#!/usr/bin/python
#
# This script extracts the hashes from all the .torrent 
# files so we can add them to the opentrackers allowlist.

import os
import sys
import hashlib
from optparse import OptionParser
from fastbencode import bencode, bdecode

def torrent_hash(fname):
    try:
        with open(fname, 'rb') as f:
            d = bdecode(f.read())
        hash_val = hashlib.sha1(bencode(d[b'info'])).hexdigest().upper()
        fn = os.path.basename(fname)
        return f"{hash_val} - {fn}"
    except FileNotFoundError:
        print(f"Error: File '{fname}' not found.", file=sys.stderr)
    except IsADirectoryError:
        print(f"Error: '{fname}' is a directory.", file=sys.stderr)
    except Exception as e:
        print(f"Error reading or decoding hash from {fname}: {e}", file=sys.stderr)
    return None

def main():
    parser = OptionParser(usage=sys.argv[0] + " [options] [torrentfiles] ...")
    parser.add_option("-o", "--output", type="string", metavar="FILE",
                      dest="output", default='-',
                      help="write hashes to FILE, default=stdout")
    (options, args) = parser.parse_args()

    outfd = sys.stdout
    if options.output != '-':
        try:
            outfd = open(options.output, 'w')
        except Exception as e:
            print(f"Error: unable to open output file {options.output}: {e}", file=sys.stderr)
            return 1

    for a in args:
        try:
            hash_val = torrent_hash(a)
            if hash_val:
                outfd.write(hash_val + '\n')
        except Exception as e:
            print(f"Error reading hash from {a}: {e}", file=sys.stderr)

    return 0

if __name__ == "__main__":
    sys.exit(main())