from collections import Counter
import operator
from types import prepare_class
import numpy as np
import copy

class Case:
    def __init__(self, values, attributes, Class):
        self.values = values
        self.attributes = attributes
        self.Class = Class

class Node:
    def __init__(self, Class, tag=None):
        self.Class = Class
        self.childs = []

def classes_of_cases (cases):
    classes = []
    for case in cases:
        if case.Class not in classes:
            classes.append(case.Class)
    return classes

def count_classes (cases):
    classes = []
    for case in cases:
        classes.append(case.Class)
    c = Counter(classes)
    return max(c.items(), key=operator.itemgetter(1))[0]

def chose_attribute (cases, attributes):
    a = ""
    max = float("-inf")
    for attribute in attributes:
        if I(cases) - E(cases, attribute) >= max:
            max = I(cases) - E(cases, attribute)
            a = attribute
    return a

def I (cases):
    i = 0
    all = len(cases)
    classes = classes_of_cases(cases)
    for Class in classes:
        noc = 0
        for case in cases:
            if case.Class == Class:
                noc += 1
        i -= (noc/all)*np.log2(noc/all)
    return i

def E(cases, attribute):
    e = 0
    values = []
    index = cases[0].attributes.index(attribute)
    for case in cases:
        if case.values[index] not in values:
            values.append(case.values[index])
    for value in values:
        ei = []
        for case in cases:
            if case.values[index] == value:
                ei.append(case)
        e += (len(ei)/len(cases))*I(ei)
    return e
        

def treelearn(cases, attributes, default_class):
    if cases == []:
        t = Node(default_class)
        return t
    if len(classes_of_cases(cases)) == 1:
        t = Node(cases[0].Class)
        return t
    if attributes == []:
        t = Node(count_classes(cases))
        return t
    A = chose_attribute(cases, attributes)
    t = Node(A)
    new_default_class = count_classes(cases)

    values = []
    index = attributes.index(A)
    for case in cases:
        if case.values[index] not in values:
            values.append(case.values[index])

    for value in values:
        new_cases = []
        for case in cases:
            if case.values[index] == value:
                new_case = copy.deepcopy(case)
                new_case.values = case.values[:index] + case.values[index+1:]
                new_case.attributes = case.attributes[:index] + case.attributes[index+1:]
                new_cases.append(new_case)
        new_attributes = attributes[:index] + attributes[index+1 :]
        child = treelearn(new_cases, new_attributes, new_default_class)
        t.childs.append([child, value])

    return t

def pretty_print(root, n):
    for _ in range(n):
            print("\t", end="")
    print(root.Class)
    for child in root.childs:
        for _ in range(n):
            print("\t", end="")
        print("== " + str(child[1]))
        pretty_print(child[0], n+1)

attr = ["hydration", "fertility", "plant_type", "ticks", "is_healthy", "tractor_there"]
ccases = []
k = Case([2, 0, "wheat", 31, 0, 0], attr, 1)
ccases.append(k)
k = Case([3, 0, "wheat", 31, 0, 0], attr, 1)
ccases.append(k)
k = Case([4, 0, "wheat", 31, 0, 0], attr, 1)
ccases.append(k)
k = Case([1, 1, "wheat", 31, 0, 0], attr, 1)
ccases.append(k)
k = Case([3, 0, "wheat", 20, 0, 0], attr, 0)
ccases.append(k)
k = Case([2, 0, "wheat", 20, 0, 0], attr, 0)
ccases.append(k)
k = Case([4, 0, "potato", 31, 0, 0], attr, 1)
ccases.append(k)
k = Case([3, 0, "potato", 31, 0, 0], attr, 1)
ccases.append(k)
k = Case([2, 0, "potato", 31, 0, 0], attr, 0)
ccases.append(k)
k = Case([2, 0, "potato", 31, 0, 0], attr, 0)
ccases.append(k)
k = Case([2, 1, "potato", 31, 0, 0], attr, 1)
ccases.append(k)
k = Case([1, 1, "potato", 31, 0, 0], attr, 0)
ccases.append(k)
k = Case([4, 1, "potato", 31, 0, 0], attr, 1)
ccases.append(k)
k = Case([4, 1, "potato", 19, 0, 0], attr, 0)
ccases.append(k)
k = Case([4, 1, "potato", 31, 1, 0], attr, 0)
ccases.append(k)
k = Case([4, 1, "wheat", 19, 0, 0], attr, 0)
ccases.append(k)
k = Case([4, 1, "potato", 31, 0, 1], attr, 0)
ccases.append(k)
k = Case([4, 1, "wheat", 31, 1, 0], attr, 0)
ccases.append(k)
k = Case([2, 0, "wheat", 31, 0, 1], attr, 0)
ccases.append(k)

tree = treelearn(ccases, attr, 0)
pretty_print(tree, 0)