// Shared podcast-RSS parsing, used by both the main show (episodes.js) and
// any sub-show fed by its own feed URL (nuggets.js).

export function extractCdata(raw) {
  const cdata = /^<!\[CDATA\[([\s\S]*?)\]\]>$/.exec(raw.trim())
  return cdata ? cdata[1].trim() : raw.trim()
}

function decodeEntities(str) {
  return str
    .replace(/&amp;/g, '&')
    .replace(/&lt;/g, '<')
    .replace(/&gt;/g, '>')
    .replace(/&quot;/g, '"')
    .replace(/&apos;/g, "'")
    .replace(/&#39;/g, "'")
    .replace(/&#(\d+);/g, (_, n) => String.fromCharCode(Number(n)))
    .replace(/&#x([0-9a-fA-F]+);/g, (_, h) => String.fromCharCode(parseInt(h, 16)))
    .replace(/&nbsp;/g, ' ')
}

export function parseRssItems(xml, limit = Infinity) {
  const items = []
  const itemRegex = /<item>([\s\S]*?)<\/item>/g
  let match
  while ((match = itemRegex.exec(xml)) !== null && items.length < limit) {
    const block = match[1]
    const titleRaw = /<title>([\s\S]*?)<\/title>/.exec(block)?.[1] ?? ''
    const title = extractCdata(titleRaw)
    if (!title) continue

    const pubDate = (/<pubDate>([\s\S]*?)<\/pubDate>/.exec(block)?.[1] ?? '').trim()
    const guidRaw = /<guid[^>]*>([\s\S]*?)<\/guid>/.exec(block)?.[1] ?? ''
    const guid = extractCdata(guidRaw)
    const enclosureUrl = /<enclosure[^>]+url="([^"]+)"/.exec(block)?.[1] ?? ''
    const link = guid.startsWith('http') ? guid : enclosureUrl
    const descRaw = /<description>([\s\S]*?)<\/description>/.exec(block)?.[1] ?? ''
    const descText = decodeEntities(extractCdata(descRaw).replace(/<[^>]+>/g, '')).replace(/\s+/g, ' ').trim()
    const duration = (/<itunes:duration>([\s\S]*?)<\/itunes:duration>/.exec(block)?.[1] ?? '').trim()
    const episode = (/<itunes:episode>([\s\S]*?)<\/itunes:episode>/.exec(block)?.[1] ?? '').trim()
    const season = (/<itunes:season>([\s\S]*?)<\/itunes:season>/.exec(block)?.[1] ?? '').trim()
    items.push({
      title, pubDate, link,
      audioUrl: enclosureUrl,
      description: descText.slice(0, 220) + (descText.length > 220 ? '…' : ''),
      duration, episode, season,
    })
  }
  return items
}