"use client";

import { useCallback, useEffect, useRef, useState } from "react";
import Link from "next/link";
import {
  Check,
  ChevronLeft,
  ChevronRight,
  ClipboardCheck,
  FileText,
  Loader2,
  MessagesSquare,
  X,
} from "lucide-react";
import {
  apiAdminPendingPosts,
  apiAdminPendingComments,
  apiAdminPendingCounts,
  apiAdminApprovePost,
  apiAdminRejectPost,
  apiAdminApproveComment,
  apiAdminRejectComment,
  type PendingCommentItem,
  type PendingCounts,
  type Post,
} from "@/lib/api";
import { formatRelative } from "@/lib/format";
import { toast } from "@/lib/toast";
import Avatar from "@/components/Avatar";

const PAGE_SIZE = 15;

type Tab = "posts" | "comments";

// 粗略去除 Markdown 标记，生成纯文本摘要
function excerpt(md: string, max = 160): string {
  const text = md
    .replace(/```[\s\S]*?```/g, " ")
    .replace(/[#>*_`~\-]/g, "")
    .replace(/\[([^\]]+)\]\([^)]+\)/g, "$1")
    .replace(/\s+/g, " ")
    .trim();
  return text.length > max ? `${text.slice(0, max)}…` : text;
}

export default function ModerationAdmin({
  initialPosts,
  initialPostsTotal,
  initError,
}: {
  initialPosts: Post[];
  initialPostsTotal: number;
  initError: string;
}) {
  const [tab, setTab] = useState<Tab>("posts");
  const [counts, setCounts] = useState<PendingCounts>({ posts: initialPostsTotal, comments: 0 });

  // 帖子队列
  const [posts, setPosts] = useState<Post[]>(initialPosts);
  const [postsTotal, setPostsTotal] = useState(initialPostsTotal);
  const [postsPage, setPostsPage] = useState(1);

  // 评论队列
  const [comments, setComments] = useState<PendingCommentItem[]>([]);
  const [commentsTotal, setCommentsTotal] = useState(0);
  const [commentsPage, setCommentsPage] = useState(1);
  const [commentsLoaded, setCommentsLoaded] = useState(false);

  const [loading, setLoading] = useState(false);
  const [error, setError] = useState(initError);
  const [actingKey, setActingKey] = useState<string | null>(null);
  // 拒绝的二次内联确认（key: posts-<id> / comments-<id>，3 秒自动复原）
  const [confirmKey, setConfirmKey] = useState<string | null>(null);
  const confirmTimer = useRef<ReturnType<typeof setTimeout> | null>(null);

  const refreshCounts = useCallback(() => {
    apiAdminPendingCounts()
      .then(setCounts)
      .catch(() => {});
  }, []);

  useEffect(() => {
    refreshCounts();
  }, [refreshCounts]);

  const loadPosts = useCallback(async (page: number) => {
    setLoading(true);
    try {
      const res = await apiAdminPendingPosts(page);
      setPosts(res.posts);
      setPostsTotal(res.total);
      setError("");
    } catch (e) {
      setError(e instanceof Error ? e.message : "获取待审帖子失败");
    } finally {
      setLoading(false);
    }
  }, []);

  const loadComments = useCallback(async (page: number) => {
    setLoading(true);
    try {
      const res = await apiAdminPendingComments(page);
      setComments(res.comments);
      setCommentsTotal(res.total);
      setError("");
    } catch (e) {
      setError(e instanceof Error ? e.message : "获取待审评论失败");
    } finally {
      setLoading(false);
    }
  }, []);

  const switchTab = (t: Tab) => {
    if (t === tab) return;
    setTab(t);
    setError("");
    setConfirmKey(null);
    if (t === "comments" && !commentsLoaded) {
      setCommentsLoaded(true);
      loadComments(1);
    }
  };

  const goPosts = (p: number) => {
    const next = Math.min(Math.max(1, p), Math.max(1, Math.ceil(postsTotal / PAGE_SIZE)));
    setPostsPage(next);
    loadPosts(next);
  };
  const goComments = (p: number) => {
    const next = Math.min(Math.max(1, p), Math.max(1, Math.ceil(commentsTotal / PAGE_SIZE)));
    setCommentsPage(next);
    loadComments(next);
  };

  const armConfirm = (key: string) => {
    setConfirmKey(key);
    if (confirmTimer.current) clearTimeout(confirmTimer.current);
    confirmTimer.current = setTimeout(() => setConfirmKey(null), 3000);
  };

  // 本地移除已处理项；当页清空且不在第一页时回退一页
  const afterAction = (kind: Tab, removedPage: number, removedPageItems: number, remaining: number) => {
    refreshCounts();
    setConfirmKey(null);
    if (remaining === 0 && removedPage > 1) {
      const prev = removedPage - 1;
      if (kind === "posts") {
        setPostsPage(prev);
        loadPosts(prev);
      } else {
        setCommentsPage(prev);
        loadComments(prev);
      }
    }
  };

  const act = async (
    key: string,
    kind: "posts" | "comments",
    id: number,
    approve: boolean,
    page: number,
    pageItems: number
  ) => {
    // 首次点拒绝进入确认态，不执行
    if (!approve && confirmKey !== key) {
      armConfirm(key);
      return;
    }
    setActingKey(key);
    try {
      if (kind === "posts") {
        if (approve) await apiAdminApprovePost(id);
        else await apiAdminRejectPost(id);
        setPosts((list) => list.filter((p) => p.id !== id));
        setPostsTotal((t) => Math.max(0, t - 1));
      } else {
        if (approve) await apiAdminApproveComment(id);
        else await apiAdminRejectComment(id);
        setComments((list) => list.filter((c) => c.id !== id));
        setCommentsTotal((t) => Math.max(0, t - 1));
      }
      toast(approve ? "已通过审核，内容已公开" : "已拒绝，作者将收到通知", "ok");
      afterAction(kind, page, pageItems, pageItems - 1);
    } catch (e) {
      toast(e instanceof Error ? e.message : "操作失败");
    } finally {
      setActingKey(null);
    }
  };

  const totalPages = tab === "posts"
    ? Math.max(1, Math.ceil(postsTotal / PAGE_SIZE))
    : Math.max(1, Math.ceil(commentsTotal / PAGE_SIZE));

  return (
    <div>
      {/* 页头 */}
      <div className="mb-5">
        <h1
          className="text-[22px] sm:text-[26px] font-extrabold tracking-tight flex items-center gap-2.5"
          style={{ color: "var(--ink)" }}
        >
          <span
            className="w-9 h-9 rounded-xl flex items-center justify-center"
            style={{ background: "var(--accent-soft)", color: "var(--accent)" }}
          >
            <ClipboardCheck size={18} />
          </span>
          内容审核
        </h1>
        <p className="meta mt-1.5 text-[12.5px]">
          普通用户发布的帖子与评论需审核通过后公开；板块管理员仅能处理授权板块的内容。内容策略与回收站见「内容管理」。
        </p>
      </div>

      {/* 队列切换 */}
      <div className="flex items-center gap-1.5 mb-4 flex-wrap" role="tablist" aria-label="审核队列">
        {(
          [
            { key: "posts" as Tab, label: "待审帖子", count: counts.posts, icon: <FileText size={14} /> },
            { key: "comments" as Tab, label: "待审评论", count: counts.comments, icon: <MessagesSquare size={14} /> },
          ]
        ).map((t) => {
          const active = tab === t.key;
          return (
            <button
              key={t.key}
              type="button"
              role="tab"
              aria-selected={active}
              onClick={() => switchTab(t.key)}
              className="inline-flex items-center gap-1.5 px-3.5 py-2 rounded-full text-[13px] transition-colors"
              style={
                active
                  ? { background: "var(--nav-active-bg)", color: "var(--nav-active-ink)" }
                  : { color: "var(--ink-2)", background: "var(--panel-2)" }
              }
            >
              {t.icon}
              {t.label}
              <span
                className="text-[11px] tabular-nums rounded-full px-1.5 leading-[1.7]"
                style={{
                  background: "var(--panel)",
                  color: active ? "var(--nav-active-ink)" : "var(--ink-3)",
                }}
              >
                {t.count}
              </span>
            </button>
          );
        })}
      </div>

      {error && <p className="alert-error mb-4">{error}</p>}

      <div aria-busy={loading} style={{ opacity: loading ? 0.6 : 1, transition: "opacity .15s" }}>
        {tab === "posts" ? (
          posts.length === 0 ? (
            <EmptyQueue icon={<FileText size={22} />} text="暂无待审核帖子" />
          ) : (
            <div className="flex flex-col gap-3">
              {posts.map((p) => {
                const key = `posts-${p.id}`;
                const busy = actingKey === key;
                const confirming = confirmKey === key;
                return (
                  <div key={p.id} className="panel p-4 sm:p-5">
                    <div className="flex items-center gap-2 flex-wrap mb-2.5">
                      <Link
                        href={`/?board=${p.board.id}`}
                        className="chip"
                        style={{ fontSize: 11.5 }}
                      >
                        {p.board.name}
                      </Link>
                      <span className="meta text-[11.5px]">{formatRelative(p.created_at)}</span>
                    </div>
                    <Link
                      href={`/post/${p.id}`}
                      target="_blank"
                      className="block text-[15.5px] font-semibold tracking-tight leading-snug hover:text-[var(--accent)] transition-colors"
                      style={{ color: "var(--ink)" }}
                    >
                      {p.title}
                    </Link>
                    <p
                      className="mt-1.5 text-[13px] leading-relaxed line-clamp-3"
                      style={{ color: "var(--ink-3)" }}
                    >
                      {excerpt(p.content) || "（无正文内容）"}
                    </p>
                    <div
                      className="mt-3.5 flex items-center justify-between gap-3 flex-wrap pt-3"
                      style={{ borderTop: "1px solid var(--line)" }}
                    >
                      <div className="flex items-center gap-2 min-w-0">
                        <Avatar name={p.user.nickname || p.user.username} src={p.user.avatar || undefined} size={26} />
                        <span className="text-[12.5px] truncate" style={{ color: "var(--ink-2)" }}>
                          {p.user.nickname}
                        </span>
                        <span className="meta text-[11.5px] truncate">@{p.user.username}</span>
                      </div>
                      <div className="flex items-center gap-2 shrink-0">
                        <button
                          type="button"
                          disabled={busy}
                          onClick={() => act(key, "posts", p.id, true, postsPage, posts.length)}
                          className="btn btn-sm"
                          style={{ background: "var(--ok-soft)", color: "var(--ok)" }}
                        >
                          {busy ? <Loader2 size={13} className="animate-spin" /> : <Check size={13} />}
                          通过
                        </button>
                        <button
                          type="button"
                          disabled={busy}
                          onClick={() => act(key, "posts", p.id, false, postsPage, posts.length)}
                          className="btn btn-sm"
                          style={{
                            background: confirming ? "var(--danger)" : "var(--danger-soft)",
                            color: confirming ? "var(--accent-on)" : "var(--danger)",
                          }}
                        >
                          {confirming ? "确认拒绝?" : <><X size={13} /> 拒绝</>}
                        </button>
                      </div>
                    </div>
                  </div>
                );
              })}
            </div>
          )
        ) : comments.length === 0 ? (
          <EmptyQueue icon={<MessagesSquare size={22} />} text="暂无待审核评论" />
        ) : (
          <div className="panel overflow-hidden">
            {comments.map((c, idx) => {
              const key = `comments-${c.id}`;
              const busy = actingKey === key;
              const confirming = confirmKey === key;
              return (
                <div
                  key={c.id}
                  className="p-4 sm:p-5 flex items-start gap-3.5"
                  style={idx === 0 ? undefined : { borderTop: "1px solid var(--line)" }}
                >
                  <Avatar name={c.user.nickname || c.user.username} src={c.user.avatar || undefined} size={34} />
                  <div className="min-w-0 flex-1">
                    <div className="flex items-center gap-2 flex-wrap">
                      <span className="text-[13.5px] truncate" style={{ color: "var(--ink)" }}>
                        {c.user.nickname}
                      </span>
                      <Link
                        href={`/?board=${c.board.id}`}
                        className="chip"
                        style={{ fontSize: 11 }}
                      >
                        {c.board.name}
                      </Link>
                      <span className="meta text-[11.5px]">{formatRelative(c.created_at)}</span>
                    </div>
                    <p
                      className="mt-1.5 text-[13.5px] leading-relaxed rounded-xl px-3.5 py-2.5"
                      style={{ background: "var(--panel-2)", color: "var(--ink-2)" }}
                    >
                      {c.content}
                    </p>
                    <Link
                      href={`/post/${c.post_id}`}
                      target="_blank"
                      className="mt-1.5 block meta text-[12px] truncate hover:text-[var(--accent)] transition-colors"
                    >
                      所属帖子：《{c.post_title}》
                    </Link>
                    <div className="flex items-center gap-2 mt-3">
                      <button
                        type="button"
                        disabled={busy}
                        onClick={() => act(key, "comments", c.id, true, commentsPage, comments.length)}
                        className="btn btn-sm"
                        style={{ background: "var(--ok-soft)", color: "var(--ok)" }}
                      >
                        {busy ? <Loader2 size={13} className="animate-spin" /> : <Check size={13} />}
                        通过
                      </button>
                      <button
                        type="button"
                        disabled={busy}
                        onClick={() => act(key, "comments", c.id, false, commentsPage, comments.length)}
                        className="btn btn-sm"
                        style={{
                          background: confirming ? "var(--danger)" : "var(--danger-soft)",
                          color: confirming ? "var(--accent-on)" : "var(--danger)",
                        }}
                      >
                        {confirming ? "确认拒绝?" : <><X size={13} /> 拒绝</>}
                      </button>
                    </div>
                  </div>
                </div>
              );
            })}
          </div>
        )}
      </div>

      {/* 分页 */}
      {totalPages > 1 && (
        <div
          className="mt-4 flex items-center justify-between gap-2 panel px-4 sm:px-5 py-3"
        >
          <span className="meta text-[12px] tabular-nums" style={{ color: "var(--ink-3)" }}>
            第 {tab === "posts" ? postsPage : commentsPage} / {totalPages} 页
          </span>
          <div className="flex items-center gap-2">
            <button
              type="button"
              onClick={() => (tab === "posts" ? goPosts(postsPage - 1) : goComments(commentsPage - 1))}
              disabled={(tab === "posts" ? postsPage : commentsPage) <= 1 || loading}
              className="btn btn-line btn-sm"
            >
              <ChevronLeft size={14} /> 上一页
            </button>
            <button
              type="button"
              onClick={() => (tab === "posts" ? goPosts(postsPage + 1) : goComments(commentsPage + 1))}
              disabled={(tab === "posts" ? postsPage : commentsPage) >= totalPages || loading}
              className="btn btn-line btn-sm"
            >
              下一页 <ChevronRight size={14} />
            </button>
          </div>
        </div>
      )}
    </div>
  );
}

function EmptyQueue({ icon, text }: { icon: React.ReactNode; text: string }) {
  return (
    <div className="panel text-center py-16 px-6">
      <span
        className="inline-flex w-12 h-12 rounded-full items-center justify-center mb-3"
        style={{ background: "var(--panel-2)", color: "var(--ink-3)" }}
      >
        {icon}
      </span>
      <p className="text-[14.5px]" style={{ color: "var(--ink)" }}>
        {text}
      </p>
      <p className="meta mt-1.5 text-[12.5px]">新提交的内容会按时间顺序出现在这里</p>
    </div>
  );
}