package html

import (
	"code.squareroundforest.org/arpio/textedit"
	"io"
)

type indentState struct {
	started, lineStarted bool
}

func indentLen(indent string) int {
	var l int
	r := []rune(indent)
	for _, ri := range r {
		if ri == '\t' {
			l += 8
			continue
		}

		l++
	}

	return l
}

func indentEdit(indent []rune) func(rune, indentState) ([]rune, indentState) {
	return func(r rune, s indentState) ([]rune, indentState) {
		var ret []rune
		if r == '\n' {
			s.started = true
			s.lineStarted = false
			ret = append(ret, '\n')
			return ret, s
		}

		if s.started && !s.lineStarted {
			ret = append(ret, indent...)
		}

		ret = append(ret, r)
		s.started = true
		s.lineStarted = true
		return ret, s
	}
}

func newIndentWriter(out io.Writer, indent string) *textedit.Writer {
	return textedit.New(
		out,
		textedit.Func(
			indentEdit([]rune(indent)),
			func(indentState) []rune { return nil },
		),
	)
}