import { MigrationInterface, QueryRunner } from "typeorm";

/**
 * A station's plan is per station AND per cargo type, not per station.
 *
 * The OCC monthly report plans "Nagad–Mojo multimodal container 122,010 t" and
 * "Nagad–Mojo fertilizer 18,000 t" as separate lines against the same station,
 * which the single `dimension_key` column cannot express: a station-keyed target
 * would apply the whole station's plan to each of its cargo types.
 *
 * `cargo_category` is nullable, so `cargo_category` and `container_class`
 * targets are unaffected — they leave it null and stay keyed on
 * `dimension_key` alone. The uniqueness index moves to include it, since
 * (station, category) is now the slot.
 */
export class OperationsTargetCargoCategory3590000000000 implements MigrationInterface {
  name = "OperationsTargetCargoCategory3590000000000";

  public async up(queryRunner: QueryRunner): Promise<void> {
    await queryRunner.query(`
      ALTER TABLE freight.operations_targets
        ADD COLUMN IF NOT EXISTS cargo_category varchar(60);
    `);

    await queryRunner.query(`DROP INDEX IF EXISTS freight.ux_operations_targets_slot;`);

    // COALESCE rather than a plain column list: a partial unique index treats
    // NULLs as distinct, which would let the same category target be entered
    // twice over.
    await queryRunner.query(`
      CREATE UNIQUE INDEX IF NOT EXISTS ux_operations_targets_slot
        ON freight.operations_targets (
          period_type, period_start, metric, dimension, dimension_key,
          COALESCE(cargo_category, '')
        )
        WHERE deleted_at IS NULL;
    `);
  }

  public async down(queryRunner: QueryRunner): Promise<void> {
    await queryRunner.query(`DROP INDEX IF EXISTS freight.ux_operations_targets_slot;`);
    await queryRunner.query(`
      CREATE UNIQUE INDEX IF NOT EXISTS ux_operations_targets_slot
        ON freight.operations_targets (period_type, period_start, metric, dimension, dimension_key)
        WHERE deleted_at IS NULL;
    `);
    await queryRunner.query(`
      ALTER TABLE freight.operations_targets DROP COLUMN IF EXISTS cargo_category;
    `);
  }
}