<?php

namespace IQParts\Cache\Adapter;

use IQParts\Cache\Serializer\SerializerInterface;

class FilesystemAdapter implements CacheAdapterInterface
{
    /**
     * @var string
     */
    private $directory;
    /**
     * @var null|int
     */
    private $chmod;
    /**
     * @var string
     */
    private $directorySeparator;
    /**
     * @var int|null
     */
    private $ttl;
    /**
     * @var array
     */
    private $timeToLive;
    /**
     * @var SerializerInterface
     */
    private $serializer;
    /**
     * @var array
     */
    private $index;
    /**
     * @var string
     */
    private $indexLocation;
    /**
     * @var string
     */
    private $ttlLocation;

    /**
     * FilesystemAdapter constructor.
     * @param string $directory
     * @param SerializerInterface $serializer
     * @param int|null $chmod
     * @param int|null $ttl
     * @param string|null $directorySeparator
     */
    public function __construct(
        string $directory,
        SerializerInterface $serializer,
        int $chmod = null,
        int $ttl = null,
        string $directorySeparator = null
    )
    {
        $this->indexLocation = $directory . '/' . md5($directory) . 'index';
        $this->ttlLocation = $directory . '/' . md5($directory) . 'ttl';
        $this->directory = $directory;
        $this->serializer = $serializer;
        $this->directorySeparator = $directorySeparator;
        $this->chmod = $chmod;
        $this->ttl = $ttl;

        if (file_exists($this->indexLocation)) {
            $this->index = json_decode(file_get_contents($this->indexLocation), true);
        } else {
            $this->index = [];
        }

        if (file_exists($this->ttlLocation)) {
            $this->timeToLive = json_decode(file_get_contents($this->ttlLocation), true);
        } else {
            $this->timeToLive = [];
        }
    }

    /**
     * @param string $key
     * @return mixed
     */
    public function get(string $key)
    {
        $file = $this->getFilename($key);
        if ($this->exists($file)) {
            if (isset($this->timeToLive[$key])) {
                if ($this->ttl($key) > 0) {
                    return $this->serializer->deserialize(file_get_contents($file));
                }
            } else {
                return $this->serializer->deserialize(file_get_contents($file));
            }

        }
        return null;
    }

    /**
     * @param string $key
     * @param $value
     * @param int|null $ttl
     * @return void
     */
    public function set(string $key, $value, int $ttl = null): void
    {
        $file = $this->getFilename($key);
        file_put_contents($file, $this->serializer->serialize($value));
        if ($this->chmod !== null) {
            chmod($file, $this->chmod);
        }
        if ($ttl !== null) {
            $this->timeToLive[$key] = $ttl;
        } else if ($this->ttl !== null) {
            $this->timeToLive[$key] = $this->ttl;
        }

        $this->index[$key] = $file;
        $this->saveIndex();
    }

    /**
     * @param string $key
     */
    public function delete(string $key)
    {
        if (strpos($key, '*') !== false) {
            $this->deleteGlob($key);
            $this->saveIndex();
        } else {
            $file = $this->getFilename($key);
            if ($this->exists($file)) {
                unlink($file);
            }
            unset($this->index[$key], $this->timeToLive[$key]);
            $this->saveIndex();
        }
    }

    /**
     * @param string $key
     * @return mixed
     */
    public function keys($key = '*')
    {
        $matches = [];
        foreach ($this->index as $name => $index) {
            if (fnmatch($key, $name)) {
                $matches[] = $name;
            }
        }
        return $matches;
    }

    /**
     * @param $key
     * @return int
     */
    public function ttl($key): int
    {
        $file = $this->getFilename($key);

        if (isset($this->timeToLive[$key])) {
            return max(filemtime($file) + $this->timeToLive[$key] - time(), 0);
        }

        return self::NO_TTL;
    }

    /**
     * @param $pattern
     */
    private function deleteGlob($pattern): void
    {
        foreach ($this->index as $key => $value) {
            if (fnmatch($pattern, $key)) {
                $this->delete($key);
            }
        }
    }

    /**
     * @param $file
     * @return bool
     */
    private function exists(string $file): bool
    {
        return file_exists($file);
    }

    /**
     * @param $key
     * @return string
     */
    private function getFilename(string $key): string
    {
        [$directory, $file] = $this->getDirectoryAndFile($key);
        return $directory . '/' . md5($file);
    }

    /**
     * @param string $key
     * @return array
     */
    private function getDirectoryAndFile(string $key): array
    {
        $directory = $this->directory;
        if ($this->directorySeparator !== null) {
            while (($position = strpos($key, $this->directorySeparator)) !== false) {
                $dirName = md5(substr($key, 0, $position));
                $directory = $directory . '/' . $dirName;
                $this->createSubDirectoryIfNotExists($directory);
                $key = substr($key, $position + 1);
            }
        }
        return [$directory, $key];
    }

    /**
     * @param $directory
     */
    private function createSubDirectoryIfNotExists($directory): void
    {
        if (file_exists($directory) === false) {
            if (!mkdir($directory) && !is_dir($directory)) {
                throw new \RuntimeException(sprintf('Directory "%s" was not created', $directory));
            }
            if ($this->chmod !== null) {
                chmod($directory, $this->chmod);
            }
        }
    }

    private function saveIndex(): void
    {
        file_put_contents($this->indexLocation, json_encode($this->index));
        file_put_contents($this->ttlLocation, json_encode($this->timeToLive));
    }
}