Fixes to how moves are counted and minor style improvements

src/Chess/board.nim

@@ -212,6 +212,18 @@ proc getEnPassantTarget*(self: ChessBoard): Location =
     return self.position.enPassantSquare.targetSquare
 
 
+proc getMoveCount*(self: ChessBoard): int =
+    ## Returns the number of full moves that
+    ## have been played
+    return self.position.fullMoveCount
+
+
+proc getHalfMoveCount*(self: ChessBoard): int =
+    ## Returns the current number of half-moves
+    ## since the last irreversible move
+    return self.position.halfMoveClock
+
+
 func getStartRow(piece: Piece): int {.inline.} =
     ## Retrieves the starting row of
     ## the given piece inside our 8x8
@@ -467,6 +479,11 @@ func rankToColumn(rank: int): int =
     return indeces[rank - 1]
 
 
+func rowToRank(row: int): int =
+    const indeces = [8, 7, 6, 5, 4, 3, 2, 1]
+    return indeces[row]
+
+
 proc algebraicToLocation*(s: string): Location =
     ## Converts a square location from algebraic
     ## notation to its corresponding row and column
@@ -480,16 +497,16 @@ proc algebraicToLocation*(s: string): Location =
     if s[1] notin '1'..'8':
         raise newException(ValueError, &"algebraic position has invalid second character ('{s[1]}')")
 
-    let file = int(uint8(s[0]) - uint8('a'))
-    # Convert the rank character to a number
-    let rank = rankToColumn(int(uint8(s[1]) - uint8('0')))
-    return (rank, file)
+    let rank = int(uint8(s[0]) - uint8('a'))
+    # Convert the file character to a number
+    let file = rankToColumn(int(uint8(s[1]) - uint8('0')))
+    return (file, rank)
 
 
 proc locationToAlgebraic*(loc: Location): string =
     ## Converts a location from our internal row, column
     ## notation to a square in algebraic notation
-    return &"{char(uint8(loc.col) + uint8('a'))}{char(uint8(loc.row) + uint8('0'))}"
+    return &"{char(uint8(loc.col) + uint8('a'))}{rowToRank(loc.row)}"
 
 
 proc getPiece*(self: ChessBoard, square: string): Piece =
@@ -961,14 +978,18 @@ proc doMove(self: ChessBoard, move: Move) =
     # Final checks
     
     # Needed to detect draw by the 50 move rule
-    if move.piece.kind != Pawn and not self.isCapture(move):
-        inc(self.position.halfMoveClock)
+    var 
+        halfMoveClock = self.position.halfMoveClock
+        fullMoveCount = self.position.fullMoveCount
+    if move.piece.kind == Pawn or self.isCapture(move):
+        halfMoveClock = 0
     else:
-        self.position.halfMoveClock = 0
-    if (self.position.halfMoveClock and 1) == 0:   # Equivalent to (x mod 2) == 0, just much faster
-        inc(self.position.fullMoveCount)
+        inc(halfMoveClock)
+    if move.piece.color == Black:
+        inc(fullMoveCount)
     # TODO: Castling
 
+    # Record the move in the position
     self.position.move = move
 
     # Update position and attack metadata
@@ -979,6 +1000,8 @@ proc doMove(self: ChessBoard, move: Move) =
     self.positions.add(self.position)
     # Create new position with
     var newPos = Position(plyFromRoot: self.position.plyFromRoot + 1,
+                          halfMoveClock: halfMoveClock,
+                          fullMoveCount: fullMoveCount,
                           captured: emptyPiece(),
                           turn: self.getActiveColor().opposite,
                           # Inherit values from current position

src/Chess/player.nim

@@ -13,13 +13,14 @@ when isMainModule:
         data: string
         move: Move
 
-
+    echo "\x1Bc"
     while true:
         echo &"{board.pretty()}"
         echo &"Turn: {board.getActiveColor()}"
+        echo &"Moves: {board.getMoveCount()} full, {board.getHalfMoveCount()} half"
         stdout.write(&"En passant target: ")
         if board.getEnPassantTarget() != emptyLocation():
-            echo board.getEnPassantTarget()
+            echo board.getEnPassantTarget().locationToAlgebraic()
         else:
             echo "None"
         stdout.write(&"Check: ")
@@ -34,13 +35,16 @@ when isMainModule:
             echo ""
             break
         if data == "undo":
-            echo &"Undo: {board.undoLastMove()}"
+            echo &"\x1BcUndo: {board.undoLastMove()}"
             continue
         if len(data) != 4:
+            echo "\x1BcError: invalid move"
             continue
         try:
             move = board.makeMove(data[0..1], data[2..3])
         except ValueError:
-            echo &"Error: {getCurrentExceptionMsg()}"
+            echo &"\x1BcError: {getCurrentExceptionMsg()}"
         if move == emptyMove():
-            echo &"Error: move is illegal"
+            echo &"\x1BcError: move is illegal"
+        else:
+            echo "\x1Bc"