#include "gtest/gtest.h"
#include "rtabmap/utilite/UEvent.h"
#include "rtabmap/utilite/UEventsHandler.h"
#include "rtabmap/utilite/UEventsManager.h"
#include "rtabmap/utilite/UEventsSender.h"
#include "rtabmap/utilite/UTimer.h"
#include <thread>
#include <chrono>
#include <atomic>

// Test event classes
class TestEvent : public UEvent
{
public:
    TestEvent(int code = 0) : UEvent(code) {}
    virtual ~TestEvent() {}
    virtual std::string getClassName() const {return "TestEvent";}
};

class AnotherEvent : public UEvent
{
public:
    AnotherEvent() : UEvent(0) {}
    virtual ~AnotherEvent() {}
    virtual std::string getClassName() const {return "AnotherEvent";}
};

// Test handler class
class TestHandler : public UEventsHandler
{
public:
    TestHandler() : eventCount_(0), lastEventCode_(0){}
    
    int getEventCount() const { return eventCount_; }
    int getLastEventCode() const { return lastEventCode_; }
    const std::string & getLastEventClassName() const { return lastEventClassName_; }
    void reset() { eventCount_ = 0; lastEventCode_ = 0; lastEventClassName_.clear(); }
    
protected:
    virtual bool handleEvent(UEvent * event)
    {
        eventCount_++;
        lastEventCode_ = event->getCode();
        lastEventClassName_ = event->getClassName();
        return false;
    }

private:
    int eventCount_;
    int lastEventCode_;
    std::string lastEventClassName_;
    bool ownershipTaken_;
};

// Handler that takes ownership
class OwnershipHandler : public UEventsHandler
{
public:
    OwnershipHandler() : event_(nullptr) {}
    ~OwnershipHandler() {delete event_;}
    const UEvent * getEvent() const {return event_;} 
    void reset() { delete event_; event_ = nullptr;}
    
protected:
    virtual bool handleEvent(UEvent * event)
    {
        event_ = event; // Take ownership
        return true;
    }
    
private:
    UEvent * event_;
};

// Handler that filters events
class FilteringHandler : public UEventsHandler
{
public:
    FilteringHandler() : testEventCount_(0), anotherEventCount_(0) {}
    int getTestEventCount() const { return testEventCount_; }
    int getAnotherEventCount() const { return anotherEventCount_; }
    void reset() { testEventCount_ = 0; anotherEventCount_ = 0; }
    
protected:
    virtual bool handleEvent(UEvent * event)
    {
        if(event->getClassName() == "TestEvent")
        {
            testEventCount_++;
        }
        else if(event->getClassName() == "AnotherEvent")
        {
            anotherEventCount_++;
        }
        return false;
    }
    
private:
    int testEventCount_;
    int anotherEventCount_;
};

// Test sender class that can post events
class TestSender : public UEventsSender
{
public:
    TestSender() {}
    
    // Public method to test protected post() method
    void testPost(UEvent* event, bool async = true) const
    {
        post(event, async);
    }
};

TEST(UEventsTest, UEventGetClassName)
{
    TestEvent event;
    EXPECT_EQ(event.getClassName(), "TestEvent");
    EXPECT_EQ(event.getCode(), 0);
}

TEST(UEventsTest, UEventGetCode)
{
    TestEvent event(42);
    EXPECT_EQ(event.getCode(), 42);
}

TEST(UEventsTest, UEventsHandlerRegisterUnregister)
{
    TestHandler handler;
    
    // Register handler
    handler.registerToEventsManager();
    
    // Post an event
    UEventsManager::post(new TestEvent(), true);
    
    // Give time for event to be processed
    std::this_thread::sleep_for(std::chrono::milliseconds(50));
    
    EXPECT_GT(handler.getEventCount(), 0);
    
    // Unregister handler
    handler.unregisterFromEventsManager();
    
    // Post another event
    int countBefore = handler.getEventCount();
    UEventsManager::post(new TestEvent(), true);
    std::this_thread::sleep_for(std::chrono::milliseconds(50));
    
    // Should not receive event after unregister
    EXPECT_EQ(handler.getEventCount(), countBefore);
}

TEST(UEventsTest, UEventsHandlerDestructorUnregisters)
{
    TestHandler* handler = new TestHandler();
    handler->registerToEventsManager();
    
    // Post an event
    UEventsManager::post(new TestEvent(), true);
    std::this_thread::sleep_for(std::chrono::milliseconds(50));

    EXPECT_EQ(handler->getEventCount(), 1);
    
    // Delete handler (should unregister automatically)
    handler->unregisterFromEventsManager();
    
    // Post another event
    UEventsManager::post(new TestEvent(), true);
    std::this_thread::sleep_for(std::chrono::milliseconds(50));
    
    EXPECT_EQ(handler->getEventCount(), 1);
}

TEST(UEventsTest, UEventsManagerAddRemoveHandler)
{
    TestHandler handler1;
    TestHandler handler2;
    
    UEventsManager::addHandler(&handler1);
    UEventsManager::addHandler(&handler2);
    
    UEventsManager::post(new TestEvent(), true);
    std::this_thread::sleep_for(std::chrono::milliseconds(50));
    
    EXPECT_GT(handler1.getEventCount(), 0);
    EXPECT_GT(handler2.getEventCount(), 0);
    
    UEventsManager::removeHandler(&handler1);
    
    int count1Before = handler1.getEventCount();
    int count2Before = handler2.getEventCount();
    
    UEventsManager::post(new TestEvent(), true);
    std::this_thread::sleep_for(std::chrono::milliseconds(50));
    
    EXPECT_EQ(handler1.getEventCount(), count1Before);
    EXPECT_GT(handler2.getEventCount(), count2Before);
    
    UEventsManager::removeHandler(&handler2);
}

TEST(UEventsTest, UEventsManagerPostAsync)
{
    TestHandler handler;
    UEventsManager::addHandler(&handler);
    
    handler.reset();
    
    UEventsManager::post(new TestEvent(), true);
    
    // Give time for async processing
    std::this_thread::sleep_for(std::chrono::milliseconds(100));
    
    EXPECT_GT(handler.getEventCount(), 0);
    
    UEventsManager::removeHandler(&handler);
}

TEST(UEventsTest, UEventsManagerPostSync)
{
    TestHandler handler;
    UEventsManager::addHandler(&handler);
    
    handler.reset();
    
    UEventsManager::post(new TestEvent(), false);
    
    // Sync should be immediate
    EXPECT_GT(handler.getEventCount(), 0);
    
    UEventsManager::removeHandler(&handler);
}

TEST(UEventsTest, UEventsManagerMultipleHandlers)
{
    TestHandler handler1;
    TestHandler handler2;
    TestHandler handler3;
    
    UEventsManager::addHandler(&handler1);
    UEventsManager::addHandler(&handler2);
    UEventsManager::addHandler(&handler3);
    
    handler1.reset();
    handler2.reset();
    handler3.reset();
    
    UEventsManager::post(new TestEvent(), true);
    std::this_thread::sleep_for(std::chrono::milliseconds(50));
    
    EXPECT_GT(handler1.getEventCount(), 0);
    EXPECT_GT(handler2.getEventCount(), 0);
    EXPECT_GT(handler3.getEventCount(), 0);
    
    UEventsManager::removeHandler(&handler1);
    UEventsManager::removeHandler(&handler2);
    UEventsManager::removeHandler(&handler3);
}

TEST(UEventsTest, UEventsManagerEventOrdering)
{
    TestHandler handler;
    UEventsManager::addHandler(&handler);
    
    handler.reset();
    
    // Post multiple events
    UEventsManager::post(new TestEvent(1), true);
    UEventsManager::post(new TestEvent(2), true);
    UEventsManager::post(new TestEvent(3), true);
    
    std::this_thread::sleep_for(std::chrono::milliseconds(100));
    
    // Should receive all events (order may vary in async mode)
    EXPECT_GE(handler.getEventCount(), 3);
    
    UEventsManager::removeHandler(&handler);
}

TEST(UEventsTest, UEventsHandlerOwnership)
{
    OwnershipHandler handler;
    TestHandler handler0;
    TestHandler handler2;
    UEventsManager::addHandler(&handler0);
    UEventsManager::addHandler(&handler);
    UEventsManager::addHandler(&handler2);
    
    UEventsManager::post(new TestEvent(42), true);
    std::this_thread::sleep_for(std::chrono::milliseconds(50));
    
    EXPECT_NE(handler.getEvent(), nullptr);
    EXPECT_EQ(handler.getEvent()->getCode(), 42);

    // Should have received the event
    EXPECT_GT(handler0.getEventCount(), 0);

    // Should not have received the event
    EXPECT_EQ(handler2.getEventCount(), 0);
    
    UEventsManager::removeHandler(&handler0);
    UEventsManager::removeHandler(&handler);
    UEventsManager::removeHandler(&handler2);
}

TEST(UEventsTest, UEventsHandlerFiltering)
{
    FilteringHandler handler;
    UEventsManager::addHandler(&handler);
    
    handler.reset();
    
    UEventsManager::post(new TestEvent(), true);
    UEventsManager::post(new AnotherEvent(), true);
    UEventsManager::post(new TestEvent(), true);
    
    std::this_thread::sleep_for(std::chrono::milliseconds(100));
    
    EXPECT_EQ(handler.getTestEventCount(), 2);
    EXPECT_EQ(handler.getAnotherEventCount(), 1);
    
    UEventsManager::removeHandler(&handler);
}

TEST(UEventsTest, UEventsSenderPost)
{
    TestSender sender;
    TestHandler handler;
    
    UEventsManager::addHandler(&handler);
    
    handler.reset();
    
    // Test protected post() method through TestSender
    sender.testPost(new TestEvent(), true);
    
    std::this_thread::sleep_for(std::chrono::milliseconds(50));
    
    EXPECT_GT(handler.getEventCount(), 0);
    
    UEventsManager::removeHandler(&handler);
}

TEST(UEventsTest, UEventsSenderDestructorRemovesPipes)
{
    TestSender* sender = new TestSender();
    TestHandler handler;
    
    UEventsManager::addHandler(&handler);
    UEventsManager::createPipe(sender, &handler, "TestEvent");
    
    // Delete sender - should remove pipes automatically
    delete sender;
    
    // Should not crash and pipes should be removed
    SUCCEED();
    
    UEventsManager::removeHandler(&handler);
}

TEST(UEventsTest, UEventsManagerCreateRemovePipe)
{
    TestSender sender;
    TestHandler handler;
    TestHandler handler2;
    
    UEventsManager::addHandler(&handler);
    UEventsManager::addHandler(&handler2);
    
    // Create a pipe
    UEventsManager::createPipe(&sender, &handler, "TestEvent");
    
    handler.reset();
    
    // Post event with sender
    sender.testPost(new TestEvent());
    std::this_thread::sleep_for(std::chrono::milliseconds(50));
    EXPECT_EQ(handler.getEventCount(), 1);
    EXPECT_EQ(handler2.getEventCount(), 0);

    // Post event with sender using UEventsManager
    UEventsManager::post(new TestEvent(), true, &sender);
    std::this_thread::sleep_for(std::chrono::milliseconds(50));
    EXPECT_EQ(handler.getEventCount(), 2);
    EXPECT_EQ(handler2.getEventCount(), 0);

    // Post global event
    UEventsManager::post(new TestEvent(), true);
    std::this_thread::sleep_for(std::chrono::milliseconds(50));
    EXPECT_EQ(handler.getEventCount(), 3);
    EXPECT_EQ(handler2.getEventCount(), 1);
    
    // Remove pipe
    UEventsManager::removePipe(&sender, &handler, "TestEvent");
    

    // Post another event
    UEventsManager::post(new TestEvent(), true, &sender);
    std::this_thread::sleep_for(std::chrono::milliseconds(50));
    
    // Should still receive events, no pipe filtering
    EXPECT_EQ(handler.getEventCount(), 4);
    EXPECT_EQ(handler2.getEventCount(), 2);
    
    UEventsManager::removeHandler(&handler);
    UEventsManager::removeHandler(&handler2);
}

TEST(UEventsTest, UEventsManagerRemoveAllPipes)
{
    TestSender sender;
    TestHandler handler1;
    TestHandler handler2;
    
    UEventsManager::addHandler(&handler1);
    UEventsManager::addHandler(&handler2);
    
    UEventsManager::createPipe(&sender, &handler1, "TestEvent");
    UEventsManager::createPipe(&sender, &handler2, "AnotherEvent");

    sender.testPost(new TestEvent());
    sender.testPost(new AnotherEvent());
    std::this_thread::sleep_for(std::chrono::milliseconds(50));
    EXPECT_EQ(handler1.getEventCount(), 1);
    EXPECT_EQ(handler2.getEventCount(), 1);
    
    UEventsManager::removeAllPipes(&sender);
    
    sender.testPost(new TestEvent());
    sender.testPost(new AnotherEvent());
    std::this_thread::sleep_for(std::chrono::milliseconds(50));
    EXPECT_EQ(handler1.getEventCount(), 3);
    EXPECT_EQ(handler2.getEventCount(), 3);
    
    UEventsManager::removeHandler(&handler1);
    UEventsManager::removeHandler(&handler2);
}

TEST(UEventsTest, MultipleEventTypes)
{
    FilteringHandler handler;
    UEventsManager::addHandler(&handler);
    
    handler.reset();
    
    UEventsManager::post(new TestEvent(), true);
    UEventsManager::post(new AnotherEvent(), true);
    UEventsManager::post(new TestEvent(), true);
    
    std::this_thread::sleep_for(std::chrono::milliseconds(100));
    
    EXPECT_EQ(handler.getTestEventCount(), 2);
    EXPECT_EQ(handler.getAnotherEventCount(), 1);
    
    UEventsManager::removeHandler(&handler);
}

TEST(UEventsTest, HandlerReceivesCorrectEvent)
{
    TestHandler handler;
    UEventsManager::addHandler(&handler);

    handler.reset();

    TestEvent* event = new TestEvent(42);
    UEventsManager::post(event, true);

    std::this_thread::sleep_for(std::chrono::milliseconds(50));

    EXPECT_EQ(handler.getLastEventCode(), 42);
    EXPECT_STREQ(handler.getLastEventClassName().c_str(), "TestEvent");

    UEventsManager::removeHandler(&handler);
}

// Handler that blocks inside handleEvent until released, used to observe
// whether removeHandler() waits for an in-flight dispatch to finish.
class BlockingHandler : public UEventsHandler
{
public:
    BlockingHandler() : inHandler_(false), finishedHandler_(false), release_(false) {}

    bool inHandler() const { return inHandler_.load(); }
    bool finishedHandler() const { return finishedHandler_.load(); }
    void release() { release_ = true; }

protected:
    virtual bool handleEvent(UEvent *)
    {
        inHandler_ = true;
        while(!release_.load())
        {
            std::this_thread::sleep_for(std::chrono::milliseconds(1));
        }
        finishedHandler_ = true;
        return false;
    }

private:
    std::atomic<bool> inHandler_;
    std::atomic<bool> finishedHandler_;
    std::atomic<bool> release_;
};

// Regression test: removeHandler() must not return while another thread is
// inside handleEvent() for that handler. Otherwise the caller can destroy the
// handler (or data it points at) while the dispatcher still uses it, causing
// heap corruption.
TEST(UEventsTest, RemoveHandlerBlocksUntilHandleEventCompletes)
{
    BlockingHandler handler;
    UEventsManager::addHandler(&handler);

    UEventsManager::post(new TestEvent(), true);

    // Wait until the dispatcher thread is inside handleEvent.
    UTimer waitEnter;
    while(!handler.inHandler() && waitEnter.ticks() < 1.0)
    {
        std::this_thread::sleep_for(std::chrono::milliseconds(1));
    }
    ASSERT_TRUE(handler.inHandler())
        << "Dispatcher never entered handleEvent within 1s";

    // Call removeHandler from a separate thread; it must block until the
    // dispatcher exits handleEvent.
    std::atomic<bool> removeReturned(false);
    std::thread remover([&]() {
        UEventsManager::removeHandler(&handler);
        removeReturned = true;
    });

    // Give the remover thread time to call into removeHandler and (correctly)
    // get stuck waiting for the dispatcher.
    std::this_thread::sleep_for(std::chrono::milliseconds(50));
    EXPECT_FALSE(removeReturned.load())
        << "removeHandler returned while handleEvent was still running";
    EXPECT_FALSE(handler.finishedHandler());

    // Let the dispatcher finish; removeHandler should now complete promptly.
    handler.release();

    UTimer waitReturn;
    while(!removeReturned.load() && waitReturn.ticks() < 1.0)
    {
        std::this_thread::sleep_for(std::chrono::milliseconds(1));
    }
    EXPECT_TRUE(removeReturned.load())
        << "removeHandler did not return after handleEvent completed";
    EXPECT_TRUE(handler.finishedHandler());
    remover.join();
}

// Handler that removes itself from within handleEvent, exercising the
// recursive-mutex behavior of handlersMutex_.
class SelfRemovingHandler : public UEventsHandler
{
public:
    SelfRemovingHandler() : called_(false) {}
    bool called() const { return called_.load(); }

protected:
    virtual bool handleEvent(UEvent *)
    {
        called_ = true;
        // Must not deadlock: handlersMutex_ is recursive, so the dispatcher
        // thread can re-enter it via removeHandler() while still holding it
        // for the surrounding dispatch.
        UEventsManager::removeHandler(this);
        return false;
    }

private:
    std::atomic<bool> called_;
};

TEST(UEventsTest, HandlerCanRemoveItselfFromWithinHandleEvent)
{
    SelfRemovingHandler handler;
    UEventsManager::addHandler(&handler);

    UEventsManager::post(new TestEvent(), true);

    UTimer t;
    while(!handler.called() && t.ticks() < 1.0)
    {
        std::this_thread::sleep_for(std::chrono::milliseconds(1));
    }
    EXPECT_TRUE(handler.called())
        << "Handler appears to be deadlocked inside handleEvent";

    // After self-removal, further events must not reach the handler. Since
    // handleEvent flipped 'called_' once, post again and confirm no further
    // calls are observed (we can only verify via a second handler that the
    // dispatcher is still alive afterwards).
    TestHandler sentinel;
    UEventsManager::addHandler(&sentinel);
    UEventsManager::post(new TestEvent(), true);
    std::this_thread::sleep_for(std::chrono::milliseconds(50));
    EXPECT_GT(sentinel.getEventCount(), 0)
        << "Dispatcher is no longer delivering events after self-removal";
    UEventsManager::removeHandler(&sentinel);
}