#include <stdio.h>
#include <math.h>
#include <float.h>
#include "function.h"

float max(float a, float b) {
    return a<b?b:a;
}

float sigmoid(float x) {
    return 1/(1 + exp(-x));
}

float sigmoid_derivative(float x) {
    float tmp = exp(-x);
    return tmp/((1+tmp)*(1+tmp));
}

float relu(float x) {
    return max(0, x);
}

float relu_derivative(float x) {
    if (x > 0)
        return 1;
    return 0;
}

float tanh_(float x) {
    return tanh(x);
}

float tanh_derivative(float x) {
    float a = tanh(x);
    return 1 - a*a;
}

void apply_softmax_input(float ***input, int depth, int rows, int columns) {
    int i, j, k;
    float m = FLT_MIN;
    float sum=0;
    for (i=0; i<depth; i++) {
        for (j=0; j<rows; j++) {
            for (k=0; k<columns; k++) {
                m = max(m, input[i][j][k]);
            }
        }
    }
    for (i=0; i<depth; i++) {
        for (j=0; j<rows; j++) {
            for (k=0; k<columns; k++) {
                input[i][j][k] = exp(m-input[i][j][k]);
                sum += input[i][j][k];
            }
        }
    }
    for (i=0; i<depth; i++) {
        for (j=0; j<rows; j++) {
            for (k=0; k<columns; k++) {
                input[i][j][k] = input[i][j][k]/sum;
            }
        }
    }
}

void apply_function_input(float (*f)(float), float*** input, int depth, int rows, int columns) {
    int i, j ,k;
    for (i=0; i<depth; i++) {
        for (j=0; j<rows; j++) {
            for (k=0; k<columns; k++) {
                input[i][j][k] = (*f)(input[i][j][k]);
            }
        }
    }
}

void choose_apply_function_input(int activation, float*** input, int depth, int rows, int columns) {
    if (activation == RELU) {
        apply_function_input(relu, input, depth, rows, columns);
    }
    else if (activation == SIGMOID) {
        apply_function_input(sigmoid, input, depth, rows, columns);
    }
    else if (activation == SOFTMAX) {
        apply_softmax_input(input, depth, rows, columns);
    }
    else if (activation == TANH) {
        apply_function_input(tanh_, input, depth, rows, columns);
    }
    else {
        printf("Erreur, fonction d'activation inconnue");
    }
}