import sys

from matplotlib import pyplot as plt
from numint.riemann_sum import numint_epsilon
from numint.input_parser import parse_function, parse_value


def plot_cli(function_expr:str, start:str, end:str, epsilon: str):
    f = parse_function(function_expr)

    (a, b) = (parse_value(start), parse_value(end))
    eps = parse_value(epsilon)
    (x, y, l, r, n) = numint_epsilon(f, a, b, eps)
    fig, ax = plt.subplots()
    ax.stairs(y[1:], x, baseline=0, fill=True, alpha=1,label=function_expr)
    ax.stairs(y[0:-1], x, baseline=0, fill=True, color="orange", alpha=0.5, label=function_expr)
    #ax.step(x, y, label=function_expr)
    #ax.step(x, y, where="post", label=function_expr)

    ax.plot(x, y, color="black")

    plt.show()
    pass


def main():
    function_expr = sys.argv[1]
    start = sys.argv[2]
    end = sys.argv[3]
    eps = sys.argv[4]
    plot_cli(function_expr, start, end, eps)


if __name__ == "__main__":
    main()