/**
 * Podcast RSS Feed Generation Utilities
 * Generates RSS 2.0 with iTunes extensions for podcast distribution
 */

import { createClient } from "@supabase/supabase-js";

const supabaseUrl = process.env.NEXT_PUBLIC_SUPABASE_URL!;
const supabaseAnonKey = process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY!;

const supabase = createClient(supabaseUrl, supabaseAnonKey);

export interface PodcastEpisode {
  id: string;
  title: string;
  description: string;
  content: string;
  date: string;
  timestamp: number;
  audioUrl?: string;
  audioDuration?: number;
  tags?: string[];
}

export interface PodcastConfig {
  title: string;
  description: string;
  author: string;
  email: string;
  category: string;
  language: string;
  websiteUrl: string;
  imageUrl: string;
  explicit: boolean;
}

// Default podcast configuration
export const DEFAULT_CONFIG: PodcastConfig = {
  title: "OpenClaw Daily Digest",
  description: "Daily curated tech news covering AI coding assistants, iOS development, and digital entrepreneurship. AI-powered summaries delivered as audio.",
  author: "OpenClaw",
  email: "podcast@openclaw.ai",
  category: "Technology",
  language: "en-US",
  websiteUrl: "https://blog-backup-two.vercel.app",
  imageUrl: "https://blog-backup-two.vercel.app/podcast-cover.png",
  explicit: false,
};

/**
 * Parse title from markdown content
 */
export function extractTitle(content: string): string {
  const lines = content.split("\n");
  const titleLine = lines.find((l) => l.startsWith("# ") || l.startsWith("## "));
  return titleLine?.replace(/#{1,2}\s/, "").trim() || "Daily Digest";
}

/**
 * Extract plain text excerpt from markdown
 */
export function extractExcerpt(content: string, maxLength: number = 300): string {
  const plainText = content
    .replace(/#{1,6}\s/g, "")
    .replace(/(\*\*|__|\*|_)/g, "")
    .replace(/\[([^\]]+)\]\([^)]+\)/g, "$1")
    .replace(/```[\s\S]*?```/g, "")
    .replace(/`([^`]+)`/g, "$1")
    .replace(/<[^>]+>/g, "")
    .replace(/\n+/g, " ")
    .trim();

  if (plainText.length <= maxLength) return plainText;
  return plainText.substring(0, maxLength).trim() + "...";
}

/**
 * Format duration in seconds to HH:MM:SS or MM:SS
 */
export function formatDuration(seconds: number): string {
  const hours = Math.floor(seconds / 3600);
  const minutes = Math.floor((seconds % 3600) / 60);
  const secs = seconds % 60;

  if (hours > 0) {
    return `${hours}:${minutes.toString().padStart(2, "0")}:${secs.toString().padStart(2, "0")}`;
  }
  return `${minutes}:${secs.toString().padStart(2, "0")}`;
}

/**
 * Format date to RFC 2822 format for RSS
 */
export function formatRFC2822(date: Date | string | number): string {
  const d = new Date(date);
  return d.toUTCString();
}

/**
 * Escape XML special characters
 */
export function escapeXml(text: string): string {
  return text
    .replace(/&/g, "&amp;")
    .replace(/</g, "&lt;")
    .replace(/>/g, "&gt;")
    .replace(/"/g, "&quot;")
    .replace(/'/g, "&apos;");
}

/**
 * Generate unique GUID for episode
 */
export function generateGuid(episodeId: string): string {
  return `openclaw-digest-${episodeId}`;
}

/**
 * Fetch episodes from database
 */
export async function fetchEpisodes(limit: number = 50): Promise<PodcastEpisode[]> {
  const { data, error } = await supabase
    .from("blog_messages")
    .select("id, date, content, timestamp, audio_url, audio_duration, tags")
    .not("audio_url", "is", null) // Only episodes with audio
    .order("timestamp", { ascending: false })
    .limit(limit);

  if (error) {
    console.error("Error fetching episodes:", error);
    throw error;
  }

  return (data || []).map(item => ({
    id: item.id,
    title: extractTitle(item.content),
    description: extractExcerpt(item.content),
    content: item.content,
    date: item.date,
    timestamp: item.timestamp,
    audioUrl: item.audio_url,
    audioDuration: item.audio_duration || 300, // Default 5 min if not set
    tags: item.tags || [],
  }));
}

/**
 * Generate RSS feed XML
 */
export function generateRSS(episodes: PodcastEpisode[], config: PodcastConfig = DEFAULT_CONFIG): string {
  const now = new Date();
  const lastBuildDate = episodes.length > 0 
    ? new Date(episodes[0].timestamp) 
    : now;

  const itemsXml = episodes.map(episode => {
    const guid = generateGuid(episode.id);
    const pubDate = formatRFC2822(episode.timestamp);
    const duration = formatDuration(episode.audioDuration || 300);
    const enclosureUrl = escapeXml(episode.audioUrl || "");
    const title = escapeXml(episode.title);
    const description = escapeXml(episode.description);
    const keywords = episode.tags?.join(", ") || "technology, ai, programming";

    return `
    <item>
      <title>${title}</title>
      <description>${description}</description>
      <pubDate>${pubDate}</pubDate>
      <guid isPermaLink="false">${guid}</guid>
      <link>${escapeXml(`${config.websiteUrl}/?post=${episode.id}`)}</link>
      <enclosure url="${enclosureUrl}" length="${episode.audioDuration || 300}" type="audio/mpeg"/>
      <itunes:title>${title}</itunes:title>
      <itunes:author>${escapeXml(config.author)}</itunes:author>
      <itunes:summary>${description}</itunes:summary>
      <itunes:duration>${duration}</itunes:duration>
      <itunes:explicit>${config.explicit ? "yes" : "no"}</itunes:explicit>
      <itunes:keywords>${escapeXml(keywords)}</itunes:keywords>
    </item>`;
  }).join("\n");

  return `<?xml version="1.0" encoding="UTF-8"?>
<rss xmlns:itunes="http://www.itunes.com/dtds/podcast-1.0.dtd" xmlns:atom="http://www.w3.org/2005/Atom" version="2.0">
  <channel>
    <title>${escapeXml(config.title)}</title>
    <link>${escapeXml(config.websiteUrl)}</link>
    <description>${escapeXml(config.description)}</description>
    <language>${config.language}</language>
    <lastBuildDate>${formatRFC2822(lastBuildDate)}</lastBuildDate>
    <atom:link href="${escapeXml(`${config.websiteUrl}/api/podcast/rss`)}" rel="self" type="application/rss+xml"/>
    <itunes:author>${escapeXml(config.author)}</itunes:author>
    <itunes:summary>${escapeXml(config.description)}</itunes:summary>
    <itunes:category text="${escapeXml(config.category)}"/>
    <itunes:explicit>${config.explicit ? "yes" : "no"}</itunes:explicit>
    <itunes:image href="${escapeXml(config.imageUrl)}"/>
    <itunes:owner>
      <itunes:name>${escapeXml(config.author)}</itunes:name>
      <itunes:email>${escapeXml(config.email)}</itunes:email>
    </itunes:owner>
    ${itemsXml}
  </channel>
</rss>`;
}