class Controller

def initialize(app, root: Utopia::default_root, base: Controller::Base)
	@app = app
	@root = root
	
	@controller_cache = Concurrent::Map.new
	
	@base = base
end

def lookup_controller(path)
	@controller_cache.fetch_or_store(path.to_s) do
		load_controller_file(path)
	end
end

def load_controller_file(uri_path)
	base_path = File.join(@root, uri_path.components)
	
	controller_path = File.join(base_path, CONTROLLER_RB)
	# puts "load_controller_file(#{path.inspect}) => #{controller_path}"
	
	if File.exist?(controller_path)
		klass = Class.new(@base)
		
		# base_path is expected to be a string representing a filesystem path:
		klass.const_set(:BASE_PATH, base_path.freeze)
		
		# uri_path is expected to be an instance of Path:
		klass.const_set(:URI_PATH, uri_path.dup.freeze)
		
		klass.const_set(:CONTROLLER, self)
		
		klass.class_eval(File.read(controller_path), controller_path)
		
		# We lock down the controller class to prevent unsafe modifications:
		klass.freeze
		
		# Create an instance of the controller:
		return klass.new
	else
		return nil
	end
end

def invoke_controllers(request)
	request_path = Path.from_string(request.path_info)
	
	# The request path must be absolute. We could handle this internally but it is probably better for this to be an error:
	raise ArgumentError.new("Invalid request path #{request_path}") unless request_path.absolute?
	
	# The controller path contains the current complete path being evaluated:
	controller_path = Path.new
	
	# Controller instance variables which eventually get processed by the view:
	variables = request.env[VARIABLES_KEY]
	
	while request_path.components.any?
		# We copy one path component from the relative path to the controller path at a time. The controller, when invoked, can modify the relative path (by assigning to relative_path.components). This allows for controller-relative rewrites, but only the remaining path postfix can be modified.
		controller_path.components << request_path.components.shift
		
		if controller = lookup_controller(controller_path)
			# Don't modify the original controller:
			controller = controller.clone
			
			# Append the controller to the set of controller variables, updates the controller with all current instance variables.
			variables << controller
			
			if result = controller.process!(request, request_path)
				return result
			end
		end
	end
	
	# Controllers can directly modify relative_path, which is copied into controller_path. The controllers may have rewriten the path so we update the path info:
	request.env[Rack::PATH_INFO] = controller_path.to_s
	
	# No controller gave a useful result:
	return nil
end