piece spec hash implementation in ruby

piece_spec_hash.rb

require "digest"

def av_hash_62bit(av_components)
  av_components.
      map(&Digest::SHA256.method(:digest)).
      reduce(Digest::SHA256.new, &:update).
      digest.
      unpack("Q>").
      first & 0x3fffffffffffffff
end

def piece_spec_hash(sku_id, av_components)
  return sku_id if av_components.empty?

  sha256 = Digest::SHA256.new

  [sku_id, *av_components.map(&method(:av_hash_62bit)).sort.uniq].each do |int|
    sha256.update([int].pack("Q>"))
  end

  sha256.digest[0,4].unpack("N").first
end

components = [
  [[4242].pack("Q>"), "", ""],
  [[2].pack("Q>"), "qualifier 1 value", "qualifier 2 value"]
]

puts "av1 62-bit hash: #{av_hash_62bit(components[0])}"
puts "av2 62-bit hash: #{av_hash_62bit(components[1])}"
puts "piece_spec_hash: #{piece_spec_hash(88662, components)}"