xstate_durable_entity_index.ts

import { entity } from 'durable-functions';
import { State, interpret } from 'xstate';
import { getMachine } from './machines';
import { updateEntity, waitForMachineToResolve } from '../Shared/utilities';

export default entity(async (context) => {
  let machine = getMachine(context);

  switch (context.df.operationName) {
    case 'send':
      try {
        // Initilize
        const input = context.df.getInput() as any;

        // Get previous state
        const previousState = context.df.getState(
          () => machine.initialState
        ) as typeof machine.initialState;

        // Set up machine
        const state = machine.resolveState(State.create(previousState));
        const service = interpret(machine);
        service.start(state);

        // Send action
        if (service.state.nextEvents.some(x => x == 'INITIALIZE')) {
          service.send({ type: "INITIALIZE", id: context.df.entityId.key, config: machine.config })
        }
        else {
          // Kickoff some action
          service.send(input.data)
        }

        // Wait for state to settle
        await waitForMachineToResolve(service);

        // Update local entity
        context.df.setState(service.state);

        let events = service.state.nextEvents.filter(x => x.toLowerCase().startsWith("process_") && service.nextState({ type: x, isInternalXState: true })?.changed);

        // Update remote entity
        if (service.state.context.metadata.domainEntityId) {
          await updateEntity(service.state.context.metadata.domainEntityId, JSON.stringify(service.state), JSON.stringify(machine.config), JSON.stringify(events))
        }

        service.stop();
      }
      catch (error) {
        context.log(error);
      }
      break;
    default:
      break;
  }
});