;; The first three lines of this file were inserted by DrRacket. They record metadata
;; about the language level of this file in a form that our tools can easily process.
#reader(lib "htdp-intermediate-lambda-reader.ss" "lang")((modname week10_f_full) (read-case-sensitive #t) (teachpacks ((lib "image.ss" "teachpack" "htdp"))) (htdp-settings #(#t constructor repeating-decimal #f #t none #f ((lib "image.ss" "teachpack" "htdp")))))
(require "snake-lib.rkt")

(require "graphs.rkt")

(define AUTO true)

;; advance-game : game -> game
(define (advance-game g)
  (cond [AUTO (advance-game-auto g)]
        [else (advance-game-manual g)]))

(define (advance-game-auto g) 
  (local [(define bp (best-path g) )]
    (cond [(false? bp) (advance-game-manual g)]
          [else (second bp)])))


(define (best-path-try g) 
  (find-shortest-path-to-cond (make-graph empty autosnake-neighbor (lambda (x y) false))
                              g (lambda (g2) 
                                  (> (game-score g2) (game-score g)))))

; best-path game -> list-of-game
; returns the "best" path through games from the passed-in game
(define (best-path g) 
  (find-shortest-path-to-cond (make-graph empty autosnake-neighbor (lambda (x y) false))
                              g (lambda (g2) 
                                  (or (> (game-score g2) (game-score g))
                                      (and (not (game-over? g2))
                                           (< (food-dist g2) (- (food-dist g) 2)))
                                      (> (game-ticks g2) (+ (game-ticks g) 3))))))

; autosnake-neighbor : game -> list-of-game
; returns all games reachable from this game with a change of direction
(define (autosnake-neighbor g)
  (cond [(game-over? g) empty]
  [else (map (lambda (x) (advance-game-manual (change-direction g x)))
       (list 'up 'down 'left 'right))]))


                 

; dist : posn posn -> number 
; returns distance between points
(define (dist a b)
  (sqrt (+ (sqr (- (posn-x a) (posn-x b)))
           (sqr (- (posn-y a) (posn-y b))))))
        

; food-dist : game -> number
; returns the distance from the snake to food
(define (food-dist g)
  (cond[(empty? (game-food g)) 0]
  [else (argmin abs (map (lambda (x) (dist (first (snake-segments (game-snake g))) x)) (game-food g)))]))