// SPDX-License-Identifier: GPL-3.0-only
/*
 *  Prism Launcher - Minecraft Launcher
 *  Copyright (c) 2022 flowln <flowlnlnln@gmail.com>
 *  Copyright (c) 2023 Rachel Powers <508861+Ryex@users.noreply.github.com>
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, version 3.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
 *
 * This file incorporates work covered by the following copyright and
 * permission notice:
 *
 *      Copyright 2013-2021 MultiMC Contributors
 *
 *      Licensed under the Apache License, Version 2.0 (the "License");
 *      you may not use this file except in compliance with the License.
 *      You may obtain a copy of the License at
 *
 *          http://www.apache.org/licenses/LICENSE-2.0
 *
 *      Unless required by applicable law or agreed to in writing, software
 *      distributed under the License is distributed on an "AS IS" BASIS,
 *      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *      See the License for the specific language governing permissions and
 *      limitations under the License.
 */
#include "ConcurrentTask.h"

#include <QCoreApplication>
#include <QDebug>
#include "tasks/Task.h"

ConcurrentTask::ConcurrentTask(QObject* parent, QString task_name, int max_concurrent)
    : Task(parent), m_name(task_name), m_total_max_size(max_concurrent)
{
    setObjectName(task_name);
}

ConcurrentTask::~ConcurrentTask()
{
    for (auto task : m_queue) {
        if (task)
            task->deleteLater();
    }
}

auto ConcurrentTask::getStepProgress() const -> TaskStepProgressList
{
    return m_task_progress.values();
}

void ConcurrentTask::addTask(Task::Ptr task)
{
    m_queue.append(task);
}

void ConcurrentTask::executeTask()
{
    // Start one task, startNext handles starting the up to the m_total_max_size
    // while tracking the number currently being done
    QMetaObject::invokeMethod(this, &ConcurrentTask::startNext, Qt::QueuedConnection);
}

bool ConcurrentTask::abort()
{
    m_queue.clear();
    m_aborted = true;

    if (m_doing.isEmpty()) {
        // Don't call emitAborted() here, we want to bypass the 'is the task running' check
        emit aborted();
        emit finished();

        return true;
    }

    bool suceedeed = true;

    QMutableHashIterator<Task*, Task::Ptr> doing_iter(m_doing);
    while (doing_iter.hasNext()) {
        auto task = doing_iter.next();
        disconnect(task->get(), &Task::aborted, this, 0);
        suceedeed &= (task.value())->abort();
    }

    if (suceedeed)
        emitAborted();
    else
        emitFailed(tr("Failed to abort all running tasks."));

    return suceedeed;
}

void ConcurrentTask::clear()
{
    Q_ASSERT(!isRunning());

    m_done.clear();
    m_failed.clear();
    m_queue.clear();

    m_aborted = false;

    m_progress = 0;
    m_stepProgress = 0;
}

void ConcurrentTask::startNext()
{
    if (m_aborted || m_doing.count() > m_total_max_size)
        return;

    if (m_queue.isEmpty() && m_doing.isEmpty() && !wasSuccessful()) {
        emitSucceeded();
        return;
    }

    if (m_queue.isEmpty())
        return;

    Task::Ptr next = m_queue.dequeue();

    connect(next.get(), &Task::succeeded, this, [this, next]() { subTaskSucceeded(next); });
    connect(next.get(), &Task::failed, this, [this, next](QString msg) { subTaskFailed(next, msg); });
    connect(next.get(), &Task::aborted, this, [this, next] { subTaskFailed(next, "Aborted"); });

    connect(next.get(), &Task::status, this, [this, next](QString msg) { subTaskStatus(next, msg); });
    connect(next.get(), &Task::details, this, [this, next](QString msg) { subTaskDetails(next, msg); });
    connect(next.get(), &Task::stepProgress, this, [this, next](TaskStepProgress const& tp) { subTaskStepProgress(next, tp); });

    connect(next.get(), &Task::progress, this, [this, next](qint64 current, qint64 total) { subTaskProgress(next, current, total); });

    m_doing.insert(next.get(), next);
    qsizetype num_starts = qMin(m_queue.size(), m_total_max_size - m_doing.size());
    auto task_progress = std::make_shared<TaskStepProgress>(next->getUid());
    m_task_progress.insert(next->getUid(), task_progress);

    updateState();
    updateStepProgress(*task_progress.get(), Operation::ADDED);

    QCoreApplication::processEvents();

    QMetaObject::invokeMethod(next.get(), &Task::start, Qt::QueuedConnection);

    // Allow going up the number of concurrent tasks in case of tasks being added in the middle of a running task.
    for (int i = 0; i < num_starts; i++)
        QMetaObject::invokeMethod(this, &ConcurrentTask::startNext, Qt::QueuedConnection);
}

void ConcurrentTask::subTaskSucceeded(Task::Ptr task)
{
    m_done.insert(task.get(), task);
    m_succeeded.insert(task.get(), task);

    m_doing.remove(task.get());
    auto task_progress = m_task_progress.value(task->getUid());
    task_progress->state = TaskStepState::Succeeded;

    disconnect(task.get(), 0, this, 0);

    emit stepProgress(*task_progress);
    updateState();
    updateStepProgress(*task_progress, Operation::REMOVED);
    startNext();
}

void ConcurrentTask::subTaskFailed(Task::Ptr task, [[maybe_unused]] const QString& msg)
{
    m_done.insert(task.get(), task);
    m_failed.insert(task.get(), task);

    m_doing.remove(task.get());

    auto task_progress = m_task_progress.value(task->getUid());
    task_progress->state = TaskStepState::Failed;

    disconnect(task.get(), 0, this, 0);

    emit stepProgress(*task_progress);
    updateState();
    updateStepProgress(*task_progress, Operation::REMOVED);
    startNext();
}

void ConcurrentTask::subTaskStatus(Task::Ptr task, const QString& msg)
{
    auto task_progress = m_task_progress.value(task->getUid());
    task_progress->status = msg;
    task_progress->state = TaskStepState::Running;

    emit stepProgress(*task_progress);

    if (totalSize() == 1) {
        setStatus(msg);
    }
}

void ConcurrentTask::subTaskDetails(Task::Ptr task, const QString& msg)
{
    auto task_progress = m_task_progress.value(task->getUid());
    task_progress->details = msg;
    task_progress->state = TaskStepState::Running;

    emit stepProgress(*task_progress);

    if (totalSize() == 1) {
        setDetails(msg);
    }
}

void ConcurrentTask::subTaskProgress(Task::Ptr task, qint64 current, qint64 total)
{
    auto task_progress = m_task_progress.value(task->getUid());

    task_progress->update(current, total);

    emit stepProgress(*task_progress);
    updateStepProgress(*task_progress, Operation::CHANGED);
    updateState();

    if (totalSize() == 1) {
        setProgress(task_progress->current, task_progress->total);
    }
}

void ConcurrentTask::subTaskStepProgress(Task::Ptr task, TaskStepProgress const& task_progress)
{
    Operation op = Operation::ADDED;

    if (!m_task_progress.contains(task_progress.uid)) {
        m_task_progress.insert(task_progress.uid, std::make_shared<TaskStepProgress>(task_progress));
        op = Operation::ADDED;
        emit stepProgress(task_progress);
        updateStepProgress(task_progress, op);
    } else {
        auto tp = m_task_progress.value(task_progress.uid);

        tp->old_current = tp->current;
        tp->old_total = tp->total;

        tp->current = task_progress.current;
        tp->total = task_progress.total;
        tp->status = task_progress.status;
        tp->details = task_progress.details;

        op = Operation::CHANGED;
        emit stepProgress(*tp.get());
        updateStepProgress(*tp.get(), op);
    }
}

void ConcurrentTask::updateStepProgress(TaskStepProgress const& changed_progress, Operation op)
{
    switch (op) {
        case Operation::ADDED:
            m_stepProgress += changed_progress.current;
            m_stepTotalProgress += changed_progress.total;
            break;
        case Operation::REMOVED:
            m_stepProgress -= changed_progress.current;
            m_stepTotalProgress -= changed_progress.total;
            break;
        case Operation::CHANGED:
            m_stepProgress -= changed_progress.old_current;
            m_stepTotalProgress -= changed_progress.old_total;
            m_stepProgress += changed_progress.current;
            m_stepTotalProgress += changed_progress.total;
            break;
    }
}

void ConcurrentTask::updateState()
{
    if (totalSize() > 1) {
        setProgress(m_done.count(), totalSize());
        setStatus(tr("Executing %1 task(s) (%2 out of %3 are done)")
                      .arg(QString::number(m_doing.count()), QString::number(m_done.count()), QString::number(totalSize())));
    } else {
        setProgress(m_stepProgress, m_stepTotalProgress);
        QString status = tr("Please wait...");
        if (m_queue.size() > 0) {
            status = tr("Waiting for a task to start...");
        } else if (m_doing.size() > 0) {
            status = tr("Executing 1 task:");
        } else if (m_done.size() > 0) {
            status = tr("Task finished.");
        }
        setStatus(status);
    }
}
