import talib
import numpy as np
def init(context):
    # context内引入全局变量s1
    context.s1 = get_dominant_future('J')#自制主力连续
   # 初始化context.last_main_symbol
    context.last_main_symbol = context.s1
    # 将判断主力是否更新的flag初始设置为False
    context.main_changed = False
    subscribe(context.s1)
    
    context.bollLen = 50 #布林通道参数
    context.Offset = 1.25 #布林通道参数
    context.rocCalLen = 30 #过滤器参数
    context.liqLen = 50 #自适应出场均线参数
    context.liqDays = context.liqLen
def before_trading(context): #每天开盘前判断主力合约是否更新。
    context.s1 = get_dominant_future('J')
    if context.last_main_symbol != context.s1:
        subscribe(context.s1)
        # 如果更新了，设置main_changed这个flag为True
        context.main_changed = True

def handle_bar(context, bar_dict):
    sell_qty = context.portfolio.positions[context.s1].sell_quantity
    buy_qty = context.portfolio.positions[context.s1].buy_quantity

    # 检测当前主力合约，如果发生变化，先对原有合约平仓
    if context.main_changed:
        # 主力合约发变化，平仓
        print ('Symbol Changed! before:', context.last_main_symbol, 'after: ', context.s1, context.now)
        # 空单平仓
        if context.portfolio.positions[context.last_main_symbol].sell_quantity !=0:
            buy_close(context.last_main_symbol,1)
            print ('close short:', context.now)
        # 多头平仓
        if context.portfolio.positions[context.last_main_symbol].buy_quantity!= 0:
            sell_close(context.last_main_symbol,1)
            print ('close long', context.now)
        context.main_changed = False
        context.last_main_symbol = context.s1
    
    close = history_bars(context.s1,context.bollLen+1,'1d','close')
    high = history_bars(context.s1,context.bollLen+1, '1d','high')
    low = history_bars(context.s1,context.bollLen+1,'1d','low')
    
    #布林通道中轨
    MidLine = talib.SMA(close,context.bollLen)
    Band = np.std(close[-context.bollLen:],ddof = 1) #计算样本方差
    #布林上下轨
    UpBand = MidLine + context.Offset*Band
    DnBand = MidLine - context.Offset*Band
    plot('MidLine',MidLine[-1])
    plot('UpBand',UpBand[-1])
    plot('DnBand',DnBand[-1])
    #进场过滤器
    rocCalc = close - close[-context.rocCalLen]
    
    #多头
    #开仓：满足过滤条件，并且价格突破布林通道上轨
    if sell_qty == 0 and buy_qty == 0:
        #设置自适应出场均线
        context.liqDays = context.liqLen
        if rocCalc[-1] > 0 and bar_dict[context.s1].high >= UpBand[-1]:
            buy_open(context.s1,1)
    else:        
        context.liqDays = context.liqDays -1
        context.liqDays = max(context.liqDays, 10)
    #自适应均线   
    liqPoint = talib.SMA(close,context.liqDays)    
    plot('liqPoint',liqPoint[-1])

    #平仓：当自适应出场均线低于布林通道上轨，并且价格下破自适应出场均线
    if buy_qty!=0 and liqPoint[-1] < UpBand[-1] and bar_dict[context.s1].low < liqPoint[-1]:
        sell_close(context.s1,1)
    
    #空头
    #开仓：满足过滤条件，并且价格突破布林通道下轨
    if sell_qty == 0 and buy_qty == 0:
        if rocCalc[-1] < 0 and bar_dict[context.s1].low <= DnBand[-1]:
            sell_open(context.s1,1)
    #平仓：当自适应出场均线高于布林通道下轨，并且价格上破自适应出场均线
    if sell_qty!=0 and liqPoint[-1] > DnBand[-1] and bar_dict[context.s1].high > liqPoint[-1]:
        buy_close(context.s1,1)