prevent same color & same user pixels to be placed on top of each other (fixes #19)

packages/client/src/lib/canvas.ts

@@ -237,14 +237,34 @@ export class Canvas extends EventEmitter<CanvasEvents> {
           this.lastPlace = Date.now();
           this.handlePixel(ack.data);
         } else {
-          // TODO: handle undo pixel
-          toast.info(ack.error);
           console.warn(
             "Attempted to place pixel",
             { x, y, color: this.Pallete.getSelectedColor()!.id },
             "and got error",
             ack
           );
+
+          switch (ack.error) {
+            case "invalid_pixel":
+              toast.error(
+                "Cannot place, invalid pixel location. Are you even on the canvas?"
+              );
+              break;
+            case "no_user":
+              toast.error("You are not logged in.");
+              break;
+            case "palette_color_invalid":
+              toast.error("This isn't a color that you can use...?");
+              break;
+            case "pixel_cooldown":
+              toast.error("You're on pixel cooldown, cannot place");
+              break;
+            case "you_already_placed_that":
+              toast.error("You already placed this color at this location");
+              break;
+            default:
+              toast.error("Error while placing pixel: " + ack.error);
+          }
         }
       });
   }

packages/lib/src/net.ts

@@ -19,7 +19,11 @@ export interface ClientToServerEvents {
     ack: (
       _: PacketAck<
         Pixel,
-        "no_user" | "invalid_pixel" | "pixel_cooldown" | "palette_color_invalid"
+        | "no_user"
+        | "invalid_pixel"
+        | "pixel_cooldown"
+        | "palette_color_invalid"
+        | "you_already_placed_that"
       >
     ) => void
   ) => void;

packages/server/src/lib/Canvas.ts

@@ -82,17 +82,7 @@ class Canvas {
 
     for (let x = 0; x < this.canvasSize[0]; x++) {
       for (let y = 0; y < this.canvasSize[1]; y++) {
-        const pixel = await prisma.pixel.findFirst({
-          where: {
-            x,
-            y,
-          },
-          orderBy: [
-            {
-              createdAt: "asc",
-            },
-          ],
-        });
+        const pixel = await this.getPixel(x, y);
 
         await redis.set(key(x, y), pixel?.color || "transparent");
       }
@@ -152,12 +142,18 @@ class Canvas {
   }
 
   async getPixel(x: number, y: number) {
-    return await prisma.pixel.findFirst({
-      where: {
-        x,
-        y,
-      },
-    });
+    return (
+      await prisma.pixel.findMany({
+        where: {
+          x,
+          y,
+        },
+        orderBy: {
+          createdAt: "desc",
+        },
+        take: 1,
+      })
+    )?.[0];
   }
 
   async setPixel(user: { sub: string }, x: number, y: number, hex: string) {
@@ -194,10 +190,7 @@ class Canvas {
     const key = Redis.key("pixelColor", x, y);
 
     // find if any pixels exist at this spot, and pick the most recent one
-    const pixel = await prisma.pixel.findFirst({
-      where: { x, y },
-      orderBy: { createdAt: "desc" },
-    });
+    const pixel = await this.getPixel(x, y);
     let paletteColorID = -1;
 
     // if pixel exists in redis

packages/server/src/lib/SocketServer.ts

@@ -229,6 +229,17 @@ export class SocketServer {
         return;
       }
 
+      const pixelAtTheSameLocation = await Canvas.getPixel(pixel.x, pixel.y);
+
+      if (
+        pixelAtTheSameLocation &&
+        pixelAtTheSameLocation.userId === user.sub &&
+        pixelAtTheSameLocation.color === paletteColor.hex
+      ) {
+        ack({ success: false, error: "you_already_placed_that" });
+        return;
+      }
+
       await user.modifyStack(-1);
       await Canvas.setPixel(user, pixel.x, pixel.y, paletteColor.hex);
       // give undo capabilities