import math

"""
Energy - General functions
"""
multipliers = {
    'Y': 1e24,
    'Z': 1e21,
    'E': 1e18,
    'P': 1e15,
    'T': 1e12,
    'G': 1e9,
    'M': 1e6,
    'K': 1e3,
    'x': 1.0,
    'm': 1e-3,
    'u': 1e-6,
    'n': 1e-9,
    'p': 1e-12,
    'f': 1e-15,
    'a': 1e-18,
    'z': 1e-21,
    'y': 1e-24,
}

mult_pow = {
    24: 'Y',
    21: 'Z',
    18: 'E',
    15: 'P',
    12: 'T',
    9: 'G',
    6: 'M',
    3: 'K',
    0: '',
    -3: 'm',
    -6: 'u',
    -9: 'n',
    -12: 'p',
    -15: 'f',
    -18: 'a',
    -21: 'z',
    -24: 'y',
}

def float_to_str(value, round_val=None, omit_dot_zero=False):
    sign = ''

    if value < 0:
        sign = '-'
        value = -1 * value

    target_mult = 0

    if value == 0:
        return "0"

    elif value < 1:
        while value < 1:
            target_mult -= 3
            value = value * 1000.0
    else:
        while value >= 1000:
            target_mult += 3
            value = value / 1000.0

    if round_val is not None:
        value = round(value, round_val)

    if omit_dot_zero and value.is_integer():
        value = int(value)

    return f"{sign}{value}{mult_pow[target_mult]}"

def str_to_float(value):
    """
    Converts a string to a float, accounting for unit multipliers such as M/k/m/u
    """
    multiplier = str(value)[-1]

    # account for multiplier
    if multiplier in multipliers:
        number = float(value[:-1])
        multiplier = float(multipliers[multiplier])
        value = number * multiplier

    return float(value)

def str_to_int(value):
    """
    Converts a string to an int, accounting for unit multipliers such as M/k/m/u
    """
    float_value = str_to_float(value)

    return int(float_value)

def str_add_vals(val1, val2):
    """
    Adds two values in str representation
    :param val1: first value (with unit multipliers)
    :param val2: second value (with unit multipliers)
    :return: the sum in textual representation (with unit multipliers)
    """
    mul1 = str(val1[-1])
    mul2 = str(val2[-1])

    if mul1 not in multipliers:
        val1 = f"{val1}x"
        mul1 = "x"

    if mul2 not in multipliers:
        val2 = f"{val2}x"
        mul2 = "x"

    # equal multiplier -> sum vals
    if mul1 == mul2:
        number = float(val1[:-1]) + float(val2[:-1])

    else:
        # Invert numbers so that mul1 < mul2
        if multipliers[mul1] > multipliers[mul2]:
            mul1, mul2 = mul2, mul1
            val1, val2 = val2, val1

        # mul1 < mul2 -> calculate multiplication ratio
        ratio = multipliers[mul2]/multipliers[mul1]
        number = float(val1[:-1]) + float(val2[:-1]) * ratio

    if '.' not in str(val1) and '.' not in str(val2):
        number = int(number)

    return f"{number}{mul1 if mul1 != 'x' else ''}"


def energy_from_I_t(V, I, t):
    """
    Calculates the energy consumption in the time interval t
    :param V: voltage
    :param I: current draw
    :param t: time interval
    """
    return float(V) * float(I) * float(t)

def energy_from_R_t(V, R, t):
    """
    Calculates the energy consumption in the time interval t
    :param V: voltage
    :param R: resistance
    :param t: time interval
    """
    return float(V) * (float(V) / float(R)) * float(t)

def energy_from_I_f(V, I, f):
    """
    Calculates the energy consumption of a clock cycle with frequency f
    :param V: voltage
    :param I: current draw
    :param f: clock frequency
    """
    return float(V) * float(I) / float(f)

def energy_from_R_f(V, R, f):
    """
    Calculates the energy consumption of a clock cycle with frequency f
    :param V: voltage
    :param R: resistance
    :param f: clock frequency
    """
    return float(V) * (float(V) / float(R) ) / float(f)

def equivalent_resistance(V, I):
    """
    Calculates the equivalent resistance of a given voltage and current draw
    :param V: Voltage (V)
    :param I: Current Draw (A)
    """
    i = str_to_float(I)
    v = str_to_float(V)
    r = v / i

    return r

def R_from_energy_t(V, e, t):
    """
    Calculates the instantaneous equivalent resistance given the energy consumption in an instant t under the voltage V
    :param V: Voltage (V)
    :param e: energy consumed in t
    :param t: time interval
    :return: the equivalent resistance
    """
    # e = V * I * t -> I = e / (V * t)
    # V = R * I -> R = V / I
    # R = V / (e / (V * t)) = V * V * t / e
    if e == 0.0:
        return float('inf')

    r = (V * V * t) / e
    return r

def R_from_parallel_r(R1, R2):
    """
    Calculates the equivalent resistance of two parallel resistors
    :param R1: resistor 1
    :param R2: resistor 2
    :return: the equivalent resistance
    """
    if R1 == 0.0:
        return R2
    elif R2 == 0.0:
        return R1

    return 1.0 / (1.0 / R1 + 1.0 / R2)

def P_R_to_V(P, R):
    """
    Calculates the voltage from instantaneous power and equivalent resistance
    :param P: power
    :param R: resistance
    """
    # P = I * V
    # V = R * I; I = V / R;
    # P = (V * V) / R
    # V = SQRT(P * R)

    return math.sqrt(P*R)