import Parser from "rss-parser";

import type { ContentItem } from "../content/types";

type YoutubeApiVideo = {
  id: string;
  url: string;
  title: string;
  summary?: string;
  publishedAt: string;
  thumbnailUrl?: string;
  views?: number;
};

function stripHtml(s: string) {
  return (s || "")
    .replace(/<[^>]+>/g, " ")
    .replace(/\s+/g, " ")
    .trim();
}

function truncate(s: string, n: number) {
  const t = stripHtml(s);
  if (!t) return "";
  if (t.length <= n) return t;
  return `${t.slice(0, Math.max(0, n - 1)).trimEnd()}…`;
}

export async function fetchYoutubeViaRss(channelId: string, limit = 20): Promise<ContentItem[]> {
  const feedUrl = `https://www.youtube.com/feeds/videos.xml?channel_id=${encodeURIComponent(channelId)}`;
  const parser = new Parser();
  const feed = await parser.parseURL(feedUrl);

  return normalizeYoutubeRssFeedItems(feed.items || [], limit);
}

async function youtubeApiGetJson<T>(url: string): Promise<T> {
  const res = await fetch(url);
  if (!res.ok) throw new Error(`YouTube API request failed: ${res.status} ${res.statusText}`);
  return (await res.json()) as T;
}

export function normalizeYoutubeRssFeedItems(items: any[], limit: number): ContentItem[] {
  return (items || [])
    .slice(0, limit)
    .map((it) => {
      const url = it.link || "";
      const id = (it.id || url).toString();
      const publishedAt = (it.isoDate || it.pubDate || new Date(0).toISOString()).toString();
      const summary = truncate(
        (it.contentSnippet || it.summary || it.content || it["content:encoded"] || "").toString(),
        240,
      );
      return {
        id,
        source: "youtube" as const,
        url,
        title: (it.title || "").toString(),
        summary: summary || undefined,
        publishedAt: new Date(publishedAt).toISOString(),
        thumbnailUrl: (it.enclosure?.url || undefined) as string | undefined,
      };
    })
    .filter((x) => x.url && x.title);
}

export function normalizeYoutubeApiVideos(
  items: Array<{
    id: string;
    snippet: {
      title: string;
      description?: string;
      publishedAt: string;
      thumbnails?: Record<string, { url: string }>;
    };
    statistics?: { viewCount?: string };
  }>,
): ContentItem[] {
  const normalized: YoutubeApiVideo[] = (items || []).map((v) => ({
    id: v.id,
    url: `https://www.youtube.com/watch?v=${encodeURIComponent(v.id)}`,
    title: v.snippet.title,
    summary: v.snippet.description ? truncate(v.snippet.description, 240) : undefined,
    publishedAt: new Date(v.snippet.publishedAt).toISOString(),
    thumbnailUrl: v.snippet.thumbnails?.high?.url || v.snippet.thumbnails?.default?.url,
    views: v.statistics?.viewCount ? Number(v.statistics.viewCount) : undefined,
  }));

  return normalized.map<ContentItem>((v) => ({
    id: v.id,
    source: "youtube",
    url: v.url,
    title: v.title,
    summary: v.summary,
    publishedAt: v.publishedAt,
    thumbnailUrl: v.thumbnailUrl,
    metrics: v.views !== undefined ? { views: v.views } : undefined,
  }));
}

export async function fetchYoutubeViaApi(
  channelId: string,
  apiKey: string,
  limit = 20,
): Promise<ContentItem[]> {
  // 1) Get latest video IDs from channel.
  const searchUrl =
    "https://www.googleapis.com/youtube/v3/search" +
    `?part=snippet&channelId=${encodeURIComponent(channelId)}` +
    `&maxResults=${encodeURIComponent(String(limit))}` +
    `&order=date&type=video&key=${encodeURIComponent(apiKey)}`;

  const search = await youtubeApiGetJson<{
    items: Array<{
      id: { videoId: string };
      snippet: { title: string; publishedAt: string; thumbnails?: any };
    }>;
  }>(searchUrl);

  const videoIds = (search.items || []).map((x) => x.id.videoId).filter(Boolean);
  if (videoIds.length === 0) return [];

  // 2) Fetch statistics.
  const videosUrl =
    "https://www.googleapis.com/youtube/v3/videos" +
    `?part=snippet,statistics&maxResults=${encodeURIComponent(String(videoIds.length))}` +
    `&id=${encodeURIComponent(videoIds.join(","))}` +
    `&key=${encodeURIComponent(apiKey)}`;

  const videos = await youtubeApiGetJson<{
    items: Array<{
      id: string;
      snippet: { title: string; publishedAt: string; thumbnails?: Record<string, { url: string }> };
      statistics?: { viewCount?: string };
    }>;
  }>(videosUrl);

  return normalizeYoutubeApiVideos(videos.items || []);
}