Bart Realtime CLI

bart.rb

#!/usr/bin/env ruby

# $ bart
# Usage:
#   bart stations            #=> list all stations with abbreviations
#   bart ORIG[:DEST[:DEST]]  #=> show estimates for up to three origin stations

# Example:
#   $ bart POWL:PITT:RICH:PHIL RICH:MLBR
#   POWL=>PITT Pittsburg/Bay Point  10 min, 25 min, 40 min
#   POWL=>PHIL Pleasant Hill        34 min, 64 min
#   POWL=>RICH Richmond             3 min, 18 min, 32 min
#   RICH=>MLBR Millbrae             13 min, 28 min

require 'open-uri'
require 'nokogiri'

class Bart
  KEY = 'MW9S-E7SL-26DU-VV8V'

  def self.help
    [
      "Usage:",
      "  bart stations            #=> list all stations with abbreviations",
      "  bart ORIG[:DEST[:DEST]]  #=> show estimates for up to three origin stations",
      "", "Example:",
      "  $ bart POWL:PITT:RICH:PHIL RICH:MLBR",
      "  POWL=>PITT Pittsburg/Bay Point  10 min, 25 min, 40 min",
      "  POWL=>PHIL Pleasant Hill        34 min, 64 min",
      "  POWL=>RICH Richmond             3 min, 18 min, 32 min",
      "  RICH=>MLBR Millbrae             13 min, 28 min"
    ]
  end

  def self.stations
    doc = Nokogiri::XML open(stn_url)
    doc.css('station').map do |station|
      { abbr: station.css('abbr').text, name: station.css('name').text }
    end
  end

  def self.times(station)
    doc = Nokogiri::XML open(etd_url(station))

    {
      name: doc.css('station name').text,
      abbr: doc.css('station abbr').text,
      times: extract_times(doc)
    }
  end

  private

  def self.extract_times(doc)
    doc.css('station etd').map do |etd|
      {
        destination: etd.css('destination').text,
        abbreviation: etd.css('abbreviation').text,
        arrivals: humanize(etd.css('estimate').map { |e| e.css('minutes').text.to_i })
      }
    end
  end

  def self.humanize(times)
    times.map do |time|
      time == 0 ? 'now' : "#{time} min"
    end.join(', ')
  end

  def self.stn_url
    "http://api.bart.gov/api/stn.aspx?cmd=stns&key=#{KEY}"
  end

  def self.etd_url(station)
    "http://api.bart.gov/api/etd.aspx?cmd=etd&orig=#{station}&key=#{KEY}"
  end
end

origin, *destinations = ARGV[0].to_s.split(':')
if origin.nil?
  puts Bart.help
  exit(0)
elsif origin == 'stations'
  Bart.stations.each{ |s| printf "%-4s %s\n", s[:abbr], s[:name] }
  exit 0
end

2.times do |n|
  Bart.times(origin)[:times].each do |time|
    next unless destinations.empty? || destinations.include?(time[:abbreviation])

    printf "%-30s %s\n", "#{origin}=>#{time[:destination]}", time[:arrivals]
  end
  origin, *destinations = ARGV[n+1].to_s.split(':')
end