"use client";
import { useEffect, useRef, useState } from "react";
import type { EditPlan } from "@/lib/video-canvas/smart-edit/contract";

/** Only amplified cross-origin sources need a same-origin copy for Web Audio. */
export function usePreviewGain(plan: EditPlan, onError: (message: string) => void) {
  const remote = [
    ...new Set(
      [...plan.clips, ...(plan.audioClips || [])]
        .filter((clip) => clip.gain > 1)
        .map((clip) => plan.assets.find((asset) => asset.id === clip.assetId)!.url)
        .filter(
          (url) =>
            typeof window !== "undefined" &&
            new URL(url, window.location.href).origin !== window.location.origin,
        ),
    ),
  ].sort();
  const key = JSON.stringify(remote);
  const [copies, setCopies] = useState<{ key: string; urls: Record<string, string> }>({
    key: "",
    urls: {},
  });
  const [attempt, setAttempt] = useState(0),
    [failed, setFailed] = useState(false);
  const error = useRef(onError);
  error.current = onError;
  const graph = useRef<{
    context: AudioContext;
    nodes: Map<HTMLMediaElement, { source: MediaElementAudioSourceNode; gain: GainNode }>;
  }>();
  useEffect(() => {
    setFailed(false);
    const controller = new AbortController(),
      urls: Record<string, string> = {};
    void Promise.all(
      (JSON.parse(key) as string[]).map(async (url) => {
        const response = await fetch("/api/canvas/download-image", {
          method: "POST",
          headers: { "Content-Type": "application/json" },
          body: JSON.stringify({ url, name: "剪辑音量预览" }),
          signal: controller.signal,
        });
        if (!response.ok) throw Error("无法读取音量预览素材，请检查链接后重试");
        const blob = await response.blob();
        if (!blob.size) throw Error("音量预览素材为空");
        if (!controller.signal.aborted) urls[url] = URL.createObjectURL(blob);
      }),
    )
      .then(() => {
        if (!controller.signal.aborted) setCopies({ key, urls });
      })
      .catch((e) => {
        if (!controller.signal.aborted) {
          setFailed(true);
          error.current(`${e.message}，可点击播放重试`);
        }
      });
    return () => {
      controller.abort();
      Object.values(urls).forEach(URL.revokeObjectURL);
    };
  }, [key, attempt]);
  useEffect(
    () => () => {
      void graph.current?.context.close();
      graph.current = undefined;
    },
    [],
  );
  return {
    retry() {
      if (failed) setAttempt((value) => value + 1);
    },
    source(url: string) {
      return copies.key === key ? copies.urls[url] || url : url;
    },
    ready(url: string) {
      return !remote.includes(url) || (copies.key === key && Boolean(copies.urls[url]));
    },
    retain(elements: HTMLMediaElement[]) {
      for (const [element, node] of graph.current?.nodes || [])
        if (!elements.includes(element)) {
          element.pause();
          node.source.disconnect();
          node.gain.disconnect();
          graph.current!.nodes.delete(element);
        }
    },
    volume(element: HTMLMediaElement, gain: number, playing: boolean) {
      let node = graph.current?.nodes.get(element);
      if (gain > 1 && !node) {
        graph.current ||= { context: new AudioContext(), nodes: new Map() };
        const source = graph.current.context.createMediaElementSource(element),
          amplifier = graph.current.context.createGain();
        source.connect(amplifier);
        amplifier.connect(graph.current.context.destination);
        node = { source, gain: amplifier };
        graph.current.nodes.set(element, node);
      }
      if (node) {
        element.volume = 1;
        node.gain.gain.value = Math.max(0, gain);
        if (playing && graph.current?.context.state === "suspended")
          void graph.current.context
            .resume()
            .catch(() => error.current("请再次点击播放以启用音频预览"));
      } else element.volume = Math.min(1, Math.max(0, gain));
    },
  };
}