from sympy import *
import math

class Model():
    def __init__(self):
        self.layers = []

    def append(self, layer):
        if len(self.layers)!=0:
            layer._connect(self.layers[-1])
        self.layers.append(layer)

    def collapse(self):
        act = symbols(' '.join(['x'+str(i) for i in range(self.layers[0].length)]))
        for layer in self.layers[1:]:
            act = layer.activate(act)
        return list(act)

class Layer():
    def __init__(self, length):
        self.length = length
        self.layNum = 0

    def _connect(self, prev):
        self.prev = prev
        self.weights = []
        self.layNum = self.prev.layNum + 1
        for w in range(self.length * (self.prev.length+1)):
            self.weights.append(symbols('w'+str(self.layNum)+'_'+str(w)))

    def activate(self, inp):
        act = []
        for neuron in range(self.length):
            accum = self.weights[(self.prev.length+1)*neuron]*self.prev.length
            for iNeuron in range(self.prev.length):
                accum += inp[iNeuron]*self.weights[(self.prev.length+1)*neuron+iNeuron+1]
            a = 1/(1+math.e**(-(accum)/self.prev.length))
            act.append(a)
        return act