import { readdirSync, readFileSync } from "node:fs";
import { join } from "node:path";
import type { Db } from "./connect";

const MIGRATIONS_DIR = join(import.meta.dir, "..", "migrations");

function statements(text: string): string[] {
  const noComments = text.split("\n").filter((l) => !l.trim().startsWith("--")).join("\n");
  return noComments.split(";").map((s) => s.trim()).filter(Boolean);
}

export async function migrate(db: Db): Promise<string[]> {
  await db.sql.unsafe("CREATE TABLE IF NOT EXISTS schema_migrations (name TEXT PRIMARY KEY, applied_at TEXT NOT NULL)");
  const done = new Set((await db.sql`SELECT name FROM schema_migrations`).map((r: { name: string }) => r.name));
  const files = readdirSync(MIGRATIONS_DIR).filter((f) => f.endsWith(".sql")).sort();
  const applied: string[] = [];
  for (const name of files) {
    if (done.has(name)) continue;
    const stmts = statements(readFileSync(join(MIGRATIONS_DIR, name), "utf8"));
    await db.sql.begin(async (tx) => {
      for (const s of stmts) await tx.unsafe(s);
      await tx`INSERT INTO schema_migrations (name, applied_at) VALUES (${name}, ${new Date().toISOString()})`;
    });
    applied.push(name);
  }
  return applied;
}