package mailparser

import "regexp"

// encodedWordRe matches an RFC 2047 encoded-word (=?charset?B|Q?text?=).
// Used to detect header values that were stored raw because decoding failed
// (e.g. Windows-1252 before the CharsetReader fix in decodeMIMEHeader).
var encodedWordRe = regexp.MustCompile(`=\?[^?\s]+\?[BbQq]\?[^?]*\?=`)

// HasEncodedWord reports whether s still contains an undecoded RFC 2047
// encoded-word. A correctly decoded subject never contains one.
func HasEncodedWord(s string) bool {
	return encodedWordRe.MatchString(s)
}

// DecodeMIMEHeader is the exported form of decodeMIMEHeader. It decodes
// RFC 2047 encoded-word headers including charsets outside UTF-8/US-ASCII/
// ISO-8859-1 (e.g. Windows-1252). Callers outside the parser need it for
// metadata repair runs (subject backfill).
func DecodeMIMEHeader(s string) string {
	return decodeMIMEHeader(s)
}