Add a copy file header to state the source file for handwritten files (GoogleCloudPlatform#13725)

Author: iyabchen

mmv1/provider/terraform.go

@@ -423,7 +423,9 @@ func (t Terraform) CopyFileList(outputFolder string, files map[string]string, ge
 		if filepath.Ext(target) == ".go" || (filepath.Ext(target) == ".mod" && generateCode) {
 			t.replaceImportPath(outputFolder, target)
 		}
-
+		if filepath.Ext(target) == ".go" || filepath.Ext(target) == ".markdown" {
+			t.addCopyfileHeader(source, outputFolder, target)
+		}
 		if filepath.Ext(target) == ".go" {
 			t.addHashicorpCopyRightHeader(outputFolder, target)
 		}
@@ -523,10 +525,70 @@ func (t Terraform) CompileFileList(outputFolder string, files map[string]string,
 			continue
 		}
 		t.replaceImportPath(outputFolder, target)
+		if filepath.Ext(targetFile) == ".go" || filepath.Ext(targetFile) == ".markdown" {
+			t.addCopyfileHeader(source, outputFolder, target)
+		}
 		t.addHashicorpCopyRightHeader(outputFolder, target)
 	}
 }
 
+func (t Terraform) addCopyfileHeader(srcpath, outputFolder, target string) {
+	githubPrefix := "https://github.com/GoogleCloudPlatform/magic-modules/tree/main/mmv1/"
+	if !strings.HasPrefix(srcpath, githubPrefix) {
+		srcpath = githubPrefix + srcpath
+	}
+
+	targetFile := filepath.Join(outputFolder, target)
+	sourceByte, err := os.ReadFile(targetFile)
+	if err != nil {
+		log.Fatalf("Cannot read file %s to add copy file header: %s", targetFile, err)
+	}
+
+	srcStr := string(sourceByte)
+	if strings.Contains(srcStr, "***     AUTO GENERATED CODE    ***    Type: Handwritten     ***") {
+		return
+	}
+
+	templateFormat := `// ----------------------------------------------------------------------------
+//
+//     ***     AUTO GENERATED CODE    ***    Type: Handwritten     ***
+//
+// ----------------------------------------------------------------------------
+//
+//     This code is generated by Magic Modules using the following:
+//
+//     Source file: %s
+//
+//     DO NOT EDIT this file directly. Any changes made to this file will be
+//     overwritten during the next generation cycle.
+//
+// ----------------------------------------------------------------------------
+%s`
+	content := srcStr
+	if filepath.Ext(target) == ".markdown" {
+		// insert the header after ---
+		templateFormat = "---\n" + strings.Replace(templateFormat, "//", "#", -1)
+		content = strings.TrimPrefix(srcStr, "---\n")
+	}
+
+	fileStr := fmt.Sprintf(templateFormat, srcpath, content)
+
+	sourceByte = []byte(fileStr)
+	// format go file
+	if filepath.Ext(targetFile) == ".go" {
+		sourceByte, err = format.Source(sourceByte)
+		if err != nil {
+			log.Printf("error formatting %s: %s\n", targetFile, err)
+			return
+		}
+	}
+
+	err = os.WriteFile(targetFile, sourceByte, 0644)
+	if err != nil {
+		log.Fatalf("Cannot write file %s to add copy file header: %s", target, err)
+	}
+}
+
 func (t Terraform) addHashicorpCopyRightHeader(outputFolder, target string) {
 	if !expectedOutputFolder(outputFolder) {
 		log.Printf("Unexpected output folder (%s) detected "+