def lookahead(iterable): # https://stackoverflow.com/a/1630350
	"""Pass through all values from the given iterable, augmented by the
	information if there are more values to come after the current one
	(True), or if it is the last value (False).
	"""
	# Get an iterator and pull the first value.
	it = iter(iterable)
	try:
	    last = next(it)
	except StopIteration:
	    return
	# Run the iterator to exhaustion (starting from the second value).
	for val in it:
	    # Report the *previous* value (more to come).
	    yield last, False
	    last = val
	# Report the last value.
	yield last, True

def email2html(mailtext:str,extraclasses="",ispatch=False):
	from html import escape
	if ispatch:
		from pygments import highlight
		from pygments.lexers import DiffLexer
		from pygments.formatters import HtmlFormatter
		extraclasses+=" highlight"

	res='<article class="email %s"><p>'%extraclasses

	mailtext=mailtext.replace("\r\n","\n") # we assume unix lineendings so remove all CRLF

	if ispatch:
		mail=highlight(mailtext,lexer=DiffLexer(),formatter=HtmlFormatter(style="monokai"))
	else:
		mail=escape(mailtext)
		lastlf=0
		while '\n' in mail:
			newlf=mail.find('\n',lastlf)
			if 70<newlf-lastlf<85:
				replacement=' '
			elif len(mail)>newlf+1 and mail[newlf+1]=="\n": # two newlines
				replacement="</p><p>"
			elif newlf-lastlf<=1: # ignore the second newline of 2
				replacement=''
			else:
				replacement='<br>'

			mail=mail[:newlf]+replacement+mail[newlf+1:]
			lastlf=newlf+len(replacement)


	res+=mail
	res+="</p></article>"
	return res