feat: Add cmd for go:generate commands

Author: murarustefaan

cmd/flatten/main.go

@@ -0,0 +1,79 @@
+// flatten generates an optimized Go struct from a source file.
+//
+// Usage:
+//
+//	//go:generate go run github.com/cloudquery/codegen/cmd/flatten -source=../api/models.go -from=Finding -to=flatFinding -output=finding_generated.go -package=services -sort
+//	//go:generate go run github.com/cloudquery/codegen/cmd/flatten -source=../api/models.go -from=Finding -to=flatFinding -output=finding_generated.go -package=services -sort -extra=AssetType:string:assetType,omitempty
+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"path/filepath"
+	"strings"
+
+	"github.com/cloudquery/codegen/structs"
+)
+
+func main() {
+	source := flag.String("source", "", "path to Go source file containing the struct")
+	from := flag.String("from", "", "name of the source struct")
+	to := flag.String("to", "", "name of the generated struct")
+	output := flag.String("output", "", "output filename")
+	pkg := flag.String("package", "", "Go package name for the generated file")
+	sort := flag.Bool("sort", false, "sort fields: ID first, then alphabetically")
+	extra := flag.String("extra", "", "extra fields to prepend (Name:Type:JSONTag)")
+	flag.Parse()
+
+	if *source == "" || *from == "" || *to == "" || *output == "" {
+		flag.Usage()
+		log.Fatal("required flags: -source, -from, -to, -output")
+	}
+
+	cfg := structs.StructConfig{
+		SourceName:  *from,
+		OutputName:  *to,
+		OutputFile:  filepath.Base(*output),
+		ExtraFields: parseExtraFields(*extra),
+	}
+
+	outputDir := filepath.Dir(*output)
+	if outputDir == "" || outputDir == "." {
+		outputDir = "."
+	}
+
+	var opts []structs.Option
+	if *pkg != "" {
+		opts = append(opts, structs.WithPackageName(*pkg))
+	}
+	if *sort {
+		opts = append(opts, structs.WithSortFields())
+	}
+
+	if err := structs.Flatten(*source, []structs.StructConfig{cfg}, outputDir, opts...); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func parseExtraFields(s string) []structs.Field {
+	if s == "" {
+		return nil
+	}
+	parts := strings.SplitN(s, ":", 3)
+	if len(parts) != 3 {
+		log.Fatalf("invalid -extra %q: expected Name:Type:JSONTag", s)
+	}
+	return []structs.Field{{
+		Name:    strings.TrimSpace(parts[0]),
+		Type:    strings.TrimSpace(parts[1]),
+		JSONTag: strings.TrimSpace(parts[2]),
+	}}
+}
+
+func init() {
+	flag.Usage = func() {
+		fmt.Fprintf(flag.CommandLine.Output(), "Usage: flatten [flags]\n\nGenerates an optimized Go struct with nested fields replaced by map[string]any.\n\nFlags:\n")
+		flag.PrintDefaults()
+	}
+}