handlenetworkreply.h

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/**********************************************************************
 * LeechCraft - modular cross-platform feature rich internet client.
 * Copyright (C) 2006-2014  Georg Rudoy
 *
 * Distributed under the Boost Software License, Version 1.0.
 * (See accompanying file LICENSE or copy at https://www.boost.org/LICENSE_1_0.txt)
 **********************************************************************/
 
#pragma once
 
#include <QNetworkReply>
#include <util/sll/either.h>
#include <util/sll/void.h>
#include <util/sll/typelist.h>
#include <util/threads/futures.h>
#include "networkconfig.h"
 
namespace LC::Util
{
    template<typename F>
    void HandleNetworkReply (QObject *context, QNetworkReply *reply, F f)
    {
        QObject::connect (reply,
                &QNetworkReply::finished,
                context,
                [reply, f]
                {
                    reply->deleteLater ();
                    f (reply->readAll ());
                });
    }
 
    template<typename>
    struct ErrorInfo;
 
    template<typename>
    struct ResultInfo;
 
    struct UTIL_NETWORK_API ReplyWithHeaders
    {
        int Code_;
        QByteArray Data_;
        QHash<QByteArray, QList<QByteArray>> Headers_;
 
        explicit ReplyWithHeaders (QNetworkReply*);
    };
 
    struct UTIL_NETWORK_API ReplyError
    {
        QNetworkReply::NetworkError Error_;
        QString ErrorString_;
 
        QVariant HttpStatusCode_;
 
        explicit ReplyError (QNetworkReply*);
    };
 
    template<typename... Args>
    auto HandleReply (QNetworkReply *reply, QObject *context)
    {
        using Err = Find<ErrorInfo, Void, Args...>;
        using Res = Find<ResultInfo, QByteArray, Args...>;
 
        using Result_t = Either<Err, Res>;
        QFutureInterface<Result_t> promise;
        promise.reportStarted ();
 
        QObject::connect (reply,
                &QNetworkReply::finished,
                context,
                [promise, reply] () mutable
                {
                    reply->deleteLater ();
 
                    if constexpr (std::is_same_v<Res, QByteArray>)
                        Util::ReportFutureResult (promise, reply->readAll ());
                    else if constexpr (std::is_same_v<Res, ReplyWithHeaders>)
                        Util::ReportFutureResult (promise, Res { reply });
                    else
                        static_assert (std::is_same_v<Res, struct Dummy>, "Unsupported reply type");
                });
        QObject::connect (reply,
                &QNetworkReply::errorOccurred,
                context,
                [promise, reply] () mutable
                {
                    reply->deleteLater ();
 
                    auto report = [&] (const Err& val) { Util::ReportFutureResult (promise, Left { val }); };
 
                    if constexpr (std::is_same_v<Err, QString>)
                        report (reply->errorString ());
                    else if constexpr (std::is_same_v<Err, Void>)
                        report ({});
                    else if constexpr (std::is_same_v<Err, ReplyError>)
                        report (Err { reply });
                    else
                        static_assert (std::is_same_v<Err, struct Dummy>, "Unsupported error type");
                });
 
        return promise.future ();
    }
 
    template<typename... Args>
    auto HandleReplySeq (QNetworkReply *reply, QObject *context)
    {
        return Sequence (context, HandleReply<Args...> (reply, context));
    }
}