/**
 * Apply the schema migrations to a Postgres database.
 *
 * Reads the SQL files from infra/init-sql/ and runs them in lexical
 * order. Idempotent — safe to run on every boot.
 *
 * In production you'd use a proper migration tool (drizzle-kit,
 * prisma, knex, sqlx, etc.). For Phase 1 we just want a simple,
 * zero-deps way to get the schema into a fresh database.
 */
import { readFile, readdir } from 'node:fs/promises';
import { join, dirname, resolve } from 'node:path';
import { fileURLToPath } from 'node:url';
import type { Sql } from 'postgres';

const INIT_SQL_DEFAULT = '../../../infra/init-sql';

export async function runMigrations(
  sql: Sql,
  initDir: string = INIT_SQL_DEFAULT,
): Promise<{ applied: string[] }> {
  const dir = resolve(dirname(fileURLToPath(import.meta.url)), initDir);
  const entries = (await readdir(dir)).filter((f) => f.endsWith('.sql')).sort();

  const applied: string[] = [];
  for (const file of entries) {
    const path = join(dir, file);
    const content = await readFile(path, 'utf8');
    try {
      await sql.unsafe(content);
      applied.push(file);
    } catch (err) {
      // Some errors are non-fatal (e.g. "extension already exists" race),
      // but anything else should fail loudly.
      if (isBenignError(err)) {
        applied.push(`${file} (skipped: ${(err as Error).message.split('\n')[0]})`);
        continue;
      }
      throw new Error(`Migration ${file} failed: ${(err as Error).message}`);
    }
  }
  return { applied };
}

function isBenignError(err: unknown): boolean {
  const msg = String((err as Error).message ?? err);
  return /already exists/i.test(msg) || /duplicate key/i.test(msg);
}