import db from '@adonisjs/lucid/services/db'
import env from '#start/env'

/** Months ahead that always have a release_chunks partition. */
const AHEAD = 2

/**
 * release_chunks is partitioned by month of writing (REBUILD.md, decision a).
 * Inserts fail without a partition for now(), so the current and the next
 * months' partitions are created before they are needed; checked once per
 * process and month.
 */
class ChunkPartitions {
  private ensuredFor: string | null = null

  async ensure(now = new Date()) {
    const month = now.toISOString().slice(0, 7)
    if (this.ensuredFor === month) return
    const tablespace = env.get('CHUNK_TABLESPACE')
    for (let i = 0; i <= AHEAD; i++) {
      const from = new Date(Date.UTC(now.getUTCFullYear(), now.getUTCMonth() + i, 1))
      const to = new Date(Date.UTC(now.getUTCFullYear(), now.getUTCMonth() + i + 1, 1))
      const name = `release_chunks_${from.toISOString().slice(0, 7).replace('-', '')}`
      await db.rawQuery(
        `CREATE TABLE IF NOT EXISTS ${name} PARTITION OF release_chunks FOR VALUES FROM ('${from.toISOString()}') TO ('${to.toISOString()}')${tablespace ? ` TABLESPACE ${tablespace}` : ''}`
      )
    }
    this.ensuredFor = month
  }
}

export default new ChunkPartitions()