#!/usr/bin/env ruby
# rubocop:disable Metrics/BlockLength
#
# DOMAINS=nip.io,sslip.io rspec --format documentation --color spec
#
# Admittedly it's overkill to use rspec to run a set of assertions
# against a DNS server -- a simple shell script would have been
# shorter and more understandable. We are using rspec merely to
# practice using rspec.
#
def get_whois_nameservers(domain)
  whois_output = `whois #{domain}`
  whois_lines = whois_output.split(/\n+/)
  nameserver_lines = whois_lines.select { |line| line =~ /^Name Server:/ }
  nameservers = nameserver_lines.map { |line| line.split.last.downcase }.uniq
  # whois records don't have trailing '.'; NS records do; add trailing '.'
  nameservers.map { |ns| ns << '.' }
  nameservers
end

domains_env = ENV['DOMAINS'] || 'example.com'
domains = domains_env.split(',').map(&:strip)
sslip_version = '4.2.1'

domains.each do |domain|
  whois_nameservers = get_whois_nameservers(domain)

  describe domain do
    # I don't want a spurious failure, esp. ns-do-sg.sslip.io
    # default is 3 tries, 5 seconds timeout
    let(:dig_args) { ['+tries=15', '+timeout=10'] }
    let(:dig_cmd) { "dig #{dig_args.join(' ')}" }
    soa = nil

    context "when evaluating $DOMAINS (\"#{domains_env}\") environment variable" do
      let(:domains_env) { ENV['DOMAINS'] }
      it 'is set' do
        expect(domains_env).not_to be_nil
      end
      it 'is not an empty string' do
        expect(domains_env).not_to eq('')
      end
    end

    it 'should have at least 2 nameservers' do
      expect(whois_nameservers.size).to be > 1
    end

    whois_nameservers.each do |whois_nameserver|
      it "nameserver #{whois_nameserver}'s NS records include all whois nameservers #{whois_nameservers}, " +
         "`dig ... @#{whois_nameserver} ns #{domain} +short`" do
        dig_nameservers = `#{dig_cmd} @#{whois_nameserver} ns #{domain} +short`.split(/\n+/)
        expect(whois_nameservers - dig_nameservers).to be_empty
      end

      it "nameserver #{whois_nameserver}'s SOA record match" do
        dig_soa = `#{dig_cmd} @#{whois_nameserver} soa #{domain} +short`
        soa ||= dig_soa
        expect(dig_soa).to eq(soa)
      end

      it "nameserver #{whois_nameserver}'s has an A record" do
        expect(`#{dig_cmd} @#{whois_nameserver} a #{domain} +short`.chomp).not_to eq('')
        expect($?.success?).to be true
      end

      it "nameserver #{whois_nameserver}'s has an AAAA record" do
        expect(`#{dig_cmd} @#{whois_nameserver} a #{domain} +short`.chomp).not_to eq('')
        expect($?.success?).to be true
      end

      a = [rand(256), rand(256), rand(256), rand(256)]
      it "resolves #{a.join('.')}.#{domain} to #{a.join('.')}" do
        expect(`#{dig_cmd} @#{whois_nameserver} #{a.join('.') + '.' + domain} +short`.chomp).to  eq(a.join('.'))
      end

      a = [rand(256), rand(256), rand(256), rand(256)]
      it "resolves #{a.join('-')}.#{domain} to #{a.join('.')}" do
        expect(`#{dig_cmd} @#{whois_nameserver} #{a.join('-') + '.' + domain} +short`.chomp).to  eq(a.join('.'))
      end

      a = [rand(256), rand(256), rand(256), rand(256)]
      b = [('a'..'z').to_a, ('0'..'9').to_a].flatten.sample(8).join
      it "resolves #{b}.#{a.join('-')}.#{domain} to #{a.join('.')}" do
        expect(`#{dig_cmd} @#{whois_nameserver} #{b}.#{a.join('-') + '.' + domain} +short`.chomp).to eq(a.join('.'))
      end

      a = [rand(256), rand(256), rand(256), rand(256)]
      b = [('a'..'z').to_a, ('0'..'9').to_a].flatten.sample(8).join
      it "resolves #{a.join('-')}.#{b} to #{a.join('.')}" do
        expect(`#{dig_cmd} @#{whois_nameserver} #{a.join('-') + '.' + b} +short`.chomp).to eq(a.join('.'))
      end

      # don't begin the hostname with a double-dash -- `dig` mistakes it for an argument
      it "resolves api.--.#{domain}' to eq ::)}" do
        expect(`#{dig_cmd} @#{whois_nameserver} AAAA api.--.#{domain} +short`.chomp).to eq('::')
      end

      it "resolves localhost.--1.#{domain}' to eq ::1)}" do
        expect(`#{dig_cmd} @#{whois_nameserver} AAAA localhost.api.--1.#{domain} +short`.chomp).to eq('::1')
      end

      it "resolves 2001-4860-4860--8888.#{domain}' to eq 2001:4860:4860::8888)}" do
        expect(`#{dig_cmd} @#{whois_nameserver} AAAA 2001-4860-4860--8888.#{domain} +short`.chomp).to eq('2001:4860:4860::8888')
      end

      it "resolves 2601-646-100-69f0--24.#{domain}' to eq 2601:646:100:69f0::24)}" do
        expect(`#{dig_cmd} @#{whois_nameserver} AAAA 2601-646-100-69f0--24.#{domain} +short`.chomp).to eq('2601:646:100:69f0::24')
      end

      it "gets the expected version number, #{sslip_version}" do
        expect(`#{dig_cmd} @#{whois_nameserver} TXT version.status.#{domain} +short`).to include(sslip_version)
      end

      it "gets the source (querier's) IP address" do
        # Look on my Regular Expressions, ye mighty, and despair!
        expect(`#{dig_cmd} @#{whois_nameserver} TXT ip.#{domain} +short`).to match(/^"(\d+\.\d+\.\d+\.\d+)|(([[:xdigit:]]*:){2,7}[[:xdigit:]]*)"$/)
      end

      # check the website
      it "is able to reach https://#{domain} and get a valid response (2xx)" do
        `curl -If https://#{domain} 2> /dev/null`
        expect($?.success?).to be true
      end
    end
  end
end
# rubocop:enable Metrics/BlockLength