<?php

/*
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * This software consists of voluntary contributions made by many individuals
 * and is licensed under the LGPL. For more information, see
 * <http://www.doctrine-project.org>.
 */

namespace Doctrine\Common\Cache;

/**
 * Base class for cache provider implementations.
 *
 * @since   2.2
 * @author  Benjamin Eberlei <kontakt@beberlei.de>
 * @author  Guilherme Blanco <guilhermeblanco@hotmail.com>
 * @author  Jonathan Wage <jonwage@gmail.com>
 * @author  Roman Borschel <roman@code-factory.org>
 * @author  Fabio B. Silva <fabio.bat.silva@gmail.com>
 */
abstract class CacheProvider implements Cache
{
    const DOCTRINE_NAMESPACE_CACHEKEY = 'DoctrineNamespaceCacheKey[%s]';
    
    /** 
     * @var string The namespace to prefix all cache ids with 
     */
    private $namespace = '';

    /**
     * Set the namespace to prefix all cache ids with.
     *
     * @param string $namespace
     * @return void
     */
    public function setNamespace($namespace)
    {
        $this->namespace = (string) $namespace;
    }
    
    /**
     * Retrieve the namespace that prefixes all cache ids.
     *
     * @return string
     */
    public function getNamespace()
    {
        return $this->namespace;
    }
    
    /**
     * {@inheritdoc}
     */
    public function fetch($id)
    {
        return $this->doFetch($this->getNamespacedId($id));
    }

    /**
     * {@inheritdoc}
     */
    public function contains($id)
    {
        return $this->doContains($this->getNamespacedId($id));
    }

    /**
     * {@inheritdoc}
     */
    public function save($id, $data, $lifeTime = 0)
    {
        return $this->doSave($this->getNamespacedId($id), $data, $lifeTime);
    }

    /**
     * {@inheritdoc}
     */
    public function delete($id)
    {
        return $this->doDelete($this->getNamespacedId($id));
    }
    
    /**
     * {@inheritdoc}
     */
    public function getStats()
    {
        return $this->doGetStats();
    }

    /**
     * Deletes all cache entries.
     *
     * @return boolean TRUE if the cache entries were successfully flushed, FALSE otherwise.
     */
    public function flushAll()
    {
        return $this->doFlush();
    }
    
    /**
     * Delete all cache entries.
     *
     * @return boolean TRUE if the cache entries were successfully deleted, FALSE otherwise.
     */
    public function deleteAll()
    {
        $namespaceCacheKey = sprintf(self::DOCTRINE_NAMESPACE_CACHEKEY, $this->namespace);
        $namespaceVersion  = ($this->doContains($namespaceCacheKey)) ? $this->doFetch($namespaceCacheKey) : 1;
        
        return $this->doSave($namespaceCacheKey, $namespaceVersion + 1);
    }
    
    /**
     * Prefix the passed id with the configured namespace value
     *
     * @param string $id  The id to namespace
     * @return string $id The namespaced id
     */
    private function getNamespacedId($id)
    {
        $namespaceCacheKey = sprintf(self::DOCTRINE_NAMESPACE_CACHEKEY, $this->namespace);
        $namespaceVersion  = ($this->doContains($namespaceCacheKey)) ? $this->doFetch($namespaceCacheKey) : 1;
        $idCacheKey        = strtr($id,  array('[' => '', ']' => ''));
        
        return sprintf('%s[%s][%s]', $this->namespace, $id, $namespaceVersion);
    }

    /**
     * Fetches an entry from the cache.
     *
     * @param string $id cache id The id of the cache entry to fetch.
     * @return string The cached data or FALSE, if no cache entry exists for the given id.
     */
    abstract protected function doFetch($id);

    /**
     * Test if an entry exists in the cache.
     *
     * @param string $id cache id The cache id of the entry to check for.
     * @return boolean TRUE if a cache entry exists for the given cache id, FALSE otherwise.
     */
    abstract protected function doContains($id);

    /**
     * Puts data into the cache.
     *
     * @param string $id The cache id.
     * @param string $data The cache entry/data.
     * @param int $lifeTime The lifetime. If != false, sets a specific lifetime for this cache entry (null => infinite lifeTime).
     * @return boolean TRUE if the entry was successfully stored in the cache, FALSE otherwise.
     */
    abstract protected function doSave($id, $data, $lifeTime = false);

    /**
     * Deletes a cache entry.
     *
     * @param string $id cache id
     * @return boolean TRUE if the cache entry was successfully deleted, FALSE otherwise.
     */
    abstract protected function doDelete($id);

    /**
     * Deletes all cache entries.
     *
     * @return boolean TRUE if the cache entry was successfully deleted, FALSE otherwise.
     */
    abstract protected function doFlush();
    
     /**
     * Retrieves cached information from data store
     * 
     * @since   2.2
     * @return  array An associative array with server's statistics if available, NULL otherwise.
     */
    abstract protected function doGetStats();
}