webeditor3d/src/commands/upsert-model-instance-command.ts

import { createOpaqueId } from "../core/ids";
import { cloneEditorSelection, type EditorSelection } from "../core/selection";
import type { ToolMode } from "../core/tool-mode";
import { cloneModelInstance, getModelInstanceKindLabel, type ModelInstance } from "../assets/model-instances";
import { getProjectAssetKindLabel } from "../assets/project-assets";

import type { EditorCommand } from "./command";

interface UpsertModelInstanceCommandOptions {
  modelInstance: ModelInstance;
  label?: string;
}

function setSingleModelInstanceSelection(modelInstanceId: string): EditorSelection {
  return {
    kind: "modelInstances",
    ids: [modelInstanceId]
  };
}

function createDefaultModelInstanceCommandLabel(isNewModelInstance: boolean): string {
  const action = isNewModelInstance ? "Place" : "Update";
  return `${action} ${getModelInstanceKindLabel().toLowerCase()}`;
}

export function createUpsertModelInstanceCommand(options: UpsertModelInstanceCommandOptions): EditorCommand {
  const nextModelInstance = cloneModelInstance(options.modelInstance);
  let previousModelInstance: ModelInstance | null = null;
  let previousSelection: EditorSelection | null = null;
  let previousToolMode: ToolMode | null = null;

  return {
    id: createOpaqueId("command"),
    label: options.label ?? createDefaultModelInstanceCommandLabel(true),
    execute(context) {
      const currentDocument = context.getDocument();
      const currentAsset = currentDocument.assets[nextModelInstance.assetId];

      if (currentAsset === undefined) {
        throw new Error(`Model instance ${nextModelInstance.id} cannot reference missing asset ${nextModelInstance.assetId}.`);
      }

      if (currentAsset.kind !== "model") {
        throw new Error(`Model instance ${nextModelInstance.id} must reference a model asset, not ${getProjectAssetKindLabel(currentAsset.kind).toLowerCase()}.`);
      }

      const currentModelInstance = currentDocument.modelInstances[nextModelInstance.id];

      if (previousSelection === null) {
        previousSelection = cloneEditorSelection(context.getSelection());
      }

      if (previousToolMode === null) {
        previousToolMode = context.getToolMode();
      }

      if (previousModelInstance === null && currentModelInstance !== undefined) {
        previousModelInstance = cloneModelInstance(currentModelInstance);
      }

      context.setDocument({
        ...currentDocument,
        modelInstances: {
          ...currentDocument.modelInstances,
          [nextModelInstance.id]: cloneModelInstance(nextModelInstance)
        }
      });
      context.setSelection(setSingleModelInstanceSelection(nextModelInstance.id));
      context.setToolMode("select");
    },
    undo(context) {
      const currentDocument = context.getDocument();
      const nextModelInstances = {
        ...currentDocument.modelInstances
      };

      if (previousModelInstance === null) {
        delete nextModelInstances[nextModelInstance.id];
      } else {
        nextModelInstances[nextModelInstance.id] = cloneModelInstance(previousModelInstance);
      }

      context.setDocument({
        ...currentDocument,
        modelInstances: nextModelInstances
      });

      if (previousSelection !== null) {
        context.setSelection(previousSelection);
      }

      if (previousToolMode !== null) {
        context.setToolMode(previousToolMode);
      }
    }
  };
}