from typing import List, Tuple
from pyspark import SparkContext
from pyspark.sql import SparkSession


commands = [
    ['read'],
    ['option', ("inferSchema", "true")],
    ['option', ("header", "true")],
    ['option', ("dateFormat", "dd/MM/yyyy H:m")],
    ['option', ("timestampFormat", "dd/MM/yyyy H:m")],
    ['csv', ("retail.csv",)]
]

context = SparkContext()
spark = SparkSession(context)
spark.conf.set("spark.sql.shuffle.partitions", "5")


def execute_commands(ss: SparkSession, pairs: List[List[str, Tuple]]):
    """
    Executes commands in a SparkSession from a command list.
    Currently assumes that the first command doesn't receive parameters.

    TODO: Other starters that are not 'read' might receive parameters.
    TODO: Other commands that are not 'option' might receive more than two parameters.
    """
    root = None

    for pair in pairs:
        if root is None:
            root = getattr(ss, pair[0])
            continue
        else:
            method = getattr(root, pair[0])
            if len(pair[1]) == 1:
                root = method(pair[1][0])
            elif len(pair[1]) == 2:
                root = method(pair[1][0], pair[1][1])
            else:
                raise ValueError("Must receive len 1 or 2")

    return root


print(execute_commands(spark, commands))