#! /usr/bin/env python3
# Written by Martin v. Löwis <loewis@informatik.hu-berlin.de>

"""Generate binary message catalog from textual translation description.

This program converts a textual Uniforum-style message catalog (.po file) into
a binary GNU catalog (.mo file). This is essentially the same function as the
GNU msgfmt program, however, it is a simpler implementation.

Usage: msgfmt.py [OPTIONS] filename.po

Options:
 -o file
 --output-file=file
 Specify the output file to write to. If omitted, output will go to a
 file named filename.mo (based off the input file name).

 -h
 --help
 Print this message and exit.

 -V
 --version
 Display version information and exit.
"""

import os
import sys
import ast
import getopt
import struct
import array
from email.parser import HeaderParser

__version__ = "1.1"

MESSAGES = {}



def usage(code, msg=''):
 print(__doc__, file=sys.stderr)
 if msg:
 print(msg, file=sys.stderr)
 sys.exit(code)



def add(id, str, fuzzy):
 "Add a non-fuzzy translation to the dictionary."
 global MESSAGES
 if not fuzzy and str:
 MESSAGES[id] = str



def generate():
 "Return the generated output."
 global MESSAGES
 # the keys are sorted in the .mo file
 keys = sorted(MESSAGES.keys())
 offsets = []
 ids = strs = b''
 for id in keys:
 # For each string, we need size and file offset. Each string is NUL
 # terminated; the NUL does not count into the size.
 offsets.append((len(ids), len(id), len(strs), len(MESSAGES[id])))
 ids += id + b'0円'
 strs += MESSAGES[id] + b'0円'
 output = ''
 # The header is 7 32-bit unsigned integers. We don't use hash tables, so
 # the keys start right after the index tables.
 # translated string.
 keystart = 7*4+16*len(keys)
 # and the values start after the keys
 valuestart = keystart + len(ids)
 koffsets = []
 voffsets = []
 # The string table first has the list of keys, then the list of values.
 # Each entry has first the size of the string, then the file offset.
 for o1, l1, o2, l2 in offsets:
 koffsets += [l1, o1+keystart]
 voffsets += [l2, o2+valuestart]
 offsets = koffsets + voffsets
 output = struct.pack("Iiiiiii",
 0x950412de, # Magic
 0, # Version
 len(keys), # # of entries
 7*4, # start of key index
 7*4+len(keys)*8, # start of value index
 0, 0) # size and offset of hash table
 output += array.array("i", offsets).tobytes()
 output += ids
 output += strs
 return output



def make(filename, outfile):
 ID = 1
 STR = 2

 # Compute .mo name from .po name and arguments
 if filename.endswith('.po'):
 infile = filename
 else:
 infile = filename + '.po'
 if outfile is None:
 outfile = os.path.splitext(infile)[0] + '.mo'

 try:
 with open(infile, 'rb') as f:
 lines = f.readlines()
 except IOError as msg:
 print(msg, file=sys.stderr)
 sys.exit(1)

 section = None
 fuzzy = 0

 # Start off assuming Latin-1, so everything decodes without failure,
 # until we know the exact encoding
 encoding = 'latin-1'

 # Parse the catalog
 lno = 0
 for l in lines:
 l = l.decode(encoding)
 lno += 1
 # If we get a comment line after a msgstr, this is a new entry
 if l[0] == '#' and section == STR:
 add(msgid, msgstr, fuzzy)
 section = None
 fuzzy = 0
 # Record a fuzzy mark
 if l[:2] == '#,' and 'fuzzy' in l:
 fuzzy = 1
 # Skip comments
 if l[0] == '#':
 continue
 # Now we are in a msgid section, output previous section
 if l.startswith('msgid') and not l.startswith('msgid_plural'):
 if section == STR:
 add(msgid, msgstr, fuzzy)
 if not msgid:
 # See whether there is an encoding declaration
 p = HeaderParser()
 charset = p.parsestr(msgstr.decode(encoding)).get_content_charset()
 if charset:
 encoding = charset
 section = ID
 l = l[5:]
 msgid = msgstr = b''
 is_plural = False
 # This is a message with plural forms
 elif l.startswith('msgid_plural'):
 if section != ID:
 print('msgid_plural not preceded by msgid on %s:%d' % (infile, lno),
 file=sys.stderr)
 sys.exit(1)
 l = l[12:]
 msgid += b'0円' # separator of singular and plural
 is_plural = True
 # Now we are in a msgstr section
 elif l.startswith('msgstr'):
 section = STR
 if l.startswith('msgstr['):
 if not is_plural:
 print('plural without msgid_plural on %s:%d' % (infile, lno),
 file=sys.stderr)
 sys.exit(1)
 l = l.split(']', 1)[1]
 if msgstr:
 msgstr += b'0円' # Separator of the various plural forms
 else:
 if is_plural:
 print('indexed msgstr required for plural on %s:%d' % (infile, lno),
 file=sys.stderr)
 sys.exit(1)
 l = l[6:]
 # Skip empty lines
 l = l.strip()
 if not l:
 continue
 l = ast.literal_eval(l)
 if section == ID:
 msgid += l.encode(encoding)
 elif section == STR:
 msgstr += l.encode(encoding)
 else:
 print('Syntax error on %s:%d' % (infile, lno), \
 'before:', file=sys.stderr)
 print(l, file=sys.stderr)
 sys.exit(1)
 # Add last entry
 if section == STR:
 add(msgid, msgstr, fuzzy)

 # Compute output
 output = generate()

 try:
 with open(outfile,"wb") as f:
 f.write(output)
 except IOError as msg:
 print(msg, file=sys.stderr)



def main():
 try:
 opts, args = getopt.getopt(sys.argv[1:], 'hVo:',
 ['help', 'version', 'output-file='])
 except getopt.error as msg:
 usage(1, msg)

 outfile = None
 # parse options
 for opt, arg in opts:
 if opt in ('-h', '--help'):
 usage(0)
 elif opt in ('-V', '--version'):
 print("msgfmt.py", __version__)
 sys.exit(0)
 elif opt in ('-o', '--output-file'):
 outfile = arg
 # do it
 if not args:
 print('No input file given', file=sys.stderr)
 print("Try `msgfmt --help' for more information.", file=sys.stderr)
 return

 for filename in args:
 make(filename, outfile)


if __name__ == '__main__':
 main()