Restrict movement to valid moves

Now need to fix valid moves to be accurate

src/game.rs

@@ -167,35 +167,40 @@ impl Board {
             Err(GameError::NullMove)
         } else {
             match self.at(from.clone()) {
-                Some(from_val) => {
-                    // The current epoch is the last epoch + 1
-                    let epoch = self.current_epoch();
-
-                    // Local moves vec we can return
-                    let mut moves = vec![];
+                Some(from_piece) => {
+                    // Check if this is a valid move for this piece
+                    if self.possible_moves(from).contains(&to) {
+                        // The current epoch is the last epoch + 1
+                        let epoch = self.current_epoch();
+
+                        // Local moves vec we can return
+                        let mut moves = vec![];
+
+                        // If the position we are moving to is occupied, capture the removal in the ledger
+                        if self.inner[to.y][to.x].is_some() {
+                            moves.push(Move {
+                                epoch,
+                                from: to.clone(),
+                                to: None,
+                            });
+                        }
 
-                    // If the position we are moving to is occupied, capture the removal in the ledger
-                    if self.inner[to.y][to.x].is_some() {
+                        // Capture the intened move in the moves ledger
                         moves.push(Move {
                             epoch,
-                            from: to.clone(),
-                            to: None,
+                            from: from.clone(),
+                            to: Some(to.clone()),
                         });
-                    }
 
-                    // Capture the intened move in the moves ledger
-                    moves.push(Move {
-                        epoch,
-                        from: from.clone(),
-                        to: Some(to.clone()),
-                    });
-
-                    self.inner[to.y][to.x] = Some(*from_val);
-                    self.inner[from.y][from.x] = None;
+                        self.inner[to.y][to.x] = Some(*from_piece);
+                        self.inner[from.y][from.x] = None;
 
-                    self.moves.extend(moves.clone());
+                        self.moves.extend(moves.clone());
 
-                    Ok(moves)
+                        Ok(moves)
+                    } else {
+                        Err(GameError::InvalidIndex)
+                    }
                 }
                 None => Err(GameError::NullMove),
             }
@@ -212,6 +217,7 @@ impl Board {
     }
 
     /// Returns the possible moves the piece at this tile can make.
+    /// !!TODO: exclude pieces on your own side!!
     pub(crate) fn possible_moves(&self, BoardIndex { x, y }: BoardIndex) -> HashSet<BoardIndex> {
         let f = |(a, b): (Option<usize>, Option<usize>)| {
             if let (Some(x), Some(y)) = (a, b) {