package textfmt

import (
	"code.squareroundforest.org/arpio/html"
	"code.squareroundforest.org/arpio/html/tag"
	"errors"
	"fmt"
	"io"
	"strings"
)

func htmlText(t Txt) []any {
	if len(t.cat) > 0 {
		var c []any
		for _, ti := range t.cat {
			c = append(c, htmlText(ti)...)
		}

		return c
	}

	var text any = t.text
	if t.link != "" {
		text = tag.A(html.Attr("href", t.link), text)
	}

	if t.bold {
		text = tag.B(text)
	}

	if t.italic {
		text = tag.I(text)
	}

	return []any{text}
}

func htmlTitle(e Entry) html.Tag {
	h := tag.H6
	switch e.titleLevel {
	case 0:
		h = tag.H1
	case 1:
		h = tag.H2
	case 2:
		h = tag.H3
	case 3:
		h = tag.H4
	case 4:
		h = tag.H5
	}

	return h(htmlText(e.text)...)
}

func htmlParagraph(e Entry) html.Tag {
	return tag.P(htmlText(e.text)...)
}

func htmlList(e Entry) html.Tag {
	list := tag.Ul
	for _, item := range e.items {
		list = list(tag.Li(htmlText(item.text)...))
	}

	return list
}

func htmlNumberedList(e Entry) html.Tag {
	list := tag.Ol
	for _, item := range e.items {
		list = list(tag.Li(htmlText(item.text)...))
	}

	return list
}

func htmlDefinitions(e Entry) html.Tag {
	list := tag.Dl
	for _, definition := range e.definitions {
		list = list(
			tag.Dt(append(htmlText(definition.name), ":")...),
			tag.Dd(htmlText(definition.value)...),
		)
	}

	return list
}

func htmlNumberedDefinitions(e Entry) html.Tag {
	list := tag.Dl
	for i, definition := range e.definitions {
		list = list(
			tag.Dt(append([]any{fmt.Sprintf("%d. ", i+1)}, append(htmlText(definition.name), ":")...)...),
			tag.Dd(htmlText(definition.value)...),
		)
	}

	return list
}

func htmlTable(e Entry) html.Tag {
	table := tag.Table
	e.rows = normalizeTable(e.rows)
	for _, r := range e.rows {
		row := tag.Tr
		cell := tag.Td
		if r.header {
			cell = tag.Th
		}

		for _, c := range r.cells {
			row = row(cell(htmlText(c.text)...))
		}

		table = table(row)
	}

	return table
}

func htmlCode(e Entry) html.Tag {
	return tag.Pre(tag.Code(htmlText(e.text)...))
}

func htmlMultiple(s SyntaxItem) string {
	s.topLevel = false
	s.multiple = false
	return fmt.Sprintf("%s...", htmlSyntaxItem(s))
}

func htmlRequired(s SyntaxItem) string {
	s.delimited = true
	s.topLevel = false
	s.required = false
	return fmt.Sprintf("<%s>", htmlSyntaxItem(s))
}

func htmlOptional(s SyntaxItem) string {
	s.delimited = true
	s.topLevel = false
	s.optional = false
	return fmt.Sprintf("[%s]", htmlSyntaxItem(s))
}

func htmlSequence(s SyntaxItem) string {
	ss := htmlSyntaxItems(s.sequence)
	if s.delimited || s.topLevel {
		return strings.Join(ss, " ")
	}

	return fmt.Sprintf("(%s)", strings.Join(ss, " "))
}

func htmlChoice(s SyntaxItem) string {
	ss := htmlSyntaxItems(s.choice)
	if s.topLevel {
		return strings.Join(ss, "\n")
	}

	if s.delimited {
		return strings.Join(ss, "|")
	}

	return fmt.Sprintf("(%s)", strings.Join(ss, "|"))
}

func htmlSymbol(s SyntaxItem) string {
	return s.symbol
}

func htmlSyntaxItem(s SyntaxItem) string {
	switch {

	// foo...
	case s.multiple:
		return htmlMultiple(s)

	// <foo>
	case s.required:
		return htmlRequired(s)

	// [foo]
	case s.optional:
		return htmlOptional(s)

	// foo bar baz or (foo bar baz)
	case len(s.sequence) > 0:
		return htmlSequence(s)

	// foo|bar|baz or (foo|bar|baz)
	case len(s.choice) > 0:
		return htmlChoice(s)

	// foo
	default:
		return htmlSymbol(s)
	}
}

func htmlSyntaxItems(s []SyntaxItem) []string {
	var ss []string
	for _, si := range s {
		si.delimited = false
		ss = append(ss, htmlSyntaxItem(si))
	}

	return ss
}

func htmlSyntax(e Entry) html.Tag {
	s := e.syntax
	s.topLevel = true
	return tag.Pre(htmlSyntaxItem(s))
}

func htmlTag(e Entry) (html.Tag, error) {
	switch e.typ {
	case title:
		return htmlTitle(e), nil
	case paragraph:
		return htmlParagraph(e), nil
	case list:
		return htmlList(e), nil
	case numberedList:
		return htmlNumberedList(e), nil
	case definitions:
		return htmlDefinitions(e), nil
	case numberedDefinitions:
		return htmlNumberedDefinitions(e), nil
	case table:
		return htmlTable(e), nil
	case code:
		return htmlCode(e), nil
	case syntax:
		return htmlSyntax(e), nil
	default:
		return nil, errors.New("invalid entry")
	}
}

func htmlTags(e []Entry) ([]html.Tag, error) {
	var tags []html.Tag
	for _, ei := range e {
		tag, err := htmlTag(ei)
		if err != nil {
			return nil, err
		}

		if tag != nil {
			tags = append(tags, tag)
		}
	}

	return tags, nil
}

func renderHTMLFragment(out io.Writer, doc Document) error {
	tags, err := htmlTags(doc.entries)
	if err != nil {
		return err
	}

	if len(tags) == 0 {
		return nil
	}

	for i, tag := range tags {
		if i > 0 {
			if _, err := fmt.Fprintln(out); err != nil {
				return err
			}
		}

		indent := html.Indentation{
			Indent:    "\t",
			PWidth:    120,
			MinPWidth: 60,
		}

		if doc.entries[i].wrapWidth != 0 {
			indent.PWidth = doc.entries[i].wrapWidth
			indent.MinPWidth = indent.PWidth / 2
		}

		if doc.entries[i].indent != 0 {
			indent.Indent = timesn(" ", doc.entries[i].indent)
		}

		if err := html.WriteIndent(out, indent, tag); err != nil {
			return err
		}
	}

	if _, err := fmt.Fprintln(out); err != nil {
		return err
	}

	return nil
}

func renderHTML(out io.Writer, doc Document, lang string) error {
	tags, err := htmlTags(doc.entries)
	if err != nil {
		return err
	}

	head := tag.Head(tag.Meta(html.Attr("charset", "utf-8")))
	if len(doc.entries) > 0 && doc.entries[0].typ == title && doc.entries[0].titleLevel == 0 {
		head = head(tag.Title(htmlText(doc.entries[0].text)...))
	}

	body := tag.Body
	for _, tag := range tags {
		body = body(tag)
	}

	htmlDoc := tag.Html(head, body)
	if lang != "" {
		htmlDoc = htmlDoc(html.Attr("lang", lang))
	}

	indent := html.Indentation{
		Indent:    "\t",
		PWidth:    120,
		MinPWidth: 60,
	}

	if err := html.WriteIndent(out, indent, tag.Doctype("html"), htmlDoc); err != nil {
		return err
	}

	if _, err := fmt.Fprintln(out); err != nil {
		return err
	}

	return nil
}