fix: have no start item selection, only choose who starts (bot game type)

src/main.rs

@@ -46,6 +46,7 @@ trait Displayer {
 }
 
 /// Represents the **Tic-Tac-Toe** board game
+#[derive(Copy, Clone)]
 struct Board {
     // board array is reprensented as follow:
     // [ 0, 1, 2 ]
@@ -224,6 +225,20 @@ impl Player {
     fn new(item: Item, is_bot: bool) -> Self {
         Player { item, is_bot }
     }
+
+    fn as_bot() -> Self {
+        Player {
+            item: Item::Empty,
+            is_bot: true,
+        }
+    }
+
+    fn as_human() -> Self {
+        Player {
+            item: Item::Empty,
+            is_bot: false,
+        }
+    }
 }
 
 impl Default for Player {
@@ -239,10 +254,7 @@ impl Player {
     /// init players with the game type
     fn from_game_type(game_type: GameType) -> Vec<Player> {
         match game_type {
-            GameType::TwoPlayers => vec![
-                Player::new(Item::Empty, false),
-                Player::new(Item::Empty, false),
-            ],
+            GameType::TwoPlayers => vec![Player::new(Item::X, false), Player::new(Item::O, false)],
             GameType::Bot => vec![
                 Player::new(Item::Empty, false),
                 Player::new(Item::Empty, true),
@@ -255,7 +267,7 @@ impl Player {
 /// Two `GameType` availables:
 /// * TwoPlayers: no bot
 /// * Bot: player against the bot
-#[derive(Copy, Clone)]
+#[derive(Copy, Clone, PartialEq)]
 enum GameType {
     TwoPlayers,
     Bot,
@@ -306,15 +318,15 @@ impl TicTacToe {
         self.game_type = game_type;
     }
 
-    fn set_players_item(&mut self, first_item: Item) -> Result<(), String> {
+    fn set_players_item(&mut self) -> Result<(), String> {
         if self.players.len() != 2 {
             return Err(
                 "unable to initialize players item, 2 players must be initialized".to_string(),
             );
         }
 
-        self.players[0].item = first_item;
-        self.players[1].item = first_item.next();
+        self.players[0].item = Item::X;
+        self.players[1].item = Item::O;
 
         Ok(())
     }
@@ -334,8 +346,17 @@ impl TicTacToe {
         Ok(self.players[0])
     }
 
-    /// set the item for the first player (the one that starts)
-    fn select_first_player_item(&mut self) {
+    /// if `GameType` is againt bot, you can select who starts
+    fn select_first_player(&mut self) {
+        if self.players.len() != 2 {
+            fatal("unable to initialize the game, 2 players must be set".to_string());
+        }
+
+        // the first player always starts whith 'X'
+        if self.game_type == GameType::TwoPlayers {
+            return;
+        }
+
         let mut attempt = 0;
         loop {
             if attempt == 2 {
@@ -343,19 +364,29 @@ impl TicTacToe {
                 std::process::exit(1);
             }
 
-            let input = TicTacToe::get_user_input("first player, choose your item: ('X' or 'O')");
-            let item_start = Item::try_from(input);
-            match item_start {
-                Ok(item) => {
-                    match self.set_players_item(item) {
-                        Ok(()) => break,
-                        Err(e) => fatal(e),
+            let input = TicTacToe::get_user_input("who starts: ('B': bot, 'H': you as human)");
+            let is_bot = self.players[0].is_bot;
+
+            match &input[..] {
+                "B" | "b" => {
+                    if !is_bot {
+                        self.players.swap(0, 1)
                     }
-                    break;
                 }
-                Err(e) => error(e.to_string()),
+                "H" | "h" => {
+                    if is_bot {
+                        self.players.swap(0, 1)
                     }
+                }
+                _ => {
+                    error("bad input, please retry!".to_string());
                     attempt += 1;
+                    continue;
+                }
+            }
+
+            self.set_players_item();
+            break;
         }
     }
 
@@ -410,9 +441,22 @@ impl TicTacToe {
         Ok(available_indexes[0] + 1)
     }
 
+    /// minimax algorithm used by the bot player to find the best move (minimizing the loses)
+    fn minimax(&self, board: Option<Board>, player: Player, depth: usize) -> usize {
+        let mut board = match board {
+            Some(b) => b,
+            None => self.board.clone(),
+        };
+        let availables_indexes = board.get_available_indexes();
+        for index in availables_indexes {
+            board.set_item(player.item, index);
+        }
+        0
+    }
+
     fn run(&mut self) {
         self.select_game_type();
-        self.select_first_player_item();
+        self.select_first_player();
 
         loop {
             if self.board.is_full() {