how to write Arima Equation using modeled output

I have a daily series from 3rd jan 2016 - 28 feb 2018

Below is the output of auto.arima

model <- auto.arima(ts_268001_1,xreg=reg)

model

    **Series: ts_268001_1 
    Regression with ARIMA(3,1,2)(1,0,0)[7] errors 

    Coefficients:

     ar1     ar2     ar3      ma1      ma2     sar1  promo_1  promo_2  promo_3

    -0.4655  0.5651  0.2229  -0.0372  -0.8954  -0.1261  14.2482   9.3060   4.6454

     promo_4  promo_5     Xmas

    10.9198   6.3006  31.8271


    s.e.  
     0.0496  0.0485  0.0417   0.0332   0.0308   0.0424   2.4490   2.7639   3.8073
         s.e.   1.5005   0.8855   3.5790

 sigma^2 estimated as 32.87:  
    log likelihood=-2257.83
    AIC=4541.66   
    AICc=4542.18   
    BIC=4601.1**

How to write the the equation so that I can directly use the equation to calculate the values.?

What is this "sar1"?

Where is my intercept?