(ns emptyhead.thought.crud
  "Implements CRUD operations on thoughts.
  Since thoughts are ideas, 'missing' operations here are implemented in [[emptyhead.idea.crud]]."
  (:require [emptyhead.idea.protocol :as prtc]
            [emptyhead.idea.crud :as idea]
            [emptyhead.util.magic :as magic]))

(defn make-thought
  "Helper function to make thought object.
  You may want `register-thought!` instead."
  [operator & {:keys [data ext-stages]
               :or {data {}
                    ext-stages [[:PRE-EXECUTE] [:EXECUTE] [:POST-EXECUTE]]}}]
  (hash-map :operator operator
            :data data
            :ext-stages ext-stages
            :return []))

(defn register-thought!
  "Create a thought and register it in the state.
  Returns a reference to the created thought."
  [operator & {:keys [data ext-stages]
               :as args}]
  (idea/have-idea!
   :prefix (str "emptyhead.thought#" (magic/symbolize-ns operator))
   :properties [magic/thought-ns]
   :data (make-thought operator args)))

(defn stages
  "Get the extension stages of a `thought`.
  Returns the list of stages."
  [thought]
  (prtc/val-fn :ext-stages thought))

(defn operator
  "Get the operator id of a `thought`.
  Returns the operator keyword."
  [thought]
  (prtc/val-fn :operator thought))

(defn data
  "Get the data field of a `thought`."
  [thought]
  (prtc/val-fn :data thought))

(defn stack
  [thought]
  (prtc/val-fn :return thought))

(defn pop-stack
  [thought]
  [(assoc thought :return (-> thought prtc/copy stack butlast vec)) (-> thought prtc/copy stack peek)])

(defn add-ext-stage!
  [thought stage]
  (idea/mutate-idea! #(update % :ext-stages conj stage) thought))