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- '''Instead of sequential shortcodes, generate pseudorandom shortcodes.
- See https://github.com/ArchiveTeam/tinyback/blob/master/tinyback/generators.py
- for historical details.
- '''
- import hashlib
- import struct
- from terroroftinytown.client import alphabet
- class BaseRandMixin:
- def get_shortcode_width(self):
- '''Return the number of characters the shortcode string.'''
- raise NotImplementedError('Please override me with an integer.')
- class LegacyChainMixin(BaseRandMixin):
- def transform_sequence_num(self, sequence_num):
- # TODO: write me
- raise NotImplementedError('todo: not yet implemented')
- class HashRandMixin(BaseRandMixin):
- def transform_sequence_num(self, sequence_num):
- seed = struct.pack('>Q', sequence_num)
- hasher = hashlib.md5(seed)
- digest = hasher.digest()
- num = struct.unpack('>Q', digest[:8])[0]
- shortcode = alphabet.int_to_str(num, self.params['alphabet'])
- shortcode = shortcode[-self.get_shortcode_width():]
- return shortcode
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