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

require "optparse"
require "json"
require "open3"

OptionParser.new do |opts|
  opts.on("-e", "--profile PROFILE", "Profile Name") do |value|
    @profile_name = value
  end
end.parse!

abort "profile required" unless @profile_name

def list_tables(profile_name)
  stdout_str, stderr_str, status = Open3.capture3(
    "aws",
    "--profile", profile_name,
    "dynamodb", "list-tables"
  )
  raise stderr_str.strip unless status.success?
  JSON.parse(stdout_str).fetch("TableNames")
end

def to_filesize(size)
  {
    "B" => 1024,
    "KB" => 1024 * 1024,
    "MB" => 1024 * 1024 * 1024,
    "GB" => 1024 * 1024 * 1024 * 1024,
    "TB" => 1024 * 1024 * 1024 * 1024 * 1024
  }.each_pair { |e, s| return "#{(size / (s / 1024)).round(2)}#{e}" if size < s }
end

def describe_table(profile_name, table_name)
  stdout_str, stderr_str, status = Open3.capture3(
    "aws",
    "--profile", profile_name,
    "dynamodb", "describe-table", "--table-name", table_name
  )
  raise stderr_str.strip unless status.success?
  JSON.parse(stdout_str)
end

table_names = list_tables(@profile_name)

total_size = 0
table_names.each do |table_name|
  description = describe_table(@profile_name, table_name)
  size_in_bytes = description.dig("Table", "TableSizeBytes").to_f
  total_size += size_in_bytes
  puts "#{table_name}\t#{to_filesize(size_in_bytes)}"
end

puts "Total Size\t#{to_filesize(total_size)}"