Initial Upload

lib/Helper/HttpCacheProvider.php

@@ -0,0 +1,122 @@
+<?php
+/**
+ * Copyright (c) 2012-2015 Josh Lockhart
+ */
+namespace Xibo\Helper;
+
+use InvalidArgumentException;
+use Psr\Http\Message\ResponseInterface;
+
+/**
+ * A set of helper methods for dealing with HTTP cache
+ */
+class HttpCacheProvider
+{
+    /**
+     * Enable client-side HTTP caching
+     *
+     * @param  ResponseInterface $response       PSR7 response object
+     * @param  string            $type           Cache-Control type: "private" or "public"
+     * @param  null|int|string   $maxAge         Maximum cache age (integer timestamp or datetime string)
+     * @param  bool              $mustRevalidate add option "must-revalidate" to Cache-Control
+     *
+     * @return ResponseInterface           A new PSR7 response object with `Cache-Control` header
+     * @throws InvalidArgumentException if the cache-control type is invalid
+     */
+    public static function allowCache(ResponseInterface $response, $type = 'private', $maxAge = null, $mustRevalidate = false)
+    {
+        if (!in_array($type, ['private', 'public'])) {
+            throw new InvalidArgumentException('Invalid Cache-Control type. Must be "public" or "private".');
+        }
+        $headerValue = $type;
+        if ($maxAge || is_integer($maxAge)) {
+            if (!is_integer($maxAge)) {
+                $maxAge = strtotime($maxAge);
+            }
+            $headerValue = $headerValue . ', max-age=' . $maxAge;
+        }
+
+        if ($mustRevalidate) {
+            $headerValue = $headerValue . ", must-revalidate";
+        }
+
+        return $response->withHeader('Cache-Control', $headerValue);
+    }
+
+    /**
+     * Disable client-side HTTP caching
+     *
+     * @param  ResponseInterface $response PSR7 response object
+     *
+     * @return ResponseInterface           A new PSR7 response object with `Cache-Control` header
+     */
+    public static function denyCache(ResponseInterface $response)
+    {
+        return $response->withHeader('Cache-Control', 'no-store,no-cache');
+    }
+
+    /**
+     * Add `Expires` header to PSR7 response object
+     *
+     * @param  ResponseInterface $response A PSR7 response object
+     * @param  int|string        $time     A UNIX timestamp or a valid `strtotime()` string
+     *
+     * @return ResponseInterface           A new PSR7 response object with `Expires` header
+     * @throws InvalidArgumentException if the expiration date cannot be parsed
+     */
+    public static function withExpires(ResponseInterface $response, $time)
+    {
+        if (!is_integer($time)) {
+            $time = strtotime($time);
+            if ($time === false) {
+                throw new InvalidArgumentException('Expiration value could not be parsed with `strtotime()`.');
+            }
+        }
+
+        return $response->withHeader('Expires', gmdate('D, d M Y H:i:s T', $time));
+    }
+
+    /**
+     * Add `ETag` header to PSR7 response object
+     *
+     * @param  ResponseInterface $response A PSR7 response object
+     * @param  string            $value    The ETag value
+     * @param  string            $type     ETag type: "strong" or "weak"
+     *
+     * @return ResponseInterface           A new PSR7 response object with `ETag` header
+     * @throws InvalidArgumentException if the etag type is invalid
+     */
+    public static function withEtag(ResponseInterface $response, $value, $type = 'strong')
+    {
+        if (!in_array($type, ['strong', 'weak'])) {
+            throw new InvalidArgumentException('Invalid etag type. Must be "strong" or "weak".');
+        }
+        $value = '"' . $value . '"';
+        if ($type === 'weak') {
+            $value = 'W/' . $value;
+        }
+
+        return $response->withHeader('ETag', $value);
+    }
+
+    /**
+     * Add `Last-Modified` header to PSR7 response object
+     *
+     * @param  ResponseInterface $response A PSR7 response object
+     * @param  int|string        $time     A UNIX timestamp or a valid `strtotime()` string
+     *
+     * @return ResponseInterface           A new PSR7 response object with `Last-Modified` header
+     * @throws InvalidArgumentException if the last modified date cannot be parsed
+     */
+    public static function withLastModified(ResponseInterface $response, $time)
+    {
+        if (!is_integer($time)) {
+            $time = strtotime($time);
+            if ($time === false) {
+                throw new InvalidArgumentException('Last Modified value could not be parsed with `strtotime()`.');
+            }
+        }
+
+        return $response->withHeader('Last-Modified', gmdate('D, d M Y H:i:s T', $time));
+    }
+}