#include "../../../vm/vm.h"
#include <stdio.h>
#include <string.h>

#define CODE_SIZE 8192
#define MEMORY_SIZE 65536
u8 lmem[MEMORY_SIZE] = {0};
u32 lcode[CODE_SIZE] = {0};

bool init_vm() {
  mem = lmem;
  memset(mem, 0, MEMORY_SIZE*sizeof(u8));
  code = lcode;
  lc = 0;
  mp = 0;
  cp = 0;
  pc = 0;
  interrupt = 0;
  status = 0;
  return true;
}

u32 syscall(u32 id, u32 size, u32 mem_ptr) {
  USED(size);
  switch(id) {
    case SYSCALL_CONSOLE_WRITE: {
      u32 size = *(u32*)&mem[mem_ptr];
      u8 *ptr = &mem[mem_ptr + 4];
      for (u32 i = 0; i < size; i++) {
        putchar(*(ptr++));
      }
      return 0;
    }
    case SYSCALL_CONSOLE_READ: {
      u8 *ptr = &mem[mp];
      mcpy(ptr, &size, sizeof(u32));
      ptr += 4;
      for (u32 i = 0; i < size; i++) {
        u8 ch = getchar();
        if (ch == '\0')
          break;
        if (ch == '\n')
          break;
        *(ptr++) = ch;
      }
      ptr[size] = '\0';
      mp += 4 + size + 1;
    }
  }

  return 1; // generic error
}

void test_add_two_num() {
  i32 main_local_count = 5; 
  mp += (4 * main_local_count);
  code[cp++] = ENCODE_B(OP_LOAD_IMM, 0, 1);
  code[cp++] = ENCODE_B(OP_PUSH, 0, 0);
  code[cp++] = ENCODE_B(OP_LOAD_IMM, 1, 1);
  code[cp++] = ENCODE_B(OP_PUSH, 1, 0);
  i32 add = cp + 5;
  code[cp++] = ENCODE_B(OP_LOAD_IMM, 2, add);

  code[cp++] = ENCODE_A(OP_CALL, 2, 3, 0);
  code[cp++] = ENCODE_A(OP_INT_TO_STR, 4, 3, 0);
  code[cp++] = ENCODE_A(OP_SYSCALL, SYSCALL_CONSOLE_WRITE, 1, 4);
  code[cp++] = ENCODE_A(OP_HALT, 0, 0, 0);

  /* add */
  code[cp++] = ENCODE_A(OP_ADD_INT, 2, 1, 0);
  code[cp++] = ENCODE_B(OP_RETURN, 2, 0);
}

void test_fibonacci() {
  i32 fib = 7;
  i32 base_case = 21;
  /* function main() */
  i32 main_local_count = 4; 
  mp += (4 * main_local_count);
  /* fib(35) */
  code[cp++] = ENCODE_B(OP_LOAD_IMM, 0, 35);
  code[cp++] = ENCODE_B(OP_PUSH, 0, 0);
  code[cp++] = ENCODE_B(OP_LOAD_IMM, 1, fib);
  code[cp++] = ENCODE_A(OP_CALL, 1, 9, 2);
  /* print */
  code[cp++] = ENCODE_A(OP_INT_TO_STR, 3, 2, 0);
  code[cp++] = ENCODE_A(OP_SYSCALL, SYSCALL_CONSOLE_WRITE, 1, 3);
  code[cp++] = ENCODE_A(OP_HALT, 0, 0, 0);
  /* function fib (int n) int */
  //code[cp++] = ENCODE_A(OP_SYSCALL, SYSCALL_DBG_PRINT, 1, 0);
  code[cp++] = ENCODE_B(OP_LOAD_IMM, 8, fib);
  code[cp++] = ENCODE_B(OP_LOAD_IMM, 1, 2);
  code[cp++] = ENCODE_B(OP_LOAD_IMM, 2, base_case);
  code[cp++] = ENCODE_A(OP_JLT_INT, 2, 0, 1);
  code[cp++] = ENCODE_B(OP_LOAD_IMM, 3, 2);
  code[cp++] = ENCODE_A(OP_SUB_INT, 4, 0, 3);
  code[cp++] = ENCODE_B(OP_PUSH, 4, 0);
  code[cp++] = ENCODE_A(OP_CALL, 8, 9, 5);
  code[cp++] = ENCODE_B(OP_LOAD_IMM, 3, 1);
  code[cp++] = ENCODE_A(OP_SUB_INT, 4, 0, 3);
  code[cp++] = ENCODE_B(OP_PUSH, 4, 0);
  code[cp++] = ENCODE_A(OP_CALL, 8, 9, 6);
  code[cp++] = ENCODE_A(OP_ADD_INT, 7, 6, 5);
  code[cp++] = ENCODE_B(OP_RETURN, 7, 0);
  code[cp++] = ENCODE_B(OP_RETURN, 0, 0);
}

void test_hello() {
  u32 hello =str_alloc("nuqneH 'u'?", 12);
  u32 new_line = str_alloc("\n", 1);
  fp = mp;
  /* function main() */
  i32 main_local_count = 3; 
  mp += (4 * main_local_count);
  code[cp++] = ENCODE_B(OP_LOAD_IMM, 0, hello);
  code[cp++] = ENCODE_A(OP_SYSCALL, SYSCALL_CONSOLE_WRITE, 12, 0);
  code[cp++] = ENCODE_B(OP_LOAD_IMM, 0, new_line);
  code[cp++] = ENCODE_A(OP_SYSCALL, SYSCALL_CONSOLE_WRITE, 1, 0);
  code[cp++] = ENCODE_A(OP_HALT, 0, 0, 0);
}

i32 main() {
  init_vm();

  test_hello();

  while(step_vm()) {
    // do stuff
  }
  return 0;
}