RFC 7234 HTTP Caching Support

phpunit.xml.dist

@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <phpunit backupGlobals="false"
+    bootstrap="vendor/autoload.php"
     beStrictAboutTestsThatDoNotTestAnything="false"
     colors="true"
     processIsolation="false"

src/Fetch/Cache/CacheControl.php

@@ -0,0 +1,257 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Fetch\Cache;
+
+use Psr\Http\Message\ResponseInterface;
+
+/**
+ * Parses and handles Cache-Control headers according to RFC 7234.
+ */
+class CacheControl
+{
+    /**
+     * Parsed Cache-Control directives.
+     *
+     * @var array<string, mixed>
+     */
+    private array $directives = [];
+
+    /**
+     * Create a new CacheControl instance.
+     *
+     * @param  array<string, mixed>  $directives  The parsed directives
+     */
+    public function __construct(array $directives = [])
+    {
+        $this->directives = $directives;
+    }
+
+    /**
+     * Parse a Cache-Control header string.
+     */
+    public static function parse(string $cacheControl): self
+    {
+        $directives = [];
+
+        foreach (explode(',', $cacheControl) as $directive) {
+            $directive = trim($directive);
+            if ($directive === '') {
+                continue;
+            }
+
+            $parts = explode('=', $directive, 2);
+            $name = strtolower(trim($parts[0]));
+            $value = isset($parts[1]) ? trim($parts[1], '"') : true;
+
+            // Convert numeric values
+            if (is_string($value) && is_numeric($value)) {
+                $value = (int) $value;
+            }
+
+            $directives[$name] = $value;
+        }
+
+        return new self($directives);
+    }
+
+    /**
+     * Parse Cache-Control from a response.
+     */
+    public static function fromResponse(ResponseInterface $response): self
+    {
+        return self::parse($response->getHeaderLine('Cache-Control'));
+    }
+
+    /**
+     * Build a Cache-Control header string.
+     *
+     * @param  array<string, mixed>  $directives  The directives to include
+     */
+    public static function build(array $directives): string
+    {
+        $parts = [];
+
+        foreach ($directives as $name => $value) {
+            if ($value === true) {
+                $parts[] = $name;
+            } elseif ($value !== false && $value !== null) {
+                $parts[] = "{$name}={$value}";
+            }
+        }
+
+        return implode(', ', $parts);
+    }
+
+    /**
+     * Determine if the response should be cached.
+     */
+    public function shouldCache(ResponseInterface $response, bool $isSharedCache = false): bool
+    {
+        // Don't cache if no-store is set
+        if ($this->hasNoStore()) {
+            return false;
+        }
+
+        // Don't cache private responses in shared cache
+        if ($isSharedCache && $this->isPrivate()) {
+            return false;
+        }
+
+        // Check response status code - using RFC 7234 recommended cacheable status codes
+        // This list matches the default cache_status_codes in ManagesCache trait
+        $status = $response->getStatusCode();
+        $cacheableStatuses = [200, 203, 204, 206, 300, 301, 404, 410];
+
+        if (! in_array($status, $cacheableStatuses, true)) {
+            return false;
+        }
+
+        return true;
+    }
+
+    /**
+     * Check if the response requires validation before being served.
+     */
+    public function mustRevalidate(): bool
+    {
+        return $this->has('must-revalidate') || $this->has('proxy-revalidate');
+    }
+
+    /**
+     * Check if the response should not be cached.
+     */
+    public function hasNoCache(): bool
+    {
+        return $this->has('no-cache');
+    }
+
+    /**
+     * Check if the response should not be stored at all.
+     */
+    public function hasNoStore(): bool
+    {
+        return $this->has('no-store');
+    }
+
+    /**
+     * Check if the response is private.
+     */
+    public function isPrivate(): bool
+    {
+        return $this->has('private');
+    }
+
+    /**
+     * Check if the response is public.
+     */
+    public function isPublic(): bool
+    {
+        return $this->has('public');
+    }
+
+    /**
+     * Get the max-age directive value.
+     */
+    public function getMaxAge(): ?int
+    {
+        return $this->getInt('max-age');
+    }
+
+    /**
+     * Get the s-maxage directive value (for shared caches).
+     */
+    public function getSharedMaxAge(): ?int
+    {
+        return $this->getInt('s-maxage');
+    }
+
+    /**
+     * Get the stale-while-revalidate directive value.
+     */
+    public function getStaleWhileRevalidate(): ?int
+    {
+        return $this->getInt('stale-while-revalidate');
+    }
+
+    /**
+     * Get the stale-if-error directive value.
+     */
+    public function getStaleIfError(): ?int
+    {
+        return $this->getInt('stale-if-error');
+    }
+
+    /**
+     * Calculate the TTL for the response.
+     *
+     * @return int|null The TTL in seconds, or null if not cacheable
+     */
+    public function getTtl(ResponseInterface $response, bool $isSharedCache = false): ?int
+    {
+        // For shared caches, s-maxage takes precedence
+        if ($isSharedCache) {
+            $sMaxAge = $this->getSharedMaxAge();
+            if ($sMaxAge !== null) {
+                return $sMaxAge;
+            }
+        }
+
+        // Check max-age directive
+        $maxAge = $this->getMaxAge();
+        if ($maxAge !== null) {
+            return $maxAge;
+        }
+
+        // Fall back to Expires header
+        $expires = $response->getHeaderLine('Expires');
+        if ($expires !== '') {
+            $expiresTime = strtotime($expires);
+            if ($expiresTime !== false) {
+                return max(0, $expiresTime - time());
+            }
+        }
+
+        return null;
+    }
+
+    /**
+     * Check if a directive exists.
+     */
+    public function has(string $directive): bool
+    {
+        return isset($this->directives[$directive]);
+    }
+
+    /**
+     * Get a directive value.
+     */
+    public function get(string $directive): mixed
+    {
+        return $this->directives[$directive] ?? null;
+    }
+
+    /**
+     * Get an integer directive value.
+     */
+    public function getInt(string $directive): ?int
+    {
+        $value = $this->get($directive);
+        if ($value === null) {
+            return null;
+        }
+
+        return is_int($value) ? $value : (int) $value;
+    }
+
+    /**
+     * Get all directives.
+     *
+     * @return array<string, mixed>
+     */
+    public function getDirectives(): array
+    {
+        return $this->directives;
+    }
+}

src/Fetch/Cache/CacheInterface.php

@@ -0,0 +1,57 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Fetch\Cache;
+
+/**
+ * Interface for cache backends used by the HTTP client.
+ */
+interface CacheInterface
+{
+    /**
+     * Get a cached response by key.
+     *
+     * @param  string  $key  The cache key
+     * @return CachedResponse|null The cached response, or null if not found
+     */
+    public function get(string $key): ?CachedResponse;
+
+    /**
+     * Store a response in the cache.
+     *
+     * @param  string  $key  The cache key
+     * @param  CachedResponse  $cachedResponse  The response to cache
+     * @param  int|null  $ttl  Time to live in seconds
+     * @return bool True if the item was stored, false otherwise
+     */
+    public function set(string $key, CachedResponse $cachedResponse, ?int $ttl = null): bool;
+
+    /**
+     * Delete a cached response by key.
+     *
+     * @param  string  $key  The cache key
+     * @return bool True if the item was deleted, false otherwise
+     */
+    public function delete(string $key): bool;
+
+    /**
+     * Check if a key exists in the cache.
+     *
+     * @param  string  $key  The cache key
+     * @return bool True if the key exists, false otherwise
+     */
+    public function has(string $key): bool;
+
+    /**
+     * Clear all cached responses.
+     */
+    public function clear(): void;
+
+    /**
+     * Remove expired entries from the cache.
+     *
+     * @return int The number of entries removed
+     */
+    public function prune(): int;
+}