#ifndef SQUID_BODY_PIPE_H
#define SQUID_BODY_PIPE_H

#include "MemBuf.h"
#include "AsyncCall.h"

class BodyPipe;

// Interface for those who want to produce body content for others.
// BodyProducer is expected to create the BodyPipe.
// One pipe cannot have more than one producer.
class BodyProducer {
	public:
		virtual ~BodyProducer() {}

		virtual void noteMoreBodySpaceAvailable(BodyPipe &bp) = 0;
		virtual void noteBodyConsumerAborted(BodyPipe &bp) = 0;

	protected:
		void stopProducingFor(RefCount<BodyPipe> &pipe, bool atEof);
};

// Interface for those who want to consume body content from others.
// BodyConsumer is expected to register with an existing BodyPipe
// by calling BodyPipe::setConsumer().
// One pipe cannot have more than one consumer.
class BodyConsumer {
	public:
		virtual ~BodyConsumer() {}

		virtual void noteMoreBodyDataAvailable(BodyPipe &bp) = 0;
		virtual void noteBodyProductionEnded(BodyPipe &bp) = 0;
		virtual void noteBodyProducerAborted(BodyPipe &bp) = 0;

	protected:
		void stopConsumingFrom(RefCount<BodyPipe> &pipe);
};

// Makes raw buffer checkin/checkout interface efficient and exception-safe.
// Either append or consume operations can be performed on a checkedout buffer.
class BodyPipeCheckout {
	public:
		friend class BodyPipe;

	public:
		BodyPipeCheckout(BodyPipe &pipe); // checks out
		~BodyPipeCheckout(); // aborts checkout unless checkedIn

		void checkIn();

	public:
		BodyPipe &pipe;
		MemBuf &buf;
		const uint64_t offset; // of current content, relative to the body start

	protected:
		const size_t checkedOutSize;
		bool checkedIn;

	private:
		BodyPipeCheckout(const BodyPipeCheckout &); // prevent copying
		BodyPipeCheckout &operator =(const BodyPipeCheckout &); // prevent assignment
};

// Connects those who produces message body content with those who
// consume it. For example, connects ConnStateData with FtpStateData OR
// ICAPModXact with HttpStateData.
class BodyPipe: public RefCountable {
	public:
		typedef RefCount<BodyPipe> Pointer;
		typedef BodyProducer Producer;
		typedef BodyConsumer Consumer;
		typedef BodyPipeCheckout Checkout;

		enum { MaxCapacity = SQUID_TCP_SO_RCVBUF };

		friend class BodyPipeCheckout;

	public:
		BodyPipe(Producer *aProducer);
		~BodyPipe(); // asserts that producer and consumer are cleared

		void setBodySize(uint64_t aSize); // set body size
		bool bodySizeKnown() const { return theBodySize >= 0; }
		uint64_t bodySize() const;
		uint64_t consumedSize() const { return theGetSize; }
		bool productionEnded() const { return !theProducer; }

		// called by producers
		void clearProducer(bool atEof); // aborts or sends eof
		size_t putMoreData(const char *buf, size_t size);
		bool mayNeedMoreData() const { return !bodySizeKnown() || needsMoreData(); }
		bool needsMoreData() const { return bodySizeKnown() && unproducedSize() > 0; }
		uint64_t unproducedSize() const; // size of still unproduced data

		// called by consumers
		bool setConsumerIfNotLate(Consumer *aConsumer);
		void clearConsumer(); // aborts if still piping
		size_t getMoreData(MemBuf &buf);
		void consume(size_t size);
		bool expectMoreAfter(uint64_t offset) const;
		bool exhausted() const; // saw eof/abort and all data consumed

		// start or continue consuming when there is no consumer
		void enableAutoConsumption();

		const MemBuf &buf() const { return theBuf; }

		const char *status() const; // for debugging only

	protected:
		// lower-level interface used by Checkout
		MemBuf &checkOut(); // obtain raw buffer
		void checkIn(Checkout &checkout); // return updated raw buffer
		void undoCheckOut(Checkout &checkout); // undo checkout efffect

		void scheduleBodyDataNotification();
		void scheduleBodyEndNotification();

		// keep counters in sync and notify producer or consumer
		void postConsume(size_t size);
		void postAppend(size_t size);

		bool skipCCall(); // decides whether to skip the call, updates counters

	public: /* public to enable callbacks, but treat as private */

		/* these methods are calling producer and sibscriber note*()
		 * callbacks with this BodyPipe as a parameter, which allows
		 * a single producer or consumer to support multiple pipes. */
		 
		void tellMoreBodySpaceAvailable();
		void tellBodyConsumerAborted();
		void tellMoreBodyDataAvailable();
		void tellBodyProductionEnded();
		void tellBodyProducerAborted();

		AsyncCallWrapper(91,5, BodyPipe, tellMoreBodySpaceAvailable);
		AsyncCallWrapper(91,5, BodyPipe, tellBodyConsumerAborted);
		AsyncCallWrapper(91,5, BodyPipe, tellMoreBodyDataAvailable);
		AsyncCallWrapper(91,5, BodyPipe, tellBodyProductionEnded);
		AsyncCallWrapper(91,5, BodyPipe, tellBodyProducerAborted);

	private:
		int64_t  theBodySize;   // expected total content length, if known
		Producer *theProducer; // content producer, if any
		Consumer *theConsumer; // content consumer, if any

		uint64_t thePutSize; // ever-increasing total
		uint64_t theGetSize; // ever-increasing total

		int theCCallsPending; // outstanding calls to the consumer
		int theCCallsToSkip; // how many calls to the consumer we should skip

		MemBuf theBuf; // produced but not yet consumed content, if any

		bool mustAutoConsume; // consume when there is no consumer
		bool isCheckedOut; // to keep track of checkout violations

		CBDATA_CLASS2(BodyPipe);
};

#endif /* SQUID_BODY_PIPE_H */