#include <common/fzl_extern.h>
#include <common/fzl_types.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <vm/fzl_vm_reader.h>
#include <vm/internals/reader.h>

// Read external functions definitions
bool vm_rd_extern_fns(fzl_vm_reader_t *reader, FILE *fd)
{
  if (!reader || !fd)
    return false;

  uint16_t fns_count = reader->extern_fns_count;
  if (!fns_count)
    return true;

  reader->extern_fns = malloc(sizeof(fzl_extern_fn_t) * fns_count);
  if (!reader->extern_fns)
  {
    snprintf(internal_error, sizeof(internal_error), "out of memory");
    return false;
  }

  memset(reader->extern_fns, 0, sizeof(fzl_extern_fn_t) * fns_count);

  for (uint16_t i = 0; i < fns_count; i++)
  {
    fzl_extern_fn_t *fn = &reader->extern_fns[i];

    uint16_t lib_slot;
    if (!vm_rd_u16(fd, 1, &lib_slot))
    {
      snprintf(internal_error, sizeof(internal_error),
               "failed to read fn #%u lib slot", i);
      return false;
    }

    fn->lib_slot = lib_slot;

    uint16_t used_name_sz;
    if (!vm_rd_u16(fd, 1, &used_name_sz))
    {
      snprintf(internal_error, sizeof(internal_error),
               "failed to read fn #%u used name size", i);
      return false;
    }

    char used_name_buf[256];
    memset(used_name_buf, 0, sizeof(used_name_buf));
    if (!vm_rd_char(fd, used_name_sz, used_name_buf))
    {
      snprintf(internal_error, sizeof(internal_error),
               "failed to read fn #%u used name", i);
      return false;
    }

    char *val = malloc(sizeof(char) * used_name_sz + 1);
    if (!val)
    {
      snprintf(internal_error, sizeof(internal_error),
               "out of memory on fn #%u used name allocation", i);
      return false;
    }

    memset(val, 0, sizeof(char) * used_name_sz + 1);
    memcpy(val, used_name_buf, sizeof(char) * used_name_sz);
    fn->used_name = val;

    char has_symbol_name;
    if (!vm_rd_char(fd, 1, &has_symbol_name))
    {
      snprintf(internal_error, sizeof(internal_error),
               "failed to read fn #%u symbol name existing flag", i);
      return false;
    }

    if ((bool)has_symbol_name)
    {
      if (!vm_rd_u16(fd, 1, &used_name_sz))
      {
        snprintf(internal_error, sizeof(internal_error),
                 "failed to read fn #%u symbol name size", i);
        return false;
      }

      if (!vm_rd_char(fd, used_name_sz, used_name_buf))
      {
        snprintf(internal_error, sizeof(internal_error),
                 "failed to read fn #%u symbol name", i);
        return false;
      }

      char *symval = malloc(sizeof(char) * used_name_sz + 1);
      if (!symval)
      {
        snprintf(internal_error, sizeof(internal_error),
                 "out of memory on fn #%u symbol name allocation", i);
        return false;
      }

      memset(symval, 0, sizeof(char) * used_name_sz + 1);
      memcpy(symval, used_name_buf, sizeof(char) * used_name_sz);
      fn->symbol_name = symval;
    }

    char has_return;
    if (!vm_rd_char(fd, 1, &has_return))
    {
      snprintf(internal_error, sizeof(internal_error),
               "failed to read fn #%u return existing flag", i);
      return false;
    }

    fn->has_return = (bool)has_return;
    if ((bool)has_return)
    {
      char is_primitive;
      if (!vm_rd_char(fd, 1, &is_primitive))
      {
        snprintf(internal_error, sizeof(internal_error),
                 "failed to read fn #%u return type primitivity flag", i);
        return false;
      }

      fn->ret_type.is_primitive = (bool)is_primitive;

      if (is_primitive)
      {
        char primitive;
        if (!vm_rd_char(fd, 1, &primitive))
        {
          snprintf(internal_error, sizeof(internal_error),
                   "failed to read fn #%u return primitive", i);
          return false;
        }

        fn->ret_type.primitive = (fzl_type_t)primitive;
      }
      else
      {
        uint16_t type_slot;
        if (!vm_rd_u16(fd, 1, &type_slot))
        {
          snprintf(internal_error, sizeof(internal_error),
                   "failed to read fn #%u return type slot", i);
          return false;
        }

        fn->ret_type.type_slot = (size_t)type_slot;
      }
    }

    uint16_t args_count;
    if (!vm_rd_u16(fd, 1, &args_count))
    {
      snprintf(internal_error, sizeof(internal_error),
               "failed to read fn #%u arguments count", i);
      return false;
    }

    fn->args_count = (size_t)args_count;
    if (args_count > 0)
    {
      fzl_extern_arg_t *args = malloc(sizeof(fzl_extern_arg_t) * args_count);
      if (!args)
      {
        snprintf(internal_error, sizeof(internal_error),
                 "out of memory on fn #%u arguments array allocation", i);
        return false;
      }

      memset(args, 0, sizeof(fzl_extern_arg_t) * args_count);
      fn->args = args;

      for (uint16_t j = 0; j < args_count; j++)
      {
        fzl_extern_arg_t *arg = &args[j];

        char arg_is_out;
        if (!vm_rd_char(fd, 1, &arg_is_out))
        {
          snprintf(internal_error, sizeof(internal_error),
                   "failed to read fn #%u arg #%u out flag", i, j);
          return false;
        }

        arg->is_out = (bool)arg_is_out;

        char arg_is_primitive;
        if (!vm_rd_char(fd, 1, &arg_is_primitive))
        {
          snprintf(internal_error, sizeof(internal_error),
                   "failed to read fn #%u arg #%u return type primitivity flag",
                   i, j);
          return false;
        }

        arg->type.is_primitive = (bool)arg_is_primitive;

        if (arg_is_primitive)
        {
          char primitive;
          if (!vm_rd_char(fd, 1, &primitive))
          {
            snprintf(internal_error, sizeof(internal_error),
                     "failed to read fn #%u #%u return primitive", i, j);
            return false;
          }

          arg->type.primitive = (fzl_type_t)primitive;
        }
        else
        {
          uint16_t type_slot;
          if (!vm_rd_u16(fd, 1, &type_slot))
          {
            snprintf(internal_error, sizeof(internal_error),
                     "failed to read fn #%u #%u return type slot", i, j);
            return false;
          }

          arg->type.type_slot = (size_t)type_slot;
        }
      }
    }
  }

  return true;
}