重构进行中，preview通道尚未完全恢复全部功能

internal/db/schema.go

@@ -0,0 +1,91 @@
+package db
+
+// ================================================================
+// Schema 版本声明
+// ================================================================
+
+type SchemaVersionDef struct {
+	Version   string
+	TableName string
+	Columns   map[string]ColumnDef
+}
+
+type ColumnDef struct {
+	Type    string
+	NotNull bool
+	Default string
+	Primary bool
+}
+
+var schemaHistory = []SchemaVersionDef{
+	// v1: 初始版本
+	{
+		Version:   "v1",
+		TableName: "proxies",
+		Columns: map[string]ColumnDef{
+			"id":          {Type: "INTEGER", Primary: true},
+			"name":        {Type: "TEXT", NotNull: true},
+			"type":        {Type: "TEXT", NotNull: true, Default: "'tcp'"},
+			"local_ip":    {Type: "TEXT", NotNull: true},
+			"local_port":  {Type: "INTEGER", NotNull: true},
+			"remote_port": {Type: "INTEGER", NotNull: true},
+			"enabled":     {Type: "INTEGER", NotNull: true, Default: "1"},
+			"created_at":  {Type: "DATETIME", Default: "CURRENT_TIMESTAMP"},
+			"updated_at":  {Type: "DATETIME", Default: "CURRENT_TIMESTAMP"},
+		},
+	},
+	// v2: 当前版本
+	{
+		Version:   "v2",
+		TableName: "proxies",
+		Columns: map[string]ColumnDef{
+			"id":          {Type: "INTEGER", Primary: true},
+			"name":        {Type: "TEXT", NotNull: true},
+			"type":        {Type: "TEXT", NotNull: true, Default: "'tcp'"},
+			"local_ip":    {Type: "TEXT", NotNull: true},
+			"local_port":  {Type: "INTEGER", NotNull: true},
+			"remote_port": {Type: "INTEGER", NotNull: true},
+			"enabled":     {Type: "INTEGER", NotNull: true, Default: "1"},
+			"created_at":  {Type: "DATETIME", Default: "CURRENT_TIMESTAMP"},
+			"updated_at":  {Type: "DATETIME", Default: "CURRENT_TIMESTAMP"},
+		},
+	},
+}
+
+func getSchemaDef(version string) *SchemaVersionDef {
+	for _, def := range schemaHistory {
+		if def.Version == version {
+			return &def
+		}
+	}
+	return nil
+}
+
+func getLatestSchemaDef() *SchemaVersionDef {
+	if len(schemaHistory) == 0 {
+		return nil
+	}
+	return &schemaHistory[len(schemaHistory)-1]
+}
+
+func schemaVersionsEqual(v1, v2 *SchemaVersionDef) bool {
+	if v1 == nil || v2 == nil {
+		return false
+	}
+	if v1.TableName != v2.TableName {
+		return false
+	}
+	if len(v1.Columns) != len(v2.Columns) {
+		return false
+	}
+	for name, col1 := range v1.Columns {
+		col2, ok := v2.Columns[name]
+		if !ok {
+			return false
+		}
+		if col1.Type != col2.Type || col1.NotNull != col2.NotNull || col1.Default != col2.Default {
+			return false
+		}
+	}
+	return true
+}