<?php

namespace GoodbyeDeadlocks

use Predis\Client;
use LogicException;

class Lock
{
    /**
     * time to keep lock
     * when your script was dead the look will be keeping for that time
     * this is needed when a process is died and will never unlock the wallet
     * metric using minutes, by default = 10 minutes
     * @var integer
     */
    public $ttl = 600;

    /**
     * when a lock can't be reached right now script should pause
     * that is needed so you will never hot your redis instance
     * @var integer
     */
    public $delay = 100;

    /**
     * we don't want to remove other session locks due invalid logic
     * so this var will keep current locks list
     * @var array
     */
    public $locked = [];

    public function __construct(Client $redis)
    {
        $this->redis = $redis;
        register_shutdown_function([$this, 'unlockEverything']);
    }

    public function acquire(int $wallet)
    {
        if (func_num_args() > 1) {
            $wallets = func_get_args();
            sort($wallets);
            foreach ($wallets as $wallet) {
                $this->acquire($wallet);
            }
            return;
        }

        if (in_array($wallet, $this->locked)) {
            // simple return true if taken lock is okay
            return true;
            // or throw on exception if you want to discover how it was achieved
            // throw new LogicException("Wallet $wallet was not locked in this session!");
        }

        while (!$this->redis->set("wallet-$wallet", 1, 'EX', $this->ttl, 'NX')) {
            usleep($this->delay * 1000);
        }

        $this->locked[] = $wallet;
    }

    public function remove($wallet)
    {
        if (!in_array($wallet, $this->locked)) {
            throw new LogicException("Wallet $wallet was not locked in this session!");
        }

        if (func_num_args() > 1) {
            $wallets = func_get_args();
            sort($wallets);
            foreach ($wallets as $wallet) {
                $this->remove($wallet);
            }
            return;
        }

        $this->redis->del("wallet-$wallet");
    }

    public function unlockEverything()
    {
        foreach ($this->locked as $key) {
            $this->remove($key);
        }
    }
}