day-1.rb

#!/usr/bin/env ruby

# Run this program on the commandline as:
#
#   ruby day-1.rb <filename of csv>
#
# The output will be a prettified JSON representation of the result
#

require 'csv'
require 'json'

KILOBYTES_PER_MEGABYTE = 1024
BUCKET_LIMIT           = 120 * KILOBYTES_PER_MEGABYTE

Track = Struct.new(:url, :email, :track, :kilobytes)

#
# load up all the tracks from the file by their url
#
def load_data(path:)
  loaded_data = Hash.new { |h,k| h[k] = Array.new }

  CSV.foreach(path, headers: :first_row, converters: :integer, return_headers: false) do |row|
    track = Track.new(*row.fields)
    loaded_data[track.url] << track
  end

  return loaded_data
end

#
# bucket a list of tracks into groups where the sum of hte kilobytes in the
# group cannot exceed the bucket limit
#
def bucket_tracks(tracks: , bucket_limit: BUCKET_LIMIT)
  buckets         = []
  current_bucket  = []
  current_kb      = 0

  tracks.each do |track|
    if (current_kb + track.kilobytes) > bucket_limit then
      buckets << current_bucket
      puts "current_kb: #{current_kb} - #{track.kilobytes}"
      current_bucket = []
      current_kb = 0
    end
    current_bucket << [track.track, track.kilobytes]
    current_kb += track.kilobytes
  end

  buckets << current_bucket
  return buckets
end

###
###
###

input_file = ARGV.shift
abort "Input file required" unless input_file

organized = {}

load_data(path: input_file).each do |url, tracks|
  organized[url] = bucket_tracks(tracks: tracks)
end
puts JSON.pretty_generate(organized)