// API 基础配置
// 注意：客户端请求使用相对路径 /api/*，走 Next.js rewrite 代理到后端，
// 这样浏览器视为同源，Cookie 自动携带，无需处理 CORS。
// SSR 端（fetchPosts 等公开接口）直接请求后端 API_BASE。
const API_BASE = process.env.NEXT_PUBLIC_API_URL || "http://localhost:3001";

// 类型定义
export interface User {
  id: number;
  username: string;
  nickname: string;
  avatar: string;
  role: string;
}

export interface Board {
  id: number;
  name: string;
  description: string;
  icon: string;
  sort_order: number;
}

export interface PostListItem {
  id: number;
  board_id: number;
  user_id: number;
  title: string;
  tags: string;
  post_type: string;
  pinned: number;
  recommended: boolean;
  like_count: number;
  view_count: number;
  comment_count: number;
  liked: boolean;
  created_at: string;
  board: Board;
  user: User;
}

export interface Post {
  id: number;
  board_id: number;
  user_id: number;
  title: string;
  content: string;
  tags: string;
  post_type: string;
  pinned: number;
  recommended: boolean;
  status: string;
  like_count: number;
  view_count: number;
  comment_count: number;
  liked: boolean;
  created_at: string;
  updated_at: string;
  board: Board;
  user: User;
}

export interface Comment {
  id: number;
  post_id: number;
  user_id: number;
  content: string;
  status: string;
  created_at: string;
  user: User;
}

export interface PostsResponse {
  posts: PostListItem[];
  total: number;
  page: number;
  size: number;
}

export interface UserProfile {
  user: {
    id: number;
    username: string;
    nickname: string;
    avatar: string;
    role: string;
    created_at: string;
  };
  stats: {
    post_count: number;
    comment_count: number;
  };
  posts: PostListItem[];
  posts_total: number;
  page: number;
  size: number;
}

export interface UserCommentItem {
  id: number;
  post_id: number;
  post_title: string;
  content: string;
  created_at: string;
}

export interface UserCommentsResponse {
  comments: UserCommentItem[];
  total: number;
  page: number;
  size: number;
}

export interface NotificationItem {
  id: number;
  user_id: number;
  actor_id: number;
  type: "comment" | "like";
  post_id: number;
  comment_id: number;
  content: string;
  is_read: boolean;
  created_at: string;
  actor: User;
  post: { id: number; title: string };
}

export interface NotificationsResponse {
  notifications: NotificationItem[];
  total: number;
  page: number;
  size: number;
}

// 从 cookie 读取 CSRF token（j13_csrf 为非 HttpOnly，前端可读）
function getCSRFToken(): string {
  if (typeof document === "undefined") return "";
  const match = document.cookie.match(/(?:^|;\s*)j13_csrf=([^;]+)/);
  return match ? decodeURIComponent(match[1]) : "";
}

// 构造客户端 fetch 的通用 headers（含 CSRF token）
function clientHeaders(extra: Record<string, string> = {}): HeadersInit {
  const headers: Record<string, string> = { ...extra };
  const csrf = getCSRFToken();
  if (csrf) headers["X-CSRF-Token"] = csrf;
  return headers;
}

// ===== Refresh token 自动续期 =====

let refreshPromise: Promise<boolean> | null = null;

// 调用 /api/auth/refresh 刷新 access token（refresh cookie 由浏览器自动携带）
async function apiRefresh(): Promise<boolean> {
  try {
    const res = await fetch("/api/auth/refresh", {
      method: "POST",
      credentials: "include",
      headers: clientHeaders(),
    });
    return res.ok;
  } catch {
    return false;
  }
}

// 带自动续期的 fetch：遇到 401 时尝试 refresh，成功后重试原请求
async function fetchWithRefresh(url: string, init: RequestInit): Promise<Response> {
  let res = await fetch(url, { ...init, credentials: "include" });

  if (res.status === 401) {
    // 串行化 refresh：多个并发 401 只触发一次 refresh
    if (!refreshPromise) {
      refreshPromise = apiRefresh().finally(() => {
        refreshPromise = null;
      });
    }
    const refreshed = await refreshPromise;
    if (refreshed) {
      // refresh 成功，重试原请求（CSRF cookie 可能已更新）
      const newHeaders = clientHeaders();
      const mergedInit = { ...init, credentials: "include" as const, headers: newHeaders };
      res = await fetch(url, mergedInit);
    }
  }
  return res;
}

// ===== SSR 端 fetch（公开接口，直接请求后端） =====

// SSR 页面通过 (await cookies()).toString() 传入，后端据此识别登录用户并填充 liked 状态
function cookieHeaders(cookieHeader?: string): HeadersInit | undefined {
  return cookieHeader ? { Cookie: cookieHeader } : undefined;
}

export async function fetchPosts(
  page = 1,
  size = 20,
  boardId?: number,
  sort = "latest",
  keyword = "",
  cookieHeader?: string
): Promise<PostsResponse> {
  const params = new URLSearchParams({ page: String(page), size: String(size), sort });
  if (boardId) params.set("board_id", String(boardId));
  if (keyword) params.set("keyword", keyword);
  const res = await fetch(`${API_BASE}/api/posts?${params}`, {
    cache: "no-store",
    headers: cookieHeaders(cookieHeader),
  });
  if (!res.ok) throw new Error("获取帖子失败");
  return res.json();
}

export async function fetchBoards(): Promise<{ boards: Board[] }> {
  const res = await fetch(`${API_BASE}/api/boards`, { cache: "no-store" });
  if (!res.ok) throw new Error("获取板块失败");
  return res.json();
}

export async function fetchPostDetail(id: string, cookieHeader?: string): Promise<{ post: Post }> {
  const res = await fetch(`${API_BASE}/api/posts/${id}`, {
    cache: "no-store",
    headers: cookieHeaders(cookieHeader),
  });
  if (!res.ok) throw new Error("获取帖子失败");
  return res.json();
}

export async function fetchComments(postId: string): Promise<{ comments: Comment[] }> {
  const res = await fetch(`${API_BASE}/api/posts/${postId}/comments`, { cache: "no-store" });
  if (!res.ok) throw new Error("获取评论失败");
  return res.json();
}

export async function fetchUserProfile(id: string, page = 1, cookieHeader?: string): Promise<UserProfile> {
  const params = new URLSearchParams({ page: String(page), size: "20" });
  const res = await fetch(`${API_BASE}/api/users/${id}?${params}`, {
    cache: "no-store",
    headers: cookieHeaders(cookieHeader),
  });
  if (res.status === 404) throw new Error("用户不存在");
  if (!res.ok) throw new Error("获取用户资料失败");
  return res.json();
}

export async function fetchUserComments(id: string, page = 1): Promise<UserCommentsResponse> {
  const params = new URLSearchParams({ page: String(page), size: "20" });
  const res = await fetch(`${API_BASE}/api/users/${id}/comments?${params}`, { cache: "no-store" });
  if (res.status === 404) throw new Error("用户不存在");
  if (!res.ok) throw new Error("获取评论失败");
  return res.json();
}

// ===== 客户端 API 调用（走 rewrite，携带 cookie + CSRF） =====

// 获取当前登录用户（依赖 OptionalAuth，未登录返回 { user: null }）
export async function apiMe(): Promise<{ user: User | null }> {
  const res = await fetch("/api/me", {
    credentials: "include",
    cache: "no-store",
  });
  return res.json();
}

export async function apiLogin(username: string, password: string) {
  const res = await fetch("/api/login", {
    method: "POST",
    credentials: "include",
    headers: clientHeaders({ "Content-Type": "application/json" }),
    body: JSON.stringify({ username, password }),
  });
  return res.json();
}

export async function apiRegister(username: string, email: string, password: string) {
  const res = await fetch("/api/register", {
    method: "POST",
    credentials: "include",
    headers: clientHeaders({ "Content-Type": "application/json" }),
    body: JSON.stringify({ username, email, password }),
  });
  return res.json();
}

export async function apiLogout() {
  const res = await fetchWithRefresh("/api/logout", {
    method: "POST",
    headers: clientHeaders(),
  });
  return res.json();
}

export async function apiCreatePost(data: {
  board_id: number;
  title: string;
  content: string;
  tags?: string;
  post_type?: string;
}) {
  const res = await fetchWithRefresh("/api/posts", {
    method: "POST",
    headers: clientHeaders({ "Content-Type": "application/json" }),
    body: JSON.stringify(data),
  });
  return res.json();
}

export async function apiCreateComment(postId: string, content: string) {
  const res = await fetchWithRefresh(`/api/posts/${postId}/comments`, {
    method: "POST",
    headers: clientHeaders({ "Content-Type": "application/json" }),
    body: JSON.stringify({ content }),
  });
  return res.json();
}

export async function apiUpdatePost(
  postId: string,
  data: { title?: string; content?: string; tags?: string }
) {
  const res = await fetchWithRefresh(`/api/posts/${postId}`, {
    method: "PUT",
    headers: clientHeaders({ "Content-Type": "application/json" }),
    body: JSON.stringify(data),
  });
  return res.json();
}

export async function apiDeletePost(postId: string) {
  const res = await fetchWithRefresh(`/api/posts/${postId}`, {
    method: "DELETE",
    headers: clientHeaders(),
  });
  return res.json();
}

export async function apiTogglePin(postId: string): Promise<{ pinned: number }> {
  const res = await fetchWithRefresh(`/api/posts/${postId}/pin`, {
    method: "PUT",
    headers: clientHeaders(),
  });
  return res.json();
}

export async function apiToggleRecommend(postId: string): Promise<{ recommended: boolean }> {
  const res = await fetchWithRefresh(`/api/posts/${postId}/recommend`, {
    method: "PUT",
    headers: clientHeaders(),
  });
  return res.json();
}

export async function apiChangePassword(oldPassword: string, newPassword: string) {
  const res = await fetchWithRefresh("/api/change-password", {
    method: "POST",
    headers: clientHeaders({ "Content-Type": "application/json" }),
    body: JSON.stringify({ old_password: oldPassword, new_password: newPassword }),
  });
  return res.json();
}

export async function apiToggleLike(postId: string) {
  const res = await fetchWithRefresh(`/api/posts/${postId}/like`, {
    method: "POST",
    headers: clientHeaders(),
  });
  return res.json();
}

export async function apiDeleteComment(postId: string, commentId: number) {
  const res = await fetchWithRefresh(`/api/posts/${postId}/comments/${commentId}`, {
    method: "DELETE",
    headers: clientHeaders(),
  });
  return res.json();
}

// ===== 通知 =====

export async function apiFetchNotifications(page = 1): Promise<NotificationsResponse> {
  const res = await fetchWithRefresh(`/api/notifications?page=${page}&size=20`, {
    headers: clientHeaders(),
  });
  return res.json();
}

export async function apiUnreadCount(): Promise<{ count: number }> {
  const res = await fetchWithRefresh("/api/notifications/unread-count", {
    headers: clientHeaders(),
  });
  return res.json();
}

export async function apiMarkRead(id: number) {
  const res = await fetchWithRefresh(`/api/notifications/${id}/read`, {
    method: "PUT",
    headers: clientHeaders(),
  });
  return res.json();
}

export async function apiMarkAllRead() {
  const res = await fetchWithRefresh("/api/notifications/read-all", {
    method: "PUT",
    headers: clientHeaders(),
  });
  return res.json();
}