class BaseX

# File lib/base_x.rb, line 42
def self.base(n)
  n.between?(2, 62) or raise ArgumentError.new("Base #{n} is not valid; base must be at least 2 and at most 62")
  digits_uppercase_lowercase = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
  new(digits_uppercase_lowercase[0...n])
end

# File lib/base_x.rb, line 49
def self.bases
  constants
    .map     { |const_name| [const_name, const_get(const_name)] }
    .select  { |const_name, base| base.is_a?(BaseX) }
    .sort_by { |const_name, base| [base.base, const_name.to_s] }
    .map do |const_name, base|
      [const_name.to_s, base.base, base.encode(EXAMPLE_TOKEN), base.numerals]
    end
end

# File lib/base_x.rb, line 59
def self.bases_table
  bases.map do |name, base_size, example, numerals|
    example = example[0...21] + "…" if example.size > 22
    [
      name,
      base_size,
      example.inspect.include?("\\")  ? example.inspect  : example,
      numerals.inspect.include?("\\") ? numerals.inspect : numerals,
    ]
  end.map do |array|
    "%-15s %-3s %-22s %s" % array
  end.join("\n")
end

# File lib/base_x.rb, line 36
def self.decode(encoded, opts)
  opts[:numerals].respond_to?(:index) or
    raise ArgumentError.new("A string of numerals must be provided, e.g. BaseX.encode(\"bcaffag\", numerals: \"abcdefg\")")
  new(opts[:numerals]).decode(encoded)
end

# File lib/base_x.rb, line 30
def self.encode(string, opts)
  opts[:numerals].respond_to?(:index) or
    raise ArgumentError.new("A string of numerals must be provided, e.g. BaseX.encode(\"Hello World\", numerals: \"abcdefg\")")
  new(opts[:numerals]).encode(string)
end

# File lib/base_x.rb, line 24
def self.integer_to_string(int, opts)
  opts[:numerals].respond_to?(:index) or
    raise ArgumentError.new("A string of numerals must be provided, e.g. BaseX.integer_to_string(123, numerals: \"abcdefg\")")
  new(opts[:numerals]).integer_to_string(int)
end

# File lib/base_x.rb, line 80
def initialize(numerals)
  numerals.chars.size > 1 or
    raise ArgumentError.new("Need at least two numerals to express numbers! Numeral given: #{numerals.inspect}") 
  numerals.chars.size == numerals.chars.uniq.size or
    raise ArgumentError.new("Duplicate characters found in numerals definition: #{numerals.inspect}") 
  @numerals = numerals
  @base     = numerals.size
end

# File lib/base_x.rb, line 73
def self.print_bases
  puts bases_table
end

# File lib/base_x.rb, line 18
def self.string_to_integer(string, opts)
  opts[:numerals].respond_to?(:index) or
    raise ArgumentError.new("A string of numerals must be provided, e.g. BaseX.string_to_integer(\"bcde\", numerals: \"abcdefg\")")
  new(opts[:numerals]).string_to_integer(string)
end

# File lib/base_x.rb, line 126
def decode(encoded)
  return "" if encoded.size == 0
  int = string_to_integer(encoded)
  decoded = Base256.integer_to_string(int)
  decoded_number_size = 256**(decoded.size)
  encoded_number_size = base**(encoded.size)

  # encoded_number_size / base < decoded_number_size <= encoded_number_size
  while decoded_number_size <= encoded_number_size / base
    decoded = "\x00" + decoded
    decoded_number_size *= 256
  end

  decoded
end

# File lib/base_x.rb, line 111
def encode(string)
  return "" if string.size == 0
  int = string.each_byte.reduce(0) { |int, byte| int *= 256; int + byte }
  encoded = integer_to_string(int)
  string_number_size = 256**(string.size)
  encoded_number_size = base**(encoded.size)

  while encoded_number_size < string_number_size
    encoded = @numerals[0] + encoded
    encoded_number_size *= base
  end

  encoded
end

# File lib/base_x.rb, line 100
def integer_to_string(int)
  return @numerals[0] if int == 0
  string = ""
  while int > 0
    char = @numerals[int % base]
    string << char
    int /= base
  end
  string.reverse
end

# File lib/base_x.rb, line 89
def string_to_integer(string)
  raise EmptyString.new unless string.size > 0
  integer = 0
  string.each_char do |char|
    integer *= base
    numeral_value = @numerals.index(char) or raise InvalidNumeral.new(char)
    integer += numeral_value
  end
  integer
end