/**
 *--------------------------------------------------------------------\n
 *          HSLU T&A Hochschule Luzern Technik+Architektur            \n
 *--------------------------------------------------------------------\n
 *
 * \brief         ASYD assignment crypto 05
 * \file
 * \author        Basil Estermann, basil.estermann@stud.hslu.ch
 *                Simon Frei, simon.frei@stud.hslu.ch
 *                Jonas Arnold, jonas.arnold@stud.hslu.ch
 * \date          23.03.2023
 *
 *--------------------------------------------------------------------
 */

#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <stdint.h>

#define VALUE_LENGTH 32
#define MESSAGE_DIGEST_LENGTH 160
#define BLOCK_LENGTH (512/8)
#define INPUT_MESSAGE ("Testnachricht 123")

#pragma region SHA1-Constants
#define H0 0x67452301
#define H1 0xEFCDAB89
#define H2 0x98BADCFE
#define H3 0x10325476
#define H4 0xC3D2E1F0
#pragma endregion

void printBits(size_t const size, void const* const ptr);
uint32_t leftRotate(uint32_t n, uint32_t d);

void main(void) {

    int result = 0;

    printf("------ Set initial hash value ------\n\n");
    #pragma region Initial Hash values
    uint32_t h0, h1, h2, h3, h4;
    h0 = H0;
    h1 = H1;
    h2 = H2;
    h3 = H3;
    h4 = H4;
    #pragma endregion

    if (sizeof(INPUT_MESSAGE) * 8 > 447) {
        printf("Message too long!");
        return 1000002;
    }

    printf("------ Padding message ------\n\n");
    #pragma region Padding
    unsigned char messageNoPadding[] = INPUT_MESSAGE;
    printf("Size of message without padding: %i bits\n", sizeof(INPUT_MESSAGE) * 8);
    printf("Message without padding\n");
    printBits(sizeof(messageNoPadding), &messageNoPadding);
    unsigned char message[BLOCK_LENGTH] = "";
    // fill in message
    for (uint32_t i = 0; i < sizeof(INPUT_MESSAGE); i++)
    {
        message[i] = INPUT_MESSAGE[i];
    }
    // set bit
    message[sizeof(INPUT_MESSAGE)] = 0b10000000;
    printf("\nMessage after adding 1: \n");
    printBits(sizeof(message), &message);
    message[BLOCK_LENGTH - 1] = sizeof(INPUT_MESSAGE) * 8;
    printf("\nMessage after length 1: \n");
    printBits(sizeof(message), &message);
    #pragma endregion

    printf("------ Message scheduling ------\n\n");
    #pragma region Message scheduling
        uint32_t WordArray[80] = { 0 };
        for (uint32_t i = 0; i < 16; i++) {
            uint32_t currentbyte = message[i] << 24;
            uint32_t tmp = (uint32_t)(((uint8_t)(message[i * 4]) << 24) + ((uint8_t)(message[4 * i + 1]) << 16) + ((uint8_t)(message[4 * i + 2]) << 8) + (uint8_t)(message[4 * i + 3]));
            WordArray[i] = tmp;
        }
        for (uint32_t i = 16; i < 80; i++) {
            WordArray[i] = leftRotate((WordArray[i - 3] ^ WordArray[i - 8] ^ WordArray[i - 14] ^ WordArray[i - 16]), 1);
        }
    #pragma endregion

    return 0;
}

uint32_t leftRotate(uint32_t n, uint32_t d)
{
    /* In n<<d, last d bits are 0. To put first 3 bits of n at
      last, do bitwise or of n<<d with n >>(INT_BITS - d) */
    return (n << d) | (n >> (VALUE_LENGTH - d));
}

// Assumes little endian
void printBits(size_t const size, void const* const ptr)
{
    unsigned char* b = (unsigned char*)ptr;
    unsigned char byte;
    int i, j;

    for (i = 0; i < size; i++) {
        for (j = 7; j >= 0; j--) {
            byte = (b[i] >> j) & 1;
            printf("%u", byte);
        }
    }
    /*for (i = size - 1; i >= 0; i--) {
        for (j = 7; j >= 0; j--) {
            byte = (b[i] >> j) & 1;
            printf("%u", byte);
        }
    }*/
    puts("");
}