Function createMachine

client-src/overlay.js:119–148

* A simplified `createMachine` from `@xstate/fsm` with the following differences: * - the returned machine is technically a "service". No `interpret(machine).start()` is needed. * - the state definition only support `on` and target must be declared with { target: 'nextState', actions: [] } explici

({ states, context, initial }, { actions })

 * @returns {StateMachine} state machine
 */
function createMachine({ states, context, initial }, { actions }) {
  let currentState = initial;
  let currentContext = context;

  return {
    send: (event) => {
      const currentStateOn = states[currentState].on;
      const transitionConfig = currentStateOn && currentStateOn[event.type];

      if (transitionConfig) {
        currentState = transitionConfig.target;
        if (transitionConfig.actions) {
          transitionConfig.actions.forEach((actName) => {
            const actionImpl = actions[actName];

            const nextContextValue =
              actionImpl && actionImpl(currentContext, event);

            if (nextContextValue) {
              currentContext = {
                ...currentContext,
                ...nextContextValue,
              };
            }
          });
        }
      }
    },
  };
}

/**
 * @typedef {object} ShowOverlayData