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

//Comment to disable debug

#define DEBUG

#define IMMEDIATE(x) ((x) & 0x00FFFFFF)

#define HALT 0
#define PUSHC 1
#define ADD 2
#define SUB 3
#define MUL 4
#define DIV 5
#define MOD 6
#define RDINT 7
#define WRINT 8
#define RDCHR 9
#define WRCHR 10


unsigned int programmSpeicher[1000];

// Stack
#define maxValues 1000

unsigned int stack[maxValues];
unsigned int current = 0;

void stackPush(unsigned int value) {
    if (current > (maxValues-1)) {
        fprintf(stderr, "stack overflow\n");
        exit(EXIT_FAILURE);
    }
    stack[current] = value;
    current++;
}

unsigned int stackPop(void) {
    if (current < 1) {
        fprintf(stderr, "stack underflow\n");
        exit(EXIT_FAILURE);
    }
    return stack[--current];
}

void version(void) {
    printf("Ninja Virtual Machine version %i (compiled %s, %s)\n", 0, __DATE__, __TIME__);
}

void help(void) {
    printf("usage: ./njvm [option] [option] ...\n\t--version\tshow version and exit\n\t--help\t\tshow this help and exit\n");
}

void useption(int argc, char *argv[]) {
    if (argc > 1) {
        if (strcmp(argv[1], "--version") == 0) {
            version();
        } else if (strcmp(argv[1], "--help") == 0) {
            help();
        } else {
            printf("unknown command line argument '%s', try './njvm --help'", argv[1]);
        }
    }
}

void execute(void) {
    int i = 0;
    int intInput;
    int temp;
    char charInput;
    while (programmSpeicher[i] != 0) {

        switch (programmSpeicher[i] >> 24) {
            case HALT:
                break;
            case PUSHC:
                  stackPush(IMMEDIATE(programmSpeicher[i]));
                break;
            case ADD:
                  stackPush(stackPop()+stackPop());
                break;
            case SUB:
                  temp = stackPop();
                  stackPush(stackPop() - temp);
                break;
            case MUL:
                  stackPush(stackPop()*stackPop());
                break;
            case DIV:
                  temp = stackPop();
                  stackPush(stackPop()/temp);
                break;
            case MOD:
                  temp = stackPop();
                  stackPush(stackPop()%temp);
                break;
            case RDINT:
                  scanf("%i",&intInput);
                  stackPush(intInput);
                break;
            case WRINT:
                  printf("%i\n",stackPop());
                break;
            case RDCHR:
                  scanf("%c",&charInput);
                  stackPush(charInput);
                break;
            case WRCHR:
                  printf("%c\n",stackPop());
                break;
        }
        i++;
    }
}
#ifdef DEBUG

void printStck(){
  if(current >= 0) {return;}
  printf("----\n");
  for (int i = 0; i < current; i++) {
    printf("|%i| \n",stack[i]);
  }
  printf("----\n");
}

void tests(){
  printf("Runnig debug mode\n");
  stackPush(10);
  stackPush(15);
  stackPush(13);
  printStck();
  current = 0;
  programmSpeicher[0] = (RDINT << 24);
  programmSpeicher[1] = (RDINT << 24);
  programmSpeicher[2] = (MOD << 24);
  programmSpeicher[3] = (WRINT << 24);
  execute();
  printStck();
}

#endif /* ifdef DEBUG */

int main(int argc, char *argv[]) {
    #ifdef DEBUG
      tests();
    #endif /* ifdef DEBUG */
    if (argc > 1) useption(argc, argv);
    else {

//    Started
        printf("Ninja Virtual Machine started\n");

//    Stopped
        printf("Ninja Virtual Machine stopped\n");
        return 0;
    }
}