<?php

namespace NoccyLabs\LocalCache;

use Psr\SimpleCache\InvalidArgumentException;
use Psr\SimpleCache\CacheInterface;
use Psr\SimpleCache\CacheException;

class LocalCache implements CacheInterface
{

    private $cacheDir;

    private $poolName;

    private $defaultTtl = 3600;

    public function __construct(string $poolName)
    {
        $this->poolName = preg_replace("/[^a-zA-Z0-9_\\-]/", "_", $poolName);
        $this->cacheDir = $this->findCachePath();
    }

    protected function findCachePath(): string
    {
        $candidates = [
            '/var/cache',
            getenv("HOME").'/.cache',
        ];
        while ($candidate = array_shift($candidates)) {
            if (!is_writable($candidate)) {
                continue;
            }
            $path = $candidate . DIRECTORY_SEPARATOR . 'php-localcache';
            /*
            if (!is_dir($path)) {
                @mkdir($path);
                if (!is_dir($path)) {
                    continue;
                }
            }
            */
            return $path;
        }
        throw new CacheException("Couldn't find a usable cache directory");
    }

    protected function hashKey(string $key)
    {
        $hash = hash("sha256", $key);
        return $hash;
    }

    protected function getKeyPath(string $key)
    {
        $hash = $this->hashKey($key);
        $path = substr($hash, 0, 2) . DIRECTORY_SEPARATOR . substr($hash, 2, 2) . DIRECTORY_SEPARATOR . $hash;
        $full = $this->cacheDir . DIRECTORY_SEPARATOR . $this->poolName . DIRECTORY_SEPARATOR . $path;
        return $full;
    }

    /**
     * {@inheritDoc}
     */
    public function get($key, $default = null)
    {
        if (!$this->has($key)) {
            return $default;
        }
        $path = $this->getKeyPath($key);
        return file_get_contents($path);
    }

    /**
     * {@inheritDoc}
     */
    public function set($key, $value, $ttl = null)
    {
        $info = [
            'key' => $key,
            'ttl' => $ttl ?? $this->defaultTtl
        ];
        $info['expires'] = time() + $info['ttl'];
        $path = $this->getKeyPath($key);
        if (!is_dir(dirname($path))) {
            mkdir(dirname($path), 0777, true);
        }
        file_put_contents($path, $value);
        file_put_contents($path.".info", serialize($info));
    }

    /**
     * {@inheritDoc}
     */
    public function delete($key)
    {
        if (!$this->has($key)) {
            return;
        }
        $path = $this->getKeyPath($key);
        @unlink($path);
        @unlink($path.".info");
    }

    /**
     * {@inheritDoc}
     */
    public function has($key)
    {
        $path = $this->getKeyPath($key);
        if (!file_exists($path)) {
            return false;
        }

        $info = unserialize(file_get_contents($path.".info"));
        if ($info['expires'] < time()) {
            return false;
        }

        return true;
    }

    /**
     * {@inheritDoc}
     */
    public function clear()
    {
        /*
        $items = glob($this->cacheDir.DIRECTORY_SEPARATOR.$this->poolName.DIRECTORY_SEPARATOR."*.info");
        foreach ($items as $item) {
            unlink(substr($item, 0, -5));
            unlink($item);
        }
        @rmdir($this->cacheDir . DIRECTORY_SEPARATOR . $this->poolName);
        */

        $path = $this->cacheDir . DIRECTORY_SEPARATOR . $this->poolName;
        exec("rm -rf ".escapeshellarg($path));
    }

    /**
     * {@inheritDoc}
     */
    public function getMultiple($keys, $default = null)
    {
        if (!is_iterable($keys)) {
            throw new InvalidArgumentException("Argument not iterable");
        }       
        $ret = [];
        foreach ($keys as $key) {
            $ret[$key] = $this->get($key, $default);
        }
        return $ret;
    }

    /**
     * {@inheritDoc}
     */
    public function setMultiple($values, $ttl = null)
    {
        if (!is_iterable($values)) {
            throw new InvalidArgumentException("Argument not iterable");
        }       
        foreach ($values as $key=>$value) {
            $this->set($key, $value, $ttl);
        }        
    }

    /**
     * {@inheritDoc}
     */
    public function deleteMultiple($keys)
    {
        if (!is_iterable($keys)) {
            throw new InvalidArgumentException("Argument not iterable");
        }
        foreach ($keys as $key) {
            $this->delete($key);
        }
    }
}