[board] Add MoveCounter struct to track current color, half move counter, and full move counter

board/src/lib.rs

@@ -6,6 +6,7 @@ pub mod en_passant;
 pub mod fen;
 pub mod flags;
 pub mod macros;
+pub mod move_counter;
 
 mod board;
 mod builder;
@@ -17,4 +18,5 @@ pub use builder::Builder;
 use castle::Castle;
 use en_passant::EnPassant;
 use flags::Flags;
+use move_counter::MoveCounter;
 use piece_sets::PieceSet;

board/src/move_counter.rs

@@ -0,0 +1,34 @@
+use chessfriend_core::Color;
+
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub struct MoveCounter {
+    /// The player who's turn it is to move.
+    pub active_color: Color,
+    /// The number of completed turns. A turn finishes when every player has moved.
+    pub fullmove_number: u16,
+    /// The number of moves by all players since the last pawn advance or capture.
+    pub halfmove_number: u16,
+}
+
+impl MoveCounter {
+    pub fn advance(&mut self, should_reset_halfmove_number: bool) {
+        self.active_color = self.active_color.next();
+
+        self.fullmove_number += 1;
+        self.halfmove_number = if should_reset_halfmove_number {
+            0
+        } else {
+            self.halfmove_number + 1
+        };
+    }
+}
+
+impl Default for MoveCounter {
+    fn default() -> Self {
+        Self {
+            active_color: Color::default(),
+            fullmove_number: 0,
+            halfmove_number: 0,
+        }
+    }
+}