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kirby/src/Cache/Cache.php

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+<?php
+
+namespace Kirby\Cache;
+
+/**
+ * Cache foundation
+ * This class doesn't do anything
+ * and is perfect as foundation for
+ * other cache drivers and to be used
+ * when the cache is disabled
+ *
+ * @package   Kirby Cache
+ * @author    Bastian Allgeier <bastian@getkirby.com>
+ * @link      http://getkirby.com
+ * @copyright Bastian Allgeier
+ * @license   MIT
+ */
+class Cache
+{
+
+    /**
+     * stores all options for the driver
+     * @var array
+     */
+    protected $options = [];
+
+    /**
+     * Set all parameters which are needed to connect to the cache storage
+     *
+     * @param array $options
+     */
+    public function __construct(array $options = [])
+    {
+        $this->options = $options;
+    }
+
+    /**
+     * Write an item to the cache for a given number of minutes.
+     *
+     * <code>
+     *   // Put an item in the cache for 15 minutes
+     *   Cache::set('value', 'my value', 15);
+     * </code>
+     *
+     * @param  string  $key
+     * @param  mixed   $value
+     * @param  int     $minutes
+     * @return void
+     */
+    public function set(string $key, $value, int $minutes = 0)
+    {
+        return null;
+    }
+
+    /**
+     * Private method to retrieve the cache value
+     * This needs to be defined by the driver
+     *
+     * @param  string $key
+     * @return mixed
+     */
+    public function retrieve(string $key)
+    {
+        return null;
+    }
+
+    /**
+     * Get an item from the cache.
+     *
+     * <code>
+     *   // Get an item from the cache driver
+     *   $value = Cache::get('value');
+     *
+     *   // Return a default value if the requested item isn't cached
+     *   $value = Cache::get('value', 'default value');
+     * </code>
+     *
+     * @param  string  $key
+     * @param  mixed   $default
+     * @return mixed
+     */
+    public function get(string $key, $default = null)
+    {
+        // get the Value
+        $value = $this->retrieve($key);
+
+        // check for a valid cache value
+        if (!is_a($value, 'Kirby\Cache\Value')) {
+            return $default;
+        }
+
+        // remove the item if it is expired
+        if (time() >= $value->expires()) {
+            $this->remove($key);
+            return $default;
+        }
+
+        // get the pure value
+        $cache = $value->value();
+
+        // return the cache value or the default
+        return $cache ?? $default;
+    }
+
+    /**
+     * Calculates the expiration timestamp
+     *
+     * @param  int $minutes
+     * @return int
+     */
+    protected function expiration(int $minutes = 0): int
+    {
+        // keep forever if minutes are not defined
+        if ($minutes === 0) {
+            $minutes = 2628000;
+        }
+
+        // calculate the time
+        return time() + ($minutes * 60);
+    }
+
+    /**
+     * Checks when an item in the cache expires
+     *
+     * @param  string $key
+     * @return mixed
+     */
+    public function expires(string $key)
+    {
+        // get the Value object
+        $value = $this->retrieve($key);
+
+        // check for a valid Value object
+        if (!is_a($value, 'Kirby\Cache\Value')) {
+            return false;
+        }
+
+        // return the expires timestamp
+        return $value->expires();
+    }
+
+    /**
+     * Checks if an item in the cache is expired
+     *
+     * @param  string   $key
+     * @return boolean
+     */
+    public function expired(string $key): bool
+    {
+        return $this->expires($key) <= time();
+    }
+
+    /**
+     * Checks when the cache has been created
+     *
+     * @param  string $key
+     * @return mixed
+     */
+    public function created(string $key)
+    {
+        // get the Value object
+        $value = $this->retrieve($key);
+
+        // check for a valid Value object
+        if (!is_a($value, 'Kirby\Cache\Value')) {
+            return false;
+        }
+
+        // return the expires timestamp
+        return $value->created();
+    }
+
+    /**
+     * Alternate version for Cache::created($key)
+     *
+     * @param  string $key
+     * @return mixed
+     */
+    public function modified(string $key)
+    {
+        return static::created($key);
+    }
+
+    /**
+     * Returns Value object
+     *
+     * @param  mixed  $value    The value, which should be cached
+     * @param  int    $minutes  The number of minutes before expiration
+     * @return Value
+     */
+    protected function value($value, int $minutes): Value
+    {
+        return new Value($value, $minutes);
+    }
+
+    /**
+     * Determine if an item exists in the cache.
+     *
+     * @param  string  $key
+     * @return boolean
+     */
+    public function exists(string $key): bool
+    {
+        return !$this->expired($key);
+    }
+
+    /**
+     * Remove an item from the cache
+     *
+     * @param  string $key
+     * @return boolean
+     */
+    public function remove(string $key): bool
+    {
+        return true;
+    }
+
+    /**
+     * Flush the entire cache
+     *
+     * @return boolean
+     */
+    public function flush(): bool
+    {
+        return true;
+    }
+
+    /**
+     * Returns all passed cache options
+     *
+     * @return array
+     */
+    public function options(): array
+    {
+        return $this->options;
+    }
+}