package routes

import (
	"bytes"
	"io"
)

func countLines(r io.Reader) (int, error) {
	buf := make([]byte, 32*1024)
	bufLen := 0
	count := 0
	nl := []byte{'\n'}

	for {
		c, err := r.Read(buf)
		if c > 0 {
			bufLen += c
		}
		count += bytes.Count(buf[:c], nl)

		switch {
		case err == io.EOF:
			/* handle last line not having a newline at the end */
			if bufLen >= 1 && buf[(bufLen-1)%(32*1024)] != '\n' {
				count++
			}

			return count, nil
		case err != nil:
			return 0, err
		}
	}
}