package htmlx

import (
	"github.com/d5/tengo/v2"
	"strings"
	"html"
	"fmt"
)

const RawTag = "raw"

// The type implements basic
// way to structrize HTML elements.
type Element struct {
	tengo.ObjectImpl
	Tag string
	Attr map[string] string
	Children []*Element
	// The value makes sense only if
	// the tag is the "raw"
	Content string
	Final bool
}

func (el *Element) TypeName() string {
	return "*HTMLElement"
}

// The method renders the element to it's
// HTML representation.
func (el *Element) String() string {
	if el.Tag == RawTag {
		return html.EscapeString(el.Content)
	}

	var b strings.Builder

	fmt.Fprintf(&b, "<%s", el.Tag)
	for k, v := range el.Attr {
		fmt.Fprintf(&b, " %s=%q", k, v)
	}
	fmt.Fprint(&b, ">")

	if el.Final {
		return b.String()
	}

	for _, child := range el.Children {
		if child == nil {
			continue
		}
		fmt.Fprint(&b, child.String())
	}

	fmt.Fprintf(&b, "</%s>", el.Tag)
	return b.String()
}

func MakeElements(args ...tengo.Object) ([]*Element, error) {
	s := []*Element{}
	for _, arg := range args {
		el, ok := arg.(*Element)
		if !ok {
			str, ok := tengo.ToString(arg)
			if ok {
				s = append(s, &Element{
					Tag: RawTag,
					Content: str,
				})
			}
			continue
		}
		s = append(s, el)
	}
	return s, nil
}

func (el *Element) SetBody(
	args ...tengo.Object,
) (tengo.Object, error) {
	els, err := MakeElements(args...)
	if err != nil {
		return nil, err
	}
	el.Children = els
	return el, nil
}

func (el *Element) Add(
	args ...tengo.Object,
) (tengo.Object, error) {
	s, err := MakeElements(args...)
	if err != nil {
		return nil, err
	}
	el.Children = append(el.Children, s...)
	return el, nil
}

func (el *Element) SetFinal(
	args ...tengo.Object,
) (tengo.Object, error) {
	if len(args) > 0 {
		return nil, tengo.ErrWrongNumArguments
	}
	el.Final = true
	return el, nil
}

func (el *Element) IndexGet(
	index tengo.Object,
) (tengo.Object, error) {
	arg, ok := tengo.ToString(index)
	if !ok {
		return nil, tengo.ErrInvalidIndexValueType
	}

	switch arg {
	case "body" :
		return &tengo.UserFunction{
			Name: "element.body",
			Value: el.SetBody,
		}, nil
	case "final" :
		return &tengo.UserFunction{
			Name: "element.final",
			Value: el.SetFinal,
		}, nil
	case "add" :
		return &tengo.UserFunction{
			Name: "element.add",
			Value: el.Add,
		}, nil
	}
	return nil, nil
}