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

async function request(server, path, { method = 'GET', body, token } = {}) {
  try {
    const headers = { 'Content-Type': 'application/json' };
    if (token) {
      headers.Authorization = `Bearer ${token}`;
    }

    const response = await fetch(`${server}${path}`, {
      method,
      headers,
      body: body ? JSON.stringify(body) : undefined
    });

    const data = await response.json().catch(() => ({}));

    if (!response.ok || data.success === false) {
      const message = data.error || data.message || response.statusText;
      throw new ApiError(message, response.status);
    }

    return data;
  } catch (error) {
    if (error instanceof ApiError) {
      throw error;
    }
    throw new ApiError('无法连接到服务器，请确认服务已启动', 0);
  }
}

export async function register(server, username, password) {
  return request(server, '/api/auth/register', {
    method: 'POST',
    body: { username, password }
  });
}

export async function login(server, username, password) {
  return request(server, '/api/auth/login', {
    method: 'POST',
    body: { username, password }
  });
}

export async function fetchCurrentUser(server, token) {
  return request(server, '/api/auth/me', { token });
}

export async function fetchCalendar(server, token, year, month) {
  const params = new URLSearchParams();
  if (year !== undefined && month !== undefined) {
    params.append('year', year);
    params.append('month', month);
  }
  const queryString = params.toString();
  const path = queryString ? `/api/calendar?${queryString}` : '/api/calendar';
  return request(server, path, { token });
}


export async function saveCalendar(server, token, markedDates, deletedDates) {
  return request(server, '/api/calendar', {
    method: 'POST',
    token,
    body: { markedDates, deletedDates }
  });
}