import { readdirSync, readFileSync } from "node:fs"
import { dirname, join } from "node:path"
import { fileURLToPath } from "node:url"
import type { Pool } from "pg"

const FIRST_MIGRATION = "0000_postgresql.sql"

function migrationsDir(): string {
  const here = dirname(fileURLToPath(import.meta.url))
  const candidates = [
    join(here, "..", "..", "drizzle"),
    join(process.cwd(), "drizzle"),
    join(process.cwd(), "backend", "drizzle"),
  ]
  for (const dir of candidates) {
    try {
      readFileSync(join(dir, FIRST_MIGRATION), "utf8")
      return dir
    } catch {
      /* try next */
    }
  }
  throw new Error("Не найден backend/drizzle/0000_postgresql.sql")
}

function migrationId(file: string): string {
  return file.replace(/\.sql$/i, "")
}

export async function applySqlMigrations(pool: Pool): Promise<void> {
  await pool.query(`
    CREATE TABLE IF NOT EXISTS schema_migrations (
      id TEXT PRIMARY KEY,
      applied_at TIMESTAMPTZ NOT NULL DEFAULT now()
    )
  `)
  const dir = migrationsDir()
  const files = readdirSync(dir)
    .filter((f) => /^\d{4}_.+\.sql$/i.test(f))
    .sort((a, b) => a.localeCompare(b))
  const applied = new Set(
    (await pool.query<{ id: string }>(`SELECT id FROM schema_migrations`)).rows.map((r) => r.id),
  )
  for (const file of files) {
    const id = migrationId(file)
    if (applied.has(id)) continue
    const sql = readFileSync(join(dir, file), "utf8")
    await pool.query(sql)
    await pool.query(
      `INSERT INTO schema_migrations (id) VALUES ($1) ON CONFLICT (id) DO NOTHING`,
      [id],
    )
  }
}