module Autoconf
  extend self

  def switches(config=nil)
    case config
    when String
      switch(config)
    when Enumerable
      config.map {|item| switch(item) }.join(" ").strip
    else
      ""
    end
  end

  private
  def switch(*items)
    items = items.flatten
    case items.size
    when 1
      plain_switch(items.first)
    when 2
      value_switch(items.first, items.last)
    else
      ""
    end
  end
  
  def plain_switch(sw)
    if sw.respond_to?(:to_s)
      if sw.to_s =~ /^\s*(-|$)/
        sw
      else
        "--#{sw}"
      end
    else
      ""
    end
  end
  
  def value_switch(key, value)
    if value && key.respond_to?(:to_s) && value.respond_to?(:to_s)
      value == true ? plain_switch(key) : "--#{key}=#{value}"
    else
      ""
    end
  end
end

if $0 == __FILE__
  require 'rubygems'
  require 'spec/autorun'

  describe "Autoconf" do
    describe "switches" do
      it "should return an empty string by default" do
        Autoconf.switches.should == ""
      end
      it "should process an empty string untouched" do
        Autoconf.switches("").should == ""
      end
      it "should process a string without embedded switches as prefixed with --" do
        Autoconf.switches("debug").should == "--debug"
      end
      it "should process a string with embedded switches untouched" do
        Autoconf.switches("--debug").should == "--debug"
      end
      it "should process a hash as switches joined with =" do
        Autoconf.switches(:prefix => "/usr/local").should == "--prefix=/usr/local"
      end
      it "should process a hash with true values as singleton switches" do
        Autoconf.switches('with-ssl' => true, 'with-ssl-proxy' => true).should == "--with-ssl --with-ssl-proxy"
      end
      it "should process a hash with nil or false values ignoring those switches" do
        Autoconf.switches('debug' => false, 'with-poll' => nil).should == ""
      end
      it "should process an array with nil values ignoring them" do
        Autoconf.switches([nil]).should == ""
        Autoconf.switches(["debug", nil]).should == "--debug"
      end
    end
  end
end