From b7c1f73a9b9e82517da491ac0bd47a94c5249f78 Mon Sep 17 00:00:00 2001
From: Thomas Lindner <tom@dl6tom.de>
Date: Wed, 21 Jun 2023 23:04:31 +0200
Subject: [PATCH] highlight losing moves

---
 src/main.c | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/src/main.c b/src/main.c
index 4576ee7..94410d1 100644
--- a/src/main.c
+++ b/src/main.c
@@ -44,6 +44,25 @@ int loser(void) {
   return 0;
 }
 
+bool selected_edge_loses(void) {
+  for (int i = 0; i < 6; i++) {
+    for (int j = i + 1; j < 6; j++) {
+      for (int k = j + 1; k < 6; k++) {
+        int a = EDGE(i, j) == selected_edge ? active_player
+                                            : edge_color[EDGE(i, j)];
+        int b = EDGE(j, k) == selected_edge ? active_player
+                                            : edge_color[EDGE(j, k)];
+        int c = EDGE(i, k) == selected_edge ? active_player
+                                            : edge_color[EDGE(i, k)];
+        if (a && a == b && a == c) {
+          return true;
+        }
+      }
+    }
+  }
+  return false;
+}
+
 void input(SDL_KeyboardEvent *event) {
   switch (event->keysym.scancode) {
     case SDL_SCANCODE_UP:
@@ -115,7 +134,11 @@ void draw(SDL_Renderer *renderer) {
   for (int i = 0; i < 6; i++) {
     for (int j = i + 1; j < 6; j++) {
       if (EDGE(i, j) == selected_edge) {
-        ECHK_SDL(thickLineRGBA(renderer, VERTEX(i), VERTEX(j), 10, WHITE));
+        if (selected_edge_loses()) {
+          ECHK_SDL(thickLineRGBA(renderer, VERTEX(i), VERTEX(j), 10, RED));
+        } else {
+          ECHK_SDL(thickLineRGBA(renderer, VERTEX(i), VERTEX(j), 10, WHITE));
+        }
       } else {
         switch (edge_color[EDGE(i, j)]) {
           case -1: