#ifndef QUTEX_H
#define QUTEX_H

#include <list>
#include <atomic>
#include <memory>
#include <spinLock.h>

namespace smo {

// Forward declarations
class LockerAndInvoker;

/**
 * @brief Qutex - Queue-based mutex for asynchronous lock management
 *
 * A Qutex combines a spinlock, an ownership flag, and a queue of waiting
 * lockvokers to provide efficient asynchronous lock management with
 * priority-based acquisition for LockSets.
 */
class Qutex
{
public:
	typedef std::list<std::shared_ptr<LockerAndInvoker>> LockerAndInvokerList;

	/**
	 * @brief Constructor
	 */
	Qutex()
	{
		// TODO: Initialize member variables
	}

	/**
	 * @brief Register a lockvoker in the queue
	 * @param lockvoker The lockvoker to register
	 * @return Iterator pointing to the registered lockvoker in the queue
	 */
	LockerAndInvokerList::iterator registerInQueue(
		const std::shared_ptr<LockerAndInvoker> &lockvoker
		)
	{
		// TODO: Implement registration logic
		// - Acquire the spinlock
		// - Insert lockvoker at the rear of the queue
		// - Return iterator to the inserted element
		// - Release the spinlock
		lock.acquire();
		auto it = queue.insert(queue.end(), lockvoker);
		lock.release();
		return it;
	}

	/**
	 * @brief Unregister a lockvoker from the queue
	 * @param it Iterator pointing to the lockvoker to unregister
	 */
	void unregisterFromQueue(LockerAndInvokerList::iterator it)
	{
		// TODO: Implement unregistration logic
		// - Acquire the spinlock
		// - Erase the element at the given iterator
		// - Release the spinlock
		(void)it;  // Suppress unused parameter warning
	}

	/**
	 * @brief Try to acquire the lock for a lockvoker
	 * @param tryingLockvoker The lockvoker attempting to acquire the lock
	 * @param nRequiredLocks Number of locks required by the lockvoker's LockSet
	 * @return true if the lock was successfully acquired, false otherwise
	 */
	bool tryAcquire(LockerAndInvoker &tryingLockvoker, int nRequiredLocks)
	{
		// TODO: Implement acquisition logic
		// - Acquire the spinlock
		// - Check if lock is already owned
		// - For single-lock requests, grant immediately if available
		// - For multi-lock requests, check if in top X% of queue
		// - Set isOwned flag if successful
		// - Release the spinlock
		// - Return success/failure
		(void)tryingLockvoker;  // Suppress unused parameter warning
		(void)nRequiredLocks;   // Suppress unused parameter warning
		return false;  // Placeholder return value
	}

	/**
	 * @brief Handle backoff when a lockvoker fails to acquire all required locks
	 * @param failedAcquirer The lockvoker that failed to acquire all locks
	 */
	void backoff(LockerAndInvoker &failedAcquirer)
	{
		// TODO: Implement backoff logic
		// - Acquire the spinlock
		// - If failedAcquirer is at front, rotate queue items
		// - Move failedAcquirer to appropriate position in queue
		// - Release the spinlock
		// - Wake up the new front item
		(void)failedAcquirer;  // Suppress unused parameter warning
	}

	/**
	 * @brief Release the lock and wake up the next waiting lockvoker
	 * @param prevOwner The lockvoker that previously owned the lock
	 */
	void release(LockerAndInvoker &prevOwner)
	{
		// TODO: Implement release logic
		// - Acquire the spinlock
		// - Unregister the previous owner from the queue
		// - Clear the isOwned flag
		// - Get the new front item
		// - Release the spinlock
		// - Wake up the new front item (conditionally)
		(void)prevOwner;  // Suppress unused parameter warning
	}

	/**
	 * @brief Wake up a specific lockvoker
	 * @param lockvoker The lockvoker to wake up
	 */
	void wakeUp(LockerAndInvoker &lockvoker)
	{
		// TODO: Implement wake-up logic
		// - Post the lockvoker's invocation to its io_service
		// - This will cause the lockvoker to retry acquisition
		(void)lockvoker;  // Suppress unused parameter warning
	}

public:
	SpinLock lock;
	std::atomic<bool> isOwned;
	LockerAndInvokerList queue;
};

} // namespace smo

#endif // QUTEX_H