63 lines
1.3 KiB
Python
63 lines
1.3 KiB
Python
import re
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from .models import IdType
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def check_digit_10(isbn):
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assert len(isbn) == 9
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sum = 0
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for i in range(len(isbn)):
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c = int(isbn[i])
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w = i + 1
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sum += w * c
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r = sum % 11
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return "X" if r == 10 else str(r)
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def check_digit_13(isbn):
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assert len(isbn) == 12
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sum = 0
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for i in range(len(isbn)):
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c = int(isbn[i])
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w = 3 if i % 2 else 1
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sum += w * c
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r = 10 - (sum % 10)
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return "0" if r == 10 else str(r)
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def isbn_10_to_13(isbn):
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if not isbn or len(isbn) != 10:
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return None
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return "978" + isbn[:-1] + check_digit_13("978" + isbn[:-1])
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def isbn_13_to_10(isbn):
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if not isbn or len(isbn) != 13 or isbn[:3] != "978":
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return None
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else:
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return isbn[3:12] + check_digit_10(isbn[3:12])
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def is_isbn_13(isbn):
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return re.match(r"^\d{13}$", isbn) is not None
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def is_isbn_10(isbn):
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return re.match(r"^\d{9}[X0-9]$", isbn) is not None
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def is_asin(asin):
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return re.match(r"^B[A-Z0-9]{9}$", asin) is not None
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def detect_isbn_asin(s):
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if not s:
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return None, None
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n = re.sub(r"[^0-9A-Z]", "", s.upper())
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if is_isbn_13(n):
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return IdType.ISBN, n
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if is_isbn_10(n):
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return IdType.ISBN, isbn_10_to_13(n)
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if is_asin(n):
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return IdType.ASIN, n
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return None, None
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