1 files changed, 103 insertions, 0 deletions
diff --git a/src/engine/systems/Collision.ts b/src/engine/systems/Collision.ts
new file mode 100644
index 0000000..7b1b963
--- /dev/null
+++ b/src/engine/systems/Collision.ts
@@ -0,0 +1,103 @@
+import { System, SystemNames } from ".";
+import { Game } from "..";
+import { Entity, EntityNames } from "../entities";
+import { BoundingBox, Colliding, ComponentNames, Grid } from "../components";
+
+const collisionMap: Record<string, Set<string>> = {
+  [EntityNames.Key]: new Set([EntityNames.LockedDoor]),
+  [EntityNames.Curry]: new Set([EntityNames.Player]),
+};
+
+export class Collision extends System {
+  static canCollide(entityName: string, otherEntityName: string) {
+    if (collisionMap[entityName]) {
+      return collisionMap[entityName].has(otherEntityName);
+    }
+    return collisionMap[otherEntityName]?.has(entityName) ?? false;
+  }
+
+  constructor() {
+    super(SystemNames.Collision);
+  }
+
+  public update(_dt: number, game: Game) {
+    game.forEachEntityWithComponent(ComponentNames.Colliding, (entity) => {
+      if (!entity.hasComponent(ComponentNames.BoundingBox)) {
+        return;
+      }
+      const collidingBox = entity.getComponent<BoundingBox>(
+        ComponentNames.BoundingBox,
+      );
+      let collidingGrid = entity.hasComponent(ComponentNames.Grid)
+        ? entity.getComponent<Grid>(ComponentNames.Grid)
+        : null;
+
+      const collidingWith: Entity[] = [];
+      game.forEachEntityWithComponent(
+        ComponentNames.BoundingBox,
+        (otherEntity) => {
+          const otherBoundingBox = otherEntity.getComponent<BoundingBox>(
+            ComponentNames.BoundingBox,
+          );
+          let otherGrid = otherEntity.hasComponent(ComponentNames.Grid)
+            ? otherEntity.getComponent<Grid>(ComponentNames.Grid)
+            : null;
+
+          if (collidingGrid && otherGrid) {
+            if (
+              collidingGrid.gridPosition.x === otherGrid.gridPosition.x &&
+              collidingGrid.gridPosition.y === otherGrid.gridPosition.y
+            ) {
+              collidingWith.push(otherEntity);
+            }
+            return;
+          }
+
+          if (collidingBox.isCollidingWith(otherBoundingBox)) {
+            collidingWith.push(otherEntity);
+          }
+        },
+      );
+
+      for (const collision of collidingWith) {
+        this.handleCollision(entity, collision, game);
+      }
+    });
+  }
+
+  private handleCollision(entity: Entity, otherEntity: Entity, game: Game) {
+    if (!Collision.canCollide(entity.name, otherEntity.name)) {
+      return;
+    }
+
+    const keyDoorPair = [EntityNames.Key, EntityNames.LockedDoor].map((x) =>
+      [entity, otherEntity].find((y) => y.name === x),
+    );
+    const [key, door] = keyDoorPair;
+    if (key && door) {
+      this.handleKeyDoorCollision(key, door, game);
+    }
+
+    const curryPlayerPair = [EntityNames.Curry, EntityNames.Player].map((x) =>
+      [entity, otherEntity].find((y) => y.name === x),
+    );
+    const [curry, player] = curryPlayerPair;
+    if (curry && player) {
+      this.handleCurryPlayerCollision(curry, player, game);
+    }
+  }
+
+  private handleKeyDoorCollision(key: Entity, door: Entity, game: Game) {
+    game.removeEntity(key.id);
+    game.removeEntity(door.id);
+  }
+
+  private handleCurryPlayerCollision(
+    curry: Entity,
+    _player: Entity,
+    game: Game,
+  ) {
+    game.removeEntity(curry.id);
+    game.stop();
+  }
+}