# -*- coding: UTF-8 -*-
# Python
"""
04-07-2023
@author: jeremy auclair

Calculate NDVI images with xarray
"""

import os  # for path exploration
import csv  # open csv files
from typing import List, Union  # to declare variables
import xarray as xr  # to manage dataset
import dask.array as da  # dask xarray
from dask.distributed import Client, LocalCluster  # to parallelise calculations


def calculate_ndvi(download_path: Union[List[str], str]) -> str:
    
    # Start local cluster client
    client = Client()
    client
    
    # If a file name is provided instead of a list of paths, load the csv file that contains the list of paths
    if type(download_path) == str:
        with open(download_path, 'r') as file:
            download_path = []
            csvreader = csv.reader(file, delimiter='\n')
            for row in csvreader:
                download_path.append(row[0])
    
    products = xr.open_mfdataset(download_path, parallel = True) #, chunks = {'latitude': 100, 'longitude': 100})
    
    
    
    ndvi_cube_path =''
    
    return ndvi_cube_path