// Copyright 2021 The Mumble Developers. All rights reserved.
// Use of this source code is governed by a BSD-style license
// that can be found in the LICENSE file at the root of the
// Mumble source tree or at <https://www.mumble.info/LICENSE>.

#ifndef MUMBLE_MUMBLE_PLUGINMANAGER_H_
#define MUMBLE_MUMBLE_PLUGINMANAGER_H_

#include <QHash>
#include <QMutex>
#include <QObject>
#include <QReadWriteLock>
#include <QString>
#include <QTimer>
#ifdef Q_OS_WIN
#	ifndef NOMINMAX
#		define NOMINMAX
#	endif
#	include <windows.h>
#endif
#include "MumbleApplication.h"
#include "Plugin.h"
#include "PositionalData.h"

#include "Channel.h"
#include "ClientUser.h"
#include "PluginUpdater.h"
#include "Settings.h"
#include "User.h"

#include <functional>

/// A struct for holding the values of the current context and identity that have been sent to the server
struct PluginManager_SentData {
	QString context;
	QString identity;
};


/// The plugin manager is the central object dealing with everything plugin-related. It is responsible for
/// finding, loading and managing the plugins. It also is responsible for invoking callback functions in the plugins
/// and can be used by Mumble to communicate with them
class PluginManager : public QObject {
private:
	Q_OBJECT
	Q_DISABLE_COPY(PluginManager)
protected:
	/// Lock for pluginHashMap. This lock has to be aquired when accessing pluginHashMap
	mutable QReadWriteLock m_pluginCollectionLock;
	/// A map between plugin-IDs and the actual plugin objects. You have to aquire pluginCollectionLock before
	/// accessing this map.
	QHash< plugin_id_t, plugin_ptr_t > m_pluginHashMap;
	/// A set of directories to search plugins in
	QSet< QString > m_pluginSearchPaths;
#ifdef Q_OS_WIN
	// This stuff is apparently needed on Windows in order to deal with DLLs
	HANDLE m_hToken;
	TOKEN_PRIVILEGES m_tpPrevious;
	DWORD m_cbPrevious;
#endif
	/// The PositionalData object holding the current positional data (as retrieved by the respective plugin)
	PositionalData m_positionalData;

	/// A timer that causes the manager to regularly check for available plugins that can currently
	/// deliver positional data.
	QTimer m_positionalDataCheckTimer;

	/// The mutex for sentData. This has to be aquired before accessing sentData
	mutable QMutex m_sentDataMutex;
	/// The bits of the positional data that have already been sent to the server. It is used to determine whether
	/// the new data has to be sent to the server (in case it has changed). You have ti aquire sentDataMutex before
	/// accessing this field.
	PluginManager_SentData m_sentData;

	/// The lock for activePositionalDataPlugin. It has to be aquired before accessing the respective field.
	mutable QReadWriteLock m_activePosDataPluginLock;
	/// The plugin that is currently used to retrieve positional data. You have to aquire activePosDataPluginLock before
	/// accessing this field.
	plugin_ptr_t m_activePositionalDataPlugin;
	/// The PluginUpdater used to handle plugin updates.
	PluginUpdater m_updater;

	// We override the QObject::eventFilter function in order to be able to install the pluginManager as an event filter
	// to the main application in order to get notified about keystrokes.
	bool eventFilter(QObject *target, QEvent *event) Q_DECL_OVERRIDE;

	/// Unloads all plugins that are currently loaded.
	void unloadPlugins() const;
	/// Clears the current list of plugins
	void clearPlugins();
	/// Iterates over the plugins and tries to select a plugin that currently claims to be able to deliver positional
	/// data. If it found a plugin, activePositionalDataPlugin is set accordingly. If not, it is set to nullptr.
	///
	/// @returns Whether this function succeeded in finding such a plugin
	bool selectActivePositionalDataPlugin();

	/// A internal helper function that iterates over all plugins and calls the given function providing the current
	/// plugin as a parameter.
	void foreachPlugin(std::function< void(Plugin &) >) const;

public:
	// How often positional data (identity & context) should be synched with the server if there is any (in ms)
	static constexpr int POSITIONAL_SERVER_SYNC_INTERVAL = 500;
	// How often the manager should check for available positional data plugins
	static constexpr int POSITIONAL_DATA_CHECK_INTERVAL = 1000;

	/// Constructor
	///
	/// @param additionalSearchPaths A pointer to a set of additional search paths or nullptr if no additional
	/// paths are required.
	/// @param p The parent QObject
	PluginManager(QSet< QString > *additionalSearchPaths = nullptr, QObject *p = nullptr);
	/// Destructor
	virtual ~PluginManager() Q_DECL_OVERRIDE;

	/// @param pluginID The ID of the plugin that should be retreved
	/// @returns A pointer to the plugin with the given ID or nullptr if no such plugin could be found
	const_plugin_ptr_t getPlugin(plugin_id_t pluginID) const;
	/// Checks whether there are any updates for the plugins and if there are it invokes the PluginUpdater.
	void checkForPluginUpdates();
	/// Fetches positional data from the activePositionalDataPlugin if there is one set. This function will update the
	/// positionalData field
	///
	/// @returns Whether the positional data could be retrieved successfully
	bool fetchPositionalData();
	/// Unlinks the currently active positional data plugin. Effectively this sets activePositionalDataPlugin to nullptr
	void unlinkPositionalData();
	/// @returns Whether positional data is currently available (it has been successfully set via fetchPositionalData)
	bool isPositionalDataAvailable() const;
	/// @returns The most recent positional data
	const PositionalData &getPositionalData() const;
	/// Enables positional data gathering for the plugin with the given ID. A plugin is only even asked whether it can
	/// deliver positional data if this is enabled.
	///
	/// @param pluginID The ID of the plugin to access
	/// @param enable Whether to enable positional data (alternative is to disable it)
	void enablePositionalDataFor(plugin_id_t pluginID, bool enable = true) const;
	/// @returns A const vector of the plugins
	const QVector< const_plugin_ptr_t > getPlugins(bool sorted = false) const;
	/// Loads the plugin with the given ID. Loading means initializing the plugin.
	///
	/// @param pluginID The ID of the plugin to load
	/// @returns Whether the plugin could be successfully loaded
	bool loadPlugin(plugin_id_t pluginID) const;
	/// Unloads the plugin with the given ID. Unloading means shutting the plugign down.
	///
	/// @param pluginID The ID of the plugin to unload
	void unloadPlugin(plugin_id_t pluginID) const;
	/// Unloads the given plugin. Unloading means shutting the plugign down.
	///
	/// @param plugin The plugin to unload
	void unloadPlugin(Plugin &plugin) const;
	/// Clears the plugin from the list of known plugins
	///
	/// @param pluginID The ID of the plugin to forget about
	/// @returns Whether the plugin has been cleared successfully
	bool clearPlugin(plugin_id_t pluginID);
	/// Deactivates the given features for the plugin with the given ID
	///
	/// @param pluginID The ID of the plugin to access
	/// @param features The feature set that should be deactivated. The features are or'ed together.
	/// @returns The feature set that could not be deactivated
	uint32_t deactivateFeaturesFor(plugin_id_t pluginID, uint32_t features) const;
	/// Allows or forbids the given plugin to monitor keyboard events.
	///
	/// @param pluginID The ID of the plugin to access
	/// @param allow Whether to allow the monitoring or not
	void allowKeyboardMonitoringFor(plugin_id_t pluginID, bool allow) const;
	/// Checks whether a plugin with the given ID exists.
	///
	/// @param pluginID The ID to check
	/// @returns Whether such a plugin exists
	bool pluginExists(plugin_id_t pluginID) const;

public slots:
	/// Rescans the plugin directory and load all plugins from there after having cleared the current plugin list
	void rescanPlugins();
	/// Slot that gets called whenever data from another plugin has been received. This function will then delegate
	/// this to the respective plugin callback
	///
	/// @param sender A pointer to the ClientUser whose client has sent the data
	/// @param data The byte-array representing the sent data
	/// @param dataLength The length of the data array
	/// @param dataID The ID of the data
	void on_receiveData(const ClientUser *sender, const uint8_t *data, size_t dataLength, const char *dataID) const;
	/// Slot that gets called when the local client connects to a server. It will delegate it to the respective plugin
	/// callback.
	void on_serverConnected() const;
	/// Slot that gets called when the local client disconnects to a server. It will delegate it to the respective
	/// plugin callback.
	void on_serverDisconnected() const;
	/// Slot that gets called when a client enters a channel. It will delegate it to the respective plugin callback.
	///
	/// @param newChannel A pointer to the new channel
	/// @param prevChannel A pointer to the previous channel or nullptr if no such channel exists
	/// @param user A pointer to the user that entered the channel
	void on_channelEntered(const Channel *newChannel, const Channel *prevChannel, const User *user) const;
	/// Slot that gets called when a client leaves a channel. It will delegate it to the respective plugin callback.
	///
	/// @param channel A pointer to the channel that has been left
	/// @param user A pointer to the user that entered the channel
	void on_channelExited(const Channel *channel, const User *user) const;
	/// Slot that gets called when the local client changes its talking state. It will delegate it to the respective
	/// plugin callback.
	void on_userTalkingStateChanged() const;
	/// Slot that gets called when the local client receives audio input. It will delegate it to the respective plugin
	/// callback.
	///
	/// @param inputPCM The array containing the input PCM (pulse-code-modulation). Its length is sampleCount *
	/// channelCount
	/// @param sampleCount The amount of samples in the PCM array
	/// @param channelCount The amount of channels in the PCM array
	/// @param sampleRate The used sample rate in Hz
	/// @param isSpeech Whether Mumble considers this input as speech
	void on_audioInput(short *inputPCM, unsigned int sampleCount, unsigned int channelCount, unsigned int sampleRate,
					   bool isSpeech) const;
	/// Slot that gets called when the local client has fetched an audio source. It will delegate it to the respective
	/// plugin callback.
	///
	/// @param outputPCM The array containing the output-PCM (pulse-code-modulation). Its length is sampleCount *
	/// channelCount
	/// @param sampleCount The amount of samples in the PCM array
	/// @param channelCount The amount of channels in the PCM array
	/// @param sampleRate The used sample rate in Hz
	/// @param isSpeech Whether Mumble considers this input as speech
	/// @param user A pointer to the ClientUser the audio source corresposnds to
	void on_audioSourceFetched(float *outputPCM, unsigned int sampleCount, unsigned int channelCount,
							   unsigned int sampleRate, bool isSpeech, const ClientUser *user) const;
	/// Slot that gets called when the local client is about to play some audio. It will delegate it to the respective
	/// plugin callback.
	///
	/// @param outputPCM The array containing the output-PCM (pulse-code-modulation). Its length is sampleCount *
	/// channelCount
	/// @param sampleCount The amount of samples in the PCM array
	/// @param channelCount The amount of channels in the PCM array
	/// @param sampleRate The used sample rate in Hz
	void on_audioOutputAboutToPlay(float *outputPCM, unsigned int sampleCount, unsigned int channelCount,
								   unsigned int sampleRate, bool *modifiedAudio) const;
	/// Slot that gets called after the local client has finished synchronizing with the server. It will delegate it to
	/// the respective plugin callback.
	void on_serverSynchronized() const;
	/// Slot that gets called when a new user is added to the user model. It will delegate it to the respective plugin
	/// callbacks.
	///
	/// @param userID The ID of the added user
	void on_userAdded(unsigned int userID) const;
	/// Slot that gets called when a user is removed from the user model. It will delegate it to the respective plugin
	/// callbacks.
	///
	/// @param userID The ID of the removed user
	void on_userRemoved(unsigned int userID) const;
	/// Slot that gets called when a new channel is added to the user model. It will delegate it to the respective
	/// plugin callbacks.
	///
	/// @param channelID The ID of the added channel
	void on_channelAdded(int channelID) const;
	/// Slot that gets called when a channel is removed from the user model. It will delegate it to the respective
	/// plugin callbacks.
	///
	/// @param channelID The ID of the removed channel
	void on_channelRemoved(int channelID) const;
	/// Slot that gets called when a channel is renamed. It will delegate it to the respective plugin callbacks.
	///
	/// @param channelID The ID of the renamed channel
	void on_channelRenamed(int channelID) const;
	/// Slot that gets called when a key has been pressed or released while Mumble has keyboard focus.
	///
	/// @param key The code of the affected key (as encoded by Qt::Key)
	/// @param modifiers The modifiers that were active in the moment of the event
	/// @param isPress True if the key has been pressed, false if it has been released
	void on_keyEvent(unsigned int key, Qt::KeyboardModifiers modifiers, bool isPress) const;

	/// Slot that gets called whenever the positional data should be synchronized with the server. Before it does that,
	/// it tries to fetch new data.
	void on_syncPositionalData();
	/// Slot called if there are plugin updates available
	void on_updatesAvailable();

protected slots:
	/// If there is no active positional data plugin, this function will initiate searching for a
	/// new one.
	void checkForAvailablePositionalDataPlugin();

signals:
	/// A signal emitted if the PluginManager (acting as an event filter) detected
	/// a QKeyEvent.
	///
	/// @param key The code of the affected key (as encoded by Qt::Key)
	/// @param modifiers The modifiers that were active in the moment of the event
	/// @param isPress True if the key has been pressed, false if it has been released
	void keyEvent(unsigned int key, Qt::KeyboardModifiers modifiers, bool isPress);
};

#endif