#!/usr/bin/env python
# Wenchang Yang (wenchang@princeton.edu)
# Wed Sep 18 21:10:30 EDT 2019
from datetime import datetime
import os.path, sys, os
#import matplotlib.pyplot as plt
import xarray as xr, numpy as np, pandas as pd
#import geoxarray
import xaddon

expnames = ['m6p0sol_CTL1860_tigercpu_intelmpi_18_576PE',
    'p6p0sol_CTL1860_tigercpu_intelmpi_18_576PE',
    'm6p0sol_CTL1860_recover0501_tigercpu_intelmpi_18_576PE',
    'CTL1860_newdiag_tigercpu_intelmpi_18_576PE']
year_ranges = [range(101, 110+1),
    range(201, 400+1),
    range(451, 550+1),
    range(561, 590+1)]
data_name = 't_surf'
tag = 'lintrend'

def do_lintrend(expname, data_name, years):
    '''get global mean of a variable from model output'''
    ofile = f'{expname}.{data_name}.{tag}.{years[0]:04d}-{years[-1]:04d}.nc'
    if os.path.exists(ofile):
        print('[exists]:', ofile)
        return
    ifiles = [f'/tigress/wenchang/MODEL_OUT/{expname}/POSTP/{year:04d}0101.atmos_month.nc'
        for year in years]
    
    # open dataset
    with  xr.open_mfdataset(ifiles) as ds:
        da = ds[data_name]
    attrs = da.attrs # save the raw attrs
    
    # lintrend 
    da = da.groupby('time.year').mean('time')
    ds_rg = da.linregress.on(da.year, dim='year')
    
    # save to netcdf
    encoding = None#{data_name_new: {'zlib': True, 'complevel': 1}}
    ds_rg.to_netcdf(ofile, encoding=encoding)
    print('[saved]:', ofile)

if __name__ == '__main__':
    # record the start time
    tformat = '%Y-%m-%d %H:%M:%S'
    t0 = datetime.now()
    print('[time start]:', t0.strftime(tformat))

    for expname in expnames[0:1]:
        for years in year_ranges:
            print(expname, data_name, tag)
            do_linregress(expname, data_name, years)

    # the end
    t1 = datetime.now()
    dt = t1 - t0
    print('[time end]:', t1.strftime(tformat))
    print('[time used]:', f'{dt.seconds:,} seconds')