/**
 * Cliente API para comunicación con el backend
 */

const API_BASE_URL = process.env.NEXT_PUBLIC_API_URL || 'http://localhost:3001/api';

interface ApiResponse<T = unknown> {
  data?: T;
  error?: string;
  message?: string;
  status: number;
}

interface RequestOptions extends Omit<RequestInit, 'body'> {
  body?: unknown;
  params?: Record<string, string | number | boolean | undefined>;
}

class ApiError extends Error {
  status: number;
  data?: unknown;

  constructor(message: string, status: number, data?: unknown) {
    super(message);
    this.name = 'ApiError';
    this.status = status;
    this.data = data;
  }
}

/**
 * Obtiene el token de autenticación del storage
 */
function getAuthToken(): string | null {
  if (typeof window === 'undefined') return null;

  try {
    const stored = localStorage.getItem('horux-auth-storage');
    if (stored) {
      const parsed = JSON.parse(stored);
      return parsed?.state?.token || null;
    }
  } catch {
    return null;
  }
  return null;
}

/**
 * Construye la URL con query params
 */
function buildUrl(endpoint: string, params?: Record<string, string | number | boolean | undefined>): string {
  const url = new URL(endpoint.startsWith('http') ? endpoint : `${API_BASE_URL}${endpoint}`);

  if (params) {
    Object.entries(params).forEach(([key, value]) => {
      if (value !== undefined && value !== null) {
        url.searchParams.append(key, String(value));
      }
    });
  }

  return url.toString();
}

/**
 * Cliente fetch base con manejo de errores y auth
 */
async function fetchApi<T>(endpoint: string, options: RequestOptions = {}): Promise<ApiResponse<T>> {
  const { body, params, headers: customHeaders, ...restOptions } = options;

  const token = getAuthToken();

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

  if (token) {
    (headers as Record<string, string>)['Authorization'] = `Bearer ${token}`;
  }

  const config: RequestInit = {
    ...restOptions,
    headers,
  };

  if (body) {
    config.body = JSON.stringify(body);
  }

  try {
    const url = buildUrl(endpoint, params);
    const response = await fetch(url, config);

    let data: T | undefined;
    const contentType = response.headers.get('content-type');

    if (contentType?.includes('application/json')) {
      data = await response.json();
    }

    if (!response.ok) {
      const errorMessage = (data as { message?: string })?.message ||
                          (data as { error?: string })?.error ||
                          `Error ${response.status}`;
      throw new ApiError(errorMessage, response.status, data);
    }

    return {
      data,
      status: response.status,
    };
  } catch (error) {
    if (error instanceof ApiError) {
      throw error;
    }

    throw new ApiError(
      error instanceof Error ? error.message : 'Error de conexión',
      0
    );
  }
}

/**
 * API Client con métodos HTTP
 */
export const api = {
  get<T>(endpoint: string, options?: RequestOptions): Promise<ApiResponse<T>> {
    return fetchApi<T>(endpoint, { ...options, method: 'GET' });
  },

  post<T>(endpoint: string, body?: unknown, options?: RequestOptions): Promise<ApiResponse<T>> {
    return fetchApi<T>(endpoint, { ...options, method: 'POST', body });
  },

  put<T>(endpoint: string, body?: unknown, options?: RequestOptions): Promise<ApiResponse<T>> {
    return fetchApi<T>(endpoint, { ...options, method: 'PUT', body });
  },

  patch<T>(endpoint: string, body?: unknown, options?: RequestOptions): Promise<ApiResponse<T>> {
    return fetchApi<T>(endpoint, { ...options, method: 'PATCH', body });
  },

  delete<T>(endpoint: string, options?: RequestOptions): Promise<ApiResponse<T>> {
    return fetchApi<T>(endpoint, { ...options, method: 'DELETE' });
  },
};

/**
 * Endpoints tipados para la API
 */
export const endpoints = {
  // Auth
  auth: {
    login: '/auth/login',
    register: '/auth/register',
    logout: '/auth/logout',
    me: '/auth/me',
    refresh: '/auth/refresh',
  },

  // Users
  users: {
    base: '/users',
    byId: (id: string) => `/users/${id}`,
    profile: '/users/profile',
  },

  // Strategies
  strategies: {
    base: '/strategies',
    byId: (id: string) => `/strategies/${id}`,
    activate: (id: string) => `/strategies/${id}/activate`,
    deactivate: (id: string) => `/strategies/${id}/deactivate`,
    backtest: (id: string) => `/strategies/${id}/backtest`,
  },

  // Trades
  trades: {
    base: '/trades',
    byId: (id: string) => `/trades/${id}`,
    active: '/trades/active',
    history: '/trades/history',
  },

  // Portfolio
  portfolio: {
    base: '/portfolio',
    balance: '/portfolio/balance',
    positions: '/portfolio/positions',
    performance: '/portfolio/performance',
  },

  // Market Data
  market: {
    prices: '/market/prices',
    ticker: (symbol: string) => `/market/ticker/${symbol}`,
    candles: (symbol: string) => `/market/candles/${symbol}`,
  },

  // Analytics
  analytics: {
    dashboard: '/analytics/dashboard',
    performance: '/analytics/performance',
    risk: '/analytics/risk',
  },
} as const;

export { ApiError };
export type { ApiResponse, RequestOptions };