basically working version

game/entity.rs

@@ -1,16 +1,17 @@
 #[derive(Clone, Copy, PartialEq)]
-pub struct Cell(u8);
-pub const CELL_EMPTY: Cell = Cell(0);
-pub const CELL_X: Cell = Cell(1);
-pub const CELL_O: Cell = Cell(2);
+pub enum Cell {
+    Empty,
+    X,
+    O,
+}
 
 impl std::fmt::Display for Cell {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
-        let mut s: &str = " ";
-        if *self == CELL_X {
-            s = "X";
-        } else if *self == CELL_O {
-            s = "O";
+        let s: &str;
+        match *self {
+            Cell::X => s = "X",
+            Cell::O => s = "O",
+            Cell::Empty => s = " ",
         }
 
         write!(f, "{}", s)
@@ -20,7 +21,7 @@ impl std::fmt::Display for Cell {
 pub struct Move {
     pub x: usize,
     pub y: usize,
-    pub c: Cell,
+    pub piece: Cell,
 }
 
 pub struct Board {
@@ -30,51 +31,83 @@ pub struct Board {
 
 impl Board {
     pub fn new() -> Board {
-        return Board {
-            cells: vec![CELL_EMPTY; 9],
-            next: CELL_X,
-        };
+        Board {
+            cells: vec![Cell::Empty; 9],
+            next: Cell::X,
+        }
     }
 
     pub fn reset(&mut self) {
-        self.cells = vec![CELL_EMPTY; 9];
-        self.next = CELL_X;
+        self.cells = vec![Cell::Empty; 9];
+        self.next = Cell::X;
     }
 
-    pub fn put(&mut self, m: Move) -> bool {
+    pub fn apply(&mut self, m: Move) -> Result<(), &str> {
         let i = m.x * 1 + m.y * 3;
-        if self.cells[i] != CELL_EMPTY {
-            return false;
+
+        if !self.is_valid_move(&m) {
+            return Err("invalid move");
         }
 
-        self.cells[i] = m.c;
+        self.cells[i] = m.piece;
 
-        return true;
+        match self.next {
+            Cell::X => self.next = Cell::O,
+            Cell::O => self.next = Cell::X,
+            _ => {}
+        }
+
+        Ok(())
     }
 
-    pub fn has_winner(&self) -> Cell {
+    pub fn is_valid_move(&self, m: &Move) -> bool {
+        let i = m.x * 1 + m.y * 3;
+
+        m.piece == self.next && self.cells[i] == Cell::Empty
+    }
+
+    pub fn valid_moves_available(&self) -> bool {
+        // check for draw condition
+        let mut empty: usize = 0;
+        for i in 0..self.cells.len() {
+            if self.cells[i] == Cell::Empty {
+                empty += 1;
+            }
+        }
+
+        empty > 0
+    }
+
+    pub fn has_winner(&self) -> Option<Cell> {
         // rows and cols
         for i in 0..3 {
-            if self.cells[i] == self.cells[i + 3] && self.cells[i] == self.cells[i + 6] {
-                return self.cells[i];
-            } else if self.cells[i * 3] == self.cells[i * 3 + 1]
-                && self.cells[i * 3] == self.cells[i * 3 + 2]
+            if (self.cells[i] != Cell::Empty)
+                && (self.cells[i] == self.cells[i + 3] && self.cells[i] == self.cells[i + 6])
             {
-                return self.cells[i * 3];
+                return Some(self.cells[i]);
+            } else if (self.cells[i * 3] != Cell::Empty)
+                && (self.cells[i * 3] == self.cells[i * 3 + 1]
+                    && self.cells[i * 3] == self.cells[i * 3 + 2])
+            {
+                return Some(self.cells[i * 3]);
             }
         }
 
         // diagonals
-        if self.cells[0] == self.cells[4] && self.cells[0] == self.cells[8] {
-            return self.cells[0];
+        if (self.cells[0] != Cell::Empty)
+            && (self.cells[0] == self.cells[4] && self.cells[0] == self.cells[8])
+        {
+            return Some(self.cells[0]);
         }
 
-        if self.cells[2] == self.cells[4] && self.cells[2] == self.cells[6] {
-            return self.cells[2];
+        if (self.cells[2] != Cell::Empty)
+            && (self.cells[2] == self.cells[4] && self.cells[2] == self.cells[6])
+        {
+            return Some(self.cells[2]);
         }
 
         // no winner
-        return CELL_EMPTY;
+        return None;
     }
 }
 
@@ -82,26 +115,36 @@ impl std::fmt::Display for Board {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
         let mut s = String::new();
 
-        s.push_str("┌─┬─┬─┐\n");
+        s.push_str("    1   2   3 \n");
+
+        s.push_str("  ┌───┬───┬───┐\n");
         for i in 0..3 {
+            match i {
+                0 => s.push_str("a "),
+                1 => s.push_str("b "),
+                2 => s.push_str("c "),
+                _ => {}
+            }
             s.push_str(&format!(
-                "│{}│{}│{}│\n",
+                "│ {} │ {} │ {} │\n",
                 self.cells[i * 3],
                 self.cells[i * 3 + 1],
                 self.cells[i * 3 + 2]
             ));
             if i < 2 {
-                s.push_str("├─┼─┼─┤\n");
+                s.push_str("  ├───┼───┼───┤\n");
             }
         }
-        s.push_str("└─┴─┴─┘\n");
+        s.push_str("  └───┴───┴───┘\n");
 
-        let w = self.has_winner();
-        if w != CELL_EMPTY {
-            s.push_str(&format!("The winner is {w}"));
-        } else {
-            s.push_str(&format!("Next: {}", self.next));
+        match self.has_winner() {
+            Some(w) => s.push_str(&format!("The winner is {w}")),
+            None => match self.valid_moves_available() {
+                true => s.push_str(&format!("Next: {}", self.next)),
+                false => s.push_str("DRAW!"),
+            },
         }
+
         write!(f, "{s}")
     }
 }

game/mod.rs

@@ -1,2 +1,2 @@
 mod entity;
-pub use entity::{Board, Cell, Move, CELL_EMPTY, CELL_O, CELL_X};
+pub use entity::{Board, Cell, Move};