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""" |
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byceps.services.ticketing.ticket_code_service |
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
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:Copyright: 2006-2020 Jochen Kupperschmidt |
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:License: Modified BSD, see LICENSE for details. |
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""" |
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from random import sample |
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from typing import Set |
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from .transfer.models import TicketCode |
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def generate_ticket_codes(quantity: int) -> Set[TicketCode]: |
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"""Generate a number of ticket codes.""" |
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codes: Set[TicketCode] = set() |
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for _ in range(quantity): |
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code = _generate_ticket_code_not_in(codes) |
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codes.add(code) |
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# Check if the correct number of codes has been generated. |
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_verify_total_matches(codes, quantity) |
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return codes |
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def _generate_ticket_code_not_in( |
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codes: Set[TicketCode], *, max_attempts: int = 4 |
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) -> TicketCode: |
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"""Generate ticket codes and return the first one not in the set.""" |
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for _ in range(max_attempts): |
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code = _generate_ticket_code() |
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if code not in codes: |
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return code |
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raise TicketCodeGenerationFailed( |
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f'Could not generate unique ticket code after {max_attempts} attempts.' |
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) |
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_CODE_ALPHABET = 'BCDFGHJKLMNPQRSTVWXYZ' |
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_CODE_LENGTH = 5 |
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def _generate_ticket_code() -> TicketCode: |
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"""Generate a ticket code. |
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Generated codes are not necessarily unique! |
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""" |
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return TicketCode(''.join(sample(_CODE_ALPHABET, _CODE_LENGTH))) |
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def _verify_total_matches( |
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codes: Set[TicketCode], requested_quantity: int |
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) -> None: |
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"""Verify if the number of generated codes matches the number of |
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requested codes. |
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Raise an exception if they do not match. |
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""" |
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actual_quantity = len(codes) |
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if actual_quantity != requested_quantity: |
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raise TicketCodeGenerationFailed( |
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f'Number of generated ticket codes ({actual_quantity}) ' |
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f'does not match requested amount ({requested_quantity}).' |
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) |
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class TicketCodeGenerationFailed(Exception): |
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"""Generating one or more unique ticket codes has failed.""" |
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byceps /
byceps
