#ifndef PROTOCOL_H
#define PROTOCOL_H

#include <stdint.h>
#include <stddef.h>
#include "signal_protocol_types.h"

#ifdef __cplusplus
extern "C" {
#endif

#define KEY_EXCHANGE_INITIATE_FLAG              0x01
#define KEY_EXCHANGE_RESPONSE_FLAG              0X02
#define KEY_EXCHANGE_SIMULTAENOUS_INITIATE_FLAG 0x04

#define CIPHERTEXT_UNSUPPORTED_VERSION         1
#define CIPHERTEXT_CURRENT_VERSION             3

#define CIPHERTEXT_SIGNAL_TYPE                 2
#define CIPHERTEXT_PREKEY_TYPE                 3
#define CIPHERTEXT_SENDERKEY_TYPE              4
#define CIPHERTEXT_SENDERKEY_DISTRIBUTION_TYPE 5

/* Worst case overhead. Not always accurate, but good enough for padding. */
#define CIPHERTEXT_ENCRYPTED_MESSAGE_OVERHEAD 53

int ciphertext_message_get_type(const ciphertext_message *message);
signal_buffer *ciphertext_message_get_serialized(const ciphertext_message *message);

int signal_message_create(signal_message **message, uint8_t message_version,
        const uint8_t *mac_key, size_t mac_key_len,
        ec_public_key *sender_ratchet_key, uint32_t counter, uint32_t previous_counter,
        const uint8_t *ciphertext, size_t ciphertext_len,
        ec_public_key *sender_identity_key, ec_public_key *receiver_identity_key,
        signal_context *global_context);

int signal_message_deserialize(signal_message **message, const uint8_t *data, size_t len,
        signal_context *global_context);

int signal_message_copy(signal_message **message, signal_message *other_message, signal_context *global_context);

ec_public_key *signal_message_get_sender_ratchet_key(const signal_message *message);

uint8_t signal_message_get_message_version(const signal_message *message);

uint32_t signal_message_get_counter(const signal_message *message);

signal_buffer *signal_message_get_body(const signal_message *message);

/**
 * Verify the MAC on the Signal message.
 *
 * @return 1 if verified, 0 if invalid, negative on error
 */
int signal_message_verify_mac(signal_message *message,
        uint8_t message_version,
        ec_public_key *sender_identity_key,
        ec_public_key *receiver_identity_key,
        const uint8_t *mac_key, size_t mac_key_len,
        signal_context *global_context);

int signal_message_is_legacy(const uint8_t *data, size_t len);

void signal_message_destroy(signal_type_base *type);

int pre_key_signal_message_create(pre_key_signal_message **pre_key_message,
        uint8_t message_version, uint32_t registration_id, const uint32_t *pre_key_id,
        uint32_t signed_pre_key_id, ec_public_key *base_key, ec_public_key *identity_key,
        signal_message *message,
        signal_context *global_context);

int pre_key_signal_message_deserialize(pre_key_signal_message **message,
        const uint8_t *data, size_t len,
        signal_context *global_context);

int pre_key_signal_message_copy(pre_key_signal_message **message, pre_key_signal_message *other_message, signal_context *global_context);

uint8_t pre_key_signal_message_get_message_version(const pre_key_signal_message *message);
ec_public_key *pre_key_signal_message_get_identity_key(const pre_key_signal_message *message);
uint32_t pre_key_signal_message_get_registration_id(const pre_key_signal_message *message);
int pre_key_signal_message_has_pre_key_id(const pre_key_signal_message *message);
uint32_t pre_key_signal_message_get_pre_key_id(const pre_key_signal_message *message);
uint32_t pre_key_signal_message_get_signed_pre_key_id(const pre_key_signal_message *message);
ec_public_key *pre_key_signal_message_get_base_key(const pre_key_signal_message *message);
signal_message *pre_key_signal_message_get_signal_message(const pre_key_signal_message *message);

void pre_key_signal_message_destroy(signal_type_base *type);

int sender_key_message_create(sender_key_message **message,
        uint32_t key_id, uint32_t iteration,
        const uint8_t *ciphertext, size_t ciphertext_len,
        ec_private_key *signature_key,
        signal_context *global_context);
int sender_key_message_deserialize(sender_key_message **message,
        const uint8_t *data, size_t len,
        signal_context *global_context);
int sender_key_message_copy(sender_key_message **message, sender_key_message *other_message, signal_context *global_context);

uint32_t sender_key_message_get_key_id(sender_key_message *message);
uint32_t sender_key_message_get_iteration(sender_key_message *message);
signal_buffer *sender_key_message_get_ciphertext(sender_key_message *message);
int sender_key_message_verify_signature(sender_key_message *message, ec_public_key *signature_key);

void sender_key_message_destroy(signal_type_base *type);

int sender_key_distribution_message_create(sender_key_distribution_message **message,
        uint32_t id, uint32_t iteration,
        const uint8_t *chain_key, size_t chain_key_len,
        ec_public_key *signature_key,
        signal_context *global_context);
int sender_key_distribution_message_deserialize(sender_key_distribution_message **message,
        const uint8_t *data, size_t len,
        signal_context *global_context);
int sender_key_distribution_message_copy(sender_key_distribution_message **message, sender_key_distribution_message *other_message, signal_context *global_context);

uint32_t sender_key_distribution_message_get_id(sender_key_distribution_message *message);
uint32_t sender_key_distribution_message_get_iteration(sender_key_distribution_message *message);
signal_buffer *sender_key_distribution_message_get_chain_key(sender_key_distribution_message *message);
ec_public_key *sender_key_distribution_message_get_signature_key(sender_key_distribution_message *message);

void sender_key_distribution_message_destroy(signal_type_base *type);

#ifdef __cplusplus
}
#endif

#endif /* PROTOCOL_H */