import { connect } from '@tursodatabase/database';
import { readFile } from 'node:fs/promises';
import { resolve } from 'node:path';
import process from 'node:process';

const backupArgument = process.argv[2];
if (!backupArgument) {
	console.error('Usage: npm run db:restore -- <backup-file>');
	process.exit(2);
}

const backupPath = resolve(backupArgument);
const databasePath = resolve(process.env.TDR_DATABASE_PATH || './data/shd-build-development.db');
const backup = JSON.parse(await readFile(backupPath, 'utf8'));
if (backup?.format !== 'shd-build-database-backup' || backup?.version !== 1 || !Array.isArray(backup.tables)) {
	throw new Error('The selected file is not a supported SHD.build database backup.');
}

const quoteIdentifier = (identifier) => `"${String(identifier).replaceAll('"', '""')}"`;
const database = await connect(databasePath);

// Restores are deliberately limited to empty databases. This prevents an
// accidental merge from overwriting contributor-entered records.
for (const table of backup.tables) {
	const existing = await (
		await database.prepare(`SELECT COUNT(*) AS count FROM ${quoteIdentifier(table.name)}`)
	).get();
	if (Number(existing?.count) > 0) {
		throw new Error(
			`Restore refused: table "${table.name}" is not empty. Use a new migrated database.`
		);
	}
}

let restoredRows = 0;
await database.exec('BEGIN');
try {
	for (const table of backup.tables) {
		for (const row of table.rows) {
			const columns = Object.keys(row);
			if (!columns.length) continue;
			const columnSql = columns.map(quoteIdentifier).join(', ');
			const placeholders = columns.map(() => '?').join(', ');
			const insert = await database.prepare(
				`INSERT INTO ${quoteIdentifier(table.name)} (${columnSql}) VALUES (${placeholders})`
			);
			await insert.run(...columns.map((column) => row[column]));
			restoredRows++;
		}
	}
	await database.exec('COMMIT');
} catch (error) {
	await database.exec('ROLLBACK');
	throw error;
}

console.log(`Restored ${restoredRows} rows into ${databasePath}.`);
console.log(`Source backup: ${backupPath}`);