#include "api.h"
#include <QDebug>
#include <QJsonDocument>
#include <QJsonObject>
#include <QUrlQuery>
#include <QTimer>

#include "codes.h"
#include "finalaction.h"

constexpr const char* json = "application/json";
constexpr const char* urlEncoded = "application/x-www-form-urlencoded";

const std::map<QString, QMetaType::Type> testStructure({
    {"type", QMetaType::QString},
    {"version", QMetaType::QString},
});

const std::map<QString, QMetaType::Type> resultStructure({
    {"result", QMetaType::LongLong},
});

const std::map<QString, QMetaType::Type> tokensStructure({
    {"accessToken", QMetaType::QString},
    {"renewToken", QMetaType::QString}
});

struct NetworkReplyDeleter {
    void operator () (QNetworkReply* reply) {
        reply->deleteLater();
    }
};

API::API(const QUrl& address, QObject* parent):
    QObject(parent),
    address(address),
    network(),
    state(NoServer)
{}

QUrl API::getAddress() const {
    return address;
}

API::State API::getState() const {
    return state;
}

void API::setTokens(const QString access, const QString &renew) {
    accessToken = access;
    renewToken = renew;
    setState(Authenticating);

    //dont forget to remove
    QTimer::singleShot(1000, this, [this] () {
        setState(Authenticated);
    });
}

void API::setAddress(const QUrl& path) {
    if (address == path)
        return;

    if (state == Authenticated) {
        //do something
    }

    address = path;
    emit addressChanged(address);
    setState(address.isEmpty() ? NoServer : NotAuthenticated);
}

std::optional<QVariantMap> API::readResult(QNetworkReply* reply) {
    QVariant contentType = reply->header(QNetworkRequest::ContentTypeHeader);
    if (!
        contentType.isValid() ||
        contentType.userType() != QMetaType::QString ||
        contentType.toString() != json
    )
        return std::nullopt;

    QByteArray data = reply->readAll();
    QJsonDocument document = QJsonDocument::fromJson(data);
    if (!document.isObject())
        return std::nullopt;

    QJsonObject object = document.object();
    return object.toVariantMap();
}

bool API::validateResponse(const std::optional<QVariantMap>& data, const std::map<QString, QMetaType::Type>& structure) {
    if (!data.has_value())
        return false;

    for (const std::pair<const QString, QMetaType::Type>& pair : structure) {
        QVariantMap::ConstIterator itr = data->find(pair.first);
        if (itr == data->end())
            return false;

        if (itr->userType() != pair.second)
            return false;
    }

    return true;
}

void API::setState(State newState) {
    if (newState == state)
        return;

    state = newState;
    emit stateChanged(state);
}

void API::test(const QString& path, const QJSValue& finished) {
    qDebug() << "Testing" << path;
    if (state == Offline)
        return callCallback(finished, "Need to be online to test");

    QUrl address(path);
    QNetworkRequest request(path + "/info");
    request.setHeader(QNetworkRequest::ContentTypeHeader, json);

    QNetworkReply* reply = network.get(request);
    connect(reply, &QNetworkReply::finished,
        std::bind(&API::onTestFinished, this, reply, address, finished)
    );
}

void API::onTestFinished(QNetworkReply* reply, const QUrl& addr, const QJSValue& finished) {
    std::unique_ptr<QNetworkReply, NetworkReplyDeleter> rpl(reply);
    QNetworkReply::NetworkError error = reply->error();
    if (error != QNetworkReply::NoError)
        return callCallback(finished, reply->errorString());

    std::optional<QVariantMap> data = readResult(reply);
    if (!validateResponse(data, testStructure))
        return callCallback(finished, "Malformed response");

    QString type = data->value("type").toString();
    if (type != "pica")
        return callCallback(finished, "server of this type (" + type + ") is not supported");

    QString version = data->value("version").toString();
    if (version != "0.0.1")
        return callCallback(finished, "server of this version (" + version + ") is not supported");

    callCallback(finished, QString(), {QJSValue(true)});
    address = "";       //to provoke singal change even if it's the same server
    setAddress(addr);
}

void API::sendRegister(const QString& login, const QString& password, const QJSValue& finished) {
    qDebug() << "Registering...";
    if (state != NotAuthenticated)
        return callCallback(finished, "Can not register in current state");

    QUrlQuery params({
        {"login", login},
        {"password", password}
    });

    QString path = address.path();
    QUrl regUrl = address;
    regUrl.setPath(path + "/register");

    QNetworkRequest request(regUrl);
    request.setHeader(QNetworkRequest::ContentTypeHeader, urlEncoded);

    QNetworkReply* reply = network.post(request, params.toString(QUrl::FullyEncoded).toUtf8());
    connect(reply, &QNetworkReply::finished,
        std::bind(&API::onRegisterFinished, this, reply, finished)
    );
}

void API::sendLogin(const QString& login, const QString& password, const QJSValue& finished) {
    qDebug() << "Logging in...";
    if (state != NotAuthenticated)
        return callCallback(finished, "Can not register in current state");

    QUrlQuery params({
        {"login", login},
        {"password", password}
    });

    QString path = address.path();
    QUrl url = address;
    url.setPath(path + "/login");

    QNetworkRequest request(url);
    request.setHeader(QNetworkRequest::ContentTypeHeader, urlEncoded);
    setState(Authenticating);
    QNetworkReply* reply = network.post(request, params.toString(QUrl::FullyEncoded).toUtf8());
    connect(reply, &QNetworkReply::finished,
            std::bind(&API::onLoginFinished, this, reply, finished)
    );
}

void API::onRegisterFinished(QNetworkReply* reply, const QJSValue& finished) const {
    std::unique_ptr<QNetworkReply, NetworkReplyDeleter> rpl(reply);
    QNetworkReply::NetworkError error = reply->error();
    std::optional<QVariantMap> data = readResult(reply);
    std::optional<Codes::Register> code;
    QString detail;
    bool success = false;
    if (validateResponse(data, resultStructure)) {
        code = Codes::convertRegister(data->value("result").toInt());
        success = code.value() == Codes::Register::success;
        if (!success)
            detail = Codes::description(code.value());
    }

    if (error != QNetworkReply::NoError)
        return callCallback(finished, reply->errorString() + (success ? "" : ": " + detail));

    if (!code)
        return callCallback(finished, "Malformed result");

    callCallback(finished, detail, {QJSValue(success)});
}

void API::onLoginFinished(QNetworkReply* reply, const QJSValue& finished) {
    State state = NotAuthenticated;
    FinalAction action([this, &state]() {       //this should be executed on leaving the function in any way
        setState(state);                        //setting the state as a result of this object destruction
    });                                         //this way any error will result in NotAuthenticated, and on success it should be Authenticated

    std::unique_ptr<QNetworkReply, NetworkReplyDeleter> rpl(reply);
    QNetworkReply::NetworkError error = reply->error();
    std::optional<QVariantMap> data = readResult(reply);
    std::optional<Codes::Login> code;
    QString detail;
    bool success = false;
    if (validateResponse(data, resultStructure)) {
        code = Codes::convertLogin(data->value("result").toInt());
        success = code.value() == Codes::Login::success;
        if (!success)
            detail = Codes::description(code.value());
    }

    if (error != QNetworkReply::NoError)
        return callCallback(finished, reply->errorString() + (success ? "" : ": " + detail));

    if (!code)
        return callCallback(finished, "Malformed result");

    if (!validateResponse(data, tokensStructure))
        return callCallback(finished, "Malformed result: missing tokens");


    callCallback(finished, detail, {QJSValue(success)});

    state = Authenticated;
    accessToken = data->value("accessToken").toString();
    renewToken = data->value("renewToken").toString();
    emit storeTokens(accessToken, renewToken);
}

void API::callCallback(const QJSValue& callback, const QString& error, const QJSValueList& arguments) const {
    if (callback.isCallable()) {
        if (error.isEmpty())
            callback.call(QJSValueList({QJSValue(QJSValue::NullValue)}) + arguments);
        else
            callback.call({QJSValue(error)});
    }
}