/* =====================================================================
 * 网络层（api.js）
 * 统一调用 /api/* 接口；localStorage 只保存 token 与 username（绝不保存密码）。
 * ===================================================================== */

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

export async function api(path, { method = "GET", body } = {}) {
  const headers = { "Content-Type": "application/json" };
  const token = localStorage.getItem("token");
  if (token) headers["Authorization"] = `Bearer ${token}`;
  let res;
  try {
    res = await fetch(path, { method, headers, body: body === undefined ? undefined : JSON.stringify(body) });
  } catch (err) {
    throw new ApiError("网络请求失败，请稍后再试", 0);
  }
  let json = null;
  try { json = await res.json(); } catch (err) { /* 忽略非 JSON 响应 */ }
  if (!json || typeof json.success === "undefined") {
    throw new ApiError(`服务器响应异常（${res.status}）`, res.status);
  }
  if (!json.success) throw new ApiError(json.message || "请求失败", res.status);
  return json.data;
}

// multipart 表单提交（普通字段 + 单个文件），用于项目管理等
export async function uploadForm(path, fields = {}, file = null, method = "POST") {
  const form = new FormData();
  for (const [key, value] of Object.entries(fields)) {
    if (value !== undefined && value !== null && value !== "") form.append(key, String(value));
  }
  if (file) form.append("file", file);
  const headers = {};
  const token = localStorage.getItem("token");
  if (token) headers["Authorization"] = `Bearer ${token}`;
  const res = await fetch(path, { method, headers, body: form });
  let json = null;
  try { json = await res.json(); } catch (err) { /* 忽略非 JSON 响应 */ }
  if (!json || !json.success) throw new ApiError((json && json.message) || "操作失败", res.status);
  return json.data;
}

// multipart 上传（头像/图片/项目文件），返回 {url, filename, size}
export async function uploadFile(path, file, extra = {}) {
  const form = new FormData();
  form.append("file", file);
  // extra：附加字段（如上传文档时携带文章分区 category，供后端校验）
  for (const [key, value] of Object.entries(extra)) form.append(key, value);
  const headers = {};
  const token = localStorage.getItem("token");
  if (token) headers["Authorization"] = `Bearer ${token}`;
  const res = await fetch(path, { method: "POST", headers, body: form });
  let json = null;
  try { json = await res.json(); } catch (err) { /* 忽略非 JSON 响应 */ }
  if (!json || !json.success) throw new ApiError((json && json.message) || "上传失败", res.status);
  return json.data;
}