ActionRetro · asivery · Apr 12, 2021
diff --git a/README.md b/README.md
@@ -1,2 +1,14 @@
 # 68k-news
-Source for the 68k.news site
+Source for the 68k.news site
+
+---
+
+I added an SQLite3 cache database in which the articles are stored for 24h. After that period they automatically get deleted.
+
+The database can be disabled by changing the `USE_CACHE` define in `article.php`.
+
+If the database file becomes corrupted, the program will try to delete and recreate it. (This can be turned off by setting `RECREATE_ON_FAIL` to `false` in `cache_database.php`).
+
+The default cache freshness lifetime is 24h, however it can be changed using the `MAX_CACHE_TIME` parameter in `cache_database.php` along with the default cache database filename (`cache.db`).
+
+I also had to add a spoofed User-Agent header, because some articles couldn't load without it.
diff --git a/article.php b/article.php
@@ -1,10 +1,18 @@
 <?php
+define('USE_CACHE', true);
+
 require_once('vendor/autoload.php');
+if(USE_CACHE) require_once('cache_database.php');
 
 $article_url = "";
 $article_html = "";
 $error_text = "";
+$readable_article = "";
+$article_images = array();
+$article_title = "";
 $loc = "US";
+$from_cache = USE_CACHE;
+$database = null;
 
 if( isset( $_GET['loc'] ) ) {
     $loc = strtoupper($_GET["loc"]);
@@ -32,20 +40,42 @@
 
 $readability = new Readability($configuration);
 
-if(!$article_html = file_get_contents($article_url)) {
-    $error_text .=  "Failed to get the article :( <br>";
+if($from_cache){
+    $database = CacheDatabase::getInstance();
+    $cachedArticle = is_null($database) ? null : $database->getFromCache($article_url);
+    if(!is_null($cachedArticle)){
+        $article_title = $cachedArticle[0];
+        $readable_article = $cachedArticle[1];
+        $article_images = $cachedArticle[2];
+    }else $from_cache = false;
 }
 
-try {
-    $readability->parse($article_html);
-    $readable_article = strip_tags($readability->getContent(), '<ol><ul><li><br><p><small><font><b><strong><i><em><blockquote><h1><h2><h3><h4><h5><h6>');
-    $readable_article = str_replace( 'strong>', 'b>', $readable_article ); //change <strong> to <b>
-    $readable_article = str_replace( 'em>', 'i>', $readable_article ); //change <em> to <i>
-
-    $readable_article = clean_str($readable_article);
-
-} catch (ParseException $e) {
-    $error_text .= 'Sorry! ' . $e->getMessage() . '<br>';
+if(!$from_cache){
+    $opts = array(
+        'http'=>array(
+            'method'=>"GET",
+            'header'=>"User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:87.0) Gecko/20100101 Firefox/87.0\r\n"
+        )
+    );
+
+
+    if(!$article_html = file_get_contents($article_url, false, stream_context_create($opts))) {
+        $error_text .=  "Failed to get the article :( <br>";
+    }
+
+    try {
+        $readability->parse($article_html);
+        $readable_article = strip_tags($readability->getContent(), '<ol><ul><li><br><p><small><font><b><strong><i><em><blockquote><h1><h2><h3><h4><h5><h6>');
+        $readable_article = str_replace( 'strong>', 'b>', $readable_article ); //change <strong> to <b>
+        $readable_article = str_replace( 'em>', 'i>', $readable_article ); //change <em> to <i>
+
+        $readable_article = clean_str($readable_article);
+        $article_title = $readability->getTitle();
+        $article_images = $readability->getImages();
+        if(!is_null($database)) $database->writeToCache($article_url, $article_title, $readable_article, $article_images);
+    } catch (ParseException $e) {
+        $error_text .= 'Sorry! ' . $e->getMessage() . '<br>';
+    }
 }
 
 //replace chars that old machines probably can't handle
@@ -64,15 +94,15 @@ function clean_str($str) {
 
  <html>
  <head>
-     <title><?php echo $readability->getTitle();?></title>
+     <title><?php echo $article_title;?></title>
  </head>
  <body>
     <small><a href="/index.php?loc=<?php echo $loc ?>">< Back to <font color="#9400d3">68k.news</font> <?php echo $loc ?> front page</a></small>
-    <h1><?php echo clean_str($readability->getTitle());?></h1>
+    <h1><?php echo clean_str($article_title);?></h1>
     <p><small><a href="<?php echo $article_url ?>" target="_blank">Original source</a> (on modern site) <?php
         $img_num = 0;
         $imgline_html = "| Article images:";
-        foreach ($readability->getImages() as $image_url):
+        foreach ($article_images as $image_url):
             //we can only do png and jpg
             if (strpos($image_url, ".jpg") || strpos($image_url, ".jpeg") || strpos($image_url, ".png") === true) {
                 $img_num++;

diff --git a/cache_database.php b/cache_database.php
@@ -0,0 +1,62 @@
+<?php
+define('MAX_CACHE_TIME', 86400); //24 hours in seconds
+define('RECREATE_ON_FAIL', true);
+define('CACHE_DATABASE', "cache.db");
+
+class CacheDatabase extends SQLite3{
+    private static $instance = null;
+
+    private function __construct($path){
+        try{
+            parent::__construct($path);
+            $this->exec("CREATE TABLE IF NOT EXISTS cache(id INTEGER PRIMARY KEY AUTOINCREMENT, url TEXT UNIQUE, epoch INTEGER, title TEXT, content BLOB, images TEXT)");
+        }catch(Exception $ex){
+            trigger_error("Error opening database: " . $ex->getMessage());
+        }
+    }
+
+    public function getFromCache($url){
+        if(!$statement = $this->prepare("SELECT content, title, images FROM cache WHERE url = ?")){
+            return null;
+        }
+        $statement->bindParam(1, $url);
+        if(!$result = $statement->execute()) return null;
+        if(!$row = $result->fetchArray(SQLITE3_ASSOC)) return null;
+        return array(
+            0 => $row['title'],
+            1 => $row['content'],
+            2 => unserialize($row['images'])
+        );
+    }
+
+    public function writeToCache($url, $title, $content, $images){
+        if($cleanStatement = $this->prepare("DELETE FROM cache WHERE epoch < ?")){
+            $cleanStatement->bindValue(1, time() - MAX_CACHE_TIME);
+            $cleanStatement->execute();
+        }
+        if($statement = $this->prepare("INSERT INTO cache (url, epoch, title, content, images) VALUES (?, ?, ?, ?, ?)")){
+            $statement->bindValue(1, $url);
+            $statement->bindValue(2, time());
+            $statement->bindValue(3, $title);
+            $statement->bindValue(4, $content);
+            $statement->bindValue(5, serialize($images));
+            $statement->execute();
+        }else{
+            trigger_error("Cache database writing error");
+            if(RECREATE_ON_FAIL){
+                trigger_error("Deleting database");
+                $this->close();
+                unlink(CACHE_DATABASE);
+                self::$instance = new CacheDatabase(CACHE_DATABASE);
+            }
+        }
+    }
+
+    public static function getInstance(){
+        if(is_null(self::$instance)){
+            self::$instance = new CacheDatabase(CACHE_DATABASE);
+        }
+        return self::$instance;
+    }
+}
+?>