#!/usr/bin/env ruby
# encoding: utf-8

$LOAD_PATH.unshift(File.dirname(__FILE__) + '/../lib')

require 'nanoc-select'
require 'getoptlong'

def version(io)
  io.puts "nanoc-select #{NanocSelect::VERSION} (c) 2010 Denis Defreyne."
  io.puts "Ruby #{RUBY_VERSION} (#{RUBY_RELEASE_DATE}) running on #{RUBY_PLATFORM}"
end

def usage(io, option_definitions)
  io.puts "usage: #{$0} version"
  io.puts
  io.puts <<-EOS
Since nanoc 3.x is not backwards compatible with nanoc 2.x, it can be useful
to have multiple versions of nanoc installed simultaneously. In order to avoid
having to type `nanoc2` or `nanoc3`, the `nanoc-select` tool can be used to
make `nanoc` invoke either `nanoc2` or `nanoc3`.
EOS
  io.puts
  io.puts "Options:"
  io.puts
  option_definitions.each do |opt_def|
    io.puts "    #{opt_def[1]} #{format '%-10s', opt_def[0]} #{opt_def[-1]}"
  end
end

def list(io)
  io.puts 'Available nanoc versions:'
  io.puts
  NanocSelect::VERSIONS.each do |v|
    io.puts "    #{v} -- nanoc #{v}.x"
  end
end

# Parse options
begin
  option_definitions = [
    [ '--help',    '-h', GetoptLong::NO_ARGUMENT, 'show this help and exit'           ],
    [ '--version', '-v', GetoptLong::NO_ARGUMENT, 'show version information and exit' ],
    [ '--list',    '-l', GetoptLong::NO_ARGUMENT, 'list available versions and exit'  ]
  ]
  options = GetoptLong.new(*option_definitions.map { |od| od[0..-2] })
  options.each do |opt, arg|
    case opt
    when '--help'
      usage($stdout, option_definitions)
      exit 0

    when '--version'
      version($stdout)
      exit 0

    when '--list'
      list($stdout)
      exit 0
    end
  end
rescue GetoptLong::InvalidOption
  $stderr.puts
  usage($stderr, option_definitions)
  exit 1
end

# Get version argument
if ARGV.size != 1
  usage($stderr, option_definitions)
  exit 1
end
version_raw = ARGV[0]
version     = version_raw.to_i
if !NanocSelect::VERSIONS.include?(version)
  $stderr.puts "There is no nanoc version #{version_raw}!"
  $stderr.puts
  list($stderr)
  exit 1
end

# Switch
version_file_path = File.expand_path('~/.nanoc-select-version')
File.open(version_file_path, 'w') { |io| io.write(version.to_s + "\n") }
puts "Switched to nanoc version #{version}."