// Copyright 2020-2021, Collabora, Ltd.
// SPDX-License-Identifier: BSL-1.0
/*!
 * @file
 * @brief  Common server side code.
 * @author Pete Black <pblack@collabora.com>
 * @author Jakob Bornecrantz <jakob@collabora.com>
 * @author Ryan Pavlik <ryan.pavlik@collabora.com>
 * @ingroup ipc_server
 */

#pragma once

#include "xrt/xrt_compiler.h"

#include "util/u_logging.h"

#include "os/os_threading.h"

#include "shared/ipc_protocol.h"
#include "shared/ipc_utils.h"

#include <stdio.h>

#ifdef __cplusplus
extern "C" {
#endif

/*
 *
 * Logging
 *
 */

#define IPC_TRACE(d, ...) U_LOG_IFL_T(d->ll, __VA_ARGS__)
#define IPC_DEBUG(d, ...) U_LOG_IFL_D(d->ll, __VA_ARGS__)
#define IPC_INFO(d, ...) U_LOG_IFL_I(d->ll, __VA_ARGS__)
#define IPC_WARN(d, ...) U_LOG_IFL_W(d->ll, __VA_ARGS__)
#define IPC_ERROR(d, ...) U_LOG_IFL_E(d->ll, __VA_ARGS__)

/*
 *
 * Structs
 *
 */

#define IPC_SERVER_NUM_XDEVS 8
#define IPC_MAX_CLIENT_SWAPCHAINS 32
//#define IPC_MAX_CLIENTS 8

struct xrt_instance;
struct xrt_compositor;
struct xrt_compositor_native;


/*!
 * Information about a single swapchain.
 *
 * @ingroup ipc_server
 */
struct ipc_swapchain_data
{
	uint32_t width;
	uint32_t height;
	uint64_t format;
	uint32_t num_images;

	bool active;
};

/*!
 * Holds the state for a single client.
 *
 * @ingroup ipc_server
 */
struct ipc_client_state
{
	//! Link back to the main server.
	struct ipc_server *server;

	//! Compositor for this client.
	struct xrt_compositor *xc;

	//! Is the inputs and outputs active.
	bool io_active;

	//! Number of swapchains in use by client
	uint32_t num_swapchains;

	//! Ptrs to the swapchains
	struct xrt_swapchain *xscs[IPC_MAX_CLIENT_SWAPCHAINS];

	//! Data for the swapchains.
	struct ipc_swapchain_data swapchain_data[IPC_MAX_CLIENT_SWAPCHAINS];

	//! Socket fd used for client comms
	struct ipc_message_channel imc;

	struct ipc_app_state client_state;

	int server_thread_index;
};

enum ipc_thread_state
{
	IPC_THREAD_READY,
	IPC_THREAD_STARTING,
	IPC_THREAD_RUNNING,
	IPC_THREAD_STOPPING,
};

struct ipc_thread
{
	struct os_thread thread;
	volatile enum ipc_thread_state state;
	volatile struct ipc_client_state ics;
};


/*!
 *
 */
struct ipc_device
{
	//! The actual device.
	struct xrt_device *xdev;

	//! Is the IO suppressed for this device.
	bool io_active;
};

/*!
 * Platform-specific mainloop object for the IPC server.
 *
 * Contents are essentially implementation details, but are listed in full here so they may be included by value in the
 * main ipc_server struct.
 *
 * @see ipc_design
 *
 * @ingroup ipc_server
 */
struct ipc_server_mainloop
{

#if defined(XRT_OS_ANDROID) || defined(XRT_OS_LINUX) || defined(XRT_DOXYGEN)
	//! For waiting on various events in the main thread.
	int epoll_fd;
#endif

#if defined(XRT_OS_ANDROID) || defined(XRT_DOXYGEN)
	/*!
	 * @name Android Mainloop Members
	 * @{
	 */

	//! File descriptor for the read end of our pipe for submitting new clients
	int pipe_read;

	/*!
	 * File descriptor for the write end of our pipe for submitting new clients
	 *
	 * Must hold client_push_mutex while writing.
	 */
	int pipe_write;

	/*!
	 * Mutex for being able to register oneself as a new client.
	 *
	 * Locked only by threads in `ipc_server_mainloop_add_fd()`.
	 *
	 * This must be locked first, and kept locked the entire time a client is attempting to register and wait for
	 * confirmation. It ensures no acknowledgements of acceptance are lost and moves the overhead of ensuring this
	 * to the client thread.
	 */
	pthread_mutex_t client_push_mutex;


	/*!
	 * The last client fd we accepted, to acknowledge client acceptance.
	 *
	 * Also used as a sentinel during shutdown.
	 *
	 * Must hold accept_mutex while writing.
	 */
	int last_accepted_fd;

	/*!
	 * Condition variable for accepting clients.
	 *
	 * Signalled when @ref last_accepted_fd is updated.
	 *
	 * Associated with @ref accept_mutex
	 */
	pthread_cond_t accept_cond;

	/*!
	 * Mutex for accepting clients.
	 *
	 * Locked by both clients and server: that is, by threads in `ipc_server_mainloop_add_fd()` and in the
	 * server/compositor thread in an implementation function called from `ipc_server_mainloop_poll()`.
	 *
	 * Exists to operate in conjunction with @ref accept_cond - it exists to make sure that the client can be woken
	 * when the server accepts it.
	 */
	pthread_mutex_t accept_mutex;


	/*! @} */
#define XRT_IPC_GOT_IMPL
#endif

#if (defined(XRT_OS_LINUX) && !defined(XRT_OS_ANDROID)) || defined(XRT_DOXYGEN)
	/*!
	 * @name Desktop Linux Mainloop Members
	 * @{
	 */

	//! Socket that we accept connections on.
	int listen_socket;

	//! Were we launched by socket activation, instead of explicitly?
	bool launched_by_socket;

	//! The socket filename we bound to, if any.
	char *socket_filename;

	/*! @} */

#define XRT_IPC_GOT_IMPL
#endif

#ifndef XRT_IPC_GOT_IMPL
#error "Need port"
#endif
};

/*!
 * De-initialize the mainloop object.
 * @public @memberof ipc_server_mainloop
 */
void
ipc_server_mainloop_deinit(struct ipc_server_mainloop *ml);

/*!
 * Initialize the mainloop object.
 *
 * @return <0 on error.
 * @public @memberof ipc_server_mainloop
 */
int
ipc_server_mainloop_init(struct ipc_server_mainloop *ml);

/*!
 * @brief Poll the mainloop.
 *
 * Any errors are signalled by calling ipc_server_handle_failure()
 * @public @memberof ipc_server_mainloop
 */
void
ipc_server_mainloop_poll(struct ipc_server *vs, struct ipc_server_mainloop *ml);

/*!
 * Main IPC object for the server.
 *
 * @ingroup ipc_server
 */
struct ipc_server
{
	struct xrt_instance *xinst;

	//! Handle for the current process, e.g. pidfile on linux
	struct u_process *process;

	/* ---- HACK ---- */
	void *hack;
	/* ---- HACK ---- */


	//! System compositor.
	struct xrt_system_compositor *xsysc;

	struct ipc_device idevs[IPC_SERVER_NUM_XDEVS];
	struct xrt_tracking_origin *xtracks[IPC_SERVER_NUM_XDEVS];

	struct ipc_shared_memory *ism;
	xrt_shmem_handle_t ism_handle;

	struct ipc_server_mainloop ml;

	// Is the mainloop supposed to run.
	volatile bool running;

	// Should we exit when a client disconnects.
	bool exit_on_disconnect;

	enum u_logging_level ll;

	struct ipc_thread threads[IPC_MAX_CLIENTS];

	volatile uint32_t current_slot_index;

	struct
	{
		int active_client_index;
		int last_active_client_index;

		struct os_mutex lock;
	} global_state;
};


#ifndef XRT_OS_ANDROID
/*!
 * Main entrypoint to the compositor process.
 *
 * @ingroup ipc_server
 */
int
ipc_server_main(int argc, char **argv);
#endif

#ifdef XRT_OS_ANDROID
/*!
 * Main entrypoint to the server process.
 *
 * @param ps Pointer to populate with the server struct.
 * @param startup_complete_callback Function to call upon completing startup and populating *ps, but before entering the
 * mainloop.
 * @param data user data to pass to your callback.
 *
 * @ingroup ipc_server
 */
int
ipc_server_main_android(struct ipc_server **ps, void (*startup_complete_callback)(void *data), void *data);
#endif

/*!
 * Set the new active client.
 *
 * @ingroup ipc_server
 */
void
ipc_server_set_active_client(struct ipc_server *s, int active_client_index);

/*!
 * Called by client threads to set a session to active.
 *
 * @ingroup ipc_server
 */
void
ipc_server_activate_session(volatile struct ipc_client_state *ics);

/*!
 * Called by client threads to set a session to deactivate.
 *
 * @ingroup ipc_server
 */
void
ipc_server_deactivate_session(volatile struct ipc_client_state *ics);

/*!
 * Called by client threads to recalculate active client.
 *
 * @ingroup ipc_server
 */
void
ipc_server_update_state(struct ipc_server *s);

/*!
 * Thread function for the client side dispatching.
 *
 * @ingroup ipc_server
 */
void *
ipc_server_client_thread(void *_cs);

/*!
 * This destroyes the native compositor for this client and any extra objects
 * created from it, like all of the swapchains.
 */
void
ipc_server_client_destroy_compositor(volatile struct ipc_client_state *ics);

/*!
 * @defgroup ipc_server_internals Server Internals
 * @brief These are only called by the platform-specific mainloop polling code.
 * @ingroup ipc_server
 * @{
 */
/*!
 * Start a thread for a client connected at the other end of the file descriptor @p fd.
 * @memberof ipc_server
 */
void
ipc_server_start_client_listener_thread(struct ipc_server *vs, int fd);

/*!
 * Perform whatever needs to be done when the mainloop polling encounters a failure.
 * @memberof ipc_server
 */
void
ipc_server_handle_failure(struct ipc_server *vs);

/*!
 * Perform whatever needs to be done when the mainloop polling identifies that the server should be shut down.
 *
 * Does something like setting a flag or otherwise signalling for shutdown: does not itself explicitly exit.
 * @memberof ipc_server
 */
void
ipc_server_handle_shutdown_signal(struct ipc_server *vs);
//! @}

/*
 *
 * Helpers
 *
 */

/*!
 * Get a xdev with the given device_id.
 */
static inline struct xrt_device *
get_xdev(volatile struct ipc_client_state *ics, uint32_t device_id)
{
	return ics->server->idevs[device_id].xdev;
}

/*!
 * Get a idev with the given device_id.
 */
static inline struct ipc_device *
get_idev(volatile struct ipc_client_state *ics, uint32_t device_id)
{
	return &ics->server->idevs[device_id];
}


#ifdef __cplusplus
}
#endif