french_ssn.rb

# SETUP:
# touch french_ssn.rb
# mkdir spec
# touch spec/french_ssn_spec.rb
# mkdir data
# touch data/french_departments.yml
# curl -L https://gist.githubusercontent.com/Eschults/279682088e2f87564161e4dbf8390d68/raw/bdbc97ed036a5b21978defd9987e800c7fa67dce > 'data/french_departments.yml'

require 'date'
require 'yaml'
require 'pry-byebug'

SSN_PATTERN = /\A(?<gender>[10])\s?(?<year>\d{2})\s?(?<month>(0[1-9])|(1[12]))\s?(?<department>\d[1-9]|2[AB])\s?(\d{3}\s?){2}(?<key>\d{2})\Z/
DEPARTMENTS = YAML.load_file('data/french_departments.yml')

def french_ssn_info(ssn)
  match_data = ssn.match(SSN_PATTERN)
  if match_data && valid_key?(ssn, match_data[:key])
    gender = gender(match_data[:gender])
    month = month(match_data[:month])
    year = "19" + match_data[:year]
    department = department(match_data[:department])
    "a #{gender}, born in #{month}, #{year} in #{department}."
  else
    "The number is invalid"
  end
end

def gender(code)
  code == "1" ? "man" : "woman"
end

def month(code)
  Date::MONTHNAMES[code.to_i]
end

def department(code)
  DEPARTMENTS[code]
end

def valid_key?(ssn, key)
  # equal to the remainder of the division of (97 - ssn_without_key) by 97.)
  ssn_without_key = ssn[0, ssn.length - 2].gsub(/\W/, '')
  key.to_i == (97 - ssn_without_key.to_i) % 97
end

french_ssn_spec.rb

require_relative "../french_ssn"

describe "#french_ssn_info" do
  it "should return 'The number is invalid' when passed an empty string" do
    actual = french_ssn_info("")
    expected = "The number is invalid"
    expect(actual).to eq(expected)
  end

  it "should return 'a man, born in December, 1984 in Seine-Maritime.' when passed a valid social security number" do
    expected = "a man, born in December, 1984 in Seine-Maritime."

    valid_ssn1 = french_ssn_info("1 84 12 76 451 089 46")
    expect(valid_ssn1).to eq(expected)

    valid_ssn2 = french_ssn_info("184127645108946")
    expect(valid_ssn2).to eq(expected)
  end
end

describe "#gender" do
  it "should return 'man' if passed '1'" do
    actual = gender("1")
    expected = "man"
    expect(actual).to eq(expected)
  end

  it "should return 'woman' if passed '2'" do
    actual = gender("2")
    expected = "woman"
    expect(actual).to eq(expected)
  end
end

describe "#month" do
  it "should return 'January' if passed '01'" do
    actual = month("01")
    expected = "January"
    expect(actual).to eq(expected)
  end

  it "should return 'December' if passed '12'" do
    actual = month("12")
    expected = "December"
    expect(actual).to eq(expected)
  end
end

describe "#department" do
  it "should return 'Charente-Maritime' if passed '17'" do
    actual = department("17")
    expected = "Charente-Maritime"
    expect(actual).to eq(expected)
  end
end

describe "#valid_key?" do
  it "should return true if passed '1 84 12 76 451 089 46', '46'" do
    valid_key = valid_key?('1 84 12 76 451 089 46', '46')
    expect(valid_key).to be(true)
  end

  it "should return false if passed '1 84 12 76 451 089 47', '47'" do
    valid_key = valid_key?('1 84 12 76 451 089 47', '47')
    expect(valid_key).to be(false)
  end
end