Envelopes Support / Resistance [ESR]

Summary:
This trading system script uses Envelope indicators to generate trading signals whenever an underlying indicator touches the envelopes.

Rules:
1. Buy Market - When the underlying indicator touces the lower envelope.
2. Sell Market - When the underlying indicator touches the upper envelope.
3. Sell Short Market - When the underlying indicator touches the upper envelope.
4. Buy To Cover Market - When the underlying indicator touches the lower envelope.

	 ' Assign the script parameters to script variables.
	_hitDistance = hitDistance
	_enableShorting = enableShorting
	_stopLoss = stopLoss
	_takeProfit = takeProfit
	_trailingStop = trailingStop
	_isPercent = isPercent

	 ' Use for holding the specified indicator keys, indexed by symbol index.
	Redefine _indicatorKeys(SymbolCount() - 1)
	 ' Use for holding the ENVL indicator keys based on the specified indicator key, indexed by symbol index.
	Redefine _ENVLKeys(SymbolCount() - 1)
	 ' Use for holding the ENVU indicator keys based on the specified indicator key, indexed by symbol index.
	Redefine _ENVUKeys(SymbolCount() - 1)

	 ' Iterate over all of the account symbols.
	For i As Integer = 0 To SymbolCount() - 1
		 ' Create an indicator for each account symbol, based on the specified indicator.
		_indicatorKeys(i) = IndicatorCopy(indicatorKey, i)
		 ' Create a ENVL indicator for each account symbol, based on the specified indicator.
		_ENVLKeys(i) = IndicatorENVL(_indicatorKeys(i),percentage, periods, firstPeriods)
		 ' Create a ENVU indicator for each account symbol, based on the specified indicator.
		_ENVUKeys(i) = IndicatorENVU(_indicatorKeys(i),percentage, periods, firstPeriods)
		 ' Add the indicators to the symbol chart.
		ChartIndicator(i, 0, C_MERGE_RIGHT, _indicatorKeys(i),C_LINE, 1,0)
		ChartIndicator(i, 0, C_MERGE_RIGHT, _ENVLKeys(i),C_LINE, 1,1)
		ChartIndicator(i, 0, C_MERGE_RIGHT, _ENVUKeys(i),C_LINE, 1,1)
	Next

	 ' Get the indicator value for the specified symbol index.
	Define value As Number = IndicatorValue(_indicatorKeys(symbolIndex))
	 ' Get the ENVL indicator value for the specified symbol index.
	Define ENVL As Number = IndicatorValue(_ENVLKeys(symbolIndex))
	 ' Get the ENVU indicator value for the specified symbol index.
	Define ENVU As Number = IndicatorValue(_ENVUKeys(symbolIndex))
	 ' Calculate the percentage distance between the BBL and the underlying indicator.
	Define ENVLDistance As Number = 100 * (value - ENVL) / ENVL
	 ' Calculate the percentage distance between the BBU and the underlying indicator.
	Define ENVUDistance As Number = 100 * (ENVU - value) / value
	 ' If the indicator value is near the lower band.
	If (ENVLDistance > 0 And ENVLDistance < _hitDistance) Then
		 ' If a short position exists then generate a buy to cover order.
		If (_enableShorting And PositionExists(C_OPEN, symbolIndex, C_SHORT)) Then
			 ' Generate a buy to cover market order.
			BrokerMarket(C_BUY_TO_COVER,symbolIndex, 0, C_GTC, "Near lower envelope.")
		End If
		 ' If no long open positions exist.
		If (Not PositionExists(C_OPEN, symbolIndex, C_LONG))
			 ' Generate a buy market order.
			Define orderIndex As Number = BrokerMarket(C_BUY,symbolIndex, 0, C_GTC, "Near lower envelope.")
			 ' Set a stop loss on the order.
			BrokerSetStopLossPercent(orderIndex, _stopLoss, True)
			 ' Set a take profit on the order.
			BrokerSetTakeProfitPercent(orderIndex, _takeProfit, True)
			 ' Set a trailing stop loss on the order.
			BrokerSetTrailingStopLoss(orderIndex, _isPercent, _trailingStop)
		End If
	 ' If the indicator value is near the upper band.
	ElseIf (ENVUDistance > 0 And ENVUDistance < _hitDistance) Then
		 ' If a long open position exists.
		If (PositionExists(C_OPEN, symbolIndex, C_LONG))
			 ' Generate a sell market order.
			BrokerMarket(C_SELL,symbolIndex, 0, C_GTC, "Near upper envelope.")
		End If
		 ' If no short open positions exist.
		If (_enableShorting And Not PositionExists(C_OPEN, symbolIndex, C_SHORT)) Then
			 ' Generate a sell short market order.
			Define orderIndex As Number = BrokerMarket(C_SELL_SHORT,symbolIndex, 0, C_GTC, "Near upper envelope.")
			 ' Set a stop loss on the order.
			BrokerSetStopLossPercent(orderIndex, _stopLoss, True)
			 ' Set a take profit on the order.
			BrokerSetTakeProfitPercent(orderIndex, _takeProfit, True)
			 ' Set a trailing stop loss on the order.
			BrokerSetTrailingStopLoss(orderIndex, _isPercent, _trailingStop)
		End If
	End If