import random

from matplotlib import pyplot as plot
import numpy as np

def calc_p(U0, Ri, Rl):
	I = U0 / (Ri + Rl)
	Ul = I * Rl
	P = Ul * I

	return P


U0 = 10
Ri = 3.14
Rl_min = 0.1
Rl_max = 10.
Rl_step_start = 1
Rl_step_stop = 0.01

Rl = np.linspace(Rl_min, Rl_max, 100, dtype=float)

# --------------------------------------------------
# MPPT search
Rl_s = np.random.uniform()*(Rl_max - Rl_min) + Rl_min
Rl_step = Rl_step_start
dir = "inc"
dir_last = dir
while Rl_step > Rl_step_stop:
	p0 = calc_p(U0, Ri, Rl_s)
	p1 = p0
	if "inc" in dir:
		Rl_s = min(Rl_max, Rl_s + Rl_step)
		p1 = calc_p(U0, Ri, Rl_s)
		if p0 > p1:
			if 'inc' in dir_last:
				Rl_step /= 2
			dir = 'dec'

	elif "dec" in dir:
		Rl_s = max(Rl_min, Rl_s - Rl_step)
		p1 = calc_p(U0, Ri, Rl_s)
		if p0 > p1:
			if 'dec' in dir_last:
				Rl_step /= 2
			dir = 'inc'

	dir_last = dir
	print(f"p1 = {p1}, Rl_s = {Rl_s}, Rl_step {Rl_step}")

# --------------------------------------------------

P = calc_p(U0, Ri, Rl)
plot.plot(Rl, P)

plot.ylabel("Power [W]")
plot.xlabel("RL [Ohms]")
plot.title("Power vs RL")
plot.legend("RL [Ohms]")
plot.grid()
plot.show()