/*
 * Copyright (C) 2016 The Android Open Source Project
 *
 * 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.
 */

#ifndef _MTP_FFS_HANDLE_H
#define _MTP_FFS_HANDLE_H

#include <android-base/unique_fd.h>
#include <linux/aio_abi.h>
#include <mutex>
#include <sys/poll.h>
#include <time.h>
#include <thread>
#include <vector>

#include <IMtpHandle.h>

constexpr int NUM_IO_BUFS = 2;

struct io_buffer {
	std::vector<struct iocb> iocbs;		// Holds memory for all iocbs. Not used directly.
	std::vector<struct iocb*> iocb;		// Pointers to individual iocbs, for syscalls
	std::vector<unsigned char> bufs;	// A large buffer, used with filesystem io
	std::vector<unsigned char*> buf;	// Pointers within the larger buffer, for syscalls
	unsigned actual;					// The number of buffers submitted for this request
};

template <class T> class MtpFfsHandleTest;

class MtpFfsHandle : public IMtpHandle {
	template <class T> friend class MtpFfsHandleTest;
protected:
	void closeConfig();
	void closeEndpoints();
	void advise(int fd);
	int handleControlRequest(const struct usb_ctrlrequest *request);
	int doAsync(void* data, size_t len, bool read, bool zero_packet);
	int handleEvent();
	void cancelTransaction();
	void doSendEvent(mtp_event me);
	bool openEndpoints(bool ptp);

	static int getPacketSize(int ffs_fd);

	bool mCanceled;

	android::base::unique_fd mControl;
	// "in" from the host's perspective => sink for mtp server
	android::base::unique_fd mBulkIn;
	// "out" from the host's perspective => source for mtp server
	android::base::unique_fd mBulkOut;
	android::base::unique_fd mIntr;

	aio_context_t mCtx;

	android::base::unique_fd mEventFd;
	struct pollfd mPollFds[2];

	struct io_buffer mIobuf[NUM_IO_BUFS];

	// Submit an io request of given length. Return amount submitted or -1.
	int iobufSubmit(struct io_buffer *buf, int fd, unsigned length, bool read);

	// Cancel submitted requests from start to end in the given array. Return 0 or -1.
	int cancelEvents(struct iocb **iocb, struct io_event *events, unsigned start, unsigned end);

	// Wait for at minimum the given number of events. Returns the amount of data in the returned
	// events. Increments counter by the number of events returned.
	int waitEvents(struct io_buffer *buf, int min_events, struct io_event *events, int *counter);

public:
	int read(void *data, size_t len) override;
	int write(const void *data, size_t len) override;

	int receiveFile(mtp_file_range mfr, bool zero_packet) override;
	int sendFile(mtp_file_range mfr) override;
	int sendEvent(mtp_event me) override;

	int start(bool ptp) override;
	void close() override;

	bool writeDescriptors(bool ptp);

	MtpFfsHandle(int controlFd);
	~MtpFfsHandle();
};

struct mtp_data_header {
	/* length of packet, including this header */
	__le32 length;
	/* container type (2 for data packet) */
	__le16 type;
	/* MTP command code */
	__le16 command;
	/* MTP transaction ID */
	__le32 transaction_id;
};

#endif // _MTP_FFS_HANDLE_H