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machine.js

  // Available variables:
  // - Machine
  // - interpret
  // - assign
  // - send
  // - sendParent
  // - spawn
  // - raise
  // - actions
  // - XState (all XState exports)
  
  const fetchMachine = Machine({
    id: 'test',
    initial: 'idle',
    context: {
      H: 0,
      L: 0,
      trend: 0,
      direction: '',
    },
    states: {
      idle: {
        exit: ['saveCandle', 'showInfo'],
        on: {
          CANDLE: [
            {
              target: 'trendingUp',
              cond: 'isGoingUp',
              actions: ['incUptrend']
            },
            {
              target: 'trendingDown',
              cond: 'isGoingDown',
              actions: ['incDowntrend']
            },
            {
              target: 'idle',
              actions: ['resetTrend']
            },
          ]
        }
      },
      trendingUp: {
        on: {
          '': [
            { target: 'trend', cond: 'triedEnough' },
            { target: 'idle' }
          ]
        }
      },
      trendingDown: {
        on: {
          '': [
            { target: 'trend', cond: 'triedEnough' },
            { target: 'idle' }
          ]
        }
      },
      trend: {
        entry: ['emitTrend'], // emit start of trend
        exit: ['emitTrend', 'showInfo'], // should be 'STOP' after the 'resetTrend' action
        on: {
          CANDLE: [
            {
              target: 'idle',
              cond: 'isNotSameEvent',
              actions: ['resetTrend', 'saveCandle'],
            },
            {
              // actions: ['saveCandle', 'emitTrend'], // re-emit the trend signal each time (in case it was missed by trade machine)
              actions: ['saveCandle'],
            }
          ]
        }
      },
    }
  },
  {
    actions: {
      saveCandle: assign(
        {
          H: (ctx, event) => event.H,
          L: (ctx, event) => event.L
        }
      ),
      incUptrend: assign(
        {
          trend: ctx => {
            if (ctx.direction === 'bullish') {
              return ctx.trend + 1
            } else {
              return 1
            }
          },
          direction: 'bullish'
        }
      ),
      incDowntrend: assign(
        {
          trend: ctx => {
            if (ctx.direction === 'bearish') {
              return ctx.trend + 1
            } else {
              return 1
            }
          },
          direction: 'bearish'
        }
      ),
      resetTrend: assign(
        {
          trend: (ctx, event) => {
            if ((event.H > ctx.H && event.L > ctx.L) || (event.H < ctx.H && event.L < ctx.L)) {
              return 1
            } else {
              return 0
            }
          },
          direction: (ctx, event) => {
            if (event.H > ctx.H && event.L > ctx.L) {
              return 'bullish'
            } else if (event.H < ctx.H && event.L < ctx.L) {
              return 'bearish'
            } else {
              return 'STOP'
            }
          }
        }
      ),
      emitTrend: (ctx, event) => {
        console.log(`* * * TREND: ${ctx.direction}`)
      },
      showInfo: (context, event) => {
        console.log(`🚦[THREECANDLE FSM] event: ${event.type} H:${event.H} L:${event.L}`)
      },
    },
    guards: {
      triedEnough: ctx => (ctx.trend > 2),
      isNotDowntrend: ctx => (ctx.direction !== 'bearish'),
      isNotUptrend: ctx => (ctx.direction !== 'bullish'),
      isGoingUp: (ctx, event) => {
        return ctx.H && ctx.L && event.H > ctx.H && event.L > ctx.L
      },
      isGoingDown: (ctx, event) => {
        return ctx.H && ctx.L && event.H < ctx.H && event.L < ctx.L
      },
      isNotSameEvent: (ctx, event) => { 
        return ((ctx.direction === 'bullish' && event.H > ctx.H && event.L > ctx.L) || (ctx.direction === 'bearish' && event.H < ctx.H && event.L < ctx.L)) ? false : true
      },
    }
  })