package gax

import "bytes"

// XGoogHeader is for use by the Google Cloud Libraries only.
//
// XGoogHeader formats key-value pairs.
// The resulting string is suitable for x-goog-api-client header.
func XGoogHeader(keyval ...string) string {
	if len(keyval) == 0 {
		return ""
	}
	if len(keyval)%2 != 0 {
		panic("gax.Header: odd argument count")
	}
	var buf bytes.Buffer
	for i := 0; i < len(keyval); i += 2 {
		buf.WriteByte(' ')
		buf.WriteString(keyval[i])
		buf.WriteByte('/')
		buf.WriteString(keyval[i+1])
	}
	return buf.String()[1:]
}