require 'rake'
require 'rake/tasklib'

module Rake

  # Create a documentation task that will generate the RDoc files for
  # a project.
  #
  # The RDocTask will create the following targets:
  #
  # [<b>:<em>rdoc</em></b>]
  #   Main task for this RDOC task.
  #
  # [<b>:clobber_<em>rdoc</em></b>]
  #   Delete all the rdoc files.  This target is automatically
  #   added to the main clobber target.
  #
  # [<b>:re<em>rdoc</em></b>]
  #   Rebuild the rdoc files from scratch, even if they are not out
  #   of date.
  #
  # Simple example:
  #
  #   Rake::RDocTask.new do |rd|
  #     rd.main = "README.rdoc"
  #     rd.rdoc_files.include("README.rdoc", "lib/**/*.rb")
  #   end
  #
  # The +rd+ object passed to the block is an RDocTask object. See the
  # attributes list for the RDocTask class for available customization options.
  #
  # == Specifying different task names
  #
  # You may wish to give the task a different name, such as if you are
  # generating two sets of documentation.  For instance, if you want to have a
  # development set of documentation including private methods:
  #
  #   Rake::RDocTask.new(:rdoc_dev) do |rd|
  #     rd.main = "README.doc"
  #     rd.rdoc_files.include("README.rdoc", "lib/**/*.rb")
  #     rd.options << "--all"
  #   end
  #
  # The tasks would then be named :<em>rdoc_dev</em>, :clobber_<em>rdoc_dev</em>, and
  # :re<em>rdoc_dev</em>.
  #
  # If you wish to have completely different task names, then pass a Hash as
  # first argument. With the <tt>:rdoc</tt>, <tt>:clobber_rdoc</tt> and
  # <tt>:rerdoc</tt> options, you can customize the task names to your liking.
  # For example:
  #
  #   Rake::RDocTask.new(:rdoc => "rdoc", :clobber_rdoc => "rdoc:clean", :rerdoc => "rdoc:force")
  #
  # This will create the tasks <tt>:rdoc</tt>, <tt>:rdoc_clean</tt> and
  # <tt>:rdoc:force</tt>.
  #
  class RDocTask < TaskLib
    # Name of the main, top level task.  (default is :rdoc)
    attr_accessor :name

    # Name of directory to receive the html output files. (default is "html")
    attr_accessor :rdoc_dir

    # Title of RDoc documentation. (defaults to rdoc's default)
    attr_accessor :title

    # Name of file to be used as the main, top level file of the
    # RDoc. (default is none)
    attr_accessor :main

    # Name of template to be used by rdoc. (defaults to rdoc's default)
    attr_accessor :template

    # List of files to be included in the rdoc generation. (default is [])
    attr_accessor :rdoc_files

    # Additional list of options to be passed rdoc.  (default is [])
    attr_accessor :options

    # Whether to run the rdoc process as an external shell (default is false)
    attr_accessor :external

    attr_accessor :inline_source

    # Create an RDoc task with the given name. See the RDocTask class overview
    # for documentation.
    def initialize(name = :rdoc)  # :yield: self
      if name.is_a?(Hash)
        invalid_options = name.keys.map { |k| k.to_sym } - [:rdoc, :clobber_rdoc, :rerdoc]
        if !invalid_options.empty?
          raise ArgumentError, "Invalid option(s) passed to RDocTask.new: #{invalid_options.join(", ")}"
        end
      end

      @name = name
      @rdoc_files = Rake::FileList.new
      @rdoc_dir = 'html'
      @main = nil
      @title = nil
      @template = nil
      @external = false
      @inline_source = true
      @options = []
      yield self if block_given?
      define
    end

    # Create the tasks defined by this task lib.
    def define
      if rdoc_task_name != "rdoc"
        desc "Build the RDOC HTML Files"
      else
        desc "Build the #{rdoc_task_name} HTML Files"
      end
      task rdoc_task_name

      desc "Force a rebuild of the RDOC files"
      task rerdoc_task_name => [clobber_task_name, rdoc_task_name]

      desc "Remove rdoc products"
      task clobber_task_name do
        rm_r rdoc_dir rescue nil
      end

      task :clobber => [clobber_task_name]

      directory @rdoc_dir
      task rdoc_task_name => [rdoc_target]
      file rdoc_target => @rdoc_files + [Rake.application.rakefile] do
        rm_r @rdoc_dir rescue nil
        @before_running_rdoc.call if @before_running_rdoc
        args = option_list + @rdoc_files
        if @external
          argstring = args.join(' ')
          sh %{ruby -Ivendor vender/rd #{argstring}}
        else
          require 'rdoc/rdoc'
          RDoc::RDoc.new.document(args)
        end
      end
      self
    end

    def option_list
      result = @options.dup
      result << "-o" << @rdoc_dir
      result << "--main" << quote(main) if main
      result << "--title" << quote(title) if title
      result << "-T" << quote(template) if template
      result << "--inline-source" if inline_source && !@options.include?("--inline-source") && !@options.include?("-S")
      result
    end

    def quote(str)
      if @external
        "'#{str}'"
      else
        str
      end
    end

    def option_string
      option_list.join(' ')
    end

    # The block passed to this method will be called just before running the
    # RDoc generator. It is allowed to modify RDocTask attributes inside the
    # block.
    def before_running_rdoc(&block)
      @before_running_rdoc = block
    end

    private

    def rdoc_target
      "#{rdoc_dir}/index.html"
    end

    def rdoc_task_name
      case name
      when Hash
        (name[:rdoc] || "rdoc").to_s
      else
        name.to_s
      end
    end

    def clobber_task_name
      case name
      when Hash
        (name[:clobber_rdoc] || "clobber_rdoc").to_s
      else
        "clobber_#{name}"
      end
    end

    def rerdoc_task_name
      case name
      when Hash
        (name[:rerdoc] || "rerdoc").to_s
      else
        "re#{name}"
      end
    end

  end
end