Merge pull request #8 from makasim/fetch-database-from-dsn

Fetch database from mongo dsn.

src/CollectionFactory.php

@@ -0,0 +1,37 @@
+<?php
+namespace Makasim\Yadm;
+
+use MongoDB\Client;
+use MongoDB\Collection;
+
+class CollectionFactory
+{
+    /**
+     * @var Client
+     */
+    private $mongodb;
+
+    /**
+     * @var string
+     */
+    private $mongoDsn;
+
+    public function __construct(Client $mongodb, string $mongoDsn)
+    {
+        $this->mongodb = $mongodb;
+        $this->mongoDsn = $mongoDsn;
+    }
+
+    public function create(string $collectionName, string $databaseName = null, array $options = []): Collection
+    {
+       if (false == $databaseName) {
+           $databaseName = parse_url($this->mongoDsn, PHP_URL_PATH);
+       }
+
+       if (false == $databaseName) {
+           throw new \LogicException('Failed to guess database name, neither mongo DSN nor argument have it.');
+       }
+
+       $this->mongodb->selectCollection($databaseName, $collectionName, $options);
+    }
+}