1 files changed, 135 insertions, 0 deletions
diff --git a/lib/felflame/entity_manager.rb b/lib/felflame/entity_manager.rb
new file mode 100644
index 0000000..74fc4c3
--- /dev/null
+++ b/lib/felflame/entity_manager.rb
@@ -0,0 +1,135 @@
+class FelFlame
+  class Entities
+    # Holds the unique ID of this entity
+    # @return [Integer]
+    attr_reader :id
+
+    # A seperate attr_writer was made for documentation readability reasons.
+    # Yard will list attr_reader is readonly which is my intention.
+    # This value needs to be changable as it is set by other functions.
+    # @!visibility private
+    attr_writer :id
+
+    # Creating a new Entity
+    # @param components [Components] Can be any number of components, identical duplicates will be automatically purged however different components from the same component manager are allowed.
+    # @return [Entity]
+    def initialize(*components)
+      # Assign new unique ID
+      new_id = self.class.data.find_index(&:nil?)
+      new_id = self.class.data.size if new_id.nil?
+      self.id = new_id
+
+      # Add each component
+      add(*components)
+
+      self.class.data[id] = self
+    end
+
+    # A hash that uses component manager constant names as keys, and where the values of those keys are arrays that contain the {FelFlame::ComponentManager#id IDs} of the components attached to this entity.
+    # @return [Hash<Component_Manager, Array<Integer>>]
+    def components
+      @components ||= {}
+    end
+
+    # An alias for the {#id ID reader}
+    # @return [Integer]
+    def to_i
+      id
+    end
+
+    # Removes this Entity from the list and purges all references to this Entity from other Components, as well as its {id ID} and data.
+    # @return [Boolean] +true+
+    def delete
+      components.each do |component_manager, component_array|
+        component_array.each do |component_id|
+          component_manager[component_id].entities.delete(id)
+          #self.remove FelFlame::Components.const_get(component_manager.name)[component_id]
+        end
+      end
+      FelFlame::Entities.data[id] = nil
+      @components = {}
+      @id = nil
+      true
+    end
+
+    # Add any number components to the Entity.
+    # @param components_to_add [Component] Any number of components created from any component manager
+    # @return [Boolean] +true+
+    def add(*components_to_add)
+      components_to_add.each do |component|
+        if components[component.class].nil?
+          components[component.class] = [component.id]
+          component.entities.push id
+          check_systems component, :addition_triggers
+        elsif !components[component.class].include? component.id
+          components[component.class].push component.id
+          component.entities.push id
+          check_systems component, :addition_triggers
+        end
+      end
+      true
+    end
+
+    # triggers every system associated with this component's trigger
+    # @return [Boolean] +true+
+    # @!visibility private
+    def check_systems(component, trigger_type)
+      component_calls = component.class.send(trigger_type)
+      component.send(trigger_type).each do |system|
+        component_calls |= [system]
+      end
+      component_calls.sort_by(&:priority).reverse.each(&:call)
+      true
+    end
+
+    # Remove a component from the Entity
+    # @param components_to_remove [Component] A component created from any component manager
+    # @return [Boolean] +true+
+    def remove(*components_to_remove)
+      components_to_remove.each do |component|
+        check_systems component, :removal_triggers if component.entities.include? id
+        component.entities.delete id
+        components[component.class].delete component.id
+      end
+      true
+    end
+
+    # Export all data into a JSON String which can then be saved into a file
+    # TODO: This function is not yet complete
+    # @return [String] A JSON formatted String
+    #def to_json() end
+
+    class <<self
+      include Enumerable
+      # @return [Array<Entity>] Array of all Entities that exist
+      # @!visibility private
+      def data
+        @data ||= []
+      end
+
+      # Gets an Entity from the given {id unique ID}. Usage is simular to how an Array lookup works
+      #
+      # @example
+      #   # This gets the Entity with ID 7
+      #   FelFlame::Entities[7]
+      # @param entity_id [Integer]
+      # @return [Entity] returns the Entity that uses the given unique ID, nil if there is no Entity associated with the given ID
+      def [](entity_id)
+        data[entity_id]
+      end
+
+      # Iterates over all entities. The data is compacted so that means index does not correlate to ID.
+      # You also call other enumerable methods instead of each, such as +each_with_index+ or +select+
+      # @return [Enumerator]
+      def each(&block)
+        data.compact.each(&block)
+      end
+
+      # Creates a new entity using the data from a JSON string
+      # TODO: This function is not yet complete
+      # @param json_string [String] A string that was exported originally using the {FelFlame::Entities#to_json to_json} function
+      # @param opts [Keywords] What values(its {FelFlame::Entities#id ID} or the {FelFlame::ComponentManager#id component IDs}) should be overwritten TODO: this might change
+      #def from_json(json_string, **opts) end
+    end
+  end
+end