"use client";

import { useCallback, useEffect, useState } from "react";
import Link from "next/link";
import { Loader2 } from "lucide-react";
import Modal from "@/components/Modal";
import Avatar from "@/components/Avatar";
import MarkdownBodyClient from "@/components/MarkdownBodyClient";
import {
  apiAdminCommentHistory,
  type CommentEditHistoryItem,
} from "@/lib/api";

const PAGE_SIZE = 10;

/**
 * 版主可见：评论历次编辑前的旧正文快照（倒序分页）。
 * 宽度对齐详情页评论主栏（约 800px+），长文可滚动；底部「加载更多」。
 */
export default function CommentEditHistoryModal({
  open,
  commentId,
  onClose,
}: {
  open: boolean;
  commentId: number | null;
  onClose: () => void;
}) {
  const [loading, setLoading] = useState(false);
  const [loadingMore, setLoadingMore] = useState(false);
  const [error, setError] = useState("");
  const [items, setItems] = useState<CommentEditHistoryItem[]>([]);
  const [page, setPage] = useState(1);
  const [total, setTotal] = useState(0);

  const hasMore = items.length < total;

  const loadPage = useCallback(
    async (nextPage: number, append: boolean) => {
      if (commentId == null) return;
      if (append) setLoadingMore(true);
      else {
        setLoading(true);
        setError("");
      }
      try {
        const res = await apiAdminCommentHistory(commentId, nextPage, PAGE_SIZE);
        const batch = res.items || [];
        setError("");
        setTotal(res.total ?? 0);
        setPage(res.page ?? nextPage);
        setItems((prev) => (append ? [...prev, ...batch] : batch));
      } catch (e) {
        const msg = e instanceof Error ? e.message : "加载失败";
        if (append) {
          // 追加失败不清空已有列表
          setError(msg);
        } else {
          setError(msg);
          setItems([]);
          setTotal(0);
        }
      } finally {
        setLoading(false);
        setLoadingMore(false);
      }
    },
    [commentId]
  );

  useEffect(() => {
    if (!open || commentId == null) return;
    setItems([]);
    setPage(1);
    setTotal(0);
    setError("");
    void loadPage(1, false);
  }, [open, commentId, loadPage]);

  return (
    <Modal
      open={open}
      title="评论编辑历史"
      description={total > 0 ? `共 ${total} 条修订记录` : undefined}
      onClose={onClose}
      // 对齐详情页中间评论栏可用宽度（1440 三栏布局下约 800px）
      maxWidthClass="max-w-[min(840px,calc(100vw-2rem))]"
      panelClassName="p-5 sm:p-6 max-h-[85vh] flex flex-col min-h-0 overflow-hidden"
      bodyClassName="overflow-y-auto min-h-0 flex-1 -mx-1 px-1"
      footer={
        <button type="button" className="btn btn-line btn-sm" onClick={onClose}>
          关闭
        </button>
      }
    >
      {loading ? (
        <div className="flex items-center justify-center gap-2 py-10 meta text-[13px]">
          <Loader2 size={16} className="animate-spin" />
          加载中…
        </div>
      ) : error && items.length === 0 ? (
        <p className="text-[13.5px] py-6 text-center" style={{ color: "var(--danger)" }}>
          {error}
        </p>
      ) : items.length === 0 ? (
        <p className="meta text-[13.5px] py-8 text-center">暂无编辑记录</p>
      ) : (
        <div className="flex flex-col gap-4">
          <ul className="flex flex-col gap-4">
            {items.map((it) => {
              const name = it.editor.nickname || it.editor.username || "用户";
              return (
                <li
                  key={it.id}
                  className="rounded-md p-3 sm:p-4"
                  style={{ background: "var(--panel-2)", border: "1px solid var(--line)" }}
                >
                  <div className="flex items-center gap-2 mb-2.5">
                    <Link href={`/u/${it.editor.id}`} className="shrink-0">
                      <Avatar name={name} src={it.editor.avatar || undefined} size={28} />
                    </Link>
                    <div className="min-w-0 flex-1">
                      <Link
                        href={`/u/${it.editor.id}`}
                        className="text-[13px] hover:text-[var(--accent)]"
                        style={{ color: "var(--ink)" }}
                      >
                        {name}
                      </Link>
                      <p className="meta text-[11.5px] tabular-nums">
                        {new Date(it.created_at).toLocaleString("zh-CN")} · 编辑前正文
                      </p>
                    </div>
                  </div>
                  <MarkdownBodyClient
                    content={it.old_content}
                    className="prose-content prose-comment"
                  />
                </li>
              );
            })}
          </ul>

          {error && items.length > 0 && (
            <p className="text-[12.5px] text-center" style={{ color: "var(--danger)" }}>
              {error}
            </p>
          )}

          {hasMore && (
            <div className="flex justify-center pt-1 pb-1">
              <button
                type="button"
                className="btn btn-line btn-sm"
                disabled={loadingMore}
                onClick={() => void loadPage(page + 1, true)}
              >
                {loadingMore ? (
                  <span className="inline-flex items-center gap-1.5">
                    <Loader2 size={14} className="animate-spin" />
                    加载中…
                  </span>
                ) : (
                  `加载更多（已显示 ${items.length}/${total}）`
                )}
              </button>
            </div>
          )}
        </div>
      )}
    </Modal>
  );
}