import { execSync } from "node:child_process";
import fs from "node:fs";
import path from "node:path";
import { fileURLToPath } from "node:url";
import Database from "better-sqlite3";

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);
const ROOT_DIR = path.join(__dirname, "..");

const MIGRATIONS_DIR = path.join(ROOT_DIR, "migrations");
const TEST_DB_PATH = path.join(ROOT_DIR, "db-test.sqlite3");

export function setup() {
	ensureMigratedDb(TEST_DB_PATH);
}

/**
 * Ensures the SQLite file at `dbPath` has every migration applied: creates it
 * if missing, applies pending migrations, and rebuilds it from scratch if it
 * contains a migration that no longer exists on disk.
 */
export function ensureMigratedDb(dbPath: string) {
	const resolvedPath = path.resolve(ROOT_DIR, dbPath);

	if (!fs.existsSync(resolvedPath)) {
		migrateUp(resolvedPath);
		return;
	}

	const applied = appliedMigrations(resolvedPath);
	const onDisk = migrationFilesOnDisk();

	const hasDrift =
		applied === null || applied.some((name) => !onDisk.has(name));
	if (hasDrift) {
		deleteDbFiles(resolvedPath);
		migrateUp(resolvedPath);
		return;
	}

	const appliedSet = new Set(applied);
	const hasPending = [...onDisk].some((name) => !appliedSet.has(name));
	if (hasPending) {
		migrateUp(resolvedPath);
	}
}

function migrationFilesOnDisk() {
	return new Set(
		fs.readdirSync(MIGRATIONS_DIR).filter((file) => file.endsWith(".js")),
	);
}

function appliedMigrations(dbPath: string) {
	const db = new Database(dbPath, { readonly: true });
	try {
		const hasMigrationsTable = db
			.prepare(
				"select 1 from sqlite_master where type = 'table' and name = 'migrations'",
			)
			.get();
		if (!hasMigrationsTable) return null;

		const rows = db.prepare("select name from migrations").all() as Array<{
			name: string;
		}>;
		return rows.map((row) => row.name);
	} catch {
		return null;
	} finally {
		db.close();
	}
}

function deleteDbFiles(dbPath: string) {
	for (const suffix of ["", "-shm", "-wal"]) {
		fs.rmSync(`${dbPath}${suffix}`, { force: true });
	}
}

function migrateUp(dbPath: string) {
	execSync("pnpm run migrate up", {
		cwd: ROOT_DIR,
		stdio: "inherit",
		env: { ...process.env, DB_PATH: dbPath },
	});
}