/*
 # Copyright (c) 2009,2010 - OpenSLX Project, Computer Center University of
 # Freiburg
 #
 # This program is free software distributed under the GPL version 2.
 # See http://openslx.org/COPYING
 #
 # If you have any feedback please consult http://openslx.org/feedback and
 # send your suggestions, praise, or complaints to feedback@openslx.org
 #
 # General information about OpenSLX can be found at http://openslx.org/
 # -----------------------------------------------------------------------------
 # src/net/pvsCheckPrivileges_linux.h
 #    - Linux implementation of privilege checking
 # -----------------------------------------------------------------------------
 */

#ifndef PVSCHECKPRIVILEGES_H_
#define PVSCHECKPRIVILEGES_H_

#include <sys/types.h>
#include <QObject>
#include <QString>
#include <QList>
#include <QMultiMap>
#include <QHash>
#include "inputEventHandler.h"

/**
 * Store the information in an InputEventContext as a plain old datatype.
 */
struct CachedInputContext
{
	CachedInputContext(InputEventContext const* source)
	{
		if(source)
		{
			pid = source->senderPid();
			uid = source->senderUid();
			gid = source->senderGid();
		}
		else
		{
			pid = (pid_t)-1;
			uid = (uid_t)-1;
			gid = (gid_t)-1;
		}
	}

	CachedInputContext()
	{
		pid = (pid_t)-1;
		uid = (uid_t)-1;
		gid = (gid_t)-1;
	}

	pid_t pid;
	uid_t uid;
	gid_t gid;

	bool isValid() const
	{
		return (pid != (pid_t)-1) && (uid != (uid_t)-1) && (gid != (gid_t)-1);
	}

	bool operator==(CachedInputContext const& other) const
	{
		return (other.pid == pid) && (other.uid == uid) && (other.gid == gid);
	}
};
uint qHash(CachedInputContext const& p);

class QFileSystemWatcher;

/**
 * Check user privileges and handle communications with ConsoleKit and PolicyKit.
 * This is a singleton class.
 */
class PVSCheckPrivileges : public QObject
{
	Q_OBJECT
public:
	/**
	 * SessionKind distinguishes between local and remote users.
	 */
	typedef enum {
		SESSION_LOCAL,				/**< User is local */
		SESSION_NONLOCAL,			/**< User is remote */
		SESSION_LOOKUP_FAILURE,		/**< Failure to look up whether the user is local or remote */
		SESSION_UNKNOWN				/**< User session kind not (yet) known */
	} SessionKind;

	/**
	 * UserPrivilege distinguishes between privileged and unprivileged users.
	 */
	typedef enum {
		USER_PRIVILEGED,			/**< User is privileged */
		USER_UNPRIVILEGED,			/**< User is unprivileged */
		USER_LOOKUP_FAILURE,		/**< Failure to look up whether the user is privileged or unprivileged */
		USER_UNKNOWN				/**< User privilege level not (yet) known */
	} UserPrivilege;

	/** \name Conversion Functions */
	/* @{ */

	static QString toString(SessionKind k)
	{
		switch(k)
		{
		case SESSION_LOOKUP_FAILURE: return "SESSION_LOOKUP_FAILURE";
		case SESSION_LOCAL: return "SESSION_LOCAL";
		case SESSION_NONLOCAL: return "SESSION_NONLOCAL";
		case SESSION_UNKNOWN: return "SESSION_UNKNOWN";
		default: return QString("unknown value (%1)").arg(k);
		}
	}

	static QString toString(UserPrivilege k)
	{
		switch(k)
		{
		case USER_PRIVILEGED: return "USER_PRIVILEGED";
		case USER_UNPRIVILEGED: return "USER_UNPRIVILEGED";
		case USER_LOOKUP_FAILURE: return "USER_LOOKUP_FAILURE";
		case USER_UNKNOWN: return "USER_UNKNOWN";
		default: return QString("unknown value (%1)").arg(k);
		}
	}

	/* @} */

	/** \name Singleton pattern */
	/* @{ */

	/** Retrieve the singleton instance. */
	static PVSCheckPrivileges* instance();

	/** Delete the singleton instance. */
	static void deleteInstance();

	/* @} */

	/** \name Privilege Checks */
	/* @{ */

	/** Check for a minimum SessionKind level. \return true if the requirement is fulfilled. */
	bool require(SessionKind sessionKind, CachedInputContext const& sender);

	/** Check for a minimum UserPrivilege level. \return true if the requirement is fulfilled. */
	bool require(UserPrivilege userPrivilege, CachedInputContext const& sender);

	/** Check for a minimum SessionKind and UserPrivilege level. \return true if both requirements are fulfilled. */
	bool require(SessionKind sessionKind, UserPrivilege userPrivilege, CachedInputContext const& sender);

	/* @} */

	/** \name Session Information */
	/* @{ */

	/** Retrieve the name of the user's X session, according to ConsoleKit. */
	QString getX11SessionName(CachedInputContext const& sender);

	/** Retrieve the TTY device of the user's X session, according to ConsoleKit. */
	QString getX11DisplayDevice(CachedInputContext const& sender);

public slots:
	void updateCachedUserDatabase();
	void rereadConfiguration();

private:
	PVSCheckPrivileges(QObject* parent = 0);
	virtual ~PVSCheckPrivileges();

	typedef QPair<pid_t, QPair<uid_t, gid_t> > piduidgid;
	piduidgid makePidUidGid(pid_t pid, uid_t uid, gid_t gid)
	{
		return qMakePair(pid, qMakePair(uid, gid));
	}

	QString getSessionReference(CachedInputContext const& sender);
	SessionKind getSessionKind(CachedInputContext const& sender);
	UserPrivilege getUserPrivilege(CachedInputContext const& sender);

	static PVSCheckPrivileges* _instance;

	QHash<CachedInputContext, UserPrivilege> _savedUserPrivilege;
	QHash<CachedInputContext, SessionKind> _savedSessionKind;
	QHash<CachedInputContext, QString> _savedConsoleKitSession;

	QList<uid_t> _privilegedUsers;
	QList<gid_t> _privilegedGroups;
	QMultiMap<uid_t, gid_t> _userGroupMap;
	QFileSystemWatcher* _watcher;
};

#endif /* PVSCHECKPRIVILEGES_H_ */