;; https://adventofcode.com/2022/day/19
(defpackage :day-19
  (:use :cl))
(in-package :day-19)

(defparameter *all-types* '(:geode :obsidian :clay :ore))

(defclass state ()
  ((resources :accessor resources :initform nil :initarg :resources)
   (robots :accessor robots :initform (list :ore 1) :initarg :robots)))

(defmethod print-object ((obj state) stream)
  (print-unreadable-object (obj stream :type t)
    (with-slots (resources robots)
        obj
      (format stream "collected: ~a, with robots: ~a"
              resources robots))))

;; example of blueprint:
(defparameter *test-blueprint*
  '(:id 1
    :ore (:ore 4)
    :clay (:ore 2)
    :obsidian (:ore 3 :clay 14)
    :geode (:ore 2 :obsidian 7)))

;; thank you blambert & stackoverflow
;; https://stackoverflow.com/questions/11067899/is-there-a-generic-method-for-cloning-clos-objects
;; oh, but this is shallow copy and lists reused. crap

(defmethod copy-state ((s state))
  (make-instance 'state :resources (copy-list (resources s))
                        :robots (copy-list (robots s))))

(defmethod can-create-robot (blueprints type (s state))
  (let ((this-robot-costs (getf blueprints type)))
    (loop for (resource amount) on this-robot-costs by #'cddr
          always (>= (getf (resources s) resource 0) amount))))

(defmethod create-robot (blueprints type (s state))
  (when (can-create-robot blueprints type s)
    (let ((this-robot-costs (getf blueprints type))
          (copied-state (copy-state s)))
      (loop for (resource amount) on this-robot-costs by #'cddr
            do (incf (getf (resources copied-state) resource 0) (- amount)))
      (incf (getf (robots copied-state) type 0))
      copied-state)))

(defmethod calc-resources-to-be-collected ((s state))
  (robots s))

(defmethod add-resources (new-resources (s state))
  (loop for (resource amount) on new-resources by #'cddr
        do (incf (getf (resources s) resource 0) amount)))

(defmethod get-possible-bot-builds (blueprints (s state))
  (remove-if-not (lambda (robot-type) (can-create-robot blueprints robot-type s))
             *all-types*))