#!/usr/bin/env python3

import argparse
import os
from collections import defaultdict

import archpkg
from archpkg import parse_version

class PkgNameInfo(archpkg.PkgNameInfo):
  def __lt__(self, other):
    # ignore arch mismatch
    if self.name != other.name:
      return NotImplemented
    if self.version != other.version:
      return parse_version(self.version) < parse_version(other.version)
    return int(self.release) < int(other.release)

def remove_pkg(path):
  try:
    os.unlink(path)
  except FileNotFoundError:
    pass
  sig = path + '.sig'
  try:
    os.unlink(sig)
  except FileNotFoundError:
    pass

def main(args):
  pkgs = defaultdict(list)
  for f in args.packages:
    pkg = PkgNameInfo.parseFilename(f)
    pkgs[pkg.name].append((pkg, f))
  for _, v in pkgs.items():
    try:
      v.sort()
    except TypeError:
      print('Bad things happen: %s' % v)
      raise

    for pkg, f in v[:-args.keep]:
      if args.dry_run:
        print('would remove %s.' % f)
      else:
        print('removing %s.' % f)
        remove_pkg(f)

    if args.show_kept_fd >= 0:
      for _, f in v[-args.keep:]:
        os.write(args.show_kept_fd, f.encode('utf-8') + b'\n')

if __name__ == '__main__':
  parser = argparse.ArgumentParser(description='remove old Arch Linux packages')
  parser.add_argument('-n', '--dry-run', action='store_true',
                      help='dry run')
  parser.add_argument('-k', '--keep', metavar='N', type=int, default=2,
                      help='how many versions to keep. Default is 2')
  parser.add_argument('--show-kept-fd', metavar='FD', type=int, default=-1,
                      help='write kept package paths to fd FD, one per line')
  parser.add_argument('packages', metavar='PACKAGE', nargs='+',
                      help='package files to check')
  args = parser.parse_args()
  main(args)