feat: Enhance PostgreSQL type handling and migration scripts

- Introduced equivalent base types and variants for PostgreSQL types to normalize type comparisons.
- Added functions for normalizing SQL types and retrieving equivalent type variants.
- Updated migration writer to handle type alterations with checks for existing types.
- Implemented logic to create necessary extensions (e.g., pg_trgm) based on schema requirements.
- Enhanced tests to cover new functionality for type normalization and migration handling.
- Improved handling of GIN indexes to use appropriate operator classes based on column types.

pkg/merge/merge_test.go

@@ -1,6 +1,7 @@
 package merge
 
 import (
+	"strings"
 	"testing"
 
 	"git.warky.dev/wdevs/relspecgo/pkg/models"
@@ -140,6 +141,61 @@ func TestMergeColumns_NewColumn(t *testing.T) {
 	}
 }
 
+func TestMergeColumns_TypeConflictIsDetected(t *testing.T) {
+	target := &models.Database{
+		Schemas: []*models.Schema{
+			{
+				Name: "public",
+				Tables: []*models.Table{
+					{
+						Name:   "users",
+						Schema: "public",
+						Columns: map[string]*models.Column{
+							"email": {Name: "email", Type: "varchar", Length: 255},
+						},
+					},
+				},
+			},
+		},
+	}
+	source := &models.Database{
+		Schemas: []*models.Schema{
+			{
+				Name: "public",
+				Tables: []*models.Table{
+					{
+						Name:   "users",
+						Schema: "public",
+						Columns: map[string]*models.Column{
+							"email": {Name: "email", Type: "text"},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	result := MergeDatabases(target, source, nil)
+
+	if len(result.TypeConflicts) != 1 {
+		t.Fatalf("Expected 1 type conflict, got %d", len(result.TypeConflicts))
+	}
+	conflict := result.TypeConflicts[0]
+	if conflict.Schema != "public" || conflict.Table != "users" || conflict.Column != "email" {
+		t.Fatalf("Unexpected conflict location: %+v", conflict)
+	}
+	if conflict.TargetType != "varchar(255)" {
+		t.Fatalf("Expected target type varchar(255), got %q", conflict.TargetType)
+	}
+	if conflict.SourceType != "text" {
+		t.Fatalf("Expected source type text, got %q", conflict.SourceType)
+	}
+
+	if got := target.Schemas[0].Tables[0].Columns["email"].Type; got != "varchar" {
+		t.Fatalf("Expected target column type to remain unchanged, got %q", got)
+	}
+}
+
 func TestMergeConstraints_NewConstraint(t *testing.T) {
 	target := &models.Database{
 		Schemas: []*models.Schema{
@@ -509,6 +565,9 @@ func TestGetMergeSummary(t *testing.T) {
 		ConstraintsAdded: 3,
 		IndexesAdded:     2,
 		ViewsAdded:       1,
+		TypeConflicts: []ColumnTypeConflict{
+			{Schema: "public", Table: "users", Column: "email", TargetType: "varchar(255)", SourceType: "text"},
+		},
 	}
 
 	summary := GetMergeSummary(result)
@@ -518,6 +577,9 @@ func TestGetMergeSummary(t *testing.T) {
 	if len(summary) < 50 {
 		t.Errorf("Summary seems too short: %s", summary)
 	}
+	if !strings.Contains(summary, "Type conflicts:    1") {
+		t.Errorf("Expected type conflict count in summary, got: %s", summary)
+	}
 }
 
 func TestGetMergeSummary_Nil(t *testing.T) {