi.runAllTimersAsync();
      await expectPromise;
    });

    it('should throw error on 5xx server error', async () => {
      mockFetch.mockResolvedValue({
        ok: false,
        status: 500,
        statusText: 'Internal Server Error',
        json: async () => ({ error: 'Server crashed' }),
      });

      const promise = callApi('https://api.example.com/error', {
        retries: 0,
      });
      const expectPromise = expect(promise).rejects.toThrow();
      await vi.runAllTimersAsync();
      await expectPromise;
    });

    it('should include status code in error message', async () => {
      mockFetch.mockResolvedValue({
        ok: false,
        status: 403,
        statusText: 'Forbidden',
        json: async () => ({}),
      });

      const promise = callApi('https://api.example.com/forbidden', {
        retries: 0,
      });
      const expectPromise = expect(promise).rejects.toThrow(/403/);
      await vi.runAllTimersAsync();
      await expectPromise;
    });
  });

  describe('Zod 스키마 검증', () => {
    const UserSchema = z.object({
      id: z.number(),
      name: z.string(),
      email: z.string().email(),
    });

    it('should validate response with Zod schema (valid)', async () => {
      const validData = {
        id: 1,
        name: 'John Doe',
        email: 'john@example.com',
      };
      mockFetch.mockResolvedValueOnce({
        ok: true,
        status: 200,
        json: async () => validData,
      });

      const promise = callApi('https://api.example.com/user', {
        schema: UserSchema,
      });

      await vi.runAllTimersAsync();
      const result = await promise;

      expect(result).toEqual(validData);
      expect(UserSchema.safeParse(result).success).toBe(true);
    });

    it('should throw error on invalid schema (missing field)', async () => {
      const invalidData = {
        id: 1,
        name: 'John Doe',
        // email 누락
      };
      mockFetch.mockResolvedValueOnce({
        ok: true,
        status: 200,
        json: async () => invalidData,
      });

      const promise = callApi('https://api.example.com/user', {
        schema: UserSchema,
        retries: 0,
      });
      const expectPromise = expect(promise).rejects.toThrow();
      await vi.runAllTimersAsync();
      await expectPromise;
    });

    it('should throw error on invalid schema (wrong type)', async () => {
      const invalidData = {
        id: '123', // 숫자가 아닌 문자열
        name: 'John Doe',
        email: 'john@example.com',
      };
      mockFetch.mockResolvedValueOnce({
        ok: true,
        status: 200,
        json: async () => invalidData,
      });

      const promise = callApi('https://api.example.com/user', {
        schema: UserSchema,
        retries: 0,
      });
      const expectPromise = expect(promise).rejects.toThrow();
      await vi.runAllTimersAsync();
      await expectPromise;
    });

    it('should throw error on invalid email format', async () => {
      const invalidData = {
        id: 1,
        name: 'John Doe',
        email: 'invalid-email', // 잘못된 이메일 형식
      };
      mockFetch.mockResolvedValueOnce({
        ok: true,
        status: 200,
        json: async () => invalidData,
      });

      const promise = callApi('https://api.example.com/user', {
        schema: UserSchema,
        retries: 0,
      });
      const expectPromise = expect(promise).rejects.toThrow();
      await vi.runAllTimersAsync();
      await expectPromise;
    });
  });

  describe('타임아웃', () => {
    it('should abort request after timeout (default 30s)', async () => {
      mockFetch.mockImplementation(async (_url, options) => {
        // 타임아웃 이후까지 대기
        await new Promise(resolve => setTimeout(resolve, 35000));

        if (options?.signal?.aborted) {
          throw new DOMException('The operation was aborted', 'AbortError');
        }
        return {
          ok: true,
          status: 200,
          json: async () => ({}),
        };
      });

      const promise = callApi('https://api.example.com/slow', {
        retries: 0,
      });

      // 타임아웃 전에는 에러 없음
      await vi.advanceTimersByTimeAsync(29000);

      // 타임아웃 발생
      await vi.advanceTimersByTimeAsync(2000);
      const expectPromise = expect(promise).rejects.toThrow();
      await vi.runAllTimersAsync();
      await expectPromise;
    });

    it('should use custom timeout value', async () => {
      mockFetch.mockImplementation(async (_url, options) => {
        await new Promise(resolve => setTimeout(resolve, 6000));

        if (options?.signal?.aborted) {
          throw new DOMException('The operation was aborted', 'AbortError');
        }
        return {
          ok: true,
          status: 200,
          json: async () => ({}),
        };
      });

      const promise = callApi('https://api.example.com/slow', {
        timeout: 5000, // 5초 타임아웃
        retries: 0,
      });

      // 타임아웃 전
      await vi.advanceTimersByTimeAsync(4000);

      // 타임아웃 발생
      await vi.advanceTimersByTimeAsync(2000);
      const expectPromise = expect(promise).rejects.toThrow();
      await vi.runAllTimersAsync();
      await expectPromise;
    });

    it('should complete before timeout', async () => {
      const mockData = { status: 'ok' };
      mockFetch.mockImplementation(async () => {
        // 2초만 걸림
        await new Promise(resolve => setTimeout(resolve, 2000));
        return {
          ok: true,
          status: 200,
          json: async () => mockData,
        };
      });

      const promise = callApi('https://api.example.com/fast', {
        timeout: 5000,
      });

      await vi.advanceTimersByTimeAsync(2500);
      await vi.runAllTimersAsync();
      const result = await promise;

      expect(result).toEqual(mockData);
    });
  });

  describe('재시도 로직', () => {
    it('should retry on failure (default 3 times)', async () => {
      let attempts = 0;
      mockFetch.mockImplementation(async () => {
        attempts++;
        if (attempts < 3) {
          return {
            ok: false,
            status: 503,
            statusText: 'Service Unavailable',
            json: async () => ({}),
          };
        }
        return {
          ok: true,
          status: 200,
          json: async () => ({ success: true }),
        };
      });

      const promise = callApi('https://api.example.com/unstable');
      await vi.runAllTimersAsync();
      const result = await promise;

      expect(result).toEqual({ success: true });
      expect(attempts).toBe(3);
    });

    it('should use custom retry count', async () => {
      let attempts = 0;
      mockFetch.mockImplementation(async () => {
        attempts++;
        if (attempts < 5) {
          return {
            ok: false,
            status: 503,
            statusText: 'Service Unavailable',
            json: async () => ({}),
          };
        }
        return {
          ok: true,
          status: 200,
          json: async () => ({ success: true }),
        };
      });

      const promise = callApi('https://api.example.com/very-unstable', {
        retries: 5,
      });
      await vi.runAllTimersAsync();
      const result = await promise;

      expect(result).toEqual({ success: true });
      expect(attempts).toBe(5);
    });

    it('should throw after exhausting retries', async () => {
      mockFetch.mockResolvedValue({
        ok: false,
        status: 500,
        statusText: 'Internal Server Error',
        json: async () => ({}),
      });

      const promise = callApi('https://api.example.com/always-fails', {
        retries: 2,
      });
      const expectPromise = expect(promise).rejects.toThrow();
      await vi.runAllTimersAsync();
      await expectPromise;
      expect(mockFetch).toHaveBeenCalledTimes(3); // 초기 + 2회 재시도
    });

    it('should not retry on 4xx errors (client errors)', async () => {
      mockFetch.mockResolvedValue({
        ok: false,
        status: 404,
        statusText: 'Not Found',
        json: async () => ({}),
      });

      const promise = callApi('https://api.example.com/missing', {
        retries: 3,
      });
      const expectPromise = expect(promise).rejects.toThrow();
      await vi.runAllTimersAsync();
      await expectPromise;
      // 재시도 로직은 4xx 에러를 재시도하지 않음 (retryWithBackoff 구현에 따라 다름)
    });
  });

  describe('커스텀 헤더', () => {
    it('should merge custom headers with defaults', async () => {
      mockFetch.mockResolvedValueOnce({
        ok: true,
        status: 200,
        json: async () => ({}),
      });

      const promise = callApi('https://api.example.com/auth', {
        headers: {
          'Authorization': 'Bearer token123',
          'X-Custom-Header': 'value',
        },
      });

      await vi.runAllTimersAsync();
      await promise;

      expect(mockFetch).toHaveBeenCalledWith(
        expect.any(String),
        expect.objectContaining({
          headers: expect.objectContaining({
            'Accept': 'application/json',
            'Content-Type': 'application/json',
            'Authorization': 'Bearer token123',
            'X-Custom-Header': 'value',
          }),
        })
      );
    });

    it('should override default headers with custom ones', async () => {
      mockFetch.mockResolvedValueOnce({
        ok: true,
        status: 200,
        json: async () => ({}),
      });

      const promise = callApi('https://api.example.com/custom', {
        headers: {
          'Content-Type': 'application/xml', // Override
        },
      });

      await vi.runAllTimersAsync();
      await promise;

      expect(mockFetch).toHaveBeenCalledWith(
        expect.any(String),
        expect.objectContaining({
          headers: expect.objectContaining({
            'Content-Type': 'application/xml',
          }),
        })
      );
    });
  });

  describe('HTTP 메서드', () => {
    it('should support PUT method', async () => {
      mockFetch.mockResolvedValueOnce({
        ok: true,
        status: 200,
        json: async () => ({ updated: true }),
      });

      const promise = callApi('https://api.example.com/item/123', {
        method: 'PUT',
        body: { name: 'Updated' },
      });

      await vi.runAllTimersAsync();
      await promise;

      expect(mockFetch).toHaveBeenCalledWith(
        expect.any(String),
        expect.objectContaining({
          method: 'PUT',
        })
      );
    });

    it('should support DELETE method', async () => {
      mockFetch.mockResolvedValueOnce({
        ok: true,
        status: 204,
        json: async () => ({}),
      });

      const promise = callApi('https://api.example.com/item/123', {
        method: 'DELETE',
      });

      await vi.runAllTimersAsync();
      await promise;

      expect(mockFetch).toHaveBeenCalledWith(
        expect.any(String),
        expect.objectContaining({
          method: 'DELETE',
        })
      );
    });
  });

  describe('Edge Cases', () => {
    it('should handle empty response body', async () => {
      mockFetch.mockResolvedValueOnce({
        ok: true,
        status: 204,
        json: async () => null,
      });

      const promise = callApi('https://api.example.com/no-content');
      await vi.runAllTimersAsync();
      const result = await promise;

      expect(result).toBeNull();
    });

    it('should handle array response', async () => {
      const mockArray = [
        { id: 1, name: 'Item 1' },
        { id: 2, name: 'Item 2' },
      ];
      mockFetch.mockResolvedValueOnce({
        ok: true,
        status: 200,
        json: async () => mockArray,
      });

      const promise = callApi('https://api.example.com/items');
      await vi.runAllTimersAsync();
      const result = await promise;

      expect(result).toEqual(mockArray);
      expect(Array.isArray(result)).toBe(true);
    });

    it('should handle nested objects', async () => {
      const mockData = {
        user: {
          profile: {
            name: 'Test',
            settings: {
              theme: 'dark',
            },
          },
        },
      };
      mockFetch.mockResolvedValueOnce({
        ok: true,
        status: 200,
        json: async () => mockData,
      });

      const promise = callApi('https://api.example.com/user/profile');
      await vi.runAllTimersAsync();
      const result = await promise;

      expect(result).toEqual(mockData);
      expect(result.user.profile.settings.theme).toBe('dark');
    });
  });
});