Have I been pwned check via a ruby script

pwned_check.rb

# frozen_string_literal: true

# Requires ruby 2.1 or newer
#
# This script checks a single password or a list of passwords against
# pwnedpasswords HTTP API. The passwords are hashed and anonymized before
# sending them over the wire. Each password that has been pwned will be printed
# to standard out in clear text with the known pwnage count.
#
# Read more at https://haveibeenpwned.com/API/v2#PwnedPasswords

# Checks whether a password has been pwned against Troy Hunt's pwnedpasswords
# HTTP API. If you want to check multiple passwords, reuse the instance to use
# the same HTTP connection.
#
# @example single password
# > ruby ./pwned_check.rb secret
#
# @example multiple passwords from file, delimiter is used to split the file
# > ruby ./pwned_check.rb ./my_passwords.txt
#
# @example multiple passwords from arguments
# > ruby ./pwned_check.rb --delimiter=, secret,sauce

if RUBY_VERSION.split('.').first.to_i < 2
  raise UnsupportedRubyVersion('Need ruby version 2.1 or newer')
end

# @example
#   passwords = ['secret', 'verysecret']
#   checker = PwnedChecker.new
#   passwords.each do |password|
#     puts "#{password} has been pwned #{checker.pwned_count('secret')} times"
#   end
class PwnedChecker
  require 'digest/sha1'
  require 'net/http'

  PARTIAL_HASH_LENGTH = 5

  def initialize
    @conn = Net::HTTP.new('api.pwnedpasswords.com', 443)
    @conn.use_ssl = true
  end

  def pwned_count(password)
    if (occurrence = find_occurrence(password))
      occurrence.split(':')[1].to_i
    else
      0
    end
  end

  private

  def find_occurrence(password)
    password_hash = sha1(password)
    hash_head = password_hash[0...PARTIAL_HASH_LENGTH]
    hash_tail = password_hash[PARTIAL_HASH_LENGTH..-1]
    partial_occurrences(hash_head).find { |occ| occ.start_with?(hash_tail) }
  end

  def sha1(password)
    Digest::SHA1.hexdigest(password).upcase
  end

  def partial_occurrences(hash_head)
    @conn.start unless @conn.started?
    @conn.get("/range/#{hash_head}").body.split("\r\n")
  end
end

# Expands given input to create a list of passwords.
#
# If opts.input is a file, reads the file and splits it by opts.delimiter.
# If it is not a file, splits opts.input by opts.delimiter.
# In any case, the resulting passwords are stripped of leading and trailing
# whitespace and quotes.
class PasswordReader
  def self.read!(opts)
    new.read!(opts)
  end

  def read!(opts)
    expand_input(opts).map(&method(:strip))
  end

  private

  def strip(word)
    word
      .strip
      .sub(/^'/, '')
      .chomp("'")
      .sub(/^"/, '')
      .chomp('"')
  end

  def expand_input(opts)
    raw_input = opts.input
    if File.file?(raw_input)
      File.read(raw_input).split(opts.delimiter)
    else
      raw_input.split(opts.delimiter)
    end
  end
end

def read_opts!
  require 'optparse'
  require 'ostruct'

  delimiter = Regexp.compile(/[\n,\r]+/)

  opt_parser = OptionParser.new do |parser|
    parser.banner = "Usage: ruby ./pwned_check.rb secret\nUsage: ruby ./pwned_check.rb my_passwords.txt"
    parser.on('-d=delimiter', '--delimiter=delimiter', String, 'Password delimiter, used both when reading from arguments or file. Defaults to \n or \r\n') do |input_delimiter|
      delimiter = input_delimiter
    end
    parser.on('-h', '--help', 'Display this screen') do
      puts parser
      exit
    end
  end
  input = opt_parser.parse!.first
  OpenStruct.new(input: input, delimiter: delimiter)
end

pwned_checker = PwnedChecker.new
passwords = PasswordReader.read!(read_opts!)
passwords.each do |password|
  count = pwned_checker.pwned_count(password)
  puts "#{password}: pwned #{count} times" if count > 0
end

Made more robust and lessened ruby version requirements, allowed specifying delimiter.