"use client";

import { useState, useEffect } from "react";
import { useRouter } from "next/navigation";
import Link from "next/link";
import { ChevronRight } from "lucide-react";
import { fetchPostDetail, apiMe, apiUpdatePost, type Post, type User } from "@/lib/api";
import { canModerateBoard } from "@/lib/roles";

interface EditPageProps {
  params: Promise<{ id: string }>;
}

export default function EditPostPage({ params }: EditPageProps) {
  const router = useRouter();
  const [post, setPost] = useState<Post | null>(null);
  const [user, setUser] = useState<User | null>(null);
  const [title, setTitle] = useState("");
  const [content, setContent] = useState("");
  const [tags, setTags] = useState("");
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState("");
  const [checking, setChecking] = useState(true);

  const [id, setId] = useState("");
  useEffect(() => {
    params.then((p) => setId(p.id));
  }, [params]);

  useEffect(() => {
    if (!id) return;
    Promise.all([fetchPostDetail(id), apiMe()])
      .then(([postData, meData]) => {
        setPost(postData.post);
        setTitle(postData.post.title);
        setContent(postData.post.content);
        setTags(postData.post.tags || "");
        const u = meData.user;
        setUser(u || null);
        if (
          !u ||
          (u.id !== postData.post.user.id && !canModerateBoard(u, postData.post.board_id))
        ) {
          router.push(`/post/${id}`);
        }
      })
      .catch(() => router.push(`/post/${id}`))
      .finally(() => setChecking(false));
  }, [id, router]);

  const handleSubmit = async (e: React.FormEvent) => {
    e.preventDefault();
    if (!post) return;
    setLoading(true);
    setError("");
    try {
      const res = await apiUpdatePost(String(post.id), { title, content, tags });
      if (res.post) {
        router.push(`/post/${post.id}`);
      } else {
        setError(res.error || "更新失败");
      }
    } finally {
      setLoading(false);
    }
  };

  if (checking) {
    return (
      <div className="max-w-3xl mx-auto text-center py-20">
        <p className="meta">正在加载帖子…</p>
      </div>
    );
  }

  if (!post) return null;

  return (
    <div className="max-w-3xl mx-auto">
      <nav className="meta mb-5 flex items-center gap-1.5 flex-wrap text-[13px]">
        <Link href="/" className="hover:text-[var(--accent)] transition-colors">首页</Link>
        <ChevronRight size={13} />
        <Link href={`/post/${post.id}`} className="hover:text-[var(--accent)] transition-colors truncate max-w-[12rem]">
          帖子详情
        </Link>
        <ChevronRight size={13} />
        <span style={{ color: "var(--accent)" }}>编辑</span>
      </nav>

      <div className="mb-7">
        <h1 className="text-[26px] sm:text-[30px] font-extrabold tracking-tight" style={{ color: "var(--ink)" }}>
          编辑帖子
        </h1>
      </div>

      <form onSubmit={handleSubmit} className="panel p-5 sm:p-7 space-y-5">
        {error && <div className="alert-error">{error}</div>}

        <div>
          <label className="field-label">标题</label>
          <input
            type="text"
            value={title}
            onChange={(e) => setTitle(e.target.value)}
            required
            maxLength={256}
            className="field"
          />
        </div>

        <div>
          <label className="field-label">标签（逗号分隔，可选）</label>
          <input
            type="text"
            value={tags}
            onChange={(e) => setTags(e.target.value)}
            placeholder="Go, PostgreSQL, 架构"
            className="field"
          />
        </div>

        <div>
          <label className="field-label">正文（支持 Markdown）</label>
          <textarea
            value={content}
            onChange={(e) => setContent(e.target.value)}
            required
            rows={14}
            className="field"
          />
        </div>

        <div className="flex gap-3 pt-2">
          <button
            type="submit"
            disabled={loading || !title.trim() || !content.trim()}
            className="btn btn-primary"
          >
            {loading ? "保存中..." : "保存修改"}
          </button>
          <button
            type="button"
            onClick={() => router.push(`/post/${post.id}`)}
            className="btn btn-line"
          >
            取消
          </button>
        </div>
      </form>
    </div>
  );
}