"use client";

import Image from "next/image";
import { Download, Eye, FileText, Loader2, Play } from "lucide-react";
import { useCallback, useEffect, useRef, useState } from "react";

import MediaPreviewModal from "@/components/shared/MediaPreviewModal";
import { useNearViewport } from "@/hooks/useNearViewport";
import { apiClient } from "@/lib/api";
import { getMediaKind, type MediaPreview } from "@/lib/media";
import type { TaskAttachment } from "@/types/api";

function formatFileSize(size: number): string {
  if (size < 1024) return `${size} Б`;
  if (size < 1024 * 1024) return `${Math.ceil(size / 1024)} КБ`;
  return `${(size / (1024 * 1024)).toLocaleString("ru-RU", {
    maximumFractionDigits: 1,
  })} МБ`;
}

export default function TaskCommentAttachment({
  taskId,
  attachment,
  onDownload,
}: {
  taskId: number;
  attachment: TaskAttachment;
  onDownload: (attachment: TaskAttachment) => void | Promise<void>;
}) {
  const mediaKind = getMediaKind({
    fileName: attachment.file_name,
    mimeType: attachment.mime_type,
  });
  const image = mediaKind === "image";
  const video = mediaKind === "video";
  const media = image || video;
  const [thumbnailSource, setThumbnailSource] = useState<string | null>(null);
  const [thumbnailFailed, setThumbnailFailed] = useState(false);
  const [preview, setPreview] = useState<MediaPreview | null>(null);
  const [previewLoading, setPreviewLoading] = useState(false);
  const previewUrlRef = useRef<string | null>(null);
  const { elementRef, isNearViewport } = useNearViewport();

  useEffect(() => {
    if (!media || !isNearViewport) return;
    let active = true;
    let objectUrl: string | null = null;

    void apiClient.downloadTaskAttachmentThumbnail(taskId, attachment)
      .then((blob) => {
        if (!active) return;
        objectUrl = URL.createObjectURL(blob);
        setThumbnailSource(objectUrl);
      })
      .catch(() => {
        if (active) setThumbnailFailed(true);
      });

    return () => {
      active = false;
      if (objectUrl) URL.revokeObjectURL(objectUrl);
    };
  }, [attachment, isNearViewport, media, taskId]);

  useEffect(() => () => {
    if (previewUrlRef.current) URL.revokeObjectURL(previewUrlRef.current);
  }, []);

  const closePreview = useCallback(() => {
    setPreview(null);
    if (previewUrlRef.current) {
      URL.revokeObjectURL(previewUrlRef.current);
      previewUrlRef.current = null;
    }
  }, []);

  const openPreview = useCallback(async () => {
    if (!media || previewLoading) return;
    setPreviewLoading(true);
    try {
      const { blob } = await apiClient.downloadTaskAttachment(taskId, attachment);
      if (previewUrlRef.current) URL.revokeObjectURL(previewUrlRef.current);
      const source = URL.createObjectURL(blob);
      previewUrlRef.current = source;
      setPreview({
        type: video ? "video" : "image",
        src: source,
        name: attachment.file_name,
      });
    } finally {
      setPreviewLoading(false);
    }
  }, [attachment, media, previewLoading, taskId, video]);

  if (media) {
    return (
      <div ref={elementRef} className="app-surface-elevated overflow-hidden rounded-lg border border-[var(--border-subtle)]">
        <button
          type="button"
          onClick={() => void openPreview()}
          disabled={!thumbnailSource || thumbnailFailed || previewLoading}
          className="group relative block aspect-video min-h-32 w-full overflow-hidden bg-[var(--surface-secondary)] outline-none focus-visible:ring-2 focus-visible:ring-sky-400/70 disabled:cursor-default"
          title={`Просмотреть ${attachment.file_name}`}
        >
          {thumbnailSource ? (
            <Image
              src={thumbnailSource}
              alt={attachment.file_name}
              fill
              unoptimized
              sizes="(max-width: 640px) 100vw, 320px"
              className="object-cover"
            />
          ) : (
            <span className="app-text-muted absolute inset-0 flex items-center justify-center">
              {thumbnailFailed ? <FileText size={20} /> : <Loader2 size={18} className="animate-spin" />}
            </span>
          )}
          {thumbnailSource ? (
            <span className="pointer-events-none absolute inset-0 flex items-center justify-center bg-black/35 text-white opacity-0 transition-opacity group-hover:opacity-100 group-focus-visible:opacity-100">
              {previewLoading ? <Loader2 size={22} className="animate-spin" /> : video ? <Play size={24} fill="currentColor" /> : <Eye size={24} />}
            </span>
          ) : null}
        </button>
        <button
          type="button"
          onClick={() => void onDownload(attachment)}
          className="flex w-full min-w-0 items-center gap-2 border-t border-[var(--border-subtle)] px-2.5 py-2 text-left"
          title={`Скачать ${attachment.file_name}`}
        >
          <span className="min-w-0 flex-1 truncate text-xs font-medium text-[var(--foreground)]">
            {attachment.file_name}
          </span>
          <Download size={13} className="app-text-muted shrink-0" />
        </button>
        {preview ? <MediaPreviewModal preview={preview} onClose={closePreview} /> : null}
      </div>
    );
  }

  return (
    <button
      type="button"
      onClick={() => void onDownload(attachment)}
      className="app-surface-elevated flex min-w-0 items-center gap-2 rounded-lg border border-[var(--border-subtle)] px-2.5 py-2 text-left"
      title={`Скачать ${attachment.file_name}`}
    >
      <span className="app-selected flex h-8 w-8 shrink-0 items-center justify-center rounded-lg">
        <FileText size={15} />
      </span>
      <span className="min-w-0 flex-1">
        <span className="block truncate text-xs font-medium text-[var(--foreground)]">
          {attachment.file_name}
        </span>
        <span className="app-text-muted mt-0.5 block text-[10px]">
          {formatFileSize(attachment.file_size)}
        </span>
      </span>
      <Download size={13} className="app-text-muted shrink-0" />
    </button>
  );
}