fix(indexes): use lib/pq array parser for column names with special characters

Replace string manipulation (Trim/Split) with pq.StringArray to properly
handle PostgreSQL arrays containing column names with special characters.

Previous implementation incorrectly split on commas inside quoted identifiers,
breaking indexes with columns like "col,with,commas" or "Column Name".

Changes:
- Use pq.StringArray for scanning PostgreSQL text[] arrays
- Remove manual string parsing that failed on edge cases
- Add comprehensive test for special characters (spaces, commas, braces)

Fixes #26

Author: sgaunet

integration_test.go

@@ -436,6 +436,100 @@ func TestIntegration_App_ListIndexes(t *testing.T) {
 	assert.True(t, foundEmailIdx, "Should find email index")
 }
 
+func TestIntegration_App_ListIndexes_SpecialCharacters(t *testing.T) {
+	_, connectionString, cleanup := setupTestContainer(t)
+	defer cleanup()
+
+	db, err := sql.Open("postgres", connectionString)
+	require.NoError(t, err)
+	defer db.Close()
+
+	ctx := context.Background()
+
+	// Create test schema
+	testSchema := "test_special_chars"
+	_, err = db.ExecContext(ctx, fmt.Sprintf("DROP SCHEMA IF EXISTS %s CASCADE", testSchema))
+	require.NoError(t, err)
+	_, err = db.ExecContext(ctx, fmt.Sprintf("CREATE SCHEMA %s", testSchema))
+	require.NoError(t, err)
+
+	// Create table with columns containing special characters
+	_, err = db.ExecContext(ctx, fmt.Sprintf(`
+		CREATE TABLE %s.test_table (
+			id SERIAL PRIMARY KEY,
+			"Column Name" VARCHAR(255),
+			"col,with,commas" VARCHAR(255),
+			"col{value}" VARCHAR(255),
+			"col}data" VARCHAR(255),
+			normal_col VARCHAR(255)
+		)
+	`, testSchema))
+	require.NoError(t, err)
+
+	// Create indexes with special character column names
+	_, err = db.ExecContext(ctx, fmt.Sprintf(`
+		CREATE INDEX idx_quoted_name ON %s.test_table ("Column Name")
+	`, testSchema))
+	require.NoError(t, err)
+
+	_, err = db.ExecContext(ctx, fmt.Sprintf(`
+		CREATE INDEX idx_with_commas ON %s.test_table ("col,with,commas", normal_col)
+	`, testSchema))
+	require.NoError(t, err)
+
+	_, err = db.ExecContext(ctx, fmt.Sprintf(`
+		CREATE INDEX idx_braces ON %s.test_table ("col{value}", "col}data")
+	`, testSchema))
+	require.NoError(t, err)
+
+	// Test with app
+	appInstance, err := app.New()
+	require.NoError(t, err)
+	defer appInstance.Disconnect()
+
+	err = appInstance.Connect(connectionString)
+	require.NoError(t, err)
+
+	indexes, err := appInstance.ListIndexes(testSchema, "test_table")
+	assert.NoError(t, err)
+	assert.NotEmpty(t, indexes)
+
+	// Verify each index is parsed correctly
+	indexMap := make(map[string]*app.IndexInfo)
+	for _, idx := range indexes {
+		indexMap[idx.Name] = idx
+	}
+
+	// Check idx_quoted_name
+	if idx, ok := indexMap["idx_quoted_name"]; ok {
+		assert.Len(t, idx.Columns, 1, "idx_quoted_name should have 1 column")
+		assert.Equal(t, "Column Name", idx.Columns[0], "Column name should be 'Column Name'")
+	} else {
+		t.Error("idx_quoted_name not found")
+	}
+
+	// Check idx_with_commas - should have 2 columns, not split by commas inside quotes
+	if idx, ok := indexMap["idx_with_commas"]; ok {
+		assert.Len(t, idx.Columns, 2, "idx_with_commas should have exactly 2 columns")
+		assert.Contains(t, idx.Columns, "col,with,commas", "Should contain column with commas")
+		assert.Contains(t, idx.Columns, "normal_col", "Should contain normal_col")
+	} else {
+		t.Error("idx_with_commas not found")
+	}
+
+	// Check idx_braces
+	if idx, ok := indexMap["idx_braces"]; ok {
+		assert.Len(t, idx.Columns, 2, "idx_braces should have 2 columns")
+		assert.Contains(t, idx.Columns, "col{value}", "Should contain 'col{value}'")
+		assert.Contains(t, idx.Columns, "col}data", "Should contain 'col}data'")
+	} else {
+		t.Error("idx_braces not found")
+	}
+
+	// Cleanup
+	_, _ = db.ExecContext(ctx, fmt.Sprintf("DROP SCHEMA IF EXISTS %s CASCADE", testSchema))
+}
+
 func TestIntegration_App_ExplainQuery(t *testing.T) {
 	_, connectionString, cleanup := setupTestDatabase(t)
 	defer cleanup()

internal/app/client.go

@@ -7,7 +7,7 @@ import (
 	"fmt"
 	"strings"
 
-	_ "github.com/lib/pq"
+	"github.com/lib/pq"
 )
 
 // PostgreSQLClientImpl implements the PostgreSQLClient interface.
@@ -325,19 +325,16 @@ func (c *PostgreSQLClientImpl) ListIndexes(schema, table string) ([]*IndexInfo,
 	var indexes []*IndexInfo
 	for rows.Next() {
 		var index IndexInfo
-		var columnsStr string
+		var columns pq.StringArray
 		if err := rows.Scan(
-			&index.Name, &index.Table, &columnsStr,
+			&index.Name, &index.Table, &columns,
 			&index.IsUnique, &index.IsPrimary, &index.IndexType,
 		); err != nil {
 			return nil, fmt.Errorf("failed to scan index row: %w", err)
 		}
 
-		// Parse column array from PostgreSQL format
-		columnsStr = strings.Trim(columnsStr, "{}")
-		if columnsStr != "" {
-			index.Columns = strings.Split(columnsStr, ",")
-		}
+		// Convert pq.StringArray to []string
+		index.Columns = []string(columns)
 
 		indexes = append(indexes, &index)
 	}