<?php

abstract class CoRefPool
{
    private $mMaxClient;
    private $mFreeClients;
    private $mUsingClients;
    private $mSuspendCIDS;
    private $mStop;

    public function __construct($max_clients)
    {
        $this->mMaxClient = $max_clients;
        $this->mUsingClients = [];
        $this->mFreeClients = [];
        $this->mSuspendCIDS = [];
        $this->mStop = false;
    }

    public function get($cid)
    {

        if(array_key_exists($cid,$this->mUsingClients)) {
            $this->mUsingClients[$cid]['ref_count'] += 1;
            return $this->mUsingClients[$cid]['client'];
        }

        if(!empty($this->mFreeClients)) {
            $client = array_shift($this->mFreeClients);
            $this->mUsingClients[$cid] = ['client' => $client, 'ref_count' => 1,'ifTransacting' => false];
        }
        elseif(count($this->mUsingClients) < $this->mMaxClient) {
            $client = $this->create_client();
            $this->mUsingClients[$cid] = ['client' => $client, 'ref_count' => 1,'ifTransacting' => false];
        }
        else {
            $this->mSuspendCIDS[] = Co::getCid();
            Co::suspend();
            $client = array_shift($this->mFreeClients);
            $this->mUsingClients[$cid] = ['client' => $client, 'ref_count' => 1,'ifTransacting' => false];
        }

        return $client;
    }

    public function find($cid)
    {
        if(array_key_exists($cid,$this->mUsingClients)) {
            return $this->mUsingClients[$cid]['client'];
        } else {
            $msg = __METHOD__ . " mysqli cannot find mysqli cid={$cid} client";
            Log::record($msg,Log::DEBUG);
            throw new Exception($msg);
        }
    }

    public function reset($cid,$client)
    {
        if(array_key_exists($cid,$this->mUsingClients)) {
            return $this->mUsingClients[$cid]['client'] = $client;
        } else {
            $msg = __METHOD__ . " mysqli cannot find mysqli cid={$cid} client";
            Log::record($msg,Log::DEBUG);
            throw new Exception($msg);
        }
    }

    public function transaction($cid)
    {
        if(array_key_exists($cid,$this->mUsingClients)) {
            return $this->mUsingClients[$cid]['ifTransacting'];
        } else {
            $msg = __METHOD__ . " mysqli cannot find mysqli cid={$cid} client";
            Log::record($msg,Log::DEBUG);
            throw new Exception($msg);
        }
    }

    public function begin($cid)
    {
        if(array_key_exists($cid,$this->mUsingClients)) {
            $this->mUsingClients[$cid]['ifTransacting'] = true;
        } else {
            $msg = __METHOD__ . " mysqli cannot find mysqli cid={$cid} client";
            Log::record($msg,Log::DEBUG);
            throw new Exception($msg);
        }
    }

    public function commit($cid)
    {
        if(array_key_exists($cid,$this->mUsingClients)) {
            $this->mUsingClients[$cid]['ifTransacting'] = false;
        } else {
            $msg = __METHOD__ . " mysqli cannot find mysqli cid={$cid} client";
            Log::record($msg,Log::DEBUG);
            throw new Exception($msg);
        }
    }

    public function rollback($cid)
    {
        if(array_key_exists($cid,$this->mUsingClients)) {
            $this->mUsingClients[$cid]['ifTransacting'] = false;
        } else {
            $msg = __METHOD__ . " mysqli cannot find mysqli cid={$cid} client";
            Log::record($msg,Log::DEBUG);
            throw new Exception($msg);
        }
    }

    public function put($cid)
    {
        if(array_key_exists($cid,$this->mUsingClients))
        {
            $this->mUsingClients[$cid]['ref_count'] -= 1;
            $refcount = $this->mUsingClients[$cid]['ref_count'];

            if($refcount == 0)
            {
                $client = $this->mUsingClients[$cid]['client'];
                unset($this->mUsingClients[$cid]);

                $this->mFreeClients[] = $client;
                $suspend_cid = $this->getSuspend();
                if($suspend_cid > 0) {
                    Co::resume($suspend_cid);
                }
            }
        }
        else {
            $msg = __METHOD__ . " mysqli cannot find mysqli cid={$cid} client";
            Log::record($msg,Log::DEBUG);
            throw new Exception($msg);
        }
    }

    private function getSuspend()
    {
        if (empty($this->mSuspendCIDS)) {
            return 0;
        } else {
            $cid = array_shift($this->mSuspendCIDS);
            return $cid;
        }
    }

    public function stoped() {
        return $this->mStop;
    }
    public function stop() {
        $this->mStop = true;
    }

    abstract public function create_client();
}