1 files changed, 69 insertions, 0 deletions
diff --git a/crawler/Database.php b/crawler/Database.php
new file mode 100644
index 0000000..6d04009
--- /dev/null
+++ b/crawler/Database.php
@@ -0,0 +1,69 @@
+<?php
+/**
+ * User: Marvin Borner
+ * Date: 16/09/2018
+ * Time: 21:34
+ */
+
+class Database
+{
+    public static function getFromQueue($sort): string
+    {
+        print "\t\e[96mStarting at " . ($sort === 'DESC' ? 'bottom' : 'top') . " of queue\n";
+        $conn = self::initDbConnection();
+        $checkStmt = $conn->query('SELECT url FROM queue ORDER BY id ' . $sort . ' LIMIT 1');
+
+        return $checkStmt->fetchAll(PDO::FETCH_ASSOC)[0]['url'];
+    }
+
+    private static function initDbConnection(): PDO
+    {
+        global $servername, $dbname, $username, $password;
+        $conn = new PDO("mysql:host=$servername;dbname=$dbname;charset=utf8", $username, $password);
+        $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
+        return $conn;
+    }
+
+    public static function insertIntoQueue($url): bool
+    {
+        if (!self::alreadyCrawled($url)) {
+            $conn = self::initDbConnection();
+            $hash = md5($url);
+            $stmt = $conn->prepare('INSERT IGNORE INTO queue (url, hash) VALUES (:url, :hash)');
+            $stmt->execute([':url' => $url, 'hash' => $hash]);
+            return $stmt->rowCount() > 0;
+        }
+    }
+
+    public static function alreadyCrawled($url): bool
+    {
+        $hash = md5($url);
+        $conn = self::initDbConnection();
+        $checkStmt = $conn->prepare('(SELECT null FROM url_data WHERE hash = :hash) UNION (SELECT null FROM error_url WHERE hash = :hash)');
+        $checkStmt->execute([':hash' => $hash]);
+        return $checkStmt->rowCount() !== 0; // return true if already crawled
+    }
+
+    public static function removeFromQueue($url): void
+    {
+        $hash = md5($url);
+        $conn = self::initDbConnection();
+        $checkStmt = $conn->prepare('DELETE FROM queue WHERE hash = :hash');
+        $checkStmt->execute([':hash' => $hash]);
+    }
+
+    public static function urlHasError($url): void
+    {
+        $hash = md5($url);
+        $conn = self::initDbConnection();
+        $checkStmt = $conn->prepare('INSERT IGNORE INTO error_url (url, hash) VALUES (:url, :hash)');
+        $checkStmt->execute([':url' => $url, 'hash' => $hash]);
+    }
+
+    public static function saveUrlData($data): void
+    {
+        $conn = self::initDbConnection();
+        $stmt = $conn->prepare('INSERT IGNORE INTO url_data (url, title, description, lang, hash) VALUES (:url, :title, :description, :lang, :hash)');
+        $stmt->execute([':url' => $data[0], ':title' => $data[1], ':description' => $data[2], ':lang' => $data[3], ':hash' => $data[4]]);
+    }
+}
+\ No newline at end of file