/**
 * Base API client for backend communication
 * Handles authentication, error handling, and request/response transformation
 */

import { z } from 'zod';

// @ts-expect-error - Dynamic import for environment-specific config - Vite env types
const isProduction = import.meta.env.PROD;
const API_BASE_URL =
  import.meta.env.VITE_API_BASE_URL || (isProduction ? 'https://api.bugulma.city' : '');

// Security: Ensure HTTPS in production
const isSecureUrl =
  API_BASE_URL.startsWith('https://') ||
  API_BASE_URL.startsWith('localhost') ||
  API_BASE_URL.startsWith('/') ||
  API_BASE_URL === '/api';

// Type for API error responses (derived from Zod schema)
export type ApiErrorResponse = z.infer<typeof ApiErrorResponseSchema>;

if (isProduction && !isSecureUrl) {
  console.error('🚨 SECURITY WARNING: API_BASE_URL must use HTTPS in production!');
  // In production, throw error to prevent insecure connections
  if (typeof window === 'undefined') {
    throw new Error('API_BASE_URL must use HTTPS in production environment');
  }
}

// API Error Response Schema
export const ApiErrorResponseSchema = z
  .object({
    error: z.string(),
    message: z.string().optional(),
    details: z.record(z.unknown()).optional(),
  })
  .partial();

// API Success Response Schemas
export const UserSchema = z.object({
  id: z.string(),
  email: z.string(),
  name: z.string(),
  role: z.string(),
});

export const AuthResponseSchema = z.object({
  token: z.string(),
  user: UserSchema,
});

// Helper function for safe error response parsing
function parseApiError(response: Response): Promise<ApiErrorResponse> {
  return response
    .json()
    .then((data) => {
      // Try to validate with Zod schema
      const result = ApiErrorResponseSchema.safeParse(data);
      if (result.success) {
        return result.data;
      }
      // If validation fails, create a fallback error with the raw data
      return {
        error: typeof data?.error === 'string' ? data.error : 'Request failed',
        message: typeof data?.message === 'string' ? data.message : undefined,
        details: data,
      };
    })
    .catch(() => {
      // If JSON parsing fails, create a generic error
      return {
        error: `HTTP ${response.status}: ${response.statusText}`,
      };
    });
}

// Helper function for safe success response parsing
function parseApiResponse<T>(response: Response, schema: z.ZodSchema<T>): Promise<T> {
  return response.json().then((data) => {
    const result = schema.safeParse(data);
    if (result.success) {
      return result.data;
    }
    throw new Error(`Invalid API response format: ${result.error.message}`);
  });
}

/**
 * Schema-validated API GET request
 */
export async function apiGetValidated<T>(endpoint: string, schema: z.ZodSchema<T>): Promise<T> {
  const data = await apiGet<unknown>(endpoint);
  const result = schema.safeParse(data);
  if (result.success) {
    return result.data;
  }
  throw new ApiError(`Invalid API response format: ${result.error.message}`, 0);
}

/**
 * Schema-validated API POST request
 */
export async function apiPostValidated<T>(
  endpoint: string,
  data?: z.infer<typeof RequestDataSchema>,
  responseSchema?: z.ZodSchema<T>
): Promise<T> {
  const responseData = await apiPost<unknown>(endpoint, data);
  if (responseSchema) {
    const result = responseSchema.safeParse(responseData);
    if (result.success) {
      return result.data;
    }
    throw new ApiError(`Invalid API response format: ${result.error.message}`, 0);
  }
  return responseData as T;
}

// API Error class with proper typing
export class ApiError extends Error {
  constructor(
    message: string,
    public status: number,
    public data?: z.infer<typeof ApiErrorResponseSchema>
  ) {
    super(message);
    this.name = 'ApiError';
  }
}

// Request data validation schema
export const RequestDataSchema = z.union([
  z.record(z.unknown()),
  z.instanceof(FormData),
  z.undefined(),
]);

// Generic API response wrapper
export const ApiResponseSchema = <T extends z.ZodTypeAny>(dataSchema: T) =>
  z.object({
    data: dataSchema,
    success: z.boolean().default(true),
    message: z.string().optional(),
    timestamp: z.string().datetime().optional(),
  });

/**
 * Get the authentication token from localStorage
 */
function getAuthToken(): string | null {
  return localStorage.getItem('auth_token');
}

/**
 * Make an authenticated API request
 */
async function apiRequest<T>(endpoint: string, options: RequestInit = {}): Promise<T> {
  const token = getAuthToken();
  // Automatically add API version prefix to all endpoints
  const apiEndpoint = endpoint.startsWith('/api/v1/')
    ? endpoint
    : `/api/v1${endpoint.startsWith('/') ? endpoint : `/${endpoint}`}`;
  const url = `${API_BASE_URL}${apiEndpoint}`;

  const headers: HeadersInit = {
    'Content-Type': 'application/json',
    ...options.headers,
  };

  if (token) {
    headers['Authorization'] = `Bearer ${token}`;
  }

  const response = await fetch(url, {
    ...options,
    headers,
  });

  if (!response.ok) {
    let errorData: z.infer<typeof ApiErrorResponseSchema> | string;
    try {
      // Read response as text first to avoid consuming the stream
      const responseText = await response.text();
      // Try to parse as JSON
      const jsonData = JSON.parse(responseText);
      errorData = ApiErrorResponseSchema.parse(jsonData);
    } catch {
      // If JSON parsing fails, use the raw text
      try {
        errorData = await response.text();
      } catch {
        errorData = `HTTP ${response.status}: ${response.statusText}`;
      }
    }

    // SECURITY: Prevent information disclosure in production
    const isDev = import.meta.env.DEV;
    let errorMessage: string;

    if (response.status === 401) {
      errorMessage = 'Authentication failed. Please log in again.';
    } else if (response.status === 403) {
      errorMessage = 'You do not have permission to perform this action.';
    } else if (response.status === 404) {
      errorMessage = 'The requested resource was not found.';
    } else if (response.status >= 500) {
      errorMessage = 'A server error occurred. Please try again later.';
    } else if (typeof errorData === 'string') {
      errorMessage = isDev ? errorData : 'An error occurred. Please try again.';
    } else {
      errorMessage = isDev
        ? errorData.error || `HTTP ${response.status}: ${response.statusText}`
        : 'An error occurred. Please try again.';
    }

    throw new ApiError(
      errorMessage,
      response.status,
      isDev ? (typeof errorData === 'object' ? errorData : undefined) : undefined
    );
  }

  // Handle 204 No Content
  if (response.status === 204) {
    return undefined as T;
  }

  return response.json();
}

/**
 * GET request
 */
export async function apiGet<T>(endpoint: string): Promise<T> {
  return apiRequest<T>(endpoint, { method: 'GET' });
}

/**
 * POST request
 */
export async function apiPost<T>(
  endpoint: string,
  data?: z.infer<typeof RequestDataSchema>
): Promise<T> {
  // Handle FormData (for file uploads)
  if (data instanceof FormData) {
    const token = getAuthToken();
    const url = `${API_BASE_URL}${endpoint}`;
    const headers: HeadersInit = {};

    if (token) {
      headers['Authorization'] = `Bearer ${token}`;
    }
    // Don't set Content-Type for FormData - browser will set it with boundary

    const response = await fetch(url, {
      method: 'POST',
      headers,
      body: data,
    });

    if (!response.ok) {
      let errorData: unknown;
      try {
        errorData = await response.json();
      } catch {
        errorData = await response.text();
      }
      throw new ApiError(
        (errorData as { error?: string })?.error ||
          `HTTP ${response.status}: ${response.statusText}`,
        response.status,
        errorData
      );
    }

    if (response.status === 204) {
      return undefined as T;
    }

    return response.json();
  }

  // Regular JSON request
  return apiRequest<T>(endpoint, {
    method: 'POST',
    body: data ? JSON.stringify(data) : undefined,
  });
}

/**
 * DELETE request
 */
export async function apiDelete<T>(endpoint: string): Promise<T> {
  return apiRequest<T>(endpoint, { method: 'DELETE' });
}

/**
 * Login request (no auth token required)
 */
export async function login(
  email: string,
  password: string
): Promise<z.infer<typeof AuthResponseSchema>> {
  // Use apiRequest for consistent API versioning, but without auth token
  const url = `${API_BASE_URL}/api/v1/auth/login`;
  const response = await fetch(url, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
    },
    body: JSON.stringify({ email, password }),
  });

  if (!response.ok) {
    const errorData = await parseApiError(response);
    throw new ApiError(errorData.error || 'Login failed', response.status, errorData);
  }

  return parseApiResponse(response, AuthResponseSchema);
}

/**
 * Signup request (no auth token required)
 */
export async function signup(
  email: string,
  password: string,
  name: string,
  role: 'user' | 'admin' | 'content_manager' | 'viewer'
): Promise<z.infer<typeof AuthResponseSchema>> {
  const url = `${API_BASE_URL}/api/v1/auth/register`;
  const response = await fetch(url, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
    },
    body: JSON.stringify({ email, password, name, role }),
  });

  if (!response.ok) {
    const errorData = await parseApiError(response);
    throw new ApiError(errorData.error || 'Signup failed', response.status, errorData);
  }

  return parseApiResponse(response, AuthResponseSchema);
}

/**
 * Sanitize input to prevent XSS attacks
 */
export function sanitizeInput(input: string): string {
  return input
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;')
    .replace(/'/g, '&#x27;')
    .replace(/\//g, '&#x2F;');
}

/**
 * Validate email format
 */
export function isValidEmail(email: string): boolean {
  const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
  return emailRegex.test(email) && email.length <= 254;
}

/**
 * Validate input length and content
 */
export function validateInput(
  input: string,
  options: {
    minLength?: number;
    maxLength?: number;
    allowSpecialChars?: boolean;
    allowNumbers?: boolean;
  } = {}
): { isValid: boolean; error?: string } {
  const {
    minLength = 1,
    maxLength = 1000,
    allowSpecialChars = true,
    allowNumbers = true,
  } = options;

  if (!input || typeof input !== 'string') {
    return { isValid: false, error: 'Input must be a non-empty string' };
  }

  if (input.length < minLength) {
    return { isValid: false, error: `Input must be at least ${minLength} characters` };
  }

  if (input.length > maxLength) {
    return { isValid: false, error: `Input must be no more than ${maxLength} characters` };
  }

  if (!allowSpecialChars && /[^a-zA-Z\s]/.test(input)) {
    return { isValid: false, error: 'Special characters are not allowed' };
  }

  if (!allowNumbers && /\d/.test(input)) {
    return { isValid: false, error: 'Numbers are not allowed' };
  }

  return { isValid: true };
}

/**
 * Rate limiting for API calls to prevent abuse
 */
class RateLimiter {
  private calls = new Map<string, number[]>();

  isAllowed(key: string, maxCalls: number, windowMs: number): boolean {
    const now = Date.now();
    const calls = this.calls.get(key) || [];

    // Remove old calls outside the window
    const validCalls = calls.filter((call) => now - call < windowMs);
    this.calls.set(key, validCalls);

    if (validCalls.length >= maxCalls) {
      return false;
    }

    validCalls.push(now);
    return true;
  }

  reset(key: string): void {
    this.calls.delete(key);
  }
}

const rateLimiter = new RateLimiter();

/**
 * Rate-limited API request wrapper
 */
async function rateLimitedRequest<T>(
  endpoint: string,
  options: RequestInit = {},
  maxCalls = 10,
  windowMs = 60000 // 1 minute
): Promise<T> {
  const rateLimitKey = `${options.method || 'GET'}:${endpoint}`;

  if (!rateLimiter.isAllowed(rateLimitKey, maxCalls, windowMs)) {
    throw new ApiError('Too many requests. Please wait before trying again.', 429);
  }

  return apiRequest<T>(endpoint, options);
}

/**
 * API client object with convenience methods
 */
export const apiClient = {
  get: (endpoint: string) => rateLimitedRequest(endpoint, { method: 'GET' }),
  post: apiPost,
  delete: apiDelete,
  login,
  signup,
  sanitizeInput,
  isValidEmail,
  validateInput,
};