#include <QTest>
#include <QTimer>
#include <QThread>

#include <tasks/ConcurrentTask.h>
#include <tasks/MultipleOptionsTask.h>
#include <tasks/SequentialTask.h>
#include <tasks/Task.h>

#include <array>

/* Does nothing. Only used for testing. */
class BasicTask : public Task {
    Q_OBJECT

    friend class TaskTest;

   public:
    BasicTask(bool show_debug_log = true) : Task(nullptr, show_debug_log) {}

   private:
    void executeTask() override
    {
        emitSucceeded();
    };
};

/* Does nothing. Only used for testing. */
class BasicTask_MultiStep : public Task {
    Q_OBJECT

    friend class TaskTest;

   private:
    auto isMultiStep() const -> bool override { return true; }

    void executeTask() override {};   
};

class BigConcurrentTask : public ConcurrentTask {
    Q_OBJECT

    void startNext() override
    {
        // This is here only to help fill the stack a bit more quickly (if there's an issue, of course :^))
        // Each tasks thus adds 1024 * 4 bytes to the stack, at the very least.
        [[maybe_unused]] volatile std::array<uint32_t, 1024> some_data_on_the_stack {};

        ConcurrentTask::startNext();
    }
};

class BigConcurrentTaskThread : public QThread {
    Q_OBJECT

    BigConcurrentTask big_task;

    void run() override
    {
        QTimer deadline;
        deadline.setInterval(10000);
        connect(&deadline, &QTimer::timeout, this, [this]{ passed_the_deadline = true; });
        deadline.start();

        // NOTE: Arbitrary value that manages to trigger a problem when there is one.
        //       Considering each tasks, in a problematic state, adds 1024 * 4 bytes to the stack,
        //       this number is enough to fill up 16 MiB of stack, more than enough to cause a problem.
        static const unsigned s_num_tasks = 1 << 12;
        auto sub_tasks = new BasicTask::Ptr[s_num_tasks];

        for (unsigned i = 0; i < s_num_tasks; i++) {
            sub_tasks[i] = makeShared<BasicTask>(false);
            big_task.addTask(sub_tasks[i]);
        }

        big_task.run();

        while (!big_task.isFinished() && !passed_the_deadline)
            QCoreApplication::processEvents();

        emit finished();
    }

   public:
    bool passed_the_deadline = false;

   signals:
    void finished();
};

class TaskTest : public QObject {
    Q_OBJECT

   private slots:
    void test_SetStatus_NoMultiStep(){
        BasicTask t;
        QString status {"test status"};

        t.setStatus(status);

        QCOMPARE(t.getStatus(), status);
        QCOMPARE(t.getStepStatus(), status);
    }

    void test_SetStatus_MultiStep(){
        BasicTask_MultiStep t;
        QString status {"test status"};

        t.setStatus(status);

        QCOMPARE(t.getStatus(), status);
        // Even though it is multi step, it does not override the getStepStatus method,
        // so it should remain the same.
        QCOMPARE(t.getStepStatus(), status);
    }

    void test_SetProgress(){
        BasicTask t;
        int current = 42;
        int total = 207;

        t.setProgress(current, total);

        QCOMPARE(t.getProgress(), current);
        QCOMPARE(t.getTotalProgress(), total);
    }

    void test_basicRun(){
        BasicTask t;
        QObject::connect(&t, &Task::finished, [&]{ QVERIFY2(t.wasSuccessful(), "Task finished but was not successful when it should have been."); });
        t.start();

        QVERIFY2(QTest::qWaitFor([&]() {
            return t.isFinished();
        }, 1000), "Task didn't finish as it should.");
    }

    void test_basicConcurrentRun(){
        auto t1 = makeShared<BasicTask>();
        auto t2 = makeShared<BasicTask>();
        auto t3 = makeShared<BasicTask>();

        ConcurrentTask t;

        t.addTask(t1);
        t.addTask(t2);
        t.addTask(t3);

        QObject::connect(&t, &Task::finished, [&]{
                QVERIFY2(t.wasSuccessful(), "Task finished but was not successful when it should have been.");
                QVERIFY(t1->wasSuccessful());
                QVERIFY(t2->wasSuccessful());
                QVERIFY(t3->wasSuccessful());
        });

        t.start();
        QVERIFY2(QTest::qWaitFor([&]() {
            return t.isFinished();
        }, 1000), "Task didn't finish as it should.");
    }

    // Tests if starting new tasks after the 6 initial ones is working
    void test_moreConcurrentRun(){
        auto t1 = makeShared<BasicTask>();
        auto t2 = makeShared<BasicTask>();
        auto t3 = makeShared<BasicTask>();
        auto t4 = makeShared<BasicTask>();
        auto t5 = makeShared<BasicTask>();
        auto t6 = makeShared<BasicTask>();
        auto t7 = makeShared<BasicTask>();
        auto t8 = makeShared<BasicTask>();
        auto t9 = makeShared<BasicTask>();

        ConcurrentTask t;

        t.addTask(t1);
        t.addTask(t2);
        t.addTask(t3);
        t.addTask(t4);
        t.addTask(t5);
        t.addTask(t6);
        t.addTask(t7);
        t.addTask(t8);
        t.addTask(t9);

        QObject::connect(&t, &Task::finished, [&]{
                QVERIFY2(t.wasSuccessful(), "Task finished but was not successful when it should have been.");
                QVERIFY(t1->wasSuccessful());
                QVERIFY(t2->wasSuccessful());
                QVERIFY(t3->wasSuccessful());
                QVERIFY(t4->wasSuccessful());
                QVERIFY(t5->wasSuccessful());
                QVERIFY(t6->wasSuccessful());
                QVERIFY(t7->wasSuccessful());
                QVERIFY(t8->wasSuccessful());
                QVERIFY(t9->wasSuccessful());
        });

        t.start();
        QVERIFY2(QTest::qWaitFor([&]() {
            return t.isFinished();
        }, 1000), "Task didn't finish as it should.");
    }

    void test_basicSequentialRun(){
        auto t1 = makeShared<BasicTask>();
        auto t2 = makeShared<BasicTask>();
        auto t3 = makeShared<BasicTask>();

        SequentialTask t;

        t.addTask(t1);
        t.addTask(t2);
        t.addTask(t3);

        QObject::connect(&t, &Task::finished, [&]{
                QVERIFY2(t.wasSuccessful(), "Task finished but was not successful when it should have been.");
                QVERIFY(t1->wasSuccessful());
                QVERIFY(t2->wasSuccessful());
                QVERIFY(t3->wasSuccessful());
        });

        t.start();
        QVERIFY2(QTest::qWaitFor([&]() {
            return t.isFinished();
        }, 1000), "Task didn't finish as it should.");
    }

    void test_basicMultipleOptionsRun(){
        auto t1 = makeShared<BasicTask>();
        auto t2 = makeShared<BasicTask>();
        auto t3 = makeShared<BasicTask>();

        MultipleOptionsTask t;

        t.addTask(t1);
        t.addTask(t2);
        t.addTask(t3);

        QObject::connect(&t, &Task::finished, [&]{
                QVERIFY2(t.wasSuccessful(), "Task finished but was not successful when it should have been.");
                QVERIFY(t1->wasSuccessful());
                QVERIFY(!t2->wasSuccessful());
                QVERIFY(!t3->wasSuccessful());
        });

        t.start();
        QVERIFY2(QTest::qWaitFor([&]() {
            return t.isFinished();
        }, 1000), "Task didn't finish as it should.");
    }

    void test_stackOverflowInConcurrentTask()
    {
        QEventLoop loop;

        auto thread = new BigConcurrentTaskThread;

        connect(thread, &BigConcurrentTaskThread::finished, &loop, &QEventLoop::quit);

        thread->start();

        loop.exec();

        QVERIFY(!thread->passed_the_deadline);
        thread->deleteLater();
    }
};

QTEST_GUILESS_MAIN(TaskTest)

#include "Task_test.moc"