#include "rpc/RpcClient.hpp"

#include <utility>

#include <QLoggingCategory>

#include "rpc/RpcConnection.hpp"

namespace velox::gui::rpc {

// Off by default; enable with QT_LOGGING_RULES="velox.rpc.info=true".
Q_LOGGING_CATEGORY(lcRpc, "velox.rpc")

RpcClient::RpcClient(QString socketPath, QObject *parent) : QObject(parent) {
    conn_ = new RpcConnection(std::move(socketPath));
    conn_->moveToThread(&thread_);
    // QThread flushes DeferredDelete for its objects after the loop exits, so this is the
    // safe way to destroy an object that lives on the worker thread.
    connect(&thread_, &QThread::finished, conn_, &QObject::deleteLater);

    connect(conn_, &RpcConnection::stateChanged, this, &RpcClient::onConnectionState);
    connect(conn_, &RpcConnection::notificationReceived, this, &RpcClient::onNotification);
    connect(conn_, &RpcConnection::callCompleted, this, &RpcClient::onCallCompleted);
}

RpcClient::~RpcClient() {
    if (thread_.isRunning()) {
        stop();  // joins thread_; the finished -> deleteLater above disposes of conn_
    } else {
        delete conn_;  // start() was never called: no loop will service deleteLater
    }
    conn_ = nullptr;
    // Nothing will ever complete the in-flight callbacks now.
    const auto pending = std::move(callbacks_);
    callbacks_.clear();
    for (const auto &cb : pending) {
        if (cb) {
            RpcReply reply;
            reply.error = {-1, QStringLiteral("client shutting down"), {}};
            cb(reply);
        }
    }
}

void RpcClient::start() {
    if (!thread_.isRunning()) {
        thread_.start();
    }
    QMetaObject::invokeMethod(conn_, "start", Qt::QueuedConnection);
}

void RpcClient::stop() {
    if (!thread_.isRunning()) {
        return;
    }
    QMetaObject::invokeMethod(conn_, "stop", Qt::QueuedConnection);
    thread_.quit();
    thread_.wait();
    // thread_.wait() does not return until thread_'s own finish() has already flushed the
    // DeferredDelete this class's own connect(&thread_, &QThread::finished, conn_,
    // &QObject::deleteLater) posted — conn_ is gone by now. Null it out so a later call
    // (stop() is a public slot; a caller stopping and then destroying the client is normal
    // use, and the destructor's own `delete conn_` for the never-started case must not
    // run a second time against memory this path already freed).
    conn_ = nullptr;
}

void RpcClient::call(const QString &methodName, const QJsonObject &params,
                     std::function<void(const RpcReply &)> cb) {
    const quint64 tag = nextTag_++;
    callbacks_.insert(tag, std::move(cb));
    QMetaObject::invokeMethod(conn_, "sendCall", Qt::QueuedConnection, Q_ARG(quint64, tag),
                              Q_ARG(QString, methodName), Q_ARG(QJsonObject, params));
}

void RpcClient::onConnectionState(int state) {
    state_ = static_cast<ConnectionState>(state);
    qCInfo(lcRpc, "connection state: %s", toString(state_));
    emit stateChanged(state_);
    if (state_ == ConnectionState::Connected) {
        requestInitialList();
    }
}

void RpcClient::requestInitialList() {
    fetchListPage(0, {});
}

// download.list.schema.json: "Filtering, sorting and paging all happen in the daemon so
// the GUI never materializes 100k rows to show 40" — limit maxes out at 5000, so one call
// cannot ever return everything for a table the DoD's own gate says can hold 10 000 rows.
// A single fixed-limit call here silently truncated the table below that (caught by
// gui/tests/dod's scroll-60fps gate refusing to run against a 1000-row table when mockd
// seeded 10000). Page until `total` is satisfied, then reset the model exactly once.
void RpcClient::fetchListPage(int offset, QJsonArray accumulated) {
    constexpr int kPageSize = 5000;  // download.list's own maximum
    constexpr int kMaxPages = 100;   // 500 000 rows — a safety cap, not an expected ceiling
    call(QString::fromLatin1(method::kDownloadList),
         QJsonObject{{"offset", offset}, {"limit", kPageSize}},
         [this, offset, accumulated](const RpcReply &reply) mutable {
             if (!reply.ok()) {
                 qCWarning(lcRpc, "download.list failed: %d %s", reply.error.code,
                           qUtf8Printable(reply.error.message));
                 if (!accumulated.isEmpty()) {
                     emit taskListReset(accumulated);  // show what we got rather than nothing
                 }
                 return;
             }
             const QJsonObject result = reply.result.toObject();
             const QJsonArray page = result.value("items").toArray();
             const qint64 total = static_cast<qint64>(result.value("total").toDouble());
             for (const QJsonValue &item : page) {
                 accumulated.append(item);
             }
             const bool morePages =
                 !page.isEmpty() && accumulated.size() < total && (offset / kPageSize) < kMaxPages;
             if (morePages) {
                 fetchListPage(offset + static_cast<int>(page.size()), accumulated);
                 return;
             }
             qCInfo(lcRpc, "initial download.list: %lld of %lld row(s)",
                    static_cast<long long>(accumulated.size()), static_cast<long long>(total));
             emit taskListReset(accumulated);
         });
}

void RpcClient::onNotification(const QString &methodName, const QJsonObject &params) {
    qCDebug(lcRpc, "notification: %s", qUtf8Printable(methodName));
    if (methodName == QLatin1String(event::kTaskProgress)) {
        const QJsonArray tasks = params.value("tasks").toArray();
        qCDebug(lcRpc, "progress batch: %lld task(s)", static_cast<long long>(tasks.size()));
        emit taskProgress(tasks);
    } else if (methodName == QLatin1String(event::kTaskAdded)) {
        emit taskAdded(params.value("summary").toObject());
    } else if (methodName == QLatin1String(event::kTaskState)) {
        emit taskStateChanged(params);
    } else if (methodName == QLatin1String(event::kTaskRemoved)) {
        emit taskRemoved(params.value("taskId").toString());
    } else if (methodName == QLatin1String(event::kSpeedGlobal)) {
        emit speedGlobal(params);
    } else if (methodName == QLatin1String(event::kNotify)) {
        emit notify(params);
    } else if (methodName == QLatin1String(event::kSettingsChanged)) {
        emit settingsChanged(params);
    } else if (methodName == QLatin1String(event::kGrabberProgress)) {
        emit grabberProgress(params);
    }
}

void RpcClient::onCallCompleted(quint64 tag, const QJsonObject &envelope) {
    const auto cb = callbacks_.take(tag);
    if (!cb) {
        return;
    }
    RpcReply reply;
    if (envelope.contains("error")) {
        const QJsonObject e = envelope.value("error").toObject();
        reply.error = {e.value("code").toInt(), e.value("message").toString(), e.value("data")};
    } else {
        reply.result = envelope.value("result");
    }
    cb(reply);
}

}  // namespace velox::gui::rpc