encoded_histogram_format.cr

require "base64"
require "zlib"

def read(type, bytes_or_io)
  IO::ByteFormat::BigEndian.decode(type, bytes_or_io)
end

string = "HISTFAAAAEV42pNpmSzMwMCgyAABTBDKT4GBgdnNYMcCBvsPEBEJISEuATEZMQ4uASkhIR4nrxg9v2lMaxhvMekILGZkKmcCAEf2CsI"
bytes = Base64.decode(string)

cookie = read Int32, bytes[0, 4]
compressed_payload_length = read Int32, bytes[4, 4]

deflate = Zlib::Inflate.new(IO::Memory.new(bytes[8, compressed_payload_length]))
cookie = read Int32, deflate
payload_length = read Int32, deflate
normalizing_index_offset = read Int32, deflate
number_of_significant_value_digits = read Int32, deflate
lowest_trackable_value = read Int64, deflate
highest_trackable_value = read Int64, deflate
integer_to_double_conversion_ratio = read Float64, deflate
rest = deflate.gets_to_end.to_slice
pp cookie,
  payload_length,
  normalizing_index_offset,
  number_of_significant_value_digits,
  lowest_trackable_value,
  highest_trackable_value,
  integer_to_double_conversion_ratio,
  rest