import { BaseSchema } from '@adonisjs/lucid/schema'

/**
 * yEnc CRCs of body-derived articles, so split volumes can be verified
 * without downloading them (CONCEPT.md D20): the combined part CRCs of a
 * volume must equal the whole-file crc32 in its last part.
 */
export default class extends BaseSchema {
  async up() {
    for (const tableName of ['parts', 'part_conflicts']) {
      this.schema.alterTable(tableName, (table) => {
        table.string('pcrc32', 8)
        // Decoded length of the part (=ypart end - begin + 1).
        table.integer('part_size')
        // Whole-file CRC32, when the poster included it (usually in the last part).
        table.string('file_crc32', 8)
      })
    }
  }

  async down() {
    for (const tableName of ['parts', 'part_conflicts']) {
      this.schema.alterTable(tableName, (table) => {
        table.dropColumn('pcrc32')
        table.dropColumn('part_size')
        table.dropColumn('file_crc32')
      })
    }
  }
}