#! /usr/bin/env python3
# Check that all ".pyc" files exist and are up-to-date
# Uses module 'os'

import sys
import os
from stat import ST_MTIME
import importlib.util

# PEP 3147 compatibility (PYC Repository Directories)
cache_from_source = (importlib.util.cache_from_source if sys.implementation.cache_tag
 else lambda path: path + 'c')


def main():
 if len(sys.argv) > 1:
 verbose = (sys.argv[1] == '-v')
 silent = (sys.argv[1] == '-s')
 else:
 verbose = silent = False
 MAGIC = importlib.util.MAGIC_NUMBER
 if not silent:
 print('Using MAGIC word', repr(MAGIC))
 for dirname in sys.path:
 try:
 names = os.listdir(dirname)
 except OSError:
 print('Cannot list directory', repr(dirname))
 continue
 if not silent:
 print('Checking ', repr(dirname), '...')
 for name in sorted(names):
 if name.endswith('.py'):
 name = os.path.join(dirname, name)
 try:
 st = os.stat(name)
 except OSError:
 print('Cannot stat', repr(name))
 continue
 if verbose:
 print('Check', repr(name), '...')
 name_c = cache_from_source(name)
 try:
 with open(name_c, 'rb') as f:
 magic_str = f.read(4)
 mtime_str = f.read(4)
 except IOError:
 print('Cannot open', repr(name_c))
 continue
 if magic_str != MAGIC:
 print('Bad MAGIC word in ".pyc" file', end=' ')
 print(repr(name_c))
 continue
 mtime = get_long(mtime_str)
 if mtime in {0, -1}:
 print('Bad ".pyc" file', repr(name_c))
 elif mtime != st[ST_MTIME]:
 print('Out-of-date ".pyc" file', end=' ')
 print(repr(name_c))


def get_long(s):
 if len(s) != 4:
 return -1
 return s[0] + (s[1] << 8) + (s[2] << 16) + (s[3] << 24)


if __name__ == '__main__':
 main()