import db from '@adonisjs/lucid/services/db'
import { decodeChunk } from '#lib/chunks/index'
import { buildNzb } from '#lib/nzb/index'

/**
 * A release's NZB (REBUILD.md, part 9), from its chunks in the chunk store:
 * every chunk decoded, its files in name order. A file stored twice (the same
 * name and first article, e.g. a range read again) is taken once.
 */
class NzbService {
  async build(releaseId: number): Promise<{ name: string; xml: string } | null> {
    const release = await db.from('releases').where('id', releaseId).select('name').first()
    if (!release) return null
    const chunks = await db.from('release_chunks').where('release_id', releaseId).orderBy('id').select('payload')
    const files = new Map<string, ReturnType<typeof decodeChunk>[number]>()
    for (const chunk of chunks) {
      for (const file of decodeChunk(chunk.payload)) files.set(`${file.name}\n${file.segments[0]?.[1] ?? ''}`, file)
    }
    const xml = buildNzb(
      [...files.values()]
        .sort((a, b) => a.name.localeCompare(b.name))
        .map((f) => ({
          name: f.name,
          poster: f.poster,
          date: f.postedAt ?? 0,
          groups: f.groups,
          segments: f.segments.map(([number, id, size]) => ({ number, id, size })),
        })),
      { title: release.name }
    )
    return { name: release.name, xml }
  }
}

export default new NzbService()