import hashing

def write_header(f, file_comment):
	"""write_header(file(wb), str)
	Writes the header to the given file."""
	assert type(file_comment) == str
	# b'SSHWOT' magic
	f.write(b'SSHWOT')
	# Separating space
	f.write(b' ')
	# Version number
	f.write(b'0')
	# b' ' + file_comment, if there is one
	if len(file_comment) > 0:
		f.write(b' ')
		assert b'\n' not in file_comment
		f.write(file_comment)
	# End of header marked with b'\n'
	f.write(b'\n')

def write_entry(f, salt, hashed_host, fingerprint, comment):
	"""write_entry(file(wb), bytes[32], bytes[32], bytes[32], str)
	Writes an entry to the given file."""
	assert type(salt) == bytes and len(salt) == 32
	assert type(hashed_host) == bytes and len(hashed_host) == 32
	assert type(fingerprint) == bytes and len(fingerprint) == 32
	assert type(comment) == str

	# base64 encoded salt
	f.write(hashing.base64enc(salt))

	# Separating space
	f.write(b' ')

	# base64 encoded hashed_host
	f.write(hashing.base64enc(hashed_host))

	# Separating space
	f.write(b' ')

	# base64 encoded fingerprint
	f.write(hashing.base64enc(fingerprint))

	# b' ' + comment, if there is one
	if len(comment) > 0:
		f.write(b' ')
		assert '\n' not in comment
		f.write(comment.encode('utf-8'))

	# End of entry marked with b'\n'
	f.write(b'\n')

def write(f, entries, file_comment = ''):
	"""write(file(wb), [Entry], str)
	Creates a file containing all of the entries"""
	assert type(file_comment) == str

	write_header(f, file_comment)
	
	for entry in entries:
		write_entry(f, entry.salt, entry.hashed_host, entry.fingerprint, entry.comment)