module Iowa

	# Provides high level functionality for all component subclasses.
	# Each "page" in an Iowa app is a Component subclass.
	
	class Component < Element
	
	  # Returns an empty hash.
	
		def Component.bindings
			{}
		end
	
	  # Returns the template for the component.
	
		def Component.template
			Iowa.app.templateForComponent(self.name)
		end
	
	  # Finds and returns the named component.  Other methods calling this
	  # one with different values for session and prevPage could induce some
	  # interesting (or bizarre) behaviors.  See pageNamed(name) below for
	  # the standard invocation.
	
		def Component.pageNamed(name, session, prevPage=nil)
			Iowa.app.reloadModified(name,true)
			klass = ElementClasses[name.to_s.downcase]
			if(klass && klass.ancestors.include?(Component))
				page = klass.new("page", {}, {}, nil)
				page.prevPage = prevPage
				page.session = session
				page
			else
				el = ''
				ElementClasses.each_pair do |k,v|
					el << "#{k} == #{v}<br/>\n"
				end
				raise "#{name}: no such page in #{el}"
			end
		end
	
	  # Provides a method to define component attributes which another
	  # component can bind to.
	
		def Component.attr_binding(*symbols)
			symbols.each do |symbol|
				class_eval %{
					def #{symbol}
						@bindings['#{symbol}'].get(@parent)
					end
					def #{symbol}=(val)
						@bindings['#{symbol}'].set(@parent, val)
					end
				}
			end
		end
	
	  # Standard invocation of Component.pageNamed.  Returns the component
	  # corresponding the the given name.
	
		def page_named(name)
			Component.pageNamed(name, @session, self)
		end
		alias :pageNamed :page_named
		
		attr_accessor :session, :prevPage, :subcomponents, :parent
	
	  # Handle the initial tasks that establish the state of the new object.
	
		def initialize(name, bindings, attributes, parent)
			@creation_time = Time.now
			@parent = parent
			if parent
				@session = parent.session
			end
	
			@subcomponents = {}
	
			super(name, bindings, attributes)
	
			awake()
		end
	
	  # Stub, intended to be overridden in the subclasses, to define behavior
	  # that occurs only once, when the object is first created.
	
		def awake
		end
	
	  # Stub, intended to be overridden in the subclasses, to define behavior
	  # that occurs when backtracking.
	
		def handle_backtrack
		end
		alias :handleBacktrack :handle_backtrack
		
		# Stub, intended to be overridden in the subclasses, to define behavior
		# that occurs each time the component is displayed.
		
		def setup
		end
		
	  # Returns the Application object.
	
		def application
			Iowa.app
		end
	
	  # Trigger an action on the component.
	
		def invokeAction(action, &b)
			send(action, &b)
		end
	
		def handleResponse(context)
			@template = self.class.template
			setup
			handleRequestOrResponse(:handleResponse, context)
		end
	
		def handleRequest(context)
			handleRequestOrResponse(:handleRequest, context)
		end
	
		def handleRequestOrResponse(method, context)
			Iowa.app.reloadModified(self.class.to_s,true)
			
			context.pushRoot self
			@template.send(method, context)
			context.popRoot
		end
	
		def getBinding(binding)
			@bindings[binding].get(@parent)
		end
	
		def setBinding(binding, value)
			@bindings[binding].set(@parent, value)
		end
	
		def dup
			copy = super
			@subcomponents.each do |name, child|
				newChild = child.dup
				newChild.parent = copy
				copy.subcomponents[name] = newChild
			end
			copy
		end
	
		def back
			if @prevPage
				yield @prevPage
			end
		end
	
		def reload
		end
	
		def creation_time
			@creation_time
		end
	end

end