Class: Bookworm

Inherits:
Object
  • Object
show all
Defined in:
lib/bookworm.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(identifier) ⇒ Bookworm

Returns a new instance of Bookworm.



4
5
6
7
8
 
# File 'lib/bookworm.rb', line 4

def initialize(identifier)
  @original = identifier.to_s
  @isbn = as_new(identifier.to_s)
  @type = type
end

Instance Attribute Details

#isbn ⇒ Object (readonly)

Returns the value of attribute isbn.



2
3
4
 
# File 'lib/bookworm.rb', line 2

def isbn
  @isbn
end

#original ⇒ Object (readonly)

Returns the value of attribute original.



2
3
4
 
# File 'lib/bookworm.rb', line 2

def original
  @original
end

Instance Method Details

#as_new(identifier = isbn) ⇒ Object 



10
11
12
13
14
15
16
17
18
19
 
# File 'lib/bookworm.rb', line 10

def as_new(identifier=isbn)
  return nil unless identifier
  identifier = scrub(identifier)
  case identifier
  when /^290/ then to_thirteen("978#{identifier[3..-1]}")
  when /^291/ then to_thirteen("979#{identifier[3..-1]}")
  when /^979|978|\d{10}/ then to_thirteen(identifier)
  else nil
  end
end

#as_ten ⇒ Object 



27
28
29
30
31
 
# File 'lib/bookworm.rb', line 27

def as_ten
  return nil if not is_valid? or isbn =~ /979/
  identifier = isbn[3..-2]
  identifier + ten_check_digit(identifier)
end

#as_used ⇒ Object 



21
22
23
24
25
 
# File 'lib/bookworm.rb', line 21

def as_used
  return nil unless is_valid?
  prefix = /^979/.match(isbn) ? "291" : "290"
  to_thirteen(prefix + isbn[3..-1])
end

#is_valid? ⇒ Boolean

Returns:

  • (Boolean) 


88
89
90
91
92
93
94
 
# File 'lib/bookworm.rb', line 88

def is_valid?
  case original
  when /^\d{13}/ then original[12] == thirteen_check_digit(original)
  when /^\d{10}/ then original[9] == ten_check_digit(original)
  else false
  end
end

#scrub(string) ⇒ Object 



51
52
53
54
 
# File 'lib/bookworm.rb', line 51

def scrub(string)
  result = /^((?:978|979|291|290)\d{10}|\d{10}).*/.match(string.delete('-'))
  result ? result[1] : nil
end

#ten_check_digit(identifier = isbn) ⇒ Object 



72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
 
# File 'lib/bookworm.rb', line 72

def ten_check_digit(identifier=isbn)
  sum = 0
  
  9.times do |index|
    sum += (10 - index) * identifier[index].to_i
  end

  checksum = 11 - sum % 11

  case checksum
  when 10 then "X"
  when 11 then "0"
  else checksum.to_s
  end
end

#thirteen_check_digit(identifier = isbn) ⇒ Object 



56
57
58
59
60
61
62
63
64
65
66
 
# File 'lib/bookworm.rb', line 56

def thirteen_check_digit(identifier=isbn)
  identifier, sum = identifier.rjust(13,"978")[/(.+)\w/,1], 0

  12.times do |index|
    digit = identifier[index].to_i
    sum += index.even? ? digit : digit * 3
  end

  checksum = (10 - sum % 10)
  checksum == 10 ? '0' : checksum.to_s
end

#thirteen_strip(identifier) ⇒ Object 



68
69
70
 
# File 'lib/bookworm.rb', line 68

def thirteen_strip(identifier)
  identifier.rjust(13,"978")[0..-2]
end

#to_thirteen(identifier) ⇒ Object 



47
48
49
 
# File 'lib/bookworm.rb', line 47

def to_thirteen(identifier)
  thirteen_strip(identifier) + thirteen_check_digit(identifier)
end

#type ⇒ Object 



33
34
35
36
37
38
39
40
41
42
43
44
45
 
# File 'lib/bookworm.rb', line 33

def type
  addendum = case original
  when /^(?:978|979)\d{10}/
    addendum = /^(?:978|979)\d{10}(\d{5})$/.match(original).to_a.last
    addendum == '90000' ? 'used' : 'new'
  when /^(?:290|291)\d{10}/
    addendum = /^(?:290|291)\d{10}(\d{5})$/.match(original).to_a.last
    addendum == '99990' ? 'new' : 'used'
  when /^\d{10}$/
    'new'
  else nil
  end
end