<?php
namespace Swoole\Coroutine\Pool;

class MySQLException extends \Exception {}

use Swoole\Coroutine;

class MySQLPool
{
    static protected $init = false;

    static protected $spareConns = [];

    static protected $busyConns = [];

    static protected $connsConfig;

    static protected $connsNameMap = [];

    static protected $pendingFetchCount = [];

    static protected $resumeFetchCount = [];

    /**
     * @param array $connsConfig
     *
     * @throws MySQLException
     */
    static public function init(array $connsConfig)
    {
        if (self::$init) {
            return;
        }
        self::$connsConfig = $connsConfig;
        foreach ($connsConfig as $name => $config) {
            self::$spareConns[$name] = [];
            self::$busyConns[$name] = [];
            self::$pendingFetchCount[$name] = [];
            self::$resumeFetchCount[$name] = 0;
            if ($config['maxSpareConns'] <= 0 || $config['maxConns'] <= 0) {
                throw new MySQLException("Invalid maxSpareConns or maxConns in {$name}");
            }
        }
        self::$init = true;
    }

    /**
     * @param \Swoole\Coroutine\MySQL $conn
     *
     * @throws MySQLException
     */
    static public function recycle(\Swoole\Coroutine\MySQL $conn)
    {
        if (!self::$init) {
            throw new MySQLException('Should call MySQLPool::init.');
        }
        $id = spl_object_hash($conn);
        $connName = self::$connsNameMap[$id];
        if (isset(self::$busyConns[$connName][$id])) {
            unset(self::$busyConns[$connName][$id]);
        } else {
            throw new MySQLException('Unknow MySQL connection.');
        }
        $connsPool = &self::$spareConns[$connName];
        if ($conn->connected) {
            if (count($connsPool) >= self::$connsConfig[$connName]['maxSpareConns']) {
                $conn->close();
            } else {
                $connsPool[] = $conn;
                if (count(self::$pendingFetchCount[$connName]) > 0) {
                    self::$resumeFetchCount[$connName]++;
                    \Swoole\Coroutine::resume(array_shift(self::$pendingFetchCount[$connName]));
                }
                return;
            }
        }
        unset(self::$connsNameMap[$id]);
    }

    /**
     * @param $connName
     *
     * @return bool|mixed|\Swoole\Coroutine\MySQL
     * @throws MySQLException
     */
    static public function fetch($connName)
    {
        if (!self::$init) {
            throw new MySQLException('Should call MySQLPool::init!');
        }
        if (!isset(self::$connsConfig[$connName])) {
            throw new MySQLException("Unvalid connName: {$connName}.");
        }
        $connsPool = &self::$spareConns[$connName];
        if (!empty($connsPool) && count($connsPool) > self::$resumeFetchCount[$connName]) {
            $conn = array_pop($connsPool);
            self::$busyConns[$connName][spl_object_hash($conn)] = $conn;
            return $conn;
        }
        if (count(self::$busyConns[$connName]) + count($connsPool) == self::$connsConfig[$connName]['maxConns']) {
            $cid = Coroutine::getuid();
            self::$pendingFetchCount[$connName][$cid] = $cid;
            if (\Swoole\Coroutine::suspend($cid) == false) {
                unset(self::$pendingFetchCount[$connName][$cid]);
                throw new MySQLException('Reach max connections! Cann\'t pending fetch!');
            }
            self::$resumeFetchCount[$connName]--;
            if (!empty($connsPool)) {
                $conn = array_pop($connsPool);
                self::$busyConns[$connName][spl_object_hash($conn)] = $conn;
                return $conn;
            } else {
                return false;//should not happen
            }
        }
        $conn = new \Swoole\Coroutine\MySQL();
        $id = spl_object_hash($conn);
        self::$connsNameMap[$id] = $connName;
        self::$busyConns[$connName][$id] = $conn;
        if ($conn->connect(self::$connsConfig[$connName]['serverInfo']) == false) {
            unset(self::$busyConns[$connName][$id]);
            unset(self::$connsNameMap[$id]);
            throw new MySQLException('Cann\'t connect to MySQL server: ' . json_encode(self::$connsConfig[$connName]['serverInfo']));
        }
        return $conn;
    }

    /**
     * 短线重链
     *
     * @param $conn
     * @param $connName
     *
     * @return \Swoole\Coroutine\MySQL
     */
    public static function reconnect($conn, $connName)
    {
        if (!$conn->connected) {
            $old_id = spl_object_hash($conn);
            unset(self::$busyConns[$connName][$old_id]);
            unset(self::$connsNameMap[$old_id]);
            $conn = new \Swoole\Coroutine\MySQL();
            $conn->connect(self::$connsConfig[$connName]['serverInfo']);
            $id = spl_object_hash($conn);
            self::$connsNameMap[$id] = $connName;
            self::$busyConns[$connName][$id] = $conn;
            return $conn;
        }
        return $conn;
    }
}