<?php
namespace Vichan\Data;


class SearchQueries {
	private \PDO $pdo;
	private int $queries_per_minutes_single;
	private int $queries_per_minutes_all;
	private bool $auto_gc;


	private function checkFloodImpl(string $ip, string $phrase): bool {
		$now = \time();
		$expiry_limit = \time() - ($this->queries_per_minutes_all * 60);

		$query = $this->pdo->prepare("SELECT COUNT(*) FROM `search_queries` WHERE `ip` = :ip AND `time` > :time AND `time` <= :expiry_limit");
		$query->bindValue(':ip', $ip);
		$query->bindValue(':time', $now - ($this->queries_per_minutes_single * 60), \PDO::PARAM_INT);
		$query->bindValue(':expiry_limit', $expiry_limit, \PDO::PARAM_INT);
		$query->execute();
		if ($query->fetchColumn() > $this->queries_per_minutes_single) {
			return false;
		}

		$query = $this->pdo->prepare("SELECT COUNT(*) FROM `search_queries` WHERE `time` > :time AND `time` <= :expiry_limit");
		$query->bindValue(':time', $now - ($this->queries_per_minutes_all * 60), \PDO::PARAM_INT);
		$query->bindValue(':expiry_limit', $expiry_limit, \PDO::PARAM_INT);
		$query->execute();
		if ($query->fetchColumn() > $this->queries_per_minutes_all) {
			return false;
		}

		$query = $this->pdo->prepare("INSERT INTO `search_queries` VALUES (:ip, :time, :query)");
		$query->bindValue(':ip', $ip);
		$query->bindValue(':time', $now, \PDO::PARAM_INT);
		$query->bindValue(':query', $phrase);
		$query->execute();

		if ($this->auto_gc) {
			$this->purgeExpired();
		}

		return true;
	}

	public function __construct(\PDO $pdo, int $queries_per_minutes_single, int $queries_per_minutes_all, bool $auto_gc) {
		$this->pdo = $pdo;
		$this->queries_per_minutes_single = $queries_per_minutes_single;
		$this->queries_per_minutes_all = $queries_per_minutes_all;
		$this->auto_gc = $auto_gc;
	}

	/**
	 * Check if the IP-query pair overflows the limit.
	 *
	 * @param string $ip Source IP.
	 * @param string $phrase The search query.
	 * @return bool True if the request goes over the limit
	 */
	public function checkFlood(string $ip, string $phrase): bool {
		$this->pdo->beginTransaction();
		try {
			$ret = $this->checkFloodImpl($ip, $phrase);
			$this->pdo->commit();
			return $ret;
		} catch (\Exception $e) {
			$this->pdo->rollBack();
			throw $e;
		}
	}

	public function purgeExpired(): int {
		// Cleanup search queries table.
		$query = prepare("DELETE FROM `search_queries` WHERE `time` <= :expiry_limit");
		$query->bindValue(':expiry_limit', \time() - ($this->queries_per_minutes_all * 60), \PDO::PARAM_INT);
		$query->execute();
		return $query->rowCount();
	}
}