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

#include "pipeline_handler.h"

#include <sys/sysmacros.h>

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

#include "device_enumerator.h"
#include "log.h"
#include "media_device.h"
#include "utils.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.
 */

namespace libcamera {

LOG_DEFINE_CATEGORY(Pipeline)

/**
 * \class CameraData
 * \brief Base class for platform-specific data associated with a camera
 *
 * The CameraData base abstract class represents platform specific-data
 * a pipeline handler might want to associate with a Camera to access them
 * at a later time.
 *
 * Pipeline handlers are expected to extend this base class with platform
 * specific implementation, associate instances of the derived classes
 * using the setCameraData() method, and access them at a later time
 * with cameraData().
 */

/**
 * \fn CameraData::CameraData(PipelineHandler *pipe)
 * \brief Construct a CameraData instance for the given pipeline handler
 * \param[in] pipe The pipeline handler
 *
 * The reference to the pipeline handler is stored internally, the caller shall
 * guarantee that the pointer remains valid as long as the CameraData instance
 * exists.
 */

/**
 * \var CameraData::camera_
 * \brief The camera related to this CameraData instance
 *
 * The camera_ pointer provides access to the Camera object that this instance
 * is related to. It is set when the Camera is registered with
 * PipelineHandler::registerCamera() and remains valid until the CameraData
 * instance is destroyed.
 */

/**
 * \var CameraData::pipe_
 * \brief The pipeline handler related to this CameraData instance
 *
 * The pipe_ pointer provides access to the PipelineHandler object that this
 * instance is related to. It is set when the CameraData instance is created
 * and remains valid until the instance is destroyed.
 */

/**
 * \var CameraData::queuedRequests_
 * \brief The list of queued and not yet completed request
 *
 * The list of queued request is used to track requests queued in order to
 * ensure completion of all requests when the pipeline handler is stopped.
 *
 * \sa PipelineHandler::queueRequest(), PipelineHandler::stop(),
 * PipelineHandler::completeRequest()
 */

/**
 * \var CameraData::controlInfo_
 * \brief The set of controls supported by the camera
 *
 * The control information shall be initialised by the pipeline handler when
 * creating the camera, and shall not be modified afterwards.
 */

/**
 * \var CameraData::properties_
 * \brief The list of properties supported by the camera
 *
 * The list of camera properties shall be initialised by the pipeline handler
 * when creating the camera, and shall not be modified afterwards.
 */

/**
 * \var CameraData::ipa_
 * \brief The IPA module used by the camera
 *
 * Reference to the Image Processing Algorithms (IPA) operating on the camera's
 * stream(s). If no IPA exists for the camera, this field is set to nullptr.
 */

/**
 * \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() method implemented by the
 * respective factories.
 */
PipelineHandler::PipelineHandler(CameraManager *manager)
	: manager_(manager)
{
}

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 MediDevice 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