module Ratch

  module Taskable

    #def main
    #  @main
    #end

    def tasks
      @tasks ||= {}
    end

    # Define a main task.

    def main(name, &block)
      @main = Task.register(name, &block)
      tasks[@main.name] = @main
    end

    # Define a task.

    def task(name, &block)
      tsk = Task.register(name, &block)
      tasks[tsk.name] = tsk
    end

    # Define a file target.

    def file(name, &block)
      tasks[name.to_s] = FileTask.register(name, &block)
    end

  end

  #
  #
  #

  class Task

    def self.tasks
      @@tasks ||= {}
    end

    def self.register(name_deps, &block)
      if Hash===name_deps
        name = name_deps.keys[0]
        deps = name_deps.values[0]
      else
        name = name_deps
        deps = []
      end
      tasks[name.to_s] = new(name, *deps, &block)
    end

    attr :name
    attr :preqs
    attr :action

    #

    def initialize(name, *preqs, &action)
      @name          = name.to_s
      @preqs         = preqs
      @action        = action
    end

    def call
  #p plan
      plan.each{ |name| @@tasks[name].action_call }
      #action_call
    end

    #

    def action_call
      @action.call if @action
    end

    # TODO Check for circular dependencies.

    def plan(list=[])
      if list.include?(name)
        raise "Circular dependency #{name}."
      end

      @preqs.each do |need|
        need = need.to_s
        next if list.include?(need)
        @@tasks[need].plan(list)
      end
      list << name
      return list
    end

  end

  #
  #
  #

  class FileTask < Task
  end

end