#!/usr/bin/env ruby
$VERBOSE = nil  # Don't care about world writable dir warnings and the like
#require 'byebug' # Un-comment to debug this file
require 'fileutils'
require 'pathname'

local_gem_dir = ARGV.shift

unless ARGV.empty?
  %w(bin cache extensions gems specifications).each do |subdir|
    d = "#{local_gem_dir}/#{subdir}"
    FileUtils.mkdir_p(d) unless File.exist?(d)
  end
end

ARGV.each_slice(2) do |gem, version|
  begin
    spec = Gem::Specification.find_by_name(gem, version)
    begin
      (spec.executables || []).each do |bin|
        unless File.exist?("#{local_gem_dir}/bin/#{bin}")
          FileUtils.cp("#{spec.bin_dir}/#{bin}", "#{local_gem_dir}/bin")
        end
      end
      p = Pathname.new(spec.cache_file)
      unless File.exist?("#{local_gem_dir}/cache/#{p.basename}")
        FileUtils.cp(spec.cache_file, "#{local_gem_dir}/cache")
      end
      if spec.extension_dir && File.exist?(spec.extension_dir)
        spec.extension_dir =~ /.*extensions(.*)/
        sub_dir = Pathname.new(Regexp.last_match(1)).dirname.to_s
        local_ext_dir = "#{local_gem_dir}/extensions/#{sub_dir}"
        FileUtils.mkdir_p(local_ext_dir) unless File.exist?(local_ext_dir)

        # If the file exists in the extensions directory, skip copying it over.
        p = Pathname.new(spec.extension_dir)
        unless File.exist?("#{local_ext_dir}/#{p.basename}")
          FileUtils.cp_r(spec.extension_dir, local_ext_dir)
        end
      end

      # If the file exists in the gem directory, skip copying it over.
      p = Pathname.new(spec.gem_dir)
      unless File.exist?("#{local_gem_dir}/gems/#{p.basename}")
        FileUtils.cp_r(spec.gem_dir, "#{local_gem_dir}/gems")
      end
      # If the file exists in the specifications directory, skip copying it over.
      p = Pathname.new(spec.spec_file)
      unless File.exist?("#{local_gem_dir}/specifications/#{p.basename}")
        FileUtils.cp(spec.spec_file, "#{local_gem_dir}/specifications")
      end
    rescue
      puts "Had problems installing #{spec.name} from your system Ruby, proceeding with fingers crossed..."
    end

  rescue Gem::LoadError
    # This just means that one of the gems that should be copied from the system
    # was not actually installed in the system, so nothing we can do about that here
  end
end