// Use relative URL - works for both dev (localhost:8080) and prod (localhost)
// Nginx proxies /api to backend
const API_URL = '/api';

class ApiError extends Error {
  constructor(message, status, data) {
    super(message);
    this.name = 'ApiError';
    this.status = status;
    this.data = data;
  }
}

// CSRF Token Management (Phase 3 - Security Hardening)
let csrfToken = null;

async function getCsrfToken() {
  if (csrfToken) return csrfToken;

  try {
    const response = await fetch(`${API_URL}/csrf-token`, {
      credentials: 'include', // Important for cookies
    });
    const data = await response.json();
    csrfToken = data.csrfToken;
    return csrfToken;
  } catch (error) {
    console.warn('Failed to fetch CSRF token:', error);
    return null;
  }
}

// Reset CSRF token (call this on 403 CSRF errors)
function resetCsrfToken() {
  csrfToken = null;
}

async function fetchAPI(endpoint, options = {}) {
  const url = `${API_URL}${endpoint}`;

  const config = {
    ...options,
    credentials: 'include', // Include cookies for CSRF
    headers: {
      'Content-Type': 'application/json',
      ...options.headers,
    },
  };

  // Add auth token if available
  const token = localStorage.getItem('token');
  if (token) {
    config.headers['Authorization'] = `Bearer ${token}`;
  }

  // Add CSRF token for state-changing requests (Phase 3)
  if (['POST', 'PUT', 'DELETE', 'PATCH'].includes(options.method?.toUpperCase())) {
    const csrf = await getCsrfToken();
    if (csrf) {
      config.headers['X-CSRF-Token'] = csrf;
    }
  }

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

    // Check if response is JSON before parsing
    const contentType = response.headers.get('content-type');
    if (!contentType || !contentType.includes('application/json')) {
      throw new ApiError(
        'Server returned non-JSON response',
        response.status,
        { message: 'The server is not responding correctly. Please try again later.' }
      );
    }

    const data = await response.json();

    if (!response.ok) {
      // Handle CSRF token errors (Phase 3)
      if (response.status === 403 && data.error === 'Invalid CSRF token') {
        resetCsrfToken();
        // Retry the request once with a fresh CSRF token
        if (!options._csrfRetry) {
          return fetchAPI(endpoint, { ...options, _csrfRetry: true });
        }
      }

      throw new ApiError(
        data.error || 'API request failed',
        response.status,
        data
      );
    }

    return data;
  } catch (error) {
    if (error instanceof ApiError) {
      throw error;
    }
    // Handle JSON parsing errors
    if (error instanceof SyntaxError) {
      throw new ApiError(
        'Invalid server response',
        0,
        { message: 'The server returned an invalid response. Please check if the server is running.' }
      );
    }
    throw new ApiError('Network error', 0, { message: error.message });
  }
}

// Auth API
export const authAPI = {
  async register(username, email, password, firstName = null, lastName = null, wsdcId = null) {
    const data = await fetchAPI('/auth/register', {
      method: 'POST',
      body: JSON.stringify({ username, email, password, firstName, lastName, wsdcId }),
    });

    // Save token
    if (data.data.token) {
      localStorage.setItem('token', data.data.token);
    }

    return data.data;
  },

  async login(email, password) {
    const data = await fetchAPI('/auth/login', {
      method: 'POST',
      body: JSON.stringify({ email, password }),
    });

    // Save token
    if (data.data.token) {
      localStorage.setItem('token', data.data.token);
    }

    return data.data;
  },

  async getCurrentUser() {
    const data = await fetchAPI('/users/me');
    return data.data;
  },

  async verifyEmailByToken(token) {
    const data = await fetchAPI(`/auth/verify-email?token=${token}`);
    return data;
  },

  async verifyEmailByCode(email, code) {
    const data = await fetchAPI('/auth/verify-code', {
      method: 'POST',
      body: JSON.stringify({ email, code }),
    });
    return data;
  },

  async resendVerification(email) {
    const data = await fetchAPI('/auth/resend-verification', {
      method: 'POST',
      body: JSON.stringify({ email }),
    });
    return data;
  },

  async requestPasswordReset(email) {
    const data = await fetchAPI('/auth/request-password-reset', {
      method: 'POST',
      body: JSON.stringify({ email }),
    });
    return data;
  },

  async resetPassword(token, newPassword) {
    const data = await fetchAPI('/auth/reset-password', {
      method: 'POST',
      body: JSON.stringify({ token, newPassword }),
    });
    return data;
  },

  async updateProfile(profileData) {
    const data = await fetchAPI('/users/me', {
      method: 'PATCH',
      body: JSON.stringify(profileData),
    });

    // Update token if it was returned (email changed)
    if (data.data?.token) {
      localStorage.setItem('token', data.data.token);
    }

    return data;
  },

  async changePassword(currentPassword, newPassword) {
    const data = await fetchAPI('/users/me/password', {
      method: 'PATCH',
      body: JSON.stringify({ currentPassword, newPassword }),
    });
    return data;
  },

  async getUserByUsername(username) {
    const data = await fetchAPI(`/users/${username}`);
    return data.data;
  },

  logout() {
    localStorage.removeItem('token');
    localStorage.removeItem('user');
  },
};

// WSDC API (Phase 1.5)
export const wsdcAPI = {
  async lookupDancer(wsdcId) {
    const data = await fetchAPI(`/wsdc/lookup?id=${wsdcId}`);
    return data;
  },
};

// Events API
export const eventsAPI = {
  async getAll() {
    const data = await fetchAPI('/events');
    return data.data;
  },

  async getBySlug(slug) {
    const data = await fetchAPI(`/events/${slug}`);
    return data.data;
  },

  async getMessages(slug, before = null, limit = 20) {
    const params = new URLSearchParams({ limit: limit.toString() });
    if (before) {
      params.append('before', before.toString());
    }
    const data = await fetchAPI(`/events/${slug}/messages?${params}`);
    return data;
  },

  async getDetails(slug) {
    const data = await fetchAPI(`/events/${slug}/details`);
    return data;
  },

  async checkin(token) {
    const data = await fetchAPI(`/events/checkin/${token}`, {
      method: 'POST',
    });
    return data;
  },

  async leave(slug) {
    const data = await fetchAPI(`/events/${slug}/leave`, {
      method: 'DELETE',
    });
    return data;
  },
};

// Divisions API (Phase 1.6)
export const divisionsAPI = {
  async getAll() {
    const data = await fetchAPI('/divisions');
    return data.data;
  },
};

// Competition Types API (Phase 1.6)
export const competitionTypesAPI = {
  async getAll() {
    const data = await fetchAPI('/competition-types');
    return data.data;
  },
};

// Heats API (Phase 1.6)
export const heatsAPI = {
  async saveHeats(slug, heats) {
    const data = await fetchAPI(`/events/${slug}/heats`, {
      method: 'POST',
      body: JSON.stringify({ heats }),
    });
    return data;
  },

  async getMyHeats(slug) {
    const data = await fetchAPI(`/events/${slug}/heats/me`);
    return data.data;
  },

  async getAllHeats(slug) {
    const data = await fetchAPI(`/events/${slug}/heats/all`);
    return data.data;
  },

  async deleteHeat(slug, heatId) {
    const data = await fetchAPI(`/events/${slug}/heats/${heatId}`, {
      method: 'DELETE',
    });
    return data;
  },
};

// Matches API (Phase 2)
export const matchesAPI = {
  async createMatch(targetUserId, eventSlug) {
    const data = await fetchAPI('/matches', {
      method: 'POST',
      body: JSON.stringify({ targetUserId, eventSlug }),
    });
    return data;
  },

  async getMatches(eventSlug = null, status = null) {
    const params = new URLSearchParams();
    if (eventSlug) params.append('eventSlug', eventSlug);
    if (status) params.append('status', status);

    const queryString = params.toString();
    const endpoint = queryString ? `/matches?${queryString}` : '/matches';

    const data = await fetchAPI(endpoint);
    return data;
  },

  async getMatch(matchSlug) {
    const data = await fetchAPI(`/matches/${matchSlug}`);
    return data;
  },

  async acceptMatch(matchSlug) {
    const data = await fetchAPI(`/matches/${matchSlug}/accept`, {
      method: 'PUT',
    });
    return data;
  },

  async deleteMatch(matchSlug) {
    const data = await fetchAPI(`/matches/${matchSlug}`, {
      method: 'DELETE',
    });
    return data;
  },

  async getMatchMessages(matchSlug) {
    const data = await fetchAPI(`/matches/${matchSlug}/messages`);
    return data;
  },

  async createRating(matchSlug, { score, comment, wouldCollaborateAgain }) {
    const data = await fetchAPI(`/matches/${matchSlug}/ratings`, {
      method: 'POST',
      body: JSON.stringify({ score, comment, wouldCollaborateAgain }),
    });
    return data;
  },
};

// Ratings API
export const ratingsAPI = {
  async getUserRatings(username) {
    const data = await fetchAPI(`/users/${username}/ratings`);
    return data;
  },
};

export { ApiError };