From a9b1a03be19d7c1fd236dbb03640c845a05f28d8 Mon Sep 17 00:00:00 2001
From: Mike Brown <github@torvosoft.com>
Date: Wed, 17 Jan 2024 22:12:07 +0000
Subject: [PATCH] Add dark mode & perspective to Board.Draw()

This commit adds Board.Draw2(perspective Color, darkMode bool). This
is similar to Board.Draw() except that it allows the caller to specify
from which perspective to display and whether the display should be
reversed colors. (In a terminal window configured with white foreground
text and a black background, the current Board.Draw() displays the
opposite color).

(cherry picked from commit 2c91017f4920b7de4f3967ea9274f93955826fa6)
(cherry picked from commit 820a54f8c17c34550e649e79c144bfefbb004b83)
---
 board.go | 45 ++++++++++++++++++++++++++++++++++++++++++++-
 piece.go |  7 ++++++-
 2 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/board.go b/board.go
index a61718d..df66f70 100644
--- a/board.go
+++ b/board.go
@@ -108,6 +108,22 @@ func (b *Board) Transpose() *Board {
 
 // Draw returns visual representation of the board useful for debugging.
 func (b *Board) Draw() string {
+	return b.drawForWhite(false)
+}
+
+// Draw2 returns visual representation of the board useful for debugging.
+// It is similar to Draw() except allows the caller to specify perspective
+// and dark mode options
+func (b *Board) Draw2(perspective Color, darkMode bool) string {
+	if perspective == Black {
+		return b.drawForBlack(darkMode)
+	} // else
+
+	return b.drawForWhite(darkMode)
+}
+
+// drawForWhite returns visual representation of the board from white's perspective
+func (b *Board) drawForWhite(darkMode bool) string {
 	s := "\n A B C D E F G H\n"
 	for r := 7; r >= 0; r-- {
 		s += Rank(r).String()
@@ -116,7 +132,34 @@ func (b *Board) Draw() string {
 			if p == NoPiece {
 				s += "-"
 			} else {
-				s += p.String()
+				if darkMode {
+					s += p.DarkString()
+				} else {
+					s += p.String()
+				}
+			}
+			s += " "
+		}
+		s += "\n"
+	}
+	return s
+}
+
+// drawForBlack returns visual representation of the board from black's perspective
+func (b *Board) drawForBlack(darkMode bool) string {
+	s := "\n H G F E D C B A\n"
+	for r := 0; r <= 7; r++ {
+		s += Rank(r).String()
+		for f := numOfSquaresInRow - 1; f >= 0; f-- {
+			p := b.Piece(NewSquare(File(f), Rank(r)))
+			if p == NoPiece {
+				s += "-"
+			} else {
+				if darkMode {
+					s += p.DarkString()
+				} else {
+					s += p.String()
+				}
 			}
 			s += " "
 		}
diff --git a/piece.go b/piece.go
index 1063ba1..7a03458 100644
--- a/piece.go
+++ b/piece.go
@@ -174,8 +174,13 @@ func (p Piece) String() string {
 	return pieceUnicodes[int(p)]
 }
 
+func (p Piece) DarkString() string {
+	return pieceDarkUnicodes[int(p)]
+}
+
 var (
-	pieceUnicodes = []string{" ", "♔", "♕", "♖", "♗", "♘", "♙", "♚", "♛", "♜", "♝", "♞", "♟"}
+	pieceUnicodes     = []string{" ", "♔", "♕", "♖", "♗", "♘", "♙", "♚", "♛", "♜", "♝", "♞", "♟"}
+	pieceDarkUnicodes = []string{" ", "♚", "♛", "♜", "♝", "♞", "♟", "♔", "♕", "♖", "♗", "♘", "♙"}
 )
 
 func (p Piece) getFENChar() string {