<?php

/*
 * This file is heavily inspired and use code from Composer(getcomposer.org),
 * in particular Composer/Cache and Composer/Util/FileSystem from 1.0.0-alpha7
 *
 * The original code and this file are both released under MIT license.
 *
 * The copyright holders of the original code are:
 * (c) Nils Adermann <naderman@naderman.de>
 *     Jordi Boggiano <j.boggiano@seld.be>
 */

namespace Terminus;

use Symfony\Component\Finder\Finder;

/**
 * Reads/writes to a filesystem cache
 */
class FileCache {

  /**
   * @var string cache path
   */
  protected $root;
  /**
   * @var bool
   */
  protected $enabled = true;
  /**
   * @var int files time to live
   */
  protected $ttl = 36000;
  /**
   * @var int max total size
   */
  protected $maxSize;
  /**
   * @var string key allowed chars (regex class)
   */
  protected $whitelist;

  /**
   * @param string $cacheDir   location of the cache
   * @param int    $ttl        cache files default time to live (expiration)
   * @param int    $maxSize    max total cache size
   * @param string $whitelist  List of characters that are allowed in path names (used in a regex character class)
   */
  public function __construct( $cacheDir, $ttl, $maxSize, $whitelist = 'a-z0-9._-' ) {
    $this->root = rtrim( $cacheDir, '/\\' ) . '/';
    $this->ttl = (int) $ttl;
    $this->maxSize = (int) $maxSize;
    $this->whitelist = $whitelist;

    if ( !$this->ensure_dir_exists( $this->root ) ) {
      $this->enabled = false;
    }

  }

  /**
   * Cache is enabled
   *
   * @return bool
   */
  public function is_enabled() {
    return $this->enabled;
  }

  /**
   * Cache root
   *
   * @return string
   */
  public function get_root() {
    return $this->root;
  }


  /**
   * Check if a file is in cache and return its filename
   *
   * @param string $key cache key
   * @param int    $ttl time to live
   * @return bool|string filename or false
   */
  public function has( $key, $ttl = null ) {
    if ( !$this->enabled ) {
      return false;
    }

    $filename = $this->filename( $key );

    if ( !file_exists( $filename ) ) {
      return false;
    }

    // use ttl param or global ttl
    if ( $ttl === null ) {
      $ttl = $this->ttl;
    } elseif ( $this->ttl > 0 ) {
      $ttl = min( (int) $ttl, $this->ttl );
    } else {
      $ttl = (int) $ttl;
    }

    //
    if ( $ttl > 0 && filemtime( $filename ) + $ttl < time() ) {
      if ( $this->ttl > 0 && $ttl >= $this->ttl ) {
        unlink( $filename );
      }
      return false;
    }

    return $filename;
  }

  /**
   * Write to cache file
   *
   * @param string $key      cache key
   * @param string $contents file contents
   * @return bool
   */
  public function write( $key, $contents ) {
    $filename = $this->prepare_write( $key );

    if ( $filename ) {
      return file_put_contents( $filename, $contents ) && touch( $filename );
    } else {
      return false;
    }
  }

  public function put_data( $key, $array ) {
    $json = json_encode( $array );
    $result = $this->write( $key, $json );
    return $result;
  }

  /**
   * Read from cache file
   *
   * @param string $key cache key
   * @param int    $ttl time to live
   * @return bool|string file contents or false
   */
  public function read( $key, $ttl = null ) {
    $filename = $this->has( $key, $ttl );

    if ( $filename ) {
      return file_get_contents( $filename );
    } else {
      return false;
    }
  }

  public function get_data($key, $options = array()) {
    $defaults = array(
      'decode_array' => false,
      'ttl' => null
    );
    $options = array_merge($defaults, $options);

    $contents = $this->read($key, $options['ttl']);

    if ($contents) {
      return json_decode($contents, $options['decode_array']);
    }
    else {
      return false;
    }
  }

  /**
   * Copy a file into the cache
   *
   * @param string $key    cache key
   * @param string $source source filename
   * @return bool
   */
  public function import( $key, $source ) {
    $filename = $this->prepare_write( $key );

    if ( $filename ) {
      return copy( $source, $filename ) && touch( $filename );
    } else {
      return false;
    }
  }

  /**
   * Copy a file out of the cache
   *
   * @param string $key    cache key
   * @param string $target target filename
   * @param int    $ttl    time to live
   * @return bool
   */
  public function export( $key, $target, $ttl = null ) {
    $filename = $this->has( $key, $ttl );

    if ( $filename ) {
      return copy( $filename, $target );
    } else {
      return false;
    }
  }

  /**
   * Remove file from cache
   *
   * @param string $key cache key
   * @return bool
   */
  public function remove( $key ) {
    if ( !$this->enabled ) {
      return false;
    }

    $filename = $this->filename( $key );

    if ( file_exists( $filename ) ) {
      return unlink( $filename );
    } else {
      return false;
    }
  }

  /**
   * Clean cache based on time to live and max size
   *
   * @return bool
   */
  public function clean() {
    if ( !$this->enabled ) {
      return false;
    }

    $ttl = $this->ttl;
    $maxSize = $this->maxSize;

    // unlink expired files
    if ( $ttl > 0 ) {
      $expire = new \DateTime();
      $expire->modify( '-' . $ttl . ' seconds' );

      $finder = $this->get_finder()->date( 'until ' . $expire->format( 'Y-m-d H:i:s' ) );
      foreach ( $finder as $file ) {
        unlink( $file->getRealPath() );
      }
    }

    // unlink older files if max cache size is exceeded
    if ( $maxSize > 0 ) {
      $files = array_reverse( iterator_to_array( $this->get_finder()->sortByAccessedTime()->getIterator() ) );
      $total = 0;

      foreach ( $files as $file ) {
        if ( $total + $file->getSize() <= $maxSize ) {
          $total += $file->getSize();
        } else {
          unlink( $file->getRealPath() );
        }
      }
    }

    return true;
  }

  /**
   * Ensure directory exists
   *
   * @param string $dir directory
   * @return bool
   */
  protected function ensure_dir_exists( $dir ) {
    if ( !is_dir( $dir ) ) {
      if ( file_exists( $dir ) ) {
        // exists and not a dir
        return false;
      }
      if ( !@mkdir( $dir, 0777, true ) ) {
        return false;
      }
    }

    return true;
  }

  /**
   * Prepare cache write
   *
   * @param string $key cache key
   * @return bool|string filename or false
   */
  protected function prepare_write( $key ) {
    if ( !$this->enabled ) {
      return false;
    }

    $filename = $this->filename( $key );

    if ( !$this->ensure_dir_exists( dirname( $filename ) ) ) {
      return false;
    }

    return $filename;
  }

  /**
   * Validate cache key
   *
   * @param string $key cache key
   * @return string relative filename
   */
  protected function validate_key( $key ) {
    $url_parts = parse_url( $key );
    if ( ! empty($url_parts['scheme']) ) { // is url
      $parts = array('misc');
      $parts[] = $url_parts['scheme'] . '-' . @$url_parts['host'] .
        ( empty( $url_parts['port'] ) ? '' : '-' . $url_parts['port'] );
      $parts[] = substr($url_parts['path'], 1) .
        ( empty( $url_parts['query'] ) ? '' : '-' . $url_parts['query'] );
    } else {
      $key = str_replace( '\\', '/', $key );
      $parts = explode( '/', ltrim( $key ) );
    }

    $parts = preg_replace( "#[^{$this->whitelist}]#i", '-', $parts );

    return implode( '/', $parts );
  }

  /**
   * Filename from key
   *
   * @param string $key
   * @return string filename
   */
  protected function filename( $key ){
    return $this->root . $this->validate_key( $key );
  }

  /**
   * Get a Finder that iterates in cache root only the files
   *
   * @return Finder
   */
  public function get_finder() {
    return Finder::create()->in( $this->root )->files();
  }

  /**
   * Flushes all caches
   *
   */
  public function flush($key = null) {
    $finder = $this->get_finder();
    foreach($finder as $file) {
      unlink($file->getRealPath());
    }
  }
}