import math


with open("tora.txt", encoding="utf-8") as f:
    text = list(f.read().lower())

    #############################################################
    #  Alphabet intializing

    textLen = len(text)
    print("Длина текста:", textLen)
    symbols = {}

    for t in text:
        if t in symbols:
            symbols[t] += 1
        else:
            symbols[t] = 1

    alphabet = list(symbols.keys())

    # print("алфавит:", alphabet)
    print("Мощность алфавита:", len(alphabet))

    probabilities = {}

    for k, v in symbols.items():
        probabilities[k] = v/textLen

    # print(probabilities)

    #############################################################
    # H0 counting

    h0 = 0
    for k, v in probabilities.items():
        h0 += v * math.log(v,2)
    h0 *= -1

    print("H0:", h0)

    #############################################################
    # H1 counting

    pairs = list(zip(text[:-1], text[1:]))

    pairCounts = {}

    for p in pairs:
        if p in pairCounts:
            pairCounts[p] += 1
        else:
            pairCounts[p] = 1

    pairsCount = len(text) - 1
    pairProbs = {}

    for k, v in pairCounts.items():
        pairProbs[k] = v/pairsCount

    #Conditional entropy counting

    h1 = 0
    for i in alphabet:
        for j in alphabet:
            if (i, j) in pairProbs:
                condprob = min((pairProbs[(i, j)] / probabilities[i]), 1)
                # print(condprob)
                h1 += pairProbs[(i, j)] * math.log(condprob, 2)

    h1 *= -1
    print("H1: " + str(h1))


    #############################################################
    #H2 counting

    triplets = list(zip(text[:-2], text[1:-1], text[2:]))

    tripletCounts = {}

    for t in triplets:
        if t in tripletCounts:
            tripletCounts[t] += 1
        else:
            tripletCounts[t] = 1

    tripletsCount = textLen - 2

    tripletProbs = {}

    for k, v in tripletCounts.items():
        tripletProbs[k] = v/tripletsCount

    h2 = 0

    for i in alphabet:
        for k, v in pairProbs.items():
            key = (k[0], k[1], i)
            if key in tripletProbs:
                condprob = tripletProbs[key] / v
                h2 += tripletProbs[key] * math.log(condprob,2)
    h2 *= -1

    print("h2: " + str(h2))