Utility fn for generating a visual representation of time-based models in ruby

ascii_timeline.rb

# outputs something like the following:
# 
# <-------------------------x------------------------->
#  |-----------------|
#                 |----------------------------------|
#               |--------------------| 
#                   |------------------------------|
# 

def create_ascii_timeline_for_time_based_models(list)
  earliest_time = list.sort_by(&:begin).first.begin
  latest_time = list.sort_by(&:end).last.end

  hours_range_between_min_and_max = (latest_time - earliest_time) / (60 * 60)
  minimum_desired_width = 49
  maximum_desired_width = 193
  # add 1 as padding for middle point of timeline
  relative_desired_width = (hours_range_between_min_and_max.to_i * 2) + 1
  desired_width = [[minimum_desired_width, relative_desired_width].max, maximum_desired_width].min
  divisor = hours_range_between_min_and_max / desired_width

  output = "# <"
  # add 1 to account for the rounding down that happens with to_i
  half_width = (desired_width / 2).to_i + 1
  half_width.times { output << "-" }
  output << "x"
  half_width.times { output << "-" }
  output << ">\n"

  # the calculated length of the header minus the newline char, plus 4 spaces for padding
  num_of_chars_to_end_of_range = (output.length - 1) + 6

  list.each_with_index do |item, index|
    append_value = "#  "
    
    len_in_hours = (item.end - item.begin) / (60 * 60)
    distance_in_hours_from_min_start = (item.begin - earliest_time) / (60 * 60)
    spaces_before_start = (distance_in_hours_from_min_start / divisor).to_i

    spaces_before_start.times { append_value << " " }
    append_value << "|"

    (len_in_hours / divisor).to_i.times { append_value << "-" }
    append_value << "|"
    
    num_of_spaces = num_of_chars_to_end_of_range - append_value.length
    num_of_spaces.times { append_value << " " }

    id_text = item.id || "item: #{index + 1}"
    append_value << "<-- #{id_text}"

    append_value << "\n"


    output << append_value
  end

  puts output
end