/*
 * 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/objstr.h"

#include "aes/aes.h"
#include "memzero.h"

enum AESMode {
  ECB = 0x00,
  CBC = 0x01,
  CFB = 0x02,
  OFB = 0x03,
  CTR = 0x04,
};

/// package: trezorcrypto.__init__

/// class aes:
///     """
///     AES context.
///     """
///     ECB: int
///     CBC: int
///     CFB: int
///     OFB: int
///     CTR: int
typedef struct _mp_obj_AES_t {
  mp_obj_base_t base;
  aes_encrypt_ctx encrypt_ctx;
  aes_decrypt_ctx decrypt_ctx;
  mp_int_t mode;
  uint8_t iv[AES_BLOCK_SIZE];
} mp_obj_AES_t;

/// def __init__(
///     self,
///     mode: int,
///     key: bytes,
///     iv: bytes | None = None,
/// ) -> None:
///     """
///     Initialize AES context.
///     """
STATIC mp_obj_t mod_trezorcrypto_AES_make_new(const mp_obj_type_t *type,
                                              size_t n_args, size_t n_kw,
                                              const mp_obj_t *args) {
  mp_arg_check_num(n_args, n_kw, 2, 3, false);
  mp_obj_AES_t *o = m_new_obj_with_finaliser(mp_obj_AES_t);
  o->base.type = type;
  o->mode = mp_obj_get_int(args[0]);
  if (o->mode < ECB || o->mode > CTR) {
    mp_raise_ValueError("Invalid AES mode");
  }
  mp_buffer_info_t key = {0};
  mp_get_buffer_raise(args[1], &key, MP_BUFFER_READ);
  if (key.len != 16 && key.len != 24 && key.len != 32) {
    mp_raise_ValueError(
        "Invalid length of key (has to be 128, 192 or 256 bits)");
  }
  if (n_args > 2) {
    mp_buffer_info_t iv = {0};
    mp_get_buffer_raise(args[2], &iv, MP_BUFFER_READ);
    if (iv.len != AES_BLOCK_SIZE) {
      mp_raise_ValueError(
          "Invalid length of initialization vector (has to be 128 bits)");
    }
    memcpy(o->iv, iv.buf, AES_BLOCK_SIZE);
  } else {
    memzero(o->iv, AES_BLOCK_SIZE);
  }
  switch (key.len) {
    case 16:
      aes_decrypt_key128(key.buf, &(o->decrypt_ctx));
      aes_encrypt_key128(key.buf, &(o->encrypt_ctx));
      break;
    case 24:
      aes_decrypt_key192(key.buf, &(o->decrypt_ctx));
      aes_encrypt_key192(key.buf, &(o->encrypt_ctx));
      break;
    case 32:
      aes_decrypt_key256(key.buf, &(o->decrypt_ctx));
      aes_encrypt_key256(key.buf, &(o->encrypt_ctx));
      break;
  }
  return MP_OBJ_FROM_PTR(o);
}

static mp_obj_t aes_update(mp_obj_t self, mp_obj_t data, bool encrypt) {
  mp_buffer_info_t buf = {0};
  mp_get_buffer_raise(data, &buf, MP_BUFFER_READ);
  if (buf.len == 0) {
    return mp_const_empty_bytes;
  }
  vstr_t vstr = {0};
  vstr_init_len(&vstr, buf.len);
  mp_obj_AES_t *o = MP_OBJ_TO_PTR(self);
  switch (o->mode) {
    case ECB:
      if (buf.len & (AES_BLOCK_SIZE - 1)) {
        mp_raise_ValueError("Invalid data length");
      }
      if (encrypt) {
        aes_ecb_encrypt(buf.buf, (uint8_t *)vstr.buf, buf.len,
                        &(o->encrypt_ctx));
      } else {
        aes_ecb_decrypt(buf.buf, (uint8_t *)vstr.buf, buf.len,
                        &(o->decrypt_ctx));
      }
      break;
    case CBC:
      if (buf.len & (AES_BLOCK_SIZE - 1)) {
        mp_raise_ValueError("Invalid data length");
      }
      if (encrypt) {
        aes_cbc_encrypt(buf.buf, (uint8_t *)vstr.buf, buf.len, o->iv,
                        &(o->encrypt_ctx));
      } else {
        aes_cbc_decrypt(buf.buf, (uint8_t *)vstr.buf, buf.len, o->iv,
                        &(o->decrypt_ctx));
      }
      break;
    case CFB:
      if (encrypt) {
        aes_cfb_encrypt(buf.buf, (uint8_t *)vstr.buf, buf.len, o->iv,
                        &(o->encrypt_ctx));
      } else {
        aes_cfb_decrypt(buf.buf, (uint8_t *)vstr.buf, buf.len, o->iv,
                        &(o->encrypt_ctx));  // decrypt uses encrypt_ctx
      }
      break;
    case OFB:  // (encrypt == decrypt)
      aes_ofb_crypt(buf.buf, (uint8_t *)vstr.buf, buf.len, o->iv,
                    &(o->encrypt_ctx));
      break;
    case CTR:  // (encrypt == decrypt)
      aes_ctr_crypt(buf.buf, (uint8_t *)vstr.buf, buf.len, o->iv,
                    aes_ctr_cbuf_inc, &(o->encrypt_ctx));
      break;
  }
  return mp_obj_new_str_from_vstr(&mp_type_bytes, &vstr);
}

/// def encrypt(self, data: bytes) -> bytes:
///     """
///     Encrypt data and update AES context.
///     """
STATIC mp_obj_t mod_trezorcrypto_AES_encrypt(mp_obj_t self, mp_obj_t data) {
  return aes_update(self, data, true);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_trezorcrypto_AES_encrypt_obj,
                                 mod_trezorcrypto_AES_encrypt);

/// def decrypt(self, data: bytes) -> bytes:
///     """
///     Decrypt data and update AES context.
///     """
STATIC mp_obj_t mod_trezorcrypto_AES_decrypt(mp_obj_t self, mp_obj_t data) {
  return aes_update(self, data, false);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_trezorcrypto_AES_decrypt_obj,
                                 mod_trezorcrypto_AES_decrypt);

STATIC mp_obj_t mod_trezorcrypto_AES___del__(mp_obj_t self) {
  mp_obj_AES_t *o = MP_OBJ_TO_PTR(self);
  memzero(&(o->encrypt_ctx), sizeof(aes_encrypt_ctx));
  memzero(&(o->decrypt_ctx), sizeof(aes_decrypt_ctx));
  memzero(o->iv, AES_BLOCK_SIZE);
  return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_trezorcrypto_AES___del___obj,
                                 mod_trezorcrypto_AES___del__);

STATIC const mp_rom_map_elem_t mod_trezorcrypto_AES_locals_dict_table[] = {
    {MP_ROM_QSTR(MP_QSTR_encrypt),
     MP_ROM_PTR(&mod_trezorcrypto_AES_encrypt_obj)},
    {MP_ROM_QSTR(MP_QSTR_decrypt),
     MP_ROM_PTR(&mod_trezorcrypto_AES_decrypt_obj)},
    {MP_ROM_QSTR(MP_QSTR___del__),
     MP_ROM_PTR(&mod_trezorcrypto_AES___del___obj)},
    {MP_ROM_QSTR(MP_QSTR_ECB), MP_ROM_INT(ECB)},
    {MP_ROM_QSTR(MP_QSTR_CBC), MP_ROM_INT(CBC)},
    {MP_ROM_QSTR(MP_QSTR_CFB), MP_ROM_INT(CFB)},
    {MP_ROM_QSTR(MP_QSTR_OFB), MP_ROM_INT(OFB)},
    {MP_ROM_QSTR(MP_QSTR_CTR), MP_ROM_INT(CTR)},
};
STATIC MP_DEFINE_CONST_DICT(mod_trezorcrypto_AES_locals_dict,
                            mod_trezorcrypto_AES_locals_dict_table);

STATIC const mp_obj_type_t mod_trezorcrypto_AES_type = {
    {&mp_type_type},
    .name = MP_QSTR_AES,
    .make_new = mod_trezorcrypto_AES_make_new,
    .locals_dict = (void *)&mod_trezorcrypto_AES_locals_dict,
};