feat: add parseParams

main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"log"
 )
 
 var tmpl = `
@@ -27,8 +28,10 @@ func main() {
 	if err != nil {
 		panic(err)
 	}
-	fmt.Printf("'%s'", templateMeta)
-	render(body, map[string]string{
-		"from": "2025-07-15",
-	})
+	fmt.Println(templateMeta)
+	ctx, err := parseParams(templateMeta)
+	if err != nil {
+		log.Fatal(err)
+	}
+	render(body, ctx)
 }

params.go

@@ -0,0 +1,23 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+)
+
+func parseParams(meta TemplateMeta) (ctx TemplateContext, err error) {
+	result := make(map[string]*string)
+	for key, spec := range meta.Params {
+		result[key] = flag.String(key, spec.Default, key)
+	}
+	flag.Parse()
+	ctx = make(TemplateContext)
+	for key, spec := range meta.Params {
+		if spec.Required && *result[key] == "" {
+			err = fmt.Errorf("parameter '%s' required but not provided", key)
+			return
+		}
+		ctx[key] = *result[key]
+	}
+	return
+}