package main

import (
        "fmt"
        "template"
        "bytes"
)

// Element
type IElement interface {
        Name() string
        Value() string
}

type Element struct {
        name string
        value string

        Decorators []IDecorator
}

func (this *Element) Init(name string) {
        this.name = name

        this.AddDecorator(&TemplateDecorator{ Element : this })
        this.AddDecorator(&TagDecorator{ Element : this })
}

func (this *Element) AddDecorator(decorator IDecorator) {
        this.Decorators = append(this.Decorators, decorator)
}

func (this *Element) Name() string {
        return this.name
}

func (this *Element) Value() string {
        return this.value
}

func (this *Element) SetValue(value string) {
        this.value = value
}

func (this *Element) Template() string {
        return "**{Element.Value}**"
}

func (this *Element) String() string {
        content := ""
        for _, decorator := range this.Decorators {
                content = decorator.Decorate(content)
        }
        return content
}

// TextElement
type TextElement struct {
        Element
}

func (this *TextElement) Template() string {
        return "##{Element.Value}##"
}


// Decorators
type IDecorator interface {
        Decorate(content string) string
}

// Tag Decorator
type TagDecorator struct {
        Element IElement
}

func (this *TagDecorator) Decorate(content string) string {
        return fmt.Sprintf("<%s>%s</%s>", this.Element.Name(), content, this.Element.Name())
}

// Template Decorator
type ITplElement interface {
        IElement
        Template() string
}

type TemplateDecorator struct {
        Element ITplElement
}

func (this *TemplateDecorator) Decorate(content string) string {
        tpl := template.MustParse(this.Element.Template(), nil)

        w := bytes.NewBuffer(nil)
        if err := tpl.Execute(w, this); err != nil {
                return content
        }
        return w.String()
}

func main() {
        el := &TextElement{}
        el.Init("myname")
        el.SetValue("Valueable")

        fmt.Println(el.String())
}

#### OUTPUT ####

<myname>**Valueable**</myname>

#### INTENDED ####

<myname>##Valueable##</myname>