import { useMachine as useXStateMachine } from '@xstate/react';

const getStateStat = (state: any): string => {
    if (typeof state === 'string') {
        return state;
    }

    if (Object.keys(state).length > 1) {
        throw new Error('useMachine does not support emitting stats for parallel states');
    }

    const key = Object.keys(state)[0];

    return `${key}.${getStateStat(state[key])}`;
};

const sendTransitionStat = (state: any, machineId: string) => {
    const metric = `machines.${machineId}.${getStateStat(state.value)}`;

    const tags = state.history ? { fromState: getStateStat(state.history.value) } : undefined;

    stats.sendStats({
        metric,
        method: StatsMethod.INCREMENT,
        tags,
    });
};

const getStateAnalytics = (state: any): string => {
    if (typeof state === 'string') {
        return state;
    }

    if (Object.keys(state).length > 1) {
        throw new Error('useMachine does not support emitting stats for parallel states');
    }

    const key = Object.keys(state)[0];

    return `${key}.${getStateAnalytics(state[key])}`;
};

const sendAnalyticsOnTransition = () => {
  analytics.send('STATECHARTS_ANALYTICS_EVENT', {
        fromState: getStateAnalytics(get(state, 'history.value', '')),
        currentState: getStateAnalytics(get(state, 'value', '')),
        machineName: machine.id,
    });
};

export const useMachine = (machine, options) => {
  const { statOnTransition, analyticsOnTransition, ...rest } = options;

  const [current, send, service] = useMachine(machine, options);
  
  useEffect(() => {
    service.onTransition(state => {
        if (state.changed) {
            if (statOnTransition) {
                sendTransitionStat(state, machine.id);
            }
          
            if (analyticsOnTransition) {
                sendAnalyticsOnTransition(state, machine.id);
            }
        }
    });
  }, []);
  
  return [current, send, service];
};