/*
 * This file is part of the TREZOR project, https://trezor.io/
 *
 * Copyright (c) SatoshiLabs
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "py/runtime.h"

#include "version.h"

#if MICROPY_PY_TREZORUTILS

#include "embed/extmod/trezorobj.h"

#include <string.h>
#include "common.h"

/// def consteq(sec: bytes, pub: bytes) -> bool:
///     '''
///     Compares the private information in `sec` with public, user-provided
///     information in `pub`.  Runs in constant time, corresponding to a length
///     of `pub`.  Can access memory behind valid length of `sec`, caller is
///     expected to avoid any invalid memory access.
///     '''
STATIC mp_obj_t mod_trezorutils_consteq(mp_obj_t sec, mp_obj_t pub) {
  mp_buffer_info_t secbuf;
  mp_get_buffer_raise(sec, &secbuf, MP_BUFFER_READ);
  mp_buffer_info_t pubbuf;
  mp_get_buffer_raise(pub, &pubbuf, MP_BUFFER_READ);

  size_t diff = secbuf.len - pubbuf.len;
  for (size_t i = 0; i < pubbuf.len; i++) {
    const uint8_t *s = (uint8_t *)secbuf.buf;
    const uint8_t *p = (uint8_t *)pubbuf.buf;
    diff |= s[i] - p[i];
  }

  if (diff == 0) {
    return mp_const_true;
  } else {
    return mp_const_false;
  }
}
STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_trezorutils_consteq_obj,
                                 mod_trezorutils_consteq);

/// def memcpy(dst: bytearray, dst_ofs: int,
///            src: bytearray, src_ofs: int,
///            n: int) -> int:
///     '''
///     Copies at most `n` bytes from `src` at offset `src_ofs` to
///     `dst` at offset `dst_ofs`.  Returns the number of actually
///     copied bytes.
///     '''
STATIC mp_obj_t mod_trezorutils_memcpy(size_t n_args, const mp_obj_t *args) {
  mp_arg_check_num(n_args, 0, 5, 5, false);

  mp_buffer_info_t dst;
  mp_get_buffer_raise(args[0], &dst, MP_BUFFER_WRITE);
  uint32_t dst_ofs = trezor_obj_get_uint(args[1]);

  mp_buffer_info_t src;
  mp_get_buffer_raise(args[2], &src, MP_BUFFER_READ);
  uint32_t src_ofs = trezor_obj_get_uint(args[3]);

  uint32_t n = trezor_obj_get_uint(args[4]);

  size_t dst_rem = (dst_ofs < dst.len) ? dst.len - dst_ofs : 0;
  size_t src_rem = (src_ofs < src.len) ? src.len - src_ofs : 0;
  size_t ncpy = MIN(n, MIN(src_rem, dst_rem));

  memmove(((char *)dst.buf) + dst_ofs, ((const char *)src.buf) + src_ofs, ncpy);

  return mp_obj_new_int(ncpy);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_trezorutils_memcpy_obj, 5, 5,
                                           mod_trezorutils_memcpy);

/// def halt(msg: str = None) -> None:
///     '''
///     Halts execution.
///     '''
STATIC mp_obj_t mod_trezorutils_halt(size_t n_args, const mp_obj_t *args) {
  mp_buffer_info_t msg;
  if (n_args > 0 && mp_get_buffer(args[0], &msg, MP_BUFFER_READ)) {
    ensure(secfalse, msg.buf);
  } else {
    ensure(secfalse, "halt");
  }
  return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_trezorutils_halt_obj, 0, 1,
                                           mod_trezorutils_halt);

/// def set_mode_unprivileged() -> None:
///     '''
///     Set unprivileged mode.
///     '''
STATIC mp_obj_t mod_trezorutils_set_mode_unprivileged(void) {
#ifndef TREZOR_EMULATOR
  __asm__ volatile("msr control, %0" ::"r"(0x1));
  __asm__ volatile("isb");
#endif
  return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_0(mod_trezorutils_set_mode_unprivileged_obj,
                                 mod_trezorutils_set_mode_unprivileged);

#define PASTER(s) MP_QSTR_##s
#define MP_QSTR(s) PASTER(s)

STATIC const mp_rom_map_elem_t mp_module_trezorutils_globals_table[] = {
    {MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_trezorutils)},
    {MP_ROM_QSTR(MP_QSTR_consteq), MP_ROM_PTR(&mod_trezorutils_consteq_obj)},
    {MP_ROM_QSTR(MP_QSTR_memcpy), MP_ROM_PTR(&mod_trezorutils_memcpy_obj)},
    {MP_ROM_QSTR(MP_QSTR_halt), MP_ROM_PTR(&mod_trezorutils_halt_obj)},
    {MP_ROM_QSTR(MP_QSTR_set_mode_unprivileged),
     MP_ROM_PTR(&mod_trezorutils_set_mode_unprivileged_obj)},
    // various built-in constants
    {MP_ROM_QSTR(MP_QSTR_GITREV), MP_ROM_QSTR(MP_QSTR(GITREV))},
    {MP_ROM_QSTR(MP_QSTR_VERSION_MAJOR), MP_OBJ_NEW_SMALL_INT(VERSION_MAJOR)},
    {MP_ROM_QSTR(MP_QSTR_VERSION_MINOR), MP_OBJ_NEW_SMALL_INT(VERSION_MINOR)},
    {MP_ROM_QSTR(MP_QSTR_VERSION_PATCH), MP_OBJ_NEW_SMALL_INT(VERSION_PATCH)},
    {MP_ROM_QSTR(MP_QSTR_MODEL), MP_ROM_QSTR(MP_QSTR(TREZOR_MODEL))},
#ifdef TREZOR_EMULATOR
    {MP_ROM_QSTR(MP_QSTR_EMULATOR), mp_const_true},
#else
    {MP_ROM_QSTR(MP_QSTR_EMULATOR), mp_const_false},
#endif
};

STATIC MP_DEFINE_CONST_DICT(mp_module_trezorutils_globals,
                            mp_module_trezorutils_globals_table);

const mp_obj_module_t mp_module_trezorutils = {
    .base = {&mp_type_module},
    .globals = (mp_obj_dict_t *)&mp_module_trezorutils_globals,
};

#endif  // MICROPY_PY_TREZORUTILS
