Add player start entity command and related changes

src/commands/set-player-start-command.ts

@@ -0,0 +1,82 @@
+import type { EditorSelection } from "../core/selection";
+import type { Vec3 } from "../core/vector";
+import { createOpaqueId } from "../core/ids";
+import { createPlayerStartEntity } from "../entities/entity-instances";
+
+import type { EditorCommand } from "./command";
+
+interface SetPlayerStartCommandOptions {
+  entityId?: string;
+  position: Vec3;
+  yawDegrees: number;
+}
+
+function setSinglePlayerStartSelection(entityId: string): EditorSelection {
+  return {
+    kind: "entities",
+    ids: [entityId]
+  };
+}
+
+export function createSetPlayerStartCommand(options: SetPlayerStartCommandOptions): EditorCommand {
+  const nextEntity = createPlayerStartEntity({
+    id: options.entityId,
+    position: options.position,
+    yawDegrees: options.yawDegrees
+  });
+
+  let previousEntity = null as typeof nextEntity | null;
+  let previousSelection: EditorSelection | null = null;
+
+  return {
+    id: createOpaqueId("command"),
+    label: options.entityId === undefined ? "Place player start" : "Move player start",
+    execute(context) {
+      const currentDocument = context.getDocument();
+      const currentEntity = currentDocument.entities[nextEntity.id];
+
+      if (currentEntity !== undefined && currentEntity.kind !== "playerStart") {
+        throw new Error(`Entity ${nextEntity.id} is not a player start.`);
+      }
+
+      if (previousSelection === null) {
+        previousSelection = context.getSelection().kind === "none" ? { kind: "none" } : structuredClone(context.getSelection());
+      }
+
+      if (previousEntity === null && currentEntity !== undefined) {
+        previousEntity = currentEntity;
+      }
+
+      context.setDocument({
+        ...currentDocument,
+        entities: {
+          ...currentDocument.entities,
+          [nextEntity.id]: nextEntity
+        }
+      });
+      context.setSelection(setSinglePlayerStartSelection(nextEntity.id));
+      context.setToolMode("select");
+    },
+    undo(context) {
+      const currentDocument = context.getDocument();
+      const nextEntities = {
+        ...currentDocument.entities
+      };
+
+      if (previousEntity === null) {
+        delete nextEntities[nextEntity.id];
+      } else {
+        nextEntities[nextEntity.id] = previousEntity;
+      }
+
+      context.setDocument({
+        ...currentDocument,
+        entities: nextEntities
+      });
+
+      if (previousSelection !== null) {
+        context.setSelection(previousSelection);
+      }
+    }
+  };
+}