require "netzke/javascript/scopes"
module Netzke
  # == Component javascript code
  # Here's a brief explanation on how a javascript class for a component gets built.
  # Component gets defined as a constructor (a function) by +js_class+ class method (see "Inside component's contstructor").
  # +Ext.extend+ provides inheritance from an Ext class specified in +js_base_class+ class method.
  #
  # == Inside component's constructor
  # * Component's constructor gets called with a parameter that is a configuration object provided by +config+ instance method. This configuration is specific for the instance of the component, and, for example, contains this component's unique id. As another example, by means of this configuration object, a grid receives the configuration array for its columns, a form - for its fields, etc.
  module Javascript
    extend ActiveSupport::Concern

    included do
      include Scopes

      class_attribute :js_included_files
      self.js_included_files = []
    end

    module ClassMethods

      # Used it to specify what JavaScript class this component's JavaScript class will be extending, e.g.:
      #
      #     js_base_class "Ext.TabPanel"
      #
      # By default, "Ext.Panel" is assumed.
      #
      # If called without parameters, returns the JS base class declared for the component.
      def js_base_class(class_name = nil)
        class_name.nil? ? (read_inheritable_attribute(:js_base_class) || "Ext.Panel") : write_inheritable_attribute(:js_base_class, class_name)
      end

      # Use it to define a public method of the component's JavaScript class, e.g.:
      #
      #     js_method :do_something, <<-JS
      #       function(params){
      #         // implementation, maybe dynamically generated
      #       }
      #     JS
      #
      # This will effectively result in definition of a public method called +doSomething+ in the JavaScript class (note the conversion from underscore_name to camelCaseName).
      def js_method(name, definition = nil)
        definition = yield.l if block_given?
        current_js_methods = read_clean_inheritable_hash(:js_methods)
        current_js_methods.merge!(name => definition.l)
        write_inheritable_attribute(:js_methods, current_js_methods)
      end

      # Returns all JS method definitions in a hash
      def js_methods
        read_clean_inheritable_hash(:js_methods)
      end

      # Use it to specify JS files to be loaded before this component's JS code. Useful when using external extensions required by this component.
      # It may accept one or more symbols or strings. Strings will be interpreted as full paths to included JS file:
      #
      #     js_include "#{File.dirname(__FILE__)}/my_component/one.js","#{File.dirname(__FILE__)}/my_component/two.js"
      #
      # Symbols will be expanded following a convention, e.g.:
      #
      #     class MyComponent < Netzke::Base
      #       js_include :some_library
      #       # ...
      #     end
      #
      # This will "include" a JavaScript file +{component_location}/my_component/javascripts/some_library.js+
      def js_include(*args)
        callr = caller.first

        self.js_included_files += args.map{ |a| a.is_a?(Symbol) ? expand_js_include_path(a, callr) : a }
      end

      # Used to define default properties of the JavaScript class, e.g.:
      #
      #     js_properties :collapsible => true, :hide_collapse_tool => true
      #
      # (this will result in the definition of the following properties in the JavaScript class's prototype: +collapsible+ and +hideCollapseTool+ (note the automatic conversion from underscore to camelcase))
      #
      # Also, +js_property+ can be used to define properties one by one.
      #
      # For the complete list of available options refer to the Ext documentation, the "Config Options" section of a the component specified with +js_base_class+.
      # Note, that not all the configuration options can be defined on the prototype of the class. For example, defining +items+ on the prototype won't take any effect, so, +items+ should be passed as a configuration option at the moment of instantiation (see Netzke::Base#configuration and Netzke::Base#default_config).
      def js_properties(hsh = nil)
        if hsh.nil?
          read_clean_inheritable_hash(:js_properties)
        else
          current_js_properties = read_clean_inheritable_hash(:js_properties)
          current_js_properties.merge!(hsh)
          write_inheritable_attribute(:js_properties, current_js_properties)
        end
      end

      # Used to define a single JS class property, e.g.:
      #     js_property :title, "My Netzke Component"
      def js_property(name, value = nil)
        name = name.to_sym
        if value.nil?
          (read_inheritable_attribute(:js_properties) || {})[name]
        else
          current_js_properties = read_clean_inheritable_hash(:js_properties)
          current_js_properties[name] = value
          write_inheritable_attribute(:js_properties, current_js_properties)
        end
      end

      # Use it to "mixin" JavaScript objects defined in a separate file.
      #
      # You do not _have_ to use +js_method+ or +js_properties+ if those methods or properties are not supposed to be changed _dynamically_ (by means of configuring the component on the class level). Instead, you may "mixin" a JavaScript object defined in the JavaScript file named following a certain convention. This way static JavaScript code will rest in a corresponding .js file, not in the Ruby class. E.g.:
      #
      #     class MyComponent < Netzke::Base
      #       js_mixin :some_functionality
      #       #...
      #     end
      #
      # This will "mixin" a JavaScript object defined in a file called +{component_location}/my_component/javascripts/some_functionality.js+, which way contain something like this:
      #
      #     {
      #       someProperty: 100,
      #
      #       someMethod: function(params){
      #         // ...
      #       }
      #     }
      #
      # Also accepts a string, which will be interpreted as a full path to the file (useful for sharing mixins between classes).
      def js_mixin(*args)
        current_mixins = read_clean_inheritable_array(:js_mixins) || []
        callr = caller.first
        args.each{ |a| current_mixins << (a.is_a?(Symbol) ? File.read(expand_js_include_path(a, callr)) : File.read(a))}
        write_inheritable_attribute(:js_mixins, current_mixins)
      end

      # Returns all objects to be mixed in (as array of strings)
      def js_mixins
        read_clean_inheritable_array(:js_mixins) || []
      end

      # Builds this component's xtype
      # E.g.: netzkewindow, netzkegridpanel
      def js_xtype
        name.gsub("::", "").downcase
      end

      # Component's JavaScript class declaration.
      # It gets stored in the JS class cache storage (Netzke.classes) at the client side to be reused at the moment of component instantiation.
      def js_class
        res = []
        # Defining the scope if it isn't known yet
        res << %{Ext.ns("#{js_full_scope}");} unless js_full_scope == js_default_scope

        res << (extends_netzke_component? ? js_class_declaration_extending_component : js_class_declaration_new_component)

        res << %(Netzke.reg("#{js_xtype}", #{js_full_class_name});)

        res.join("\n")
      end


      # Returns all included JavaScript files as a string
      def js_included
        res = ""

        # Prevent re-including code that was already included by the parent
        # (thus, only include those JS files when include_js was defined in the current class, not in its ancestors)
        ((singleton_methods(false).map(&:to_sym).include?(:include_js) ? include_js : []) + js_included_files).each do |path|
          f = File.new(path)
          res << f.read << "\n"
        end

        res
      end

      # DEPRECATED. Returns an array of included files. Made to be overridden. +js_include+ is preferred way.
      def include_js
        []
      end

      # JavaScript code needed for this particulaer class. Includes external JS code and the JS class definition for self.
      def js_code
        [js_included, js_class].join("\n")
      end

      protected

        # Little helper
        def this; "this".l; end

        # Little helper. E.g.:
        #
        #     js_property :load_mask, null
        def null; "null".l; end

        # JS properties and methods merged together
        def js_extend_properties
          @js_extend_properties ||= js_properties.merge(js_methods)
        end

        # Generates declaration of the JS class as direct extension of a Ext component
        def js_class_declaration_new_component
          mixins = js_mixins.empty? ? "" : %(#{js_mixins.join(", \n")}, )
          %(#{js_full_class_name} = function(config){
            Netzke.aliasMethodChain(this, "initComponent", "netzke");
            #{js_full_class_name}.superclass.constructor.call(this, config);
          };

          Ext.extend(#{js_full_class_name}, #{js_base_class}, Netzke.chainApply(Netzke.componentMixin, #{mixins}
  #{js_extend_properties.to_nifty_json}));)
        end

        # Generates declaration of the JS class as extension of another Netzke component
        def js_class_declaration_extending_component
          base_class = superclass.js_full_class_name

          mixins = js_mixins.empty? ? "" : %(#{js_mixins.join(", \n")}, )

          %{#{js_full_class_name} = Ext.extend(#{base_class}, Netzke.chainApply(#{mixins}#{js_extend_properties.to_nifty_json}));}
        end

        def expand_js_include_path(sym, callr) # :nodoc:
          %Q(#{callr.split(".rb:").first}/javascripts/#{sym}.js)
        end

        def extends_netzke_component? # :nodoc:
          superclass != Netzke::Base
        end

    end

    module InstanceMethods
      # Config that, after being converted to JSON, is used for instantiating the component in JavaScript.
      def js_config
        res = {}

        # Unique id of the component
        res[:id] = global_id

        # Non-lazy-loaded components
        comp_hash = {}
        eager_loaded_components.each_pair do |comp_name, comp_config|
          comp_instance = component_instance(comp_name.to_sym)
          comp_instance.before_load
          comp_hash[comp_name] = comp_instance.js_config
        end

        # All our non-lazy-loaded children are specified here, while in +items+ we barely reference them, because
        # +items+, generally, only contain a subset of all non-lazy-loaded children.
        res[:components] = comp_hash unless comp_hash.empty?

        # Endpoints (besides the default "deliver_component" - JavaScript side already knows about it)
        endpoints = self.class.registered_endpoints - [:deliver_component]
        res[:endpoints] = endpoints unless endpoints.empty?

        # Inform the JavaScript side if persistent_config is enabled
        # res[:persistent_config] = persistence_enabled?

        # Include our xtype
        res[:xtype] = self.class.js_xtype

        # Merge with the rest of config options, besides those that are only meant for the server side
        res.merge!(config.reject{ |k,v| self.class.server_side_config_options.include?(k.to_sym) })

        if config[:ext_config].present?
          ::ActiveSupport::Deprecation.warn("Using ext_config option is deprecated. All config options must be specified at the same level in the hash.", caller)
          res.merge!(config[:ext_config])
        end

        # Items (nested Ext/Netzke components)
        res[:items] = items unless items.blank?

        res
      end

      # All the JS-code required by this instance of the component to be instantiated in the browser.
      # It includes JS-classes for the parents, non-lazy-loaded child components, and itself.
      def js_missing_code(cached = [])
        code = dependency_classes.inject("") do |r,k|
          cached.include?(k.js_xtype) ? r : r + k.js_code#.strip_js_comments
        end
        code.blank? ? nil : code
      end

      # DEPRECATED. Helper to access config[:ext_config].
      def ext_config
        ::ActiveSupport::Deprecation.warn("Using ext_config is deprecated. All config options must be specified at the same level in the hash.", caller)
        config[:ext_config] || {}
      end

    end
  end
end