Derive mode from DSN function

- Add headers in all files
- Minor field name changes

src/Mode.php

@@ -1,4 +1,10 @@
-<?php declare(strict_types=1);
+<?php
+/**
+ * @author Daniel J. Summers <daniel@bitbadger.solutions>
+ * @license MIT
+ */
+
+declare(strict_types=1);
 
 namespace BitBadger\PDODocument;
 
@@ -12,4 +18,19 @@ enum Mode
 
     /** Storing documents in a SQLite database */
     case SQLite;
+
+    /**
+     * Derive the mode from the Data Source Name (DSN)
+     *
+     * @return Mode The database mode based on the DSN
+     * @throws DocumentException If the DSN does not start with `pgsql:` or `sqlite:`
+     */
+    public static function deriveFromDSN(string $dsn): Mode
+    {
+        return match (true) {
+            str_starts_with($dsn, 'pgsql:')  => Mode::PgSQL,
+            str_starts_with($dsn, 'sqlite:') => Mode::SQLite,
+            default => throw new DocumentException('This library currently supports PostgreSQL and SQLite')
+        };
+    }
 }