#include "vm.h"
#include "lib/commons.h"
#include "lib/type.h"

void vm_init(vm_t* vm, err_t* err)
{
  assert(vm);

  vm->pc = 0;
  vm->bp = 0;
  vm->sp = 0;

  vm->err = err;
}

void vm_free(vm_t* vm)
{
  assert(vm);
}

param_t vm_pop(vm_t* vm)
{
  assert(vm);
  assert(vm->sp > 0);
  param_t param = vm->stack[vm->sp - 1];
  vm->sp--;

  return param;
}

size_t vm_stack_str(vm_t* vm, char* buffer, size_t size)
{
  assert(vm);
  assert(buffer);

  size_t sz = 0;

  for (size_t i=0; i<vm->sp; i++)
    {
      sz += snprintf(buffer + sz, size - sz, "| %d |\n", vm->stack[vm->sp - 1 - i]);
    }

  return sz;
}

void vm_exec_mod(vm_t* vm, mod_t* mod)
{
  assert(vm);
  vm->pc = 0;

  while (vm->pc < mod->program.size)
    {
      int status = vm_exec_instr(vm,
                                 mod,
                                 mod->program.ops[vm->pc],
                                 mod->program.params[vm->pc]);

      if (!status)
        {
          return;
        }
    }
}

int vm_exec_instr(vm_t* vm, mod_t* mod, Opcode op, param_t param)
{
  assert(vm);

  switch (op)
    {

    case OP_PUSH: {
      if (vm->sp + 1 >= RZ_STACK_LIMIT)
        {
          fprintf(stderr, "Stack overflow\n");
          abort();
        }

      vm->stack[vm->sp] = param;
      vm->sp++;
      vm->pc++;
    } break;

    case OP_ASSERT: {
      param_t top = vm_pop(vm);
      value_t* value = mod->values.data[top];

      if (value->type->kind != TYPE_BOOL)
        {
          char msg[RZ_STR_LIMIT];
          snprintf(msg, RZ_STR_LIMIT,
                   "type mismatch: BOOL expected, got %s.",
                   TypeKindStr[value->type->kind] + strlen("TYPE_"));

          err_fatal(vm->err, msg, value->line);

          vm->pc++;
          break;
        }

      if (!value->value.bool)
        {
          fprintf(stderr, "\33[31mASSERT\33[0m[:%d] assertion failed\n",
                  value->line);
          return 0;
        }

      vm->pc++;

    } break;

    default: {
      fprintf(stderr, "Cannot execute unknown opcode '%s'.\n",
              OpcodeStr[op]);
      abort();
    };
    }

  return 1;
}