package wikitext_parser

import (
	"golang.org/x/text/unicode/norm"
	"unicode"
)

type HTML struct {
	Tag *HTMLTag
}

type HTMLTag struct {
	Parent     *HTMLTag
	Name       []byte
	Parameters []byte
	Content    []*HTMLTag
}

func (t *HTMLTag) String() (r string) {
	if string(t.Name) == "#text" {
		r = string(t.Parameters)
	} else {
		for _, c := range t.Content {
			r += c.String()
		}
	}

	if string(t.Name) == "del" { //add strikethrough
		var runeList []rune
		for _, runeEntry := range []rune(norm.NFD.String(r)) {
			if runeEntry <= unicode.MaxASCII {
				runeList = append(runeList, '\u0336') //combining long stroke overlay
			}
			runeList = append(runeList, runeEntry)
		}
		r = norm.NFC.String(string(runeList))
	} else if string(t.Name) == "ref" { //remove references
		return ""
	} else if string(t.Name) == "br" { //new line
		return "\n"
	} else if string(t.Name) == "script" {
		return ""
	}
	return
}

func ParseHTML(text string, index int, depth int) (i int, html *HTML) {
	var c byte

	html = &HTML{}

	readingTag := false
	readingParameters := false
	isTerminating := false
	var tag *HTMLTag
	tagDepth := 0

	for i = index; i < len(text); i++ {
		c = text[i]

		if c == '<' && i < len(text)-1 && text[i+1] == '/' {
			isTerminating = true
			readingTag = true
			readingParameters = false
		} else if c == '<' {
			newTag := &HTMLTag{
				Parent: tag,
			}

			if tag != nil {
				tag.Content = append(tag.Content, newTag)
			}
			tag = newTag
			readingTag = true
			readingParameters = false
			isTerminating = false
			if tagDepth == 0 && html.Tag == nil {
				html.Tag = tag
			}
			tagDepth++
		} else if readingTag && c == '>' {
			readingTag = false
			readingParameters = false

			if isTerminating {
				tagDepth--
				if tag != nil {
					tag = tag.Parent
				}
				isTerminating = false
			}
			if tagDepth == 0 {
				return i + 1, html
			}
		} else if readingTag && c == '/' {
			isTerminating = true
		} else if !isTerminating && readingTag {
			if c == ' ' {
				readingParameters = true
			}
			if readingParameters {
				tag.Parameters = append(tag.Parameters, c)
			} else {
				tag.Name = append(tag.Name, c)
			}
		} else if !isTerminating && tagDepth > 0 {
			if len(tag.Content) == 0 || string(tag.Content[len(tag.Content)-1].Name) != "#text" {
				tag.Content = append(tag.Content, &HTMLTag{
					Parent: tag,
					Name:   []byte("#text"),
				})
			}
			tag.Content[len(tag.Content)-1].Parameters = append(tag.Content[len(tag.Content)-1].Parameters, c)
		}
	}

	return
}