# 默认参数
k1, k2, k3, k4, k5, k6 = (0.03691591, -0.01086697, -0.02207111, -0.04971315, -0.06927802, -0.00682166)
density = 2.7*(10**-6)
inner_radius = 665
list_fan_type = ['自然冷却', '单个大风机', '单4风机', '大风机+单4风机', '双4风机']
format_time = r'%Y-%m-%d %H:%M'

# 函数
def fun_z5(fan_type, list_fan_type=list_fan_type):
    for i, j in enumerate(list_fan_type):
        i += 1
        if i > 1:
            exec("z{} = 0".format(i), globals())
            if fan_type == j:
                exec("z{} = 1")
    return z2, z3, z4, z5

def fun_z6(width, weight, density=density, inner_radius=inner_radius):
    outer_radius = np.sqrt(
        weight/density/width/np.pi + inner_radius**2
    )
    surface_area = 2 * np.pi * (
        outer_radius*width + inner_radius*width + outer_radius**2 - inner_radius**2
    ) / 10**6
    z6 = surface_area / weight * 10**4
    return z6

def fun_k():
    k = k1 + np.dot([k2, k3, k4, k5, k6], [z2, z3, z4, z5, z6])
    return k

def fun_x(time):
    x = (pd.Timestamp(time) - pd.Timestamp(initial_time)).total_seconds() / 3600
    return x

def fun_Y(x):
    Y = (initial_temp-ambient_temp) * np.exp(k*x) + ambient_temp
    return Y

def fun_Y_x(Y):
    x = k**(-1) * np.log((Y-ambient_temp) / (initial_temp-ambient_temp))
    time = (pd.Timestamp(initial_time) + pd.Timedelta(seconds=x*3600)).strftime(format_time)
    return x, time

# 自动换算
z2, z3, z4, z5 = fun_z5(fan_type)
z6 = fun_z6(width, weight)
k = fun_k()

a = init_temp
b = ambi_temp