practice

#!/usr/bin/env ruby

class Practice
  def initialize
    @data = {}
    try_to_load_data
  end

  def record_today(minutes)
    @data[key_for(Time.now)] = minutes
  end

  def write_data_to_file!
    File.open(data_file, 'w') do |f|
      @data.keys.sort.each do |key|
        f.write("#{key}|#{@data[key]}\n")
      end
    end
  end

  def data_points
    today = Time.now
    points = [minutes_for(today)]

    1.upto(days_to_show - 1) do |offset|
      points.unshift(minutes_for(today - (offset * 86400)))
    end

    points
  end

private

  def minutes_for(date)
    @data[key_for(date)] || 0
  end

  def days_to_show
    (ENV['PRACTICE_DAYS'] || 14).to_i
  end

  def data_file
    ENV['PRACTICE_DATA'] || "#{ENV['HOME']}/.practice"
  end

  def key_for(date)
    date.strftime(date_format)
  end

  def date_format
    "%d-%m-%Y"  # 31-02-2013
  end

  def try_to_load_data
    return unless File.exist?(data_file)

    File.open(data_file, 'r').each_line do |line|
      date, minutes = line.split('|')
      @data[date] = minutes.to_i
    end
  end
end

practice = Practice.new

if ARGV.empty?
  puts practice.data_points.join(' ')
else
  case ARGV.first
  when 'record'
    minutes = ARGV[1].to_i

    practice.record_today(minutes)
    practice.write_data_to_file!

    puts "Recorded #{minutes} minutes for today."
  end
end

usage.txt

# records 120 minutes for today
$ practice record 120

# shows last 14 days
$ practice | spark
▁▁▁▁▁▁▁▁▁▁▁▁▆█

# shows last 3 days
$ PRACTICE_DAYS=3 practice | spark

# reads/writes to different data file
$ PRACTICE_DATA=/tmp/datafile.txt practice