Completed
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by Jochen
03:36
created

_verify_total_matches()   A

Complexity

Conditions 2

Size

Total Lines 12
Code Lines 6

Duplication

Lines 0
Ratio 0 %

Code Coverage

Tests 3
CRAP Score 2.0625

Importance

Changes 0
Metric Value
cc 2
eloc 6
nop 2
dl 0
loc 12
ccs 3
cts 4
cp 0.75
crap 2.0625
rs 10
c 0
b 0
f 0
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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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