if RUBY_VERSION < '1.9'
  require 'ruby2ruby'
  require 'parse_tree'
  gem 'rdp-arguments' # TODO why is this necessary?
  require 'arguments' # rogerdpack-arguments
end

class Object
  def singleton_class
    class << self; self; end
  end
end

module SourceLocationDesc

  # add a Method#desc which spits out all it knows about that method
  # ri, location, local ri, etc.
  # TODO does this work with class methods?
  def ri options = {}
    want_just_summary = options[:want_just_summary]
    want_the_description_returned = options[:want_the_description_returned]
    doc = []
    # to_s is something like "#<Method: String#strip>"
    # or #<Method: GiftCertsControllerTest(Test::Unit::TestCase)#get>
    # or "#<Method: A.go>"
    # or "#<Method: Order(id: integer, order_number: integer).get_cc_processor>"
    # or "#<Method: Order(id: integer, order_number: integer)(ActiveRecord::Base).get_cc_processor>"

    string = param_string = to_s

    # derive class_name
    parenthese_count = string.count '('

    if parenthese_count== 1
      # case #<Method: GiftCertsControllerTest(Test::Unit::TestCase)#get>
      # case #<Method: Order(id: integer, order_number: integer).get_cc_processor>
      if string.include? "id: " # TODO huh?
        string =~ /Method: (.+)\(/
      else
        string =~ /\(([^\(]+)\)[\.#]/ # extract out what is between last parentheses
      end
      class_name = $1
    elsif parenthese_count == 0
      # case "#<Method: A.go>"
      string =~ /Method: ([^#\.]+)/
      class_name = $1
    elsif parenthese_count == 2
      # case "#<Method: Order(id: integer, order_number: integer)(ActiveRecord::Base).get_cc_processor>"
      string =~ /\(([^\(]+)\)[\.#]/
      class_name = $1
    else
      raise 'bad ' + string
    end

    # now get method name, type
    string =~ /Method: .*([#\.])(.*)>/ # include the # or .
    joiner = $1
    method_name = $2
    full_name = class_name + joiner + method_name
    sig = "sig: #{full_name} arity #{arity}"
    doc << sig
    param_string = sig

    # now gather up any other information we now about it, in case there are no rdocs, so we can see it early...

    if !(respond_to? :source_location)
      # pull out names for 1.8
      begin
        klass = eval(class_name)
        # we don't call to_ruby to overcome ruby2ruby bug http://rubyforge.org/tracker/index.php?func=detail&aid=26891&group_id=1513&atid=5921
        if joiner == '#'
          raw_code = ParseTree.new.parse_tree_for_method(klass, method_name)
        else
          raw_code = ParseTree.new.parse_tree_for_method(klass.singleton_class, method_name) # singleton_class
        end
        doc << Ruby2Ruby.new.process(ParseTree.new.process(raw_code))

        args = Arguments.names(klass, method_name, false) rescue Arguments.names(klass.singleton_class, method_name, false)
        out = []
        args.each{|arg_pair|
          out << arg_pair.join(' = ')
        } if args
        out = out.join(', ')
        return out if want_just_summary

        param_string = "Parameters: #{method_name}(" + out + ")"
        doc << param_string unless want_the_description_returned
      rescue Exception => e
        doc << "appears to be a c method"
        puts "fail to parse tree: #{class_name} #{e} #{e.backtrace}" if $DEBUG
      end
    else
      # 1.9.x
      file, line = source_location
      param_string = to_s
      if file
        # then it's a pure ruby method
        all_lines = File.readlines(file)
        head_and_sig = all_lines[0...line]
        sig = head_and_sig[-1]
        head = head_and_sig[0..-2]

        doc << sig
        head.reverse_each do |line|
          break unless line =~ /^\s*#(.*)/
          doc.unshift "     " + $1.strip
        end
        doc.unshift " at #{file}:#{line}"

        # now the real code will end with 'end' same whitespace as the first
        sig_white_space = sig.scan(/^\W+/)[0] || ""
        body = all_lines[line..-1]
        body.each{|line|
          doc << line
          if line.start_with?(sig_white_space + "end")
            break
          end
        }
        already_got_ri = true
        param_string = sig
        return sig + "\n" + head[0] if want_just_summary
      else
        doc << 'appears to be a c method'
      end
      if respond_to? :parameters
        doc << "Original code signature: %s" % sig.to_s.strip if sig
        doc << "#parameters signature: %s( %p )" % [name, parameters]
      end
    end

    puts doc unless want_the_description_returned

    unless (already_got_ri || want_just_summary)
      require 'rdoc'
      require 'rdoc/ri/driver'

      # show default RI for it
      begin
        puts 'Searching ri for', sig, '...'
        RDoc::RI::Driver.run [full_name, '--no-pager']
      rescue *[StandardError, SystemExit]
        # not found
      ensure
        puts '(end ri)'
      end
    end

    if want_the_description_returned # give them something they can examine
      doc
    else
      param_string.strip # return one liner
    end

  end
  
  alias :desc :ri
  
end

class Method; include SourceLocationDesc; end
class UnboundMethod; include SourceLocationDesc; end

# TODO mixin from a separate module

class Object
  # currently rather verbose, but will attempt to describe all it knows about a method
  def ri_for name, options = {}
    if self.is_a?(Class) || self.is_a?(Module)
      # i.e. String.strip
      begin
        instance_method(name).ri(options)
      rescue NameError => e #allow for Class.instance_method_name, Module.instance_method_name
        begin
          method(name).ri(options)
        rescue NameError
          raise NameError.new("appears that this object #{self} does not have this method #{name}")
        end
      end
    else
      method(name).desc(options)
    end
  end
end