[explorer, moves, position] Implement bespoke make_move and unmake_move methods on Position

Instead of inheriting the MakeMove and UnmakeMove traits by being a BoardProvider,
implement bespoke versions of these two methods. This gives Position a chance to
do some of its own work (tracking captures, move records, etc) when making a move.

Pass the move record by reference to the unmake_move() method. Saves a copy.

Export the Result types for MakeMove and UnmakeMove.

position/src/position.rs

@@ -1,21 +1,20 @@
 // Eryn Wells <eryn@erynwells.me>
 
 mod captures;
-mod unmake_move;
 
 use chessfriend_moves::{
     generators::{
         AllPiecesMoveGenerator, BishopMoveGenerator, KingMoveGenerator, KnightMoveGenerator,
         PawnMoveGenerator, QueenMoveGenerator, RookMoveGenerator,
     },
-    GeneratedMove, MakeMove, Move, MoveRecord, ValidateMove,
+    GeneratedMove, MakeMove, MakeMoveError, Move, MoveRecord, UnmakeMove, UnmakeMoveError,
+    UnmakeMoveResult, ValidateMove,
 };
 
 use captures::CapturesList;
 use chessfriend_bitboard::BitBoard;
 use chessfriend_board::{
-    display::DiagramFormatter, fen::ToFenStr, Board, BoardProvider, PlacePieceError,
-    PlacePieceStrategy,
+    display::DiagramFormatter, fen::ToFenStr, Board, PlacePieceError, PlacePieceStrategy,
 };
 use chessfriend_core::{Color, Piece, Shape, Square};
 use std::fmt;
@@ -127,6 +126,45 @@ impl Position {
     }
 }
 
+impl Position {
+    /// Make a move on the board and record it in the move list.
+    ///
+    /// ## Errors
+    ///
+    /// Returns one of [`MakeMoveError`] if the move cannot be made.
+    ///
+    pub fn make_move(&mut self, ply: Move, validate: ValidateMove) -> Result<(), MakeMoveError> {
+        let record = self.board.make_move(ply, validate)?;
+
+        if let Some(captured_piece) = record.captured_piece {
+            self.captures.push(record.color, captured_piece);
+        }
+
+        self.moves.push(record.clone());
+
+        Ok(())
+    }
+
+    /// Unmake the last move made on the board and remove its record from the
+    /// move list.
+    ///
+    /// ## Errors
+    ///
+    /// Returns one of [`UnmakeMoveError`] if the move cannot be made.
+    ///
+    pub fn unmake_last_move(&mut self) -> UnmakeMoveResult {
+        let last_move_record = self.moves.pop().ok_or(UnmakeMoveError::NoMove)?;
+
+        let unmake_result = self.board.unmake_move(&last_move_record);
+
+        if unmake_result.is_err() {
+            self.moves.push(last_move_record);
+        }
+
+        unmake_result
+    }
+}
+
 impl Position {
     pub fn display(&self) -> DiagramFormatter {
         self.board.display()
@@ -141,16 +179,6 @@ impl ToFenStr for Position {
     }
 }
 
-impl BoardProvider for Position {
-    fn board(&self) -> &Board {
-        &self.board
-    }
-
-    fn board_mut(&mut self) -> &mut Board {
-        &mut self.board
-    }
-}
-
 impl PartialEq for Position {
     fn eq(&self, other: &Self) -> bool {
         self.board == other.board