#include "encryption.h"
#include <stdlib.h>
#include <QDebug>
#include <unistd.h>
#include <fcntl.h>
#include <QJsonDocument>
#include <cstring>

void Encryption::createNewDeviceKeys() {
    initAccount();

    // create account
    auto length = olm_create_account_random_length(account);

    void* memory = malloc(length);

    int fd = open("/dev/random", O_RDONLY);
    read(fd, memory, length);

    olm_create_account(account, memory, length);
    qDebug() << olm_account_last_error(account);

    qDebug() << "Created new device keys!";

    // retrieve identity keys
    length = olm_account_identity_keys_length(account);

    char* identity_memory = (char*)malloc(length + 1);
    identity_memory[length] = '\0';

    olm_account_identity_keys(account, identity_memory, length);

    QJsonDocument doc = QJsonDocument::fromJson((char*)identity_memory);
    identityKey = doc.object();

    qDebug() << "identity keys: " << (char*)identity_memory;
    qDebug() << "identity keys (parsed): " << identityKey;

}

QString Encryption::saveDeviceKeys() {
    auto length = olm_pickle_account_length(account);
    char* identity_memory = (char*)malloc(length + 1);
    identity_memory[length] = '\0';

    auto err = olm_pickle_account(account, "secret_key", 10, identity_memory, length);
    qDebug() << olm_account_last_error(account);
    qDebug() << err << " = " << olm_error();

    qDebug() << "Save: " << identity_memory;

    return identity_memory;
}

void Encryption::loadDeviceKeys(QString bytes) {
    initAccount();

    qDebug() << "load: " << bytes;

    auto length = bytes.length();

    std::string key = bytes.toStdString();

    olm_unpickle_account(account, "secret_key", 10, key.data(), key.length());
    qDebug() << olm_account_last_error(account);

    length = olm_account_identity_keys_length(account);
    char* identity_memory = (char*)malloc(length + 1);
    identity_memory[length] = '\0';

    olm_account_identity_keys(account, identity_memory, length);

    qDebug() << identity_memory;

    QJsonDocument doc = QJsonDocument::fromJson(identity_memory);
    qDebug() << doc;

    identityKey = doc.object();
}

QJsonObject Encryption::generateOneTimeKeys(int number_of_keys) {
    int fd = open("/dev/random", O_RDONLY);

    // generate random data
    auto length = olm_account_generate_one_time_keys_random_length(account, number_of_keys);
    auto memory = malloc(length);
    read(fd, memory, length);

    olm_account_generate_one_time_keys(account, number_of_keys, memory, length);

    // retrieve one time keys
    length = olm_account_one_time_keys_length(account);
    memory = malloc(length);
    olm_account_one_time_keys(account, memory, length);

    olm_account_mark_keys_as_published(account);

    QJsonDocument doc = QJsonDocument::fromJson((char*)memory);
    return doc.object();
}

int Encryption::getRecommendedNumberOfOneTimeKeys() {
    return olm_account_max_number_of_one_time_keys(account) / 2;
}

QString Encryption::signMessage(QString message) {
    auto length = olm_account_signature_length(account);

    void* memory = malloc(length);

    olm_account_sign(
        account,
        message.data(), message.length(),
        memory, length
    );

    qDebug() << "Signed: " << (char*)memory;

    return (char*)memory;
}

void Encryption::initAccount() {
    void* memory = malloc(olm_account_size());
    account = olm_account(memory);
}

OlmOutboundGroupSession* Encryption::beginOutboundSession() {
    void* outboundMemory = malloc(olm_outbound_group_session_size());
    auto outboundSession = olm_outbound_group_session(outboundMemory);

    auto length = olm_init_outbound_group_session_random_length(outboundSession);

    void* memory = malloc(length);

    int fd = open("/dev/random", O_RDONLY);
    read(fd, memory, length);

    olm_init_outbound_group_session(outboundSession, (uint8_t*)memory, length);

    return outboundSession;
}

std::string Encryption::getGroupSessionId(OlmOutboundGroupSession* session) {
    auto encryptedLength = olm_outbound_group_session_id_length(session);
    char* encryptedMemory = (char*)malloc(encryptedLength + 1);

    olm_outbound_group_session_id(session, (uint8_t*)encryptedMemory, encryptedLength);

    return encryptedMemory;
}

std::string Encryption::getGroupSessionKey(OlmOutboundGroupSession* session) {
    auto encryptedLength = olm_outbound_group_session_key_length(session);
    char* encryptedMemory = (char*)malloc(encryptedLength + 1);

    olm_outbound_group_session_key(session, (uint8_t*)encryptedMemory, encryptedLength);

    return encryptedMemory;
}

OlmSession* Encryption::beginOutboundOlmSession(std::string identityKey, std::string oneTimeKey) {
    void* outboundMemory = malloc(olm_session_size());
    auto outboundSession = olm_session(outboundMemory);

    auto length = olm_create_outbound_session_random_length(outboundSession);

    void* memory = malloc(length);

    int fd = open("/dev/random", O_RDONLY);
    read(fd, memory, length);

    olm_create_outbound_session(outboundSession, account, identityKey.data(), identityKey.length(), oneTimeKey.data(), oneTimeKey.length(),  (uint8_t*)memory, length);
    //qDebug() << "ERR: " << olm_session_last_error(outboundSession);

    return outboundSession;

    /*size_t olm_create_outbound_session(
        OlmSession * session,
        OlmAccount * account,
        void const * their_identity_key, size_t their_identity_key_length,
        void const * their_one_time_key, size_t their_one_time_key_length,
        void * random, size_t random_length
    );*/

}

std::string Encryption::getSessionId(OlmSession* session) {
    auto length = olm_session_id_length(session);
    char* memory = (char*)malloc(length + 1);
    memory[length] = '\0';

    /** An identifier for this session. Will be the same for both ends of the
     * conversation. If the id buffer is too small then olm_session_last_error()
     * will be "OUTPUT_BUFFER_TOO_SMALL". */
    olm_session_id(
        session,
        memory, length
    );

    return memory;
}

std::string Encryption::encrypt(OlmSession* session, std::string message) {
    auto length = olm_encrypt_random_length(session);

    void* memory = malloc(length);

    int fd = open("/dev/random", O_RDONLY);
    read(fd, memory, length);

    auto encryptedLength = olm_encrypt_message_length(session, message.length());
    char* encryptedMemory = (char*)malloc(encryptedLength + 1);

    olm_encrypt(session, message.data(), message.length(), memory, length, encryptedMemory, encryptedLength);

    return encryptedMemory;
}

std::string Encryption::encryptGroup(OlmOutboundGroupSession* session, std::string message) {
    auto encryptedLength = olm_group_encrypt_message_length(session, message.length());
    char* encryptedMemory = (char*)malloc(encryptedLength + 1);

    olm_group_encrypt(session, (uint8_t*)message.data(), message.length(), (uint8_t*)encryptedMemory, encryptedLength);

    return encryptedMemory;
}

OlmSession* Encryption::createInboundSession(std::string senderKey, std::string body) {
    void* inboundMemory = malloc(olm_session_size());
    auto inboundSession = olm_session(inboundMemory);

    olm_create_inbound_session_from(inboundSession, account, (void*)senderKey.c_str(), senderKey.length(),  (void*)body.c_str(), body.length());

    return inboundSession;
}

std::vector<std::uint8_t> Encryption::decrypt(OlmSession* session, int msgType,  std::string cipherText) {
    /*std::string maxPlaintextLengthBuffer = cipherText;

    size_t maxPlaintextLength = olm_decrypt_max_plaintext_length(session, msgType, (void*)maxPlaintextLengthBuffer.data(), maxPlaintextLengthBuffer.length());;
    qDebug() << "THE ERROR YOU ARE LOOKING FOR " << olm_session_last_error(session);
    if(maxPlaintextLength == olm_error())
        return "";

    char* plaintext = new char[maxPlaintextLength];
    //plaintext[maxPlaintextLength] = '\0';
    memset(plaintext, '\0', maxPlaintextLength);
    int size = olm_decrypt(session, msgType, (void*)cipherText.data(), cipherText.length(), (void*)plaintext, maxPlaintextLength);
    //plaintext[size] = '\0';

    plaintext[size + 1] = '\0';

    return plaintext;*/

    // because olm_group_decrypt_max_plaintext_length DESTROYS the buffer, why?
    auto tmp_plaintext_buffer = std::vector<std::uint8_t>(cipherText.size());
    std::copy(cipherText.begin(), cipherText.end(), tmp_plaintext_buffer.begin());

    // create the result buffer
    size_t length = olm_decrypt_max_plaintext_length(session, msgType, tmp_plaintext_buffer.data(), tmp_plaintext_buffer.size());
    if(length == olm_error())
        return {};

    auto result_buffer = std::vector<std::uint8_t>(length);

    // now create another buffer for olm_group_decrypt
    auto tmp_buffer = std::vector<std::uint8_t>(cipherText.size());
    std::copy(cipherText.begin(), cipherText.end(), tmp_buffer.begin());

    auto size = olm_decrypt(session, msgType, tmp_buffer.data(), tmp_buffer.size(), result_buffer.data(), result_buffer.size());
    if(size == olm_error())
        return {};

    auto output = std::vector<std::uint8_t>(size);
    std::memcpy(output.data(), result_buffer.data(), size);

    return output;
}

QString Encryption::saveSession(OlmOutboundGroupSession* session) {
    auto length = olm_pickle_outbound_group_session_length(session);
    char* identity_memory = (char*)malloc(length + 1);
    identity_memory[length] = '\0';

    auto err = olm_pickle_outbound_group_session(session, "secret_key", 10, identity_memory, length);

    return identity_memory;
}

OlmOutboundGroupSession* Encryption::loadSession(QString bytes) {
    void* outboundMemory = malloc(olm_outbound_group_session_size());
    auto outboundSession = olm_outbound_group_session(outboundMemory);

    auto length = bytes.length();

    std::string key = bytes.toStdString();

    olm_unpickle_outbound_group_session(outboundSession, "secret_key", 10, (void*)key.data(), key.length());

    return outboundSession;
}

OlmInboundGroupSession* Encryption::beginInboundSession(std::string sessionKey) {
    void* inboundMemory = malloc(olm_inbound_group_session_size());
    auto inboundSession = olm_inbound_group_session(inboundMemory);

    olm_init_inbound_group_session(inboundSession, (uint8_t*)sessionKey.data(), sessionKey.size());

    return inboundSession;
}

std::vector<std::uint8_t> Encryption::decrypt(OlmInboundGroupSession* session, std::string cipherText) {
    // because olm_group_decrypt_max_plaintext_length DESTROYS the buffer, why?
    auto tmp_plaintext_buffer = std::vector<std::uint8_t>(cipherText.size());
    std::copy(cipherText.begin(), cipherText.end(), tmp_plaintext_buffer.begin());

    // create the result buffer
    size_t length = olm_group_decrypt_max_plaintext_length(session, tmp_plaintext_buffer.data(), tmp_plaintext_buffer.size());
    if(length == olm_error())
        return {};

    auto result_buffer = std::vector<std::uint8_t>(length);

    // now create another buffer for olm_group_decrypt
    auto tmp_buffer = std::vector<std::uint8_t>(cipherText.size());
    std::copy(cipherText.begin(), cipherText.end(), tmp_buffer.begin());

    uint32_t msgIndex;
    auto size = olm_group_decrypt(session, tmp_buffer.data(), tmp_buffer.size(), result_buffer.data(), result_buffer.size(), &msgIndex);
    if(size == olm_error())
        return {};

    auto output = std::vector<std::uint8_t>(size);
    std::memcpy(output.data(), result_buffer.data(), size);

    return output;
}