#!/bin/python
from utils import parse_values

def find_bests(desired_ratio, resistors):
    # only keep the 5 best candidates
    candidates = []

    for R1 in resistors:
        for R2 in resistors:
            ratio = R2 / (R1 + R2)
            error = abs(ratio - desired_ratio)
            entry = (error, R1, R2, ratio)
            if len(candidates) < 5:
                candidates.append(entry)
                candidates.sort(key=lambda x: x[0])
            else:
                if error < candidates[-1][0]:
                    candidates[-1] = entry
                    candidates.sort(key=lambda x: x[0])

    print("Top 5 resistor pairs closest to desired ratio:\n")
    for i, (error, R1, R2, ratio) in enumerate(candidates, start=1):
        print(f"{i}. R1 = {R1} Ω, R2 = {R2} Ω  -> ratio = {ratio:.6f}, error = {error:.6e}")

def get_ratio():
    while True:
        try:
            desired_ratio = float(input("Enter desired ratio (0<ratio<=1): "))
            if 0 < desired_ratio <= 1:
                break
            else:
                print("Invalid ratio.")
        except ValueError:
            print("Invalid input.")
    return desired_ratio

def get_inputs():
    raw_input_resistors = input("Enter resistor values separated by spaces or commas: ")
    resistors = parse_values(raw_input_resistors)
    desired_ratio = get_ratio()

    return (resistors, desired_ratio)

if __name__ == '__main__':
    try:
        resistors, desired_ratio = get_inputs()
    except ValueError as e:
        print(e)
        exit(1)
    find_bests(desired_ratio, resistors)