// Episode scripts are filed by season + episode number ("2-1"), because each book of the Bible
// is its own podcast season and episode numbers can restart in every season. A script with no
// season keeps its plain episode number as its key.

export function scriptKey(season, episodeNumber) {
  const ep = String(episodeNumber ?? '').trim()
  const s = String(season ?? '').trim()
  return /^\d+$/.test(s) ? `${s}-${ep}` : ep
}

// The episode number a stored script belongs to (new entries record it; legacy ones are keyed by it).
export function scriptEpisodeNumber(key, entry) {
  if (entry && typeof entry.episodeNumber === 'string' && entry.episodeNumber) return entry.episodeNumber
  const parts = String(key).split('-')
  return parts[parts.length - 1]
}

// One-time move of legacy scripts ({ "7": { season: "1" } }) to season-episode keys ({ "1-7": ... }).
// Scripts without a season stay under their plain episode number. Never overwrites an existing key.
export function migrateScriptKeys(scripts) {
  const next = {}
  let changed = false
  for (const [key, entry] of Object.entries(scripts ?? {})) {
    if (!entry || typeof entry !== 'object') continue
    const episodeNumber = scriptEpisodeNumber(key, entry)
    const wanted = scriptKey(entry.season, episodeNumber)
    const targetKey = wanted !== key && !(wanted in scripts) && !(wanted in next) ? wanted : key
    const withEpisode = entry.episodeNumber === episodeNumber ? entry : { ...entry, episodeNumber }
    if (targetKey !== key || withEpisode !== entry) changed = true
    next[targetKey] = withEpisode
  }
  return { scripts: next, changed }
}