package io

import (
	"golang.org/x/text/transform"
)

const (
	linefeed                        = '\n'
	LineFeedRemover linefeedRemover = iota
)

type linefeedRemover int

func (linefeedRemover) Reset() {}
func (linefeedRemover) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
	cur, start := 0, 0
	for ; cur < len(src); {
		if src[cur] == linefeed {
			if nDst+1 > len(dst) {
				err = transform.ErrShortDst
				return
			}
			nSrc += cur - start
			nDst += copy(dst[nDst:], src[start:cur])
			cur++
			start = cur
		} else {
			cur++
		}
	}
	if remain := cur - start; remain == 0 {
	} else if nDst+1 > len(dst) {
		err = transform.ErrShortDst
	} else {
		nSrc += remain
		nDst += copy(dst[nDst:], src[start:cur])
	}
	return
}

type Remover struct {
	Removes []byte
}

func (r *Remover) Reset() {}
func (r *Remover) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
	cur, start := 0, 0

	for ; cur < len(src); {
		var (
			curData = src[cur]
			matched = false
		)
		for i := 0; i < len(r.Removes); i++ {
			if matched = r.Removes[i] == curData; matched {
				break
			}
		}
		if matched {
			if nDst+1 > len(dst) {
				err = transform.ErrShortDst
				return
			}
			nSrc += cur - start
			nDst += copy(dst[nDst:], src[start:cur])
			cur++
			start = cur
		} else {
			cur++
		}
	}
	if remain := cur - start; remain == 0 {
	} else if nDst+1 > len(dst) {
		err = transform.ErrShortDst
	} else {
		nSrc += remain
		nDst += copy(dst[nDst:], src[start:cur])
	}
	return
}