Cache / filter / reformat filtered routes since `rake routes` is so expensive.

routes

#!/usr/bin/env ruby

argv = ARGV

# handle help screen
if argv.any? { |arg| arg == '-h' || arg == '--help' }
  $stderr.puts <<~HELP
  Usage: routes [--load] [--reload] [filter ...]

  Runs `bin/rake routes` and caches the result so that you don't have to wait
  forever to see your routes. Pass regexes to filter the output.
  HELP
  exit
end

# load / reload routes
load_commands, argv = argv.partition { |a| a =~ /^--(re-?)?load/ }
if load_commands.any? || DATA.eof?
  require 'open3'
  out, err, status = Open3.capture3 "bin/rake routes"
  if status.success?
    File.truncate __FILE__, DATA.pos
    File.open(__FILE__, mode: 'a') { |f| f.puts out }
  else
    $stderr.puts err
    exit status.exitstatus
  end
end

# parse routes
lines  = DATA.readlines
max    = lines.map(&:size).max
delims = [0, *max.times.select { |i| lines.all? { |l| l[i] == " " } }, max]
ranges = delims.each_cons(2).map { |start, stop| start..stop }
routes = lines.map { |line| ranges.map { |r| line[r].strip } }
header = routes.shift

# filter routes
argv.each do |arg|
  regex = Regexp.new arg
  routes.select! { |r| r.join(" ") =~ regex }
end

# format string
cols  = [header, *routes].transpose
sizes = cols.map { |col| col.map(&:size).max }
fmt   = sizes.map.with_index do |size, i|
  "%#{'-' unless i.zero?}#{size unless i == sizes.length.pred}s"
end.join(" ")

# print filtered routes
begin
  puts fmt%header if $stdout.tty?
  routes.each { |route| puts fmt%route }
rescue Errno::EPIPE # don't blow up if piping the output to things like `head`
end

__END__