handle Alter Table Add Index behavior

pg4wp/rewriters/AlterTableSQLRewriter.php

@@ -35,28 +35,62 @@ class AlterTableSQLRewriter extends AbstractSQLRewriter
     {
         $sql = $this->original();
 
+        if (str_contains($sql, 'ADD INDEX') || str_contains($sql, 'ADD UNIQUE INDEX')) {
+            $sql = $this->rewriteAddIndex($sql);
+            return $sql;
+        }
         if (str_contains($sql, 'CHANGE COLUMN')) {
             $sql = $this->rewriteChangeColumn($sql);
+            return $sql;
         }
         if (str_contains($sql, 'ALTER COLUMN')) {
             $sql = $this->rewriteAlterColumn($sql);
+            return $sql;
         }
         if (str_contains($sql, 'ADD COLUMN')) {
             $sql = $this->rewriteAddColumn($sql);
+            return $sql;
         }
         if (str_contains($sql, 'ADD KEY') || str_contains($sql, 'ADD UNIQUE KEY')) {
             $sql = $this->rewriteAddKey($sql);
+            return $sql;
         }
         if (str_contains($sql, 'DROP INDEX')) {
             $sql = $this->rewriteDropIndex($sql);
+            return $sql;
         }
         if (str_contains($sql, 'DROP PRIMARY KEY')) {
             $sql = $this->rewriteDropPrimaryKey($sql);
+            return $sql;
         }
 
         return $sql;
     }
 
+    private function rewriteAddIndex(string $sql): string 
+    {
+        $pattern = '/ALTER TABLE\s+(\w+)\s+ADD (UNIQUE |)INDEX\s+([^\s]+)\s+\(((?:[^\(\)]+|\([^\(\)]+\))+)\)/';
+
+        if(1 === preg_match($pattern, $sql, $matches)) {
+            $table = $matches[1];
+            $unique = $matches[2];
+            $index = $matches[3];
+            $columns = $matches[4];
+    
+            // Remove prefix indexing
+            // Rarely used and apparently unnecessary for current uses
+            $columns = preg_replace('/\([^\)]*\)/', '', $columns);
+    
+            // Workaround for index name duplicate
+            $index = $table . '_' . $index;
+            
+            // Add backticks around index name and column name, and include IF NOT EXISTS clause
+            $sql = "CREATE {$unique}INDEX IF NOT EXISTS `{$index}` ON `{$table}` (`{$columns}`)";
+        }
+    
+        return $sql;
+    }
+
     private function rewriteChangeColumn(string $sql): string
     {
         $pattern = '/ALTER TABLE\s+(\w+)\s+CHANGE COLUMN\s+([^\s]+)\s+([^\s]+)\s+([^ ]+)( unsigned|)\s*(NOT NULL|)\s*(default (.+)|)/';
@@ -168,7 +202,7 @@ class AlterTableSQLRewriter extends AbstractSQLRewriter
         if(1 === preg_match($pattern, $sql, $matches)) {
             $table = $matches[1];
             $index = $matches[2];
-            $sql = "DROP INDEX ${table}_${index}";
+            $sql = "DROP INDEX {$table}_{$index}";
         }
 
         return $sql;
@@ -180,7 +214,7 @@ class AlterTableSQLRewriter extends AbstractSQLRewriter
 
         if(1 === preg_match($pattern, $sql, $matches)) {
             $table = $matches[1];
-            $sql = "ALTER TABLE ${table} DROP CONSTRAINT ${table}_pkey";
+            $sql = "ALTER TABLE {$table} DROP CONSTRAINT {$table}_pkey";
         }
 
         return $sql;

phpunit.xml

@@ -1,9 +1,12 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <phpunit
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"     
+  displayDetailsOnTestsThatTriggerDeprecations="true"
+  displayDetailsOnTestsThatTriggerErrors="true"
+  displayDetailsOnTestsThatTriggerNotices="true"
   displayDetailsOnTestsThatTriggerWarnings="true"
   colors="true">
-     <testsuites>
+    <testsuites>
         <testsuite name="tests">
             <directory>tests</directory>
         </testsuite>

tests/rewriteTest.php

@@ -404,6 +404,35 @@ final class rewriteTest extends TestCase
         $this->assertSame(trim($expected), trim($postgresql));
     }
 
+    public function test_it_handles_alter_tables_with_indexes() 
+    {
+        $sql = <<<SQL
+            ALTER TABLE wp_e_events ADD INDEX `created_at_index` (`created_at`)
+        SQL;
+
+        $expected = <<<SQL
+            CREATE INDEX IF NOT EXISTS wp_e_events_created_at_index ON wp_e_events (created_at)
+        SQL;
+
+        $postgresql = pg4wp_rewrite($sql);
+        $this->assertSame(trim($expected), trim($postgresql));
+
+    }
+
+    public function test_it_handles_alter_tables_with_unique_indexes() 
+    {
+        $sql = <<<SQL
+            ALTER TABLE wp_e_events ADD UNIQUE INDEX `created_at_index` (`created_at`)
+        SQL;
+
+        $expected = <<<SQL
+            CREATE UNIQUE INDEX IF NOT EXISTS wp_e_events_created_at_index ON wp_e_events (created_at)
+        SQL;
+
+        $postgresql = pg4wp_rewrite($sql);
+        $this->assertSame(trim($expected), trim($postgresql));
+    }
+
 
     protected function setUp(): void
     {