import "dotenv/config";
import { DataSource, DataSourceOptions } from "typeorm";
import {
  ensurePostgresSchemas,
  APPLICATION_SEARCH_PATH,
} from "../config/ensure-postgres-schemas";
import {
  buildDataSourceOptions,
  buildIamMigrationDataSourceOptions,
  buildFreightMigrationDataSourceOptions,
  FREIGHT_MIGRATIONS,
  // IAM_MIGRATIONS,
  LEGACY_MIGRATIONS,
} from "../config/database.config";

/**
 * Migrations run as two independent histories:
 *
 *   1. IAM  — migrations shipped by `@tria-plc/iamapi-common`, recorded in
 *      `iam.typeorm_migrations`.
 *   2. Freight — this app's `src/migrations/*`, recorded in `freight.migrations`.
 *
 * They used to share `public.migrations`, which meant a single ordered history
 * across two independently versioned sources: dropping in a new IAM package
 * release interleaved its migrations with freight's by timestamp, and
 * `migration:revert` could not tell the two apart. `adoptLegacyHistory()` below
 * moves the existing rows into the two tables on the first run after this change,
 * so nothing re-runs.
 */

/**
 * The pooler in front of the remote DB rejects the Postgres `options` startup
 * parameter, so search_path is set per physical connection instead. pg queues the
 * SET on the client before the pool hands it to a caller, so every query a
 * migration issues already sees the full schema search order.
 */
function applySearchPath(dataSource: DataSource): void {
  const pool = (dataSource.driver as { master?: unknown }).master as
    | { on?: (event: string, cb: (client: unknown) => void) => void }
    | undefined;

  pool?.on?.("connect", (client) => {
    (client as { query: (sql: string) => Promise<unknown> })
      .query(`SET search_path TO ${APPLICATION_SEARCH_PATH}`)
      .catch(() => {
        /* connection will be validated on first real query */
      });
  });
}

async function initialize(options: DataSourceOptions): Promise<DataSource> {
  const dataSource = new DataSource(options);
  await dataSource.initialize();
  applySearchPath(dataSource);
  return dataSource;
}

function qualified({
  schema,
  table,
}: {
  schema: string;
  table: string;
}): string {
  return `"${schema}"."${table}"`;
}

/** Same shape TypeORM's MigrationExecutor creates for a Postgres history table. */
async function createHistoryTable(
  dataSource: DataSource,
  target: { schema: string; table: string },
): Promise<void> {
  await dataSource.query(
    `CREATE TABLE IF NOT EXISTS ${qualified(target)} (
       "id" SERIAL NOT NULL,
       "timestamp" bigint NOT NULL,
       "name" character varying NOT NULL,
       CONSTRAINT "PK_${target.schema}_${target.table}" PRIMARY KEY ("id")
     )`,
  );
}

async function countRows(
  dataSource: DataSource,
  target: { schema: string; table: string },
): Promise<number> {
  const [{ count }] = (await dataSource.query(
    `SELECT count(*)::int AS count FROM ${qualified(target)}`,
  )) as [{ count: number }];
  return count;
}

/**
 * Copy the pre-split `public.migrations` rows into the per-owner tables.
 *
 * Only fills a table that is still empty — once a history is live it is the
 * source of truth, and re-copying would resurrect rows that a deliberate
 * `migration:revert` removed. `public.migrations` is intentionally left in place:
 * it is the rollback path if an older build of this app is redeployed.
 */
async function adoptLegacyHistory(
  dataSource: DataSource,
  iamMigrationNames: string[],
): Promise<void> {
  const legacyExists = (await dataSource.query(
    `SELECT to_regclass($1) IS NOT NULL AS present`,
    [`${LEGACY_MIGRATIONS.schema}.${LEGACY_MIGRATIONS.table}`],
  )) as [{ present: boolean }];

  if (!legacyExists[0].present) return;

  // await createHistoryTable(dataSource, IAM_MIGRATIONS);
  await createHistoryTable(dataSource, FREIGHT_MIGRATIONS);

  const adopt = async (
    target: { schema: string; table: string },
    /** true → rows whose name is an IAM migration; false → everything else. */
    isIam: boolean,
  ): Promise<void> => {
    if ((await countRows(dataSource, target)) > 0) return;

    const inserted = (await dataSource.query(
      `INSERT INTO ${qualified(target)} ("timestamp", "name")
       SELECT legacy."timestamp", legacy."name"
       FROM ${qualified(LEGACY_MIGRATIONS)} legacy
       WHERE legacy."name" ${isIam ? "= ANY" : "<> ALL"}($1::text[])
       ORDER BY legacy."timestamp"
       RETURNING "name"`,
      [iamMigrationNames],
    )) as unknown[];

    console.log(
      `adopted ${inserted.length} row(s) from ${qualified(LEGACY_MIGRATIONS)} into ${qualified(target)}`,
    );
  };

  // await adopt(IAM_MIGRATIONS, true);
  await adopt(FREIGHT_MIGRATIONS, false);
}

async function runMigrations(
  label: string,
  dataSource: DataSource,
): Promise<void> {
  const applied = await dataSource.runMigrations();
  for (const migration of applied) {
    console.log(`applied [${label}]: ${migration.name}`);
  }
  if (applied.length === 0) console.log(`no pending ${label} migrations`);
}

export async function runAllMigrations(): Promise<void> {
  await ensurePostgresSchemas(buildDataSourceOptions());

  const iam = await initialize(buildIamMigrationDataSourceOptions());
  try {
    const iamMigrationNames = iam.migrations.map(
      (migration) => migration.name ?? migration.constructor.name,
    );
    await adoptLegacyHistory(iam, iamMigrationNames);
    // IAM migrations are owned by @tria-plc/iamapi-common's own CLI, not the
    // freight deploy — do not apply them here.
    // await runMigrations("iam", iam);
  } finally {
    await iam.destroy();
  }

  const freight = await initialize(buildFreightMigrationDataSourceOptions());
  try {
    await runMigrations("freight", freight);
  } finally {
    await freight.destroy();
  }
}

if (require.main === module) {
  runAllMigrations().catch((err) => {
    console.error(err);
    process.exit(1);
  });
}