#!/usr/bin/env python
# -*- coding: utf-8 -*-
# written by Christoph Federrath

from cfpack.defaults import *
import argparse
import numpy as np
import timeit

# sum up numbers in list n using np.sum()
def sum_np(n):
    sum = np.sum(n)
    return sum

# sum up numbers in list n using a loop
def sum_loop(n):
    sum = 0
    for i in range(len(n)):
        sum += n[i]
    return sum

# loop using Numba
import numba
@numba.jit(nopython=True)
def sum_loop_jit(n):
    sum = 0
    for i in range(len(n)):
        sum += n[i]
    return sum

# ===== the following applies in case we are running this in script mode =====
if __name__ == "__main__":

    parser = argparse.ArgumentParser(description='Sum numbers from 1 to n.')
    parser.add_argument("-n", "--n", type=float, help="Number n", default=1e8)
    parser.add_argument("-m", "--method", choices=['numpy', 'loop', 'numba'], default='numpy',
                        help="The summation method to be used")

    args = parser.parse_args()

    # cast float n to int
    int_n = int(args.n)

    # print
    print("Summing all integers from 1 to "+str(int_n)+"...")

    # define array with numbers (for np.sum() below)
    numbers = np.arange(int_n)+1

    # start the timer
    start_time = timeit.default_timer()

    if args.method == 'numpy':
        print("...using numpy.sum()...")
        sum = sum_np(numbers)

    if args.method == 'loop':
        print("...using loop...")
        sum = sum_loop(numbers)

    if args.method == 'numba':
        print("...using loop with numba.jit...")
        sum = sum_loop_jit(numbers)

    # stop the timer
    end_time = timeit.default_timer()

    # print the sum to stdout
    print("Sum = "+str(sum))

    # print the time it took
    print("Run time = "+str(end_time-start_time)+" s")