Add logic for first three AI strengths.

tictactoe_clojure/tictactoe.clj

@@ -1,23 +1,11 @@
 (def win-conditions [[0 1 2] [3 4 5] [6 7 8] [0 3 6] [1 4 7] [2 5 8] [0 4 8] [2 4 6]])
 
 
-(defn ask []
-  (println "Please answer \"y\"[yes] or \"n\"[no]:")
-  (.trim (read-line)))
-
-(defn get-valid-answer [question]
-  (println question)
-  (let [answer (->> (repeatedly ask)
-                    (filter #{"y" "n"})
-                    (first))]
-    (= answer "y")))
-
 (defn swap-player [player]
   (if (= player "X")
     "O"
     "X"))
 
-(defn get-player-input [])
 
 (defn show-board [board]
   (println (str (nth board 0) " | " (nth board 1) " | " (nth board 2)))
@@ -32,7 +20,6 @@
     (println (str "Player " player " turn"))
     (show-board board)
     (let [player-input (read-string (read-line))]
-      (println player-input)
       (if (and (number? player-input) (<= 0 player-input 8))
         (assoc board player-input player)
         (do
@@ -44,17 +31,59 @@
     (do (println "Game drawn!") true)
     false))
 
-(defn won-win-condition [board player win-condition]
+(defn won-win-condition [player board win-condition]
   (every? #(= player (nth board %)) win-condition))
 
-(defn game-won [board player]
-  (if (some (partial won-win-condition board player) win-conditions)
+(defn is-win [player board]
+  (some (partial won-win-condition player board) win-conditions))
+
+(defn game-won [player board]
+  (if (is-win player board)
     (do (println (str "Player " player " wins!")) true)
     false))
 
+(defn ai-turn-easy [player board]
+  (let [empty-spaces (filter #(not (or (= % "X") (= % "O"))) board)
+        random-space (nth empty-spaces (rand-int (count empty-spaces)))]
+    (assoc board (Integer. random-space) player)))
+
+(defn try-win-move [player board]
+  (let [empty-spaces (filter #(not (or (= % "X") (= % "O"))) board)]
+    (some (fn [space]
+            (let [new-board (assoc board (Integer. space) player)]
+              (if (is-win player new-board)
+                (Integer. space)
+                false)))
+          empty-spaces)))
+
+(defn ai-turn-medium [player board]
+  (let [ win-move-spot (try-win-move player board)]
+    (if (nil? win-move-spot)
+      (ai-turn-easy player board)
+      (assoc board win-move-spot player))))
+
+(defn ai-turn-hard [player board]
+  (let [win-move-spot (try-win-move player board)]
+    (if (nil? win-move-spot)
+      (let [block-move-spot (try-win-move (swap-player player) board)]
+        (if (nil? block-move-spot)
+          (ai-turn-easy player board)
+          (assoc board block-move-spot player)))
+      (assoc board win-move-spot player))))
+
+(defn ai-turn-best [player board]
+  board)
+
 (defn ai-turn [player board strength]
   (println (str "AI turn as player " player " with strength " strength))
-  board)
+  (show-board board)
+  (let [board-after-ai-move (case strength
+                              1 (ai-turn-easy player board)
+                              2 (ai-turn-medium player board)
+                              3 (ai-turn-hard player board)
+                              (ai-turn-best player board))]
+    (Thread/sleep 1000)
+    board-after-ai-move))
 
 (defn ai-turn? [player X-strength O-strength]
   (if (= player "X")
@@ -67,14 +96,14 @@
     O-strength))
 
 (defn play [board X-strength O-strength]
-  (loop [game-board board player "X"]
-    (if (or (game-won game-board (swap-player player)) (board-full game-board))
+  (loop [player "X" game-board board]
+    (if (or (game-won (swap-player player) game-board) (board-full game-board))
       (show-board game-board)
       (let
        [new-board (if (ai-turn? player X-strength O-strength)
                     (ai-turn player game-board (strength-for-player player X-strength O-strength))
                     (player-turn player game-board))]
-        (recur new-board (swap-player player))))))
+        (recur (swap-player player) new-board)))))
 
 (defn parse-args
   "Parses command line arguments and returns a map with X-strength and O-strength."