import { MigrationInterface, QueryRunner } from 'typeorm';

export class PhaseF31FindingCatalogMerge1789844900000 implements MigrationInterface {
  name = 'PhaseF31FindingCatalogMerge1789844900000';

  public async up(queryRunner: QueryRunner): Promise<void> {
    await queryRunner.query(`
      CREATE TABLE finding_catalog_item_merges (
        id uuid PRIMARY KEY DEFAULT gen_random_uuid(),
        source_item_id uuid NOT NULL REFERENCES finding_catalog_items(id) ON DELETE RESTRICT,
        canonical_item_id uuid NOT NULL REFERENCES finding_catalog_items(id) ON DELETE RESTRICT,
        reason text NOT NULL,
        merged_at timestamptz NOT NULL DEFAULT CURRENT_TIMESTAMP,
        merged_by uuid NULL REFERENCES users(id) ON DELETE SET NULL,
        request_id varchar(128) NULL,
        source_snapshot jsonb NOT NULL,
        canonical_snapshot jsonb NOT NULL,
        CONSTRAINT chk_finding_catalog_item_merges_distinct CHECK (source_item_id <> canonical_item_id),
        CONSTRAINT uq_finding_catalog_item_merges_source UNIQUE (source_item_id)
      )
    `);
    await queryRunner.query(`CREATE INDEX idx_finding_catalog_item_merges_canonical ON finding_catalog_item_merges(canonical_item_id)`);
    await queryRunner.query(`CREATE INDEX idx_finding_catalog_item_merges_at ON finding_catalog_item_merges(merged_at)`);
    await queryRunner.query(`
      CREATE OR REPLACE FUNCTION protect_finding_catalog_item_merges_append_only()
      RETURNS trigger
      LANGUAGE plpgsql
      AS $$
      BEGIN
        RAISE EXCEPTION 'finding_catalog_item_merges es append-only; una fusión de catálogo no puede editarse ni borrarse';
      END;
      $$
    `);
    await queryRunner.query(`
      CREATE TRIGGER trg_finding_catalog_item_merges_append_only
      BEFORE UPDATE OR DELETE ON finding_catalog_item_merges
      FOR EACH ROW EXECUTE FUNCTION protect_finding_catalog_item_merges_append_only()
    `);
  }

  public async down(queryRunner: QueryRunner): Promise<void> {
    await queryRunner.query('DROP TRIGGER IF EXISTS trg_finding_catalog_item_merges_append_only ON finding_catalog_item_merges');
    await queryRunner.query('DROP FUNCTION IF EXISTS protect_finding_catalog_item_merges_append_only()');
    await queryRunner.query('DROP TABLE IF EXISTS finding_catalog_item_merges');
  }
}