/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
 * Copyright (C) 2018, Google Inc.
 *
 * pipeline_handler.cpp - Pipeline handler infrastructure
 */

#include "libcamera/internal/pipeline_handler.h"

#include <chrono>
#include <sys/sysmacros.h>

#include <libcamera/base/log.h>
#include <libcamera/base/mutex.h>
#include <libcamera/base/utils.h>

#include <libcamera/camera.h>
#include <libcamera/camera_manager.h>
#include <libcamera/framebuffer.h>

#include "libcamera/internal/camera.h"
#include "libcamera/internal/device_enumerator.h"
#include "libcamera/internal/framebuffer.h"
#include "libcamera/internal/media_device.h"
#include "libcamera/internal/request.h"
#include "libcamera/internal/tracepoints.h"

/**
 * \file pipeline_handler.h
 * \brief Create pipelines and cameras from a set of media devices
 *
 * Each pipeline supported by libcamera needs to be backed by a pipeline
 * handler implementation that operate on a set of media devices. The pipeline
 * handler is responsible for matching the media devices it requires with the
 * devices present in the system, and once all those devices can be acquired,
 * create corresponding Camera instances.
 *
 * Every subclass of PipelineHandler shall be registered with libcamera using
 * the REGISTER_PIPELINE_HANDLER() macro.
 */

using namespace std::chrono_literals;

namespace libcamera {

LOG_DEFINE_CATEGORY(Pipeline)

/**
 * \class PipelineHandler
 * \brief Create and manage cameras based on a set of media devices
 *
 * The PipelineHandler matches the media devices provided by a DeviceEnumerator
 * with the pipelines it supports and creates corresponding Camera devices.
 *
 * Pipeline handler instances are reference-counted through std::shared_ptr<>.
 * They implement std::enable_shared_from_this<> in order to create new
 * std::shared_ptr<> in code paths originating from member functions of the
 * PipelineHandler class where only the 'this' pointer is available.
 */

/**
 * \brief Construct a PipelineHandler instance
 * \param[in] manager The camera manager
 *
 * In order to honour the std::enable_shared_from_this<> contract,
 * PipelineHandler instances shall never be constructed manually, but always
 * through the PipelineHandlerFactory::create() function implemented by the
 * respective factories.
 */
PipelineHandler::PipelineHandler(CameraManager *manager)
	: manager_(manager), lockOwner_(false)
{
}

PipelineHandler::~PipelineHandler()
{
	for (std::shared_ptr<MediaDevice> media : mediaDevices_)
		media->release();
}

/**
 * \fn PipelineHandler::match(DeviceEnumerator *enumerator)
 * \brief Match media devices and create camera instances
 * \param[in] enumerator The enumerator providing all media devices found in the
 * system
 *
 * This function is the main entry point of the pipeline handler. It is called
 * by the camera manager with the \a enumerator passed as an argument. It shall
 * acquire from the \a enumerator all the media devices it needs for a single
 * pipeline, create one or multiple Camera instances and register them with the
 * camera manager.
 *
 * If all media devices needed by the pipeline handler are found, they must all
 * be acquired by a call to MediaDevice::acquire(). This function shall then
 * create the corresponding Camera instances, store them internally, and return
 * true. Otherwise it shall not acquire any media device (or shall release all
 * the media devices is has acquired by calling MediaDevice::release()) and
 * return false.
 *
 * If multiple instances of a pipeline are available in the system, the
 * PipelineHandler class will be instantiated once per instance, and its match()
 * function called for every instance. Each call shall acquire media devices for
 * one pipeline instance, until all compatible media devices are exhausted.
 *
 * If this function returns true, a new instance of the pipeline handler will
 * be created and its match() function called.
 *
 * \context This function is called from the CameraManager thread.
 *
 * \return true if media devices have been acquired and camera instances
 * created, or false otherwise
 */

/**
 * \brief Search and acquire a MediaDevice matching a device pattern
 * \param[in] enumerator Enumerator containing all media devices in the system
 * \param[in] dm Device match pattern
 *
 * Search the device \a enumerator for an available media device matching the
 * device match pattern \a dm. Matching media device that have previously been
 * acquired by MediaDevice::acquire() are not considered. If a match is found,
 * the media device is acquired and returned. The caller shall not release the
 * device explicitly, it will be automatically released when the pipeline
 * handler is destroyed.
 *
 * \context This function shall be called from the CameraManager thread.
 *
 * \return A pointer to the matching MediaDevice, or nullptr if no match is found
 */
MediaDevice *PipelineHandler::acquireMediaDevice(DeviceEnumerator *enumerator,
						 const DeviceMatch &dm)
{
	std::shared_ptr<MediaDevice> media = enumerator->search(dm);
	if (!media)
		return nullptr;

	if (!media->acquire())
		return nullptr;

	mediaDevices_.push_back(media);

	return media.get();
}

/**
 * \brief Lock all media devices acquired by the pipeline
 *
 * This function shall not be called from pipeline handler implementation, as
 * the Camera class handles locking directly.
 *
 * \context This function is \threadsafe.
 *
 * \return True if the devices could be locked, false otherwise
 * \sa unlock()
 * \sa MediaDevice::lock()
 */
bool PipelineHandler::lock()
{
	MutexLocker locker(lock_);

	/* Do not allow nested locking in the same libcamera instance. */
	if (lockOwner_)
		return false;

	for (std::shared_ptr<MediaDevice> &media : mediaDevices_) {
		if (!media->lock()) {
			unlock();
			return false;
		}
	}

	lockOwner_ = true;

	return true;
}

/**
 * \brief Unlock all media devices acquired by the pipeline
 *
 * This function shall not be called from pipeline handler implementation, as
 * the Camera class handles locking directly.
 *
 * \context This function is \threadsafe.
 *
 * \sa lock()
 */
void PipelineHandler::unlock()
{
	MutexLocker locker(lock_);

	if (!lockOwner_)
		return;

	for (std::shared_ptr<MediaDevice> &media : mediaDevices_)
		media->unlock();

	lockOwner_ = false;
}

/**
 * \fn PipelineHandler::generateConfiguration()
 * \brief Generate a camera configuration for a specified camera
 * \param[in] camera The camera to generate a default configuration for
 * \param[in] roles A list of stream roles
 *
 * Generate a default configuration for the \a camera for a specified list of
 * stream roles. The caller shall populate the \a roles with the use-cases it
 * wishes to fetch the default configuration for. The returned configuration
 * can then be examined by the caller to learn about the selected streams and
 * their default parameters.
 *
 * The intended companion to this is \a configure() which can be used to change
 * the group of streams parameters.
 *
 * \context This function may be called from any thread and shall be
 * \threadsafe. It shall not modify the state of the \a camera in the pipeline
 * handler.
 *
 * \return A valid CameraConfiguration if the requested roles can be satisfied,
 * or a null pointer otherwise. The ownership of the returned configuration is
 * passed to the caller.
 */

/**
 * \fn PipelineHandler::configure()
 * \brief Configure a group of streams for capture
 * \param[in] camera The camera to configure
 * \param[in] config The camera configurations to setup
 *
 * Configure the specified group of streams for \a camera according to the
 * configuration specified in \a config. The intended caller of this interface
 * is the Camera class which will receive configuration to apply from the
 * application.
 *
 * The configuration is guaranteed to have been validated with
 * CameraConfiguration::validate(). The pipeline handler implementation shall
 * not perform further validation and may rely on any custom field stored in its
 * custom CameraConfiguration derived class.
 *
 * When configuring the camera the pipeline handler shall associate a Stream
 * instance to each StreamConfiguration entry in the CameraConfiguration using
 * the StreamConfiguration::setStream() function.
 *
 * \context This function is called from the CameraManager thread.
 *
 * \return 0 on success or a negative error code otherwise
 */

/**
 * \fn PipelineHandler::exportFrameBuffers()
 * \brief Allocate and export buffers for \a stream
 * \param[in] camera The camera
 * \param[in] stream The stream to allocate buffers for
 * \param[out] buffers Array of buffers successfully allocated
 *
 * This function allocates buffers for the \a stream from the devices associated
 * with the stream in the corresponding pipeline handler. Those buffers shall be
 * suitable to be added to a Request for the stream, and shall be mappable to
 * the CPU through their associated dmabufs with mmap().
 *
 * The function may only be called after the Camera has been configured and
 * before it gets started, or after it gets stopped. It shall be called only for
 * streams that are part of the active camera configuration.
 *
 * The only intended caller is Camera::exportFrameBuffers().
 *
 * \context This function is called from the CameraManager thread.
 *
 * \return The number of allocated buffers on success or a negative error code
 * otherwise
 */

/**
 * \fn PipelineHandler::start()
 * \brief Start capturing from a group of streams
 * \param[in] camera The camera to start
 * \param[in] controls Controls to be applied before starting the Camera
 *
 * Start the group of streams that have been configured for capture by
 * \a configure(). The intended caller of this function is the Camera class
 * which will in turn be called from the application to indicate that it has
 * configured the streams and is ready to capture.
 *
 * \context This function is called from the CameraManager thread.
 *
 * \return 0 on success or a negative error code otherwise
 */

/**
 * \brief Stop capturing from all running streams and cancel pending requests
 * \param[in] camera The camera to stop
 *
 * This function stops capturing and processing requests immediately. All
 * pending requests are cancelled and complete immediately in an error state.
 *
 * \context This function is called from the CameraManager thread.
 */
void PipelineHandler::stop(Camera *camera)
{
	/* Stop the pipeline handler and let the queued requests complete. */
	stopDevice(camera);

	/* Cancel and signal as complete all waiting requests. */
	while (!waitingRequests_.empty()) {
		Request *request = waitingRequests_.front();
		waitingRequests_.pop();

		request->_d()->cancel();
		completeRequest(request);
	}

	/* Make sure no requests are pending. */
	Camera::Private *data = camera->_d();
	ASSERT(data->queuedRequests_.empty());

	data->requestSequence_ = 0;
}

/**
 * \fn PipelineHandler::stopDevice()
 * \brief Stop capturing from all running streams
 * \param[in] camera The camera to stop
 *
 * This function stops capturing and processing requests immediately. All
 * pending requests are cancelled and complete immediately in an error state.
 */

/**
 * \brief Determine if the camera has any requests pending
 * \param[in] camera The camera to check
 *
 * This function determines if there are any requests queued to the pipeline
 * awaiting processing.
 *
 * \return True if there are pending requests, or false otherwise
 */
bool PipelineHandler::hasPendingRequests(const Camera *camera) const
{
	return !camera->_d()->queuedRequests_.empty();
}

/**
 * \fn PipelineHandler::registerRequest()
 * \brief Register a request for use by the pipeline handler
 * \param[in] request The request to register
 *
 * This function is called when the request is created, and allows the pipeline
 * handler to perform any one-time initialization it requries for the request.
 */
void PipelineHandler::registerRequest(Request *request)
{
	/*
	 * Connect the request prepared signal to notify the pipeline handler
	 * when a request is ready to be processed.
	 */
	request->_d()->prepared.connect(this, &PipelineHandler::doQueueRequests);
}

/**
 * \fn PipelineHandler::queueRequest()
 * \brief Queue a request
 * \param[in] request The request to queue
 *
 * This function queues a capture request to the pipeline handler for
 * processing. The request is first added to the internal list of waiting
 * requests which have to be prepared to make sure they are ready for being
 * queued to the pipeline handler.
 *
 * The queue of waiting requests is iterated and all prepared requests are
 * passed to the pipeline handler in the same order they have been queued by
 * calling this function.
 *
 * If a Request fails during the preparation phase or if the pipeline handler
 * fails in queuing the request to the hardware the request is cancelled.
 *
 * Keeping track of queued requests ensures automatic completion of all requests
 * when the pipeline handler is stopped with stop(). Request completion shall be
 * signalled by the pipeline handler using the completeRequest() function.
 *
 * \context This function is called from the CameraManager thread.
 */
void PipelineHandler::queueRequest(Request *request)
{
	LIBCAMERA_TRACEPOINT(request_queue, request);

	waitingRequests_.push(request);

	request->_d()->prepare(300ms);
}

/**
 * \brief Queue one requests to the device
 */
void PipelineHandler::doQueueRequest(Request *request)
{
	LIBCAMERA_TRACEPOINT(request_device_queue, request);

	Camera *camera = request->_d()->camera();
	Camera::Private *data = camera->_d();
	data->queuedRequests_.push_back(request);

	request->_d()->sequence_ = data->requestSequence_++;

	if (request->_d()->cancelled_) {
		completeRequest(request);
		return;
	}

	int ret = queueRequestDevice(camera, request);
	if (ret) {
		request->_d()->cancel();
		completeRequest(request);
	}
}

/**
 * \brief Queue prepared requests to the device
 *
 * Iterate the list of waiting requests and queue them to the device one
 * by one if they have been prepared.
 */
void PipelineHandler::doQueueRequests()
{
	while (!waitingRequests_.empty()) {
		Request *request = waitingRequests_.front();
		if (!request->_d()->prepared_)
			break;

		doQueueRequest(request);
		waitingRequests_.pop();
	}
}

/**
 * \fn PipelineHandler::queueRequestDevice()
 * \brief Queue a request to the device
 * \param[in] camera The camera to queue the request to
 * \param[in] request The request to queue
 *
 * This function queues a capture request to the device for processing. The
 * request contains a set of buffers associated with streams and a set of
 * parameters. The pipeline handler shall program the device to ensure that the
 * parameters will be applied to the frames captured in the buffers provided in
 * the request.
 *
 * \context This function is called from the CameraManager thread.
 *
 * \return 0 on success or a negative error code otherwise
 */

/**
 * \brief Complete a buffer for a request
 * \param[in] request The request the buffer belongs to
 * \param[in] buffer The buffer that has completed
 *
 * This function shall be called by pipeline handlers to signal completion of
 * the \a buffer part of the \a request. It notifies applications of buffer
 * completion and updates the request's internal buffer tracking. The request
 * is not completed automatically when the last buffer completes to give
 * pipeline handlers a chance to perform any operation that may still be
 * needed. They shall complete requests explicitly with completeRequest().
 *
 * \context This function shall be called from the CameraManager thread.
 *
 * \return True if all buffers contained in the request have completed, false
 * otherwise
 */
bool PipelineHandler::completeBuffer(Request *request, FrameBuffer *buffer)
{
	Camera *camera = request->_d()->camera();
	camera->bufferCompleted.emit(request, buffer);
	return request->_d()->completeBuffer(buffer);
}

/**
 * \brief Signal request completion
 * \param[in] request The request that has completed
 *
 * The pipeline handler shall call this function to notify the \a camera that
 * the request has completed. The request is no longer managed by the pipeline
 * handler and shall not be accessed once this function returns.
 *
 * This function ensures that requests will be returned to the application in
 * submission order, the pipeline handler may call it on any complete request
 * without any ordering constraint.
 *
 * \context This function shall be called from the CameraManager thread.
 */
void PipelineHandler::completeRequest(Request *request)
{
	Camera *camera = request->_d()->camera();

	request->_d()->complete();

	Camera::Private *data = camera->_d();

	while (!data->queuedRequests_.empty()) {
		Request *req = data->queuedRequests_.front();
		if (req->status() == Request::RequestPending)
			break;

		ASSERT(!req->hasPendingBuffers());
		data->queuedRequests_.pop_front();
		camera->requestComplete(req);
	}
}

/**
 * \brief Register a camera to the camera manager and pipeline handler
 * \param[in] camera The camera to be added
 *
 * This function is called by pipeline handlers to register the cameras they
 * handle with the camera manager.
 *
 * \context This function shall be called from the CameraManager thread.
 */
void PipelineHandler::registerCamera(std::shared_ptr<Camera> camera)
{
	cameras_.push_back(camera);

	if (mediaDevices_.empty())
		LOG(Pipeline, Fatal)
			<< "Registering camera with no media devices!";

	/*
	 * Walk the entity list and map the devnums of all capture video nodes
	 * to the camera.
	 */
	std::vector<dev_t> devnums;
	for (const std::shared_ptr<MediaDevice> &media : mediaDevices_) {
		for (const MediaEntity *entity : media->entities()) {
			if (entity->pads().size() == 1 &&
			    (entity->pads()[0]->flags() & MEDIA_PAD_FL_SINK) &&
			    entity->function() == MEDIA_ENT_F_IO_V4L) {
				devnums.push_back(makedev(entity->deviceMajor(),
							  entity->deviceMinor()));
			}
		}
	}

	manager_->addCamera(std::move(camera), devnums);
}

/**
 * \brief Enable hotplug handling for a media device
 * \param[in] media The media device