Merge pull request #27 from tareq-halaby/tareq-halaby-patch-3

Implement SchemaInspector for database introspection

Author: tareq-halaby

src/SchemaInspector.php

@@ -0,0 +1,68 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SqlPowertools;
+
+/**
+ * SchemaInspector - Database Schema Introspection Utility
+ *
+ * Provides methods to inspect database tables, columns, indexes,
+ * and foreign keys at runtime without hardcoding schema knowledge.
+ *
+ * @package SqlPowertools
+ * @version 1.2.0
+ */
+class SchemaInspector
+{
+    public function __construct(private readonly \PDO $pdo) {}
+
+    /**
+     * List all table names in the current database.
+     */
+    public function getTables(): array
+    {
+        $stmt = $this->pdo->query('SHOW TABLES');
+        return $stmt->fetchAll(\PDO::FETCH_COLUMN);
+    }
+
+    /**
+     * Get column metadata for a given table.
+     */
+    public function getColumns(string $table): array
+    {
+        $stmt = $this->pdo->prepare('DESCRIBE `' . $table . '`');
+        $stmt->execute();
+        return $stmt->fetchAll(\PDO::FETCH_ASSOC);
+    }
+
+    /**
+     * Get index information for a given table.
+     */
+    public function getIndexes(string $table): array
+    {
+        $stmt = $this->pdo->prepare('SHOW INDEX FROM `' . $table . '`');
+        $stmt->execute();
+        return $stmt->fetchAll(\PDO::FETCH_ASSOC);
+    }
+
+    /**
+     * Check if a specific column exists on a table.
+     */
+    public function columnExists(string $table, string $column): bool
+    {
+        $columns = array_column($this->getColumns($table), 'Field');
+        return in_array($column, $columns, true);
+    }
+
+    /**
+     * Get the primary key column(s) of a table.
+     */
+    public function getPrimaryKey(string $table): array
+    {
+        return array_filter(
+            $this->getColumns($table),
+            fn($col) => $col['Key'] === 'PRI'
+        );
+    }
+}