python-创建绩效月函数

""" 
绩效月：上个月20号-本月19号
给定一个日期，输入其所在的绩效月
"""
def performance_month(date):
    
    # 提取年
    year = date[0:4]
    # 提取月
    month = date[5:7]
    # 提取日
    day = date[8:10]
    
    # 判断和拼接
    # 对12月和1月单独拎出来判断
    if(int(month)==12):
        
        if(int(day)>= 20):
            month = int(month)
            month = 1        
            performance_date = year +'-' + '12' +'-' +'20'+'~'+ str(int(year)+1) +'-' +'0'+ str(month) +'-' + '19'
        else:
            performance_date = year +'-' + str(int(month)-1)+'-' + '20' +'~'+ year +'-' + month +'-' +'19'
            
    elif(int(month)==1):
        
        if(int(day)<20):
            month = int(month)
            month = 12 
            performance_date = str(int(year)-1) +'-' + str(month) +'-' + '20' +'~'+ year +'-' + '01' +'-'+'19'
        else :
            performance_date = year +'-' + month +'-' +'20'+'~'+ year +'-' +'0'+ str(int(month)+1) +'-' + '19'
            
    # 普适情况
    elif(int(day) >= 20):
        if(int(month)<=8):
            performance_date = year +'-' + month +'-' +'20'+'~'+ year +'-' +'0'+ str(int(month)+1) +'-' + '19'
        else :
            performance_date = year +'-' + month +'-' +'20'+'~'+ year +'-' + str(int(month)+1) +'-' + '19'
    elif(int(day)<20) :
        if(int(month)<=10):
            performance_date = year +'-'   +'0'+str(int(month)-1)+'-' + '20' +'~'+ year +'-' + month +'-' +'19'
        else :
            performance_date = year +'-'   +str(int(month)-1)+'-' + '20' +'~'+ year +'-' + month +'-' +'19'
        
        
    
    return performance_date