"use client";

import { useEffect, useRef, useState } from "react";
import { ImageOff, Video, RotateCw } from "lucide-react";
import { buildImageProxyUrl } from "@/lib/image-delivery";
import { isRetiredStorageUrl } from "@/lib/storage/retired-storage";

import { queuePreview } from "@/lib/admin/preview-queue";

export function MediaThumbnail({
  url,
  video = false,
  onOpen,
}: {
  url: string;
  video?: boolean;
  onOpen?: () => void;
}) {
  const container = useRef<HTMLDivElement>(null);
  const [state, setState] = useState<"waiting" | "loading" | "ready" | "error">("waiting");
  const [attempt, setAttempt] = useState(0);
  const [source, setSource] = useState("");
  const [failure, setFailure] = useState("");
  const retired = isRetiredStorageUrl(url);
  useEffect(() => {
    setState("waiting");
    setSource("");
    setFailure("");
    if (video || retired || !url || !container.current) return;
    let dispose: (() => void) | undefined;
    let abort = () => {};
    let objectUrl = "";
    let alive = true;
    const observer = new IntersectionObserver(
      ([entry]) => {
        if (!entry.isIntersecting || dispose) return;
        observer.disconnect();
        dispose = queuePreview((release) => {
          const controller = new AbortController();
          const timeout = setTimeout(() => controller.abort(), 48000);
          setState("loading");
          // Fetch is abortable, so leaving a page also stops in-flight previews.
          const parsed = new URL(url, window.location.origin);
          const target =
            parsed.hostname === "scqnycdn.jiansun.vip" && !parsed.search
              ? `${url}?imageView2/2/w/192/q/72/format/webp`
              : buildImageProxyUrl(url, {
                  width: 192,
                  quality: 72,
                  format: "webp",
                  delivery: "proxy",
                });
          fetch(target, { signal: controller.signal })
            .then(async (response) => {
              if (!response.ok) {
                const detail = await response.json().catch(() => null);
                throw new Error(`${detail?.error || "预览请求失败"}（HTTP ${response.status}）`);
              }
              const blob = await response.blob();
              if (!blob.type.startsWith("image/")) throw new Error("Not an image");
              if (alive) {
                objectUrl = URL.createObjectURL(blob);
                setSource(objectUrl);
                setState("ready");
              }
            })
            .catch((error) => {
              if (alive) {
                setFailure(
                  error.name === "AbortError" ? "预览加载超时" : error.message || "预览加载失败",
                );
                setState("error");
              }
            })
            .finally(() => {
              clearTimeout(timeout);
              release();
            });
          abort = () => {
            controller.abort();
            clearTimeout(timeout);
          };
        });
      },
      { rootMargin: "80px" },
    );
    observer.observe(container.current);
    return () => {
      alive = false;
      observer.disconnect();
      abort();
      dispose?.();
      if (objectUrl) URL.revokeObjectURL(objectUrl);
    };
  }, [url, video, retired, attempt]);
  return (
    <div
      ref={container}
      className="relative flex h-16 w-20 shrink-0 items-center justify-center overflow-hidden rounded-lg bg-muted"
      data-preview-state={state}
    >
      {video ? (
        <button
          type="button"
          aria-label="查看视频详情"
          className="flex h-full w-full items-center justify-center"
          onClick={onOpen}
        >
          <Video className="size-5 text-muted-foreground" aria-label="视频，点击查看后播放" />
        </button>
      ) : retired ? (
        <span className="text-center text-xs text-muted-foreground">
          旧存储
          <br />
          已停用
        </span>
      ) : source && state === "ready" ? (
        <button type="button" aria-label="查看图片详情" className="h-full w-full" onClick={onOpen}>
          <img
            src={source}
            alt="生成结果预览"
            className="h-full w-full object-contain"
            onError={() => {
              setFailure("图片内容无法解码");
              setState("error");
            }}
          />
        </button>
      ) : state === "error" ? (
        <button
          type="button"
          className="flex h-full w-full flex-col items-center justify-center gap-1 text-xs text-muted-foreground hover:text-foreground"
          title={`${failure}，点击重试`}
          onClick={(e) => {
            e.stopPropagation();
            setAttempt((x) => x + 1);
          }}
        >
          <ImageOff className="size-4" />
          加载失败
        </button>
      ) : (
        <RotateCw
          className={`size-4 text-muted-foreground ${state === "loading" ? "motion-safe:animate-spin" : ""}`}
          aria-label={state === "loading" ? "正在加载预览" : "等待进入可见区域"}
        />
      )}
    </div>
  );
}