package eol

import (
	"io"

	"sourcecode.social/reiver/go-opt"

	"sourcecode.social/reiver/go-eol/cr"
	"sourcecode.social/reiver/go-eol/lf"
	"sourcecode.social/reiver/go-eol/lfcr"
)

// ReadLFCR tries to read the "\r\n" (i.e., carriage-return line-feed) end-of-line sequence.
//
// If successful, it returns the number-of-bytes read (to read in end-of-line sequence "\r\n").
//
// If the first character read is not a '\n', then ReadLFCR will try to unread the character.
// If the second character read is not a '\r', then ReadLFCR will also try to unread the second character, but will not be able to unread the first character (i.e., '\n') it already read.
//
// Example usage:
//
//	size, err := eol.ReadLFCR(runescanner)
func ReadLFCR(runescanner io.RuneScanner) (size int, err error) {

	var size0 int
	{
		var err error

		const characterNumber uint64 = 1
		var circumstance internalCircumstance = specifyCircumstance(opt.Something(lfcr.String), characterNumber)
		size0, err = readthisrune(circumstance, runescanner, lf.Rune)
		if nil != err {
			return size0, err
		}
	}

	var size1 int
	{
		var err error

		const characterNumber uint64 = 2
		var circumstance internalCircumstance = specifyCircumstance(opt.Something(lfcr.String), characterNumber)
		size1, err = readthisrune(circumstance, runescanner, cr.Rune)
		if nil != err {
			return size1+size0, err
		}
	}

	return size1+size0, nil
}