#!/usr/local/bin/ruby

Version = 'ports v.0.1'

require 'optparse'
require 'open3'

options = {}

parser = OptionParser.new do |opts|
  opts.banner = "usage: rd ports [options]"

  opts.on('-i', '--index PORT', Integer, 'Returns port-path for given index') do |index|
    options[:index] = index
  end

  opts.on('-c', '--check PATH', 'Prints ports list-index if PATH is valid port path') do |path|
    options[:check] = path
     # TODO !!
  end

  opts.on('-v', '--version', 'Show script version') do
    puts Version
    exit
  end

  opts.on('-h', '--help', 'Show help screen') do
    puts opts
    exit
  end
end

begin
  parser.parse!
rescue OptionParser::InvalidOption, OptionParser::MissingArgument, OptionParser::InvalidArgument
  puts $!.to_s
  exit
end

# Scan ports
ports = []
stdout, stderr, status = Open3.capture3("ls /dev/*usb*")
if (status.success?)
  ports += stdout.split("\n")
end

# No ports available? => terminate w/error
if ports.empty?
  STDERR.puts "No USB devices/ports detected"
  exit 1
end

# checks port-path against available ports,
# returns ports list index if path is valid
# TODO:
if (options.has_key?(:check))
  puts 'port PATH has been triggered'
  exit
end

# returns port path for option[:index]
if (options.has_key?(:index))
  if (options[:index] < ports.length) #<= index must be within range
    puts ports[options[:index]]
    exit
  else
    STDERR.puts "invalid port list index: #{options[:index]}"
    exit 1
  end
end

# default action: returns ports list
puts "....................................."
ports.each_index {|i| puts "[#{i}]: #{ports[i]}"}
puts "....................................."
exit