/*
 * Copyright (c) Pavol Rusnak, SatoshiLabs
 *
 * Licensed under TREZOR License
 * see LICENSE file for details
 */

#include "py/objstr.h"

#include "chacha20poly1305/rfc7539.h"

/// class ChaCha20Poly1305:
///     '''
///     ChaCha20Poly1305 context.
///     '''
typedef struct _mp_obj_ChaCha20Poly1305_t {
    mp_obj_base_t base;
    chacha20poly1305_ctx ctx;
    int64_t alen, plen;
} mp_obj_ChaCha20Poly1305_t;

/// def __init__(self, key: bytes, nonce: bytes) -> None:
///     '''
///     Initialize the ChaCha20 + Poly1305 context for encryption or decryption
///     using a 32 byte key and 12 byte nonce as in the RFC 7539 style.
///     '''
STATIC mp_obj_t mod_trezorcrypto_ChaCha20Poly1305_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, 2, false);
    mp_obj_ChaCha20Poly1305_t *o = m_new_obj(mp_obj_ChaCha20Poly1305_t);
    o->base.type = type;
    mp_buffer_info_t key, nonce;
    mp_get_buffer_raise(args[0], &key, MP_BUFFER_READ);
    mp_get_buffer_raise(args[1], &nonce, MP_BUFFER_READ);
    if (key.len != 32) {
        mp_raise_ValueError("Invalid length of key");
    }
    if (nonce.len != 12) {
        mp_raise_ValueError("Invalid length of nonce");
    }
    rfc7539_init(&(o->ctx), key.buf, nonce.buf);
    o->alen = 0;
    o->plen = 0;
    return MP_OBJ_FROM_PTR(o);
}

/// def encrypt(self, data: bytes) -> bytes:
///     '''
///     Encrypt data (length of data must be divisible by 64 except for the final value).
///     '''
STATIC mp_obj_t mod_trezorcrypto_ChaCha20Poly1305_encrypt(mp_obj_t self, mp_obj_t data) {
    mp_obj_ChaCha20Poly1305_t *o = MP_OBJ_TO_PTR(self);
    mp_buffer_info_t in;
    mp_get_buffer_raise(data, &in, MP_BUFFER_READ);
    vstr_t vstr;
    vstr_init_len(&vstr, in.len);
    chacha20poly1305_encrypt(&(o->ctx), in.buf, (uint8_t *)vstr.buf, in.len);
    o->plen += in.len;
    return mp_obj_new_str_from_vstr(&mp_type_bytes, &vstr);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_trezorcrypto_ChaCha20Poly1305_encrypt_obj, mod_trezorcrypto_ChaCha20Poly1305_encrypt);

/// def decrypt(self, data: bytes) -> bytes:
///     '''
///     Decrypt data (length of data must be divisible by 64 except for the final value).
///     '''
STATIC mp_obj_t mod_trezorcrypto_ChaCha20Poly1305_decrypt(mp_obj_t self, mp_obj_t data) {
    mp_obj_ChaCha20Poly1305_t *o = MP_OBJ_TO_PTR(self);
    mp_buffer_info_t in;
    mp_get_buffer_raise(data, &in, MP_BUFFER_READ);
    vstr_t vstr;
    vstr_init_len(&vstr, in.len);
    chacha20poly1305_decrypt(&(o->ctx), in.buf, (uint8_t *)vstr.buf, in.len);
    o->plen += in.len;
    return mp_obj_new_str_from_vstr(&mp_type_bytes, &vstr);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_trezorcrypto_ChaCha20Poly1305_decrypt_obj, mod_trezorcrypto_ChaCha20Poly1305_decrypt);

/// def auth(self, data: bytes) -> None:
///     '''
///     Include authenticated data in the Poly1305 MAC using the RFC 7539
///     style with 16 byte padding. This must only be called once and prior
///     to encryption or decryption.
///     '''
STATIC mp_obj_t mod_trezorcrypto_ChaCha20Poly1305_auth(mp_obj_t self, mp_obj_t data) {
    mp_obj_ChaCha20Poly1305_t *o = MP_OBJ_TO_PTR(self);
    mp_buffer_info_t in;
    mp_get_buffer_raise(data, &in, MP_BUFFER_READ);
    rfc7539_auth(&(o->ctx), in.buf, in.len);
    o->alen += in.len;
    return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_trezorcrypto_ChaCha20Poly1305_auth_obj, mod_trezorcrypto_ChaCha20Poly1305_auth);

/// def finish(self) -> bytes:
///     '''
///     Compute RFC 7539-style Poly1305 MAC.
///     '''
STATIC mp_obj_t mod_trezorcrypto_ChaCha20Poly1305_finish(mp_obj_t self) {
    mp_obj_ChaCha20Poly1305_t *o = MP_OBJ_TO_PTR(self);
    uint8_t out[16];
    rfc7539_finish(&(o->ctx), o->alen, o->plen, out);
    return mp_obj_new_bytes(out, sizeof(out));
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_trezorcrypto_ChaCha20Poly1305_finish_obj, mod_trezorcrypto_ChaCha20Poly1305_finish);

STATIC mp_obj_t mod_trezorcrypto_ChaCha20Poly1305___del__(mp_obj_t self) {
    mp_obj_ChaCha20Poly1305_t *o = MP_OBJ_TO_PTR(self);
    memset(&(o->ctx), 0, sizeof(chacha20poly1305_ctx));
    o->alen = 0;
    o->plen = 0;
    return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_trezorcrypto_ChaCha20Poly1305___del___obj, mod_trezorcrypto_ChaCha20Poly1305___del__);

STATIC const mp_rom_map_elem_t mod_trezorcrypto_ChaCha20Poly1305_locals_dict_table[] = {
    { MP_ROM_QSTR(MP_QSTR_encrypt), MP_ROM_PTR(&mod_trezorcrypto_ChaCha20Poly1305_encrypt_obj) },
    { MP_ROM_QSTR(MP_QSTR_decrypt), MP_ROM_PTR(&mod_trezorcrypto_ChaCha20Poly1305_decrypt_obj) },
    { MP_ROM_QSTR(MP_QSTR_auth), MP_ROM_PTR(&mod_trezorcrypto_ChaCha20Poly1305_auth_obj) },
    { MP_ROM_QSTR(MP_QSTR_finish), MP_ROM_PTR(&mod_trezorcrypto_ChaCha20Poly1305_finish_obj) },
    { MP_ROM_QSTR(MP_QSTR___del__), MP_ROM_PTR(&mod_trezorcrypto_ChaCha20Poly1305___del___obj) },
};
STATIC MP_DEFINE_CONST_DICT(mod_trezorcrypto_ChaCha20Poly1305_locals_dict, mod_trezorcrypto_ChaCha20Poly1305_locals_dict_table);

STATIC const mp_obj_type_t mod_trezorcrypto_ChaCha20Poly1305_type = {
    { &mp_type_type },
    .name = MP_QSTR_ChaCha20Poly1305,
    .make_new = mod_trezorcrypto_ChaCha20Poly1305_make_new,
    .locals_dict = (void*)&mod_trezorcrypto_ChaCha20Poly1305_locals_dict,
};