add feed discovery API

README.md

@@ -99,14 +99,13 @@ You can also use XRay to fetch all the rel values on a page, merging the list of
 
 ```php
 $xray = new p3k\XRay();
-$xray->http = $this->http;
 $rels = $xray->rels('https://aaronparecki.com/');
 ```
 
 This will return a similar response to the parser, but instead of a `data` key containing the parsed page, there will be `rels`, an associative array. Each key will contain an array of all the values that match that rel value.
 
 ```
-$rels = Array
+Array
 (
     [url] => https://aaronparecki.com/
     [code] => 200
@@ -125,6 +124,41 @@ $rels = Array
 ```
 
 
+### Feed Discovery
+
+You can use XRay to discover the types of feeds available at a URL.
+
+```php
+$xray = new p3k\XRay();
+$feeds = $xray->feeds('http://percolator.today');
+```
+
+This will fetch the URL, check for a Microformats feed, as well as check for rel=alternates pointing to Atom, RSS or JSONFeed URLs. The response will look like the below.
+
+```
+Array
+(
+    [url] => https://percolator.today/
+    [code] => 200
+    [feeds] => Array
+        (
+            [0] => Array
+                (
+                    [url] => https://percolator.today/
+                    [type] => microformats
+                )
+
+            [1] => Array
+                (
+                    [url] => https://percolator.today/podcast.xml
+                    [type] => rss
+                )
+
+        )
+
+)
+```
+
 ### Customizing the User Agent
 
 To set a unique user agent, (some websites will require a user agent be set), you can set the `http` property of the object to a `p3k\HTTP` object.
@@ -336,7 +370,8 @@ If the page being parsed represents a feed, then the response will look like the
   "data": {
     "type": "feed",
     "items": [
-
+      {...},
+      {...}
     ]
   }
 }
@@ -346,14 +381,24 @@ Each object in the `items` array will contain a parsed version of the item, in t
 
 Atom, RSS and JSONFeed will all be normalized to XRay's vocabulary, and only recognized properties will be returned.
 
-## Rels
+## Rels API
 
 There is also an API method to parse and return all rel values on the page, including HTTP `Link` headers and HTML rel values.
 
 ```
 GET /rels?url=https://aaronparecki.com/
 ```
 
+See [above](#rels) for the response format.
+
+## Feed Discovery API
+
+```
+GET /feeds?url=https://aaronparecki.com/
+```
+
+See [above](#feed-discovery) for the response format.
+
 
 ## Token API
 

composer.json

@@ -35,6 +35,7 @@
       "controllers/Parse.php",
       "controllers/Token.php",
       "controllers/Rels.php",
+      "controllers/Feeds.php",
       "controllers/Certbot.php"
     ]
   }

controllers/Feeds.php

@@ -0,0 +1,58 @@
+<?php
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Response;
+
+class Feeds {
+
+  public $http;
+  private $_pretty = false;
+
+  public function __construct() {
+    $this->http = new p3k\HTTP();
+  }
+
+  private function respond(Response $response, $code, $params, $headers=[]) {
+    $response->setStatusCode($code);
+    foreach($headers as $k=>$v) {
+      $response->headers->set($k, $v);
+    }
+    $response->headers->set('Content-Type', 'application/json');
+    $opts = JSON_UNESCAPED_SLASHES;
+    if($this->_pretty) $opts += JSON_PRETTY_PRINT;
+    $response->setContent(json_encode($params, $opts)."\n");
+    return $response;
+  }
+
+  public function find(Request $request, Response $response) {
+    $opts = [];
+
+    if($request->get('timeout')) {
+      // We might make 2 HTTP requests, so each request gets half the desired timeout
+      $opts['timeout'] = $request->get('timeout') / 2;
+    }
+
+    if($request->get('max_redirects')) {
+      $opts['max_redirects'] = (int)$request->get('max_redirects');
+    }
+
+    if($request->get('pretty')) {
+      $this->_pretty = true;
+    }
+
+    $url = $request->get('url');
+
+    if(!$url) {
+      return $this->respond($response, 400, [
+        'error' => 'missing_url',
+        'error_description' => 'Provide a URL to fetch'
+      ]);
+    }
+
+    $xray = new p3k\XRay();
+    $xray->http = $this->http;
+    $res = $xray->feeds($url, $opts);
+
+    return $this->respond($response, !empty($res['error']) ? 400 : 200, $res);
+  }
+
+}

lib/XRay.php

@@ -13,6 +13,11 @@ public function rels($url, $opts=[]) {
     return $rels->parse($url, $opts);
   }
 
+  public function feeds($url, $opts=[]) {
+    $feeds = new XRay\Feeds($this->http);
+    return $feeds->find($url, $opts);
+  }
+
   public function parse($url, $opts_or_body=false, $opts_for_body=[]) {
     if(!$opts_or_body || is_array($opts_or_body)) {
       $fetch = new XRay\Fetcher($this->http);

lib/XRay/Feeds.php

@@ -0,0 +1,113 @@
+<?php
+namespace p3k\XRay;
+
+use p3k\XRay\Formats;
+
+class Feeds {
+  private $http;
+
+  public function __construct($http) {
+    $this->http = $http;
+  }
+
+  public function find($url, $opts=[]) {
+    if(isset($opts['timeout']))
+      $this->http->set_timeout($opts['timeout']);
+    if(isset($opts['max_redirects']))
+      $this->http->set_max_redirects($opts['max_redirects']);
+
+    $scheme = parse_url($url, PHP_URL_SCHEME);
+    if(!in_array($scheme, ['http','https'])) {
+      return [
+        'error' => 'invalid_url',
+        'error_description' => 'Only http and https URLs are supported'
+      ];
+    }
+
+    $host = parse_url($url, PHP_URL_HOST);
+    if(!$host) {
+      return [
+        'error' => 'invalid_url',
+        'error_description' => 'The URL provided was not valid'
+      ];
+    }
+
+    $url = normalize_url($url);
+
+    $result = $this->http->get($url);
+    $body = $result['body'];
+
+    $feeds = [];
+
+    // First check the content type of the response 
+    $contentType = isset($result['headers']['Content-Type']) ? $result['headers']['Content-Type'] : '';
+
+    if(is_array($contentType))
+      $contentType = $contentType[count($contentType)-1];
+
+    if(strpos($contentType, 'application/atom+xml') !== false) {
+      $feeds[] = [
+        'url' => $result['url'],
+        'type' => 'atom'
+      ];
+    } elseif(strpos($contentType, 'application/rss+xml') !== false) {
+      $feeds[] = [
+        'url' => $result['url'],
+        'type' => 'rss'
+      ];
+    } elseif(strpos($contentType, 'application/json') !== false
+      && substr($body, 0, 1) == '{' && strpos(substr($body, 0, 100), 'https://jsonfeed.org/version/1')) {
+      $feeds[] = [
+        'url' => $result['url'],
+        'type' => 'jsonfeed'
+      ];
+    } else {
+      // Some other document was returned, parse the HTML and look for rel alternates and Microformats
+
+      $mf2 = \mf2\Parse($body, $result['url']);
+      if(isset($mf2['alternates'])) {
+        foreach($mf2['alternates'] as $alt) {
+          if(strpos($alt['type'], 'application/json') !== false) {
+            $feeds[] = [
+              'url' => $alt['url'],
+              'type' => 'jsonfeed'
+            ];
+          }
+          if(strpos($alt['type'], 'application/atom+xml') !== false) {
+            $feeds[] = [
+              'url' => $alt['url'],
+              'type' => 'atom'
+            ];
+          }
+          if(strpos($alt['type'], 'application/rss+xml') !== false) {
+            $feeds[] = [
+              'url' => $alt['url'],
+              'type' => 'rss'
+            ];
+          }
+        }
+      }
+
+      $parsed = Formats\HTML::parse($this->http, $body, $result['url'], array_merge($opts, ['expect'=>'feed']));
+      if($parsed && isset($parsed['data']['type']) && $parsed['data']['type'] == 'feed') {
+        $feeds[] = [
+          'url' => $result['url'],
+          'type' => 'microformats'
+        ];
+      }
+    }
+
+    // Sort feeds by priority
+    $rank = ['microformats'=>0,'jsonfeed'=>1,'atom'=>2,'rss'=>3];
+    usort($feeds, function($a, $b) use($rank) {
+      return $rank[$a['type']] > $rank[$b['type']];
+    });
+
+    return [
+      'url' => $result['url'],
+      'code' => $result['code'],
+      'feeds' => $feeds
+    ];
+  }
+
+}

public/index.php

@@ -24,6 +24,9 @@ class Config {
 $router->addRoute('POST', '/parse', 'Parse::parse');
 $router->addRoute('POST', '/token', 'Token::token');
 
+$router->addRoute('GET', '/feeds', 'Feeds::find');
+$router->addRoute('POST', '/feeds', 'Feeds::find');
+
 $router->addRoute('GET', '/rels', 'Rels::fetch');
 
 $router->addRoute('GET', '/cert', 'Certbot::index');