import rss from '@astrojs/rss';
import { getCollection } from 'astro:content';

function formatPubDate(date) {
  const timezone = process.env.PUBLIC_RSS_TIMEZONE
    ? process.env.PUBLIC_RSS_TIMEZONE
    : import.meta.env.PUBLIC_RSS_TIMEZONE;
  
  if (!timezone) {
    return date;
  }
  
  try {
    const year = date.getUTCFullYear();
    const month = String(date.getUTCMonth() + 1).padStart(2, '0');
    const day = String(date.getUTCDate()).padStart(2, '0');
    
    const formatter = new Intl.DateTimeFormat('en-US', {
      timeZone: timezone,
      timeZoneName: 'longOffset',
    });

    const parts = formatter.formatToParts(date);
    const offsetPart = parts.find(p => p.type === 'timeZoneName');
    const offset = offsetPart ? offsetPart.value.replace('GMT', '') : '+00:00';

    const dateStr = `${year}-${month}-${day}T00:00:00${offset}`;
    
    return new Date(dateStr);
  } catch (e) {
    console.warn(`Invalid timezone "${timezone}":`, e.message);
    return date;
  }
}

export async function GET(context) {
  const posts = await getCollection('posts');
  
  return rss({
    title: 'Atridad Lahiji',
    description: 'Recent posts from Atridad Lahiji',
    site: context.site,
    items: posts.map((post) => ({
      title: post.data.title,
      pubDate: formatPubDate(post.data.pubDate),
      description: post.data.description || '',
      link: `/post/${post.slug}/`,
    })),
    customData: `<language>en-us</language>`,
  });
}