import { textOf } from '../../../model/Properties';
import { flatDef } from '../../../properties/PropertySchema';
import type { NodeDef } from '../../NodeRegistry';
import { currentState, setState } from '../../sharedState';
import { machinePort, STATE_TRANSITION, TRANSITION_PARAM, transitionTo } from '../../stateMachine';
import { asString } from '../../values';
import { exec } from '../shared';

/** What the transitions drawn in the machine are for at runtime: one step along a named arrow. */
export const StateTransition: NodeDef = {
  type: STATE_TRANSITION,
  label: 'State transition',
  category: 'action',
  description:
    "Takes the transition of this name out of the machine's current state, then continues. " +
    'Nothing happens when that state has no transition of the name.',
  inputs: [exec(), machinePort()],
  outputs: [exec()],
  params: [flatDef(TRANSITION_PARAM, 'text', { label: 'Transition', value: '' })],
  run: (ctx, inputs, params, _def, _entry, lookup) => {
    const id = asString(inputs.machine);
    const current = currentState(ctx, id);
    const machine = current ? lookup.machine(id) : null;
    const name = textOf(params[TRANSITION_PARAM] ?? '');
    const target = machine ? transitionTo(machine, current, name) : '';
    if (target) setState(ctx, id, target, true);
    return { next: 'exec' };
  },
};