require 'bundler'

module Dionysus
  module TravisCI
    class GemfileGenerator
      def initialize(gemfile)
        @definition = Bundler::Dsl.new
        @definition.instance_eval(Bundler.read_file(gemfile), "Gemfile", 1)
      end

      def generate(filename, options={})
        File.open(filename, "w") do |f|
          f.puts %(source "http://rubygems.org")

          @definition.dependencies.each do |dep|
            next if exclude_by_group?(dep, :default, options[:without])
            f.puts dependency_line(dep)
          end

          case options[:add]
          when String
            f.puts options[:add]
          when Array
            options[:add].each {|ln| f.puts ln}
          else
            raise "Invalid :add option: %p"%[options[:add]] if options[:add]
          end

          f.puts %(gemspec :path => "../")
        end
      end

      private

      def dependency_line(dep)
        ln = [ %(gem "%s")%[dep.name] ]

        ln << %("%s")%[dep.requirement]

        groups = dep.groups.collect {|v| %(:#{v})}.join(", ")
        ln << %(:group => [%s])%[groups]

        if dep.autorequire == []
          ln << %(:require => false)
        elsif dep.autorequire
          requires = dep.autorequire.collect {|s| %("#{s}")}.join(",")
          ln << %(:require => [%s])%[requires]
        end

        if dep.source and dep.source.is_a?(Bundler::Source::Git)
          ln << %(:git => "%s")%[dep.source.options["git"]]
          ln << %(:branch => "%s")%[dep.source.options["branch"]]
        elsif dep.source
          raise "Unknown source type: %s"%[dep.source.class]
        end

        ln.join(", ")
      end

      def exclude_by_group?(dep, *without)
        return false if without.nil? or without.empty?
        without = without.compact.flatten
        !(dep.groups & without).empty?
      end
    end
  end
end