18F/identity-idp

#!/usr/bin/env ruby
# frozen_string_literal: true

require 'yaml'
require 'active_support/core_ext/hash/deep_merge'
require 'optparse'

comments = []
sources = true

parser = OptionParser.new do |opts|
  opts.banner = <<~EOS
    Usage: #{$PROGRAM_NAME} a.yml b.yml"

    Reads in YAML files and combines them via deep merge, in order
  EOS

  opts.on('-c', '--comment STR', 'a string to print as a comment at the top of the file') do |c|
    comments << c
  end

  opts.on('--[no-]sources', 'print the source files as commments at the top') do |s|
    sources = s
  end

  opts.on('-h', '--help') do
    puts opts
    exit 0
  end
end

parser.order!

comments.each do |comment|
  puts "# #{comment}"
end

if sources
  puts '# Sources:'
  ARGV.each do |path|
    puts "# - #{path}"
  end
end

result = ARGV.map do |path|
  YAML.load_file(path)
end.reduce(&:deep_merge)

puts result.to_yaml