/** Nodes
 *
 * @file
 * @author Steffen Vogel <post@steffenvogel.de>
 * @copyright 2014-2022, Institute for Automation of Complex Power Systems, EONERC
 * @license Apache 2.0
 *********************************************************************************/

#pragma once

#include <jansson.h>
#include <uuid/uuid.h>
#include <spdlog/fmt/ostr.h>

#include <villas/node_list.hpp>
#include <villas/node_direction.hpp>
#include <villas/node/memory.hpp>
#include <villas/sample.hpp>
#include <villas/list.hpp>
#include <villas/queue.h>
#include <villas/colors.hpp>
#include <villas/common.hpp>
#include <villas/stats.hpp>
#include <villas/log.hpp>
#include <villas/plugin.hpp>
#include <villas/path_source.hpp>
#include <villas/path_destination.hpp>

#if defined(LIBNL3_ROUTE_FOUND) && defined(__linux__)
  #define WITH_NETEM
#endif /* LIBNL3_ROUTE_FOUND */

/* Forward declarations */
#ifdef WITH_NETEM
  struct rtnl_qdisc;
  struct rtnl_cls;
#endif /* WITH_NETEM */

#define RE_NODE_NAME "[a-z0-9_-]{2,32}"

namespace villas {
namespace node {

/* Forward declarations */
class NodeFactory;
class SuperNode;

/** The class for a node.
 *
 * Every entity which exchanges messages is represented by a node.
 * Nodes can be remote machines and simulators or locally running processes.
 */
class Node {

	friend NodeFactory;

public:
	Logger logger;

	uint64_t sequence_init;
	uint64_t sequence;			/**< This is a counter of received samples, in case the node-type does not generate sequence numbers itself. */

	NodeDirection in, out;

	PathSourceList sources;			/**< A list of path sources which reference this node. */
	PathDestinationList destinations;	/**< A list of path destinations which reference this node. */

#ifdef __linux__
	int fwmark;				/**< Socket mark for netem, routing and filtering */

#ifdef WITH_NETEM
	struct rtnl_qdisc *tc_qdisc;		/**< libnl3: Network emulator queuing discipline */
	struct rtnl_cls *tc_classifier;		/**< libnl3: Firewall mark classifier */
#endif /* WITH_NETEM */
#endif /* __linux__ */

protected:
	enum State state;

	uuid_t uuid;

	bool enabled;

	Stats::Ptr stats;			/**< Statistic counters. This is a pointer to the statistic hooks private data. */

	json_t *config;				/**< A JSON object containing the configuration of the node. */

	std::string name_short;			/**< A short identifier of the node, only used for configuration and logging */
	std::string name_long;			/**< Singleton: A string used to print to screen. */
	std::string name_full;			/**< Singleton: A string used to print to screen. */
	std::string details;

	int affinity;				/**< CPU Affinity of this node */

	NodeFactory *factory;			/**< The factory which created this instance */

	virtual
	int _read(struct Sample * smps[], unsigned cnt)
	{
		return -1;
	}

	virtual
	int _write(struct Sample * smps[], unsigned cnt)
	{
		return -1;
	}

	virtual
	json_t * _readStatus() const
	{
		return nullptr;
	}

public:
	/** Initialize node with default values */
	Node(const uuid_t &id = {}, const std::string &name = "");

	/** Destroy node by freeing dynamically allocated memory. */
	virtual
	~Node();

	/** Do initialization after parsing the configuration */
	virtual
	int prepare();

	/** Parse settings of a node.
	 *
	 * @param json A JSON object containing the configuration of the node.
	 * @retval 0 Success. Everything went well.
	 * @retval <0 Error. Something went wrong.
	 */
	virtual
	int parse(json_t *json);

	/** Validate node configuration. */
	virtual
	int check();

	/** Start operation of a node. */
	virtual
	int start();

	/** Stops operation of a node. */
	virtual
	int stop();

	/** Pauses operation of a node. */
	virtual
	int pause()
	{
		if (state != State::STARTED)
			return -1;

		logger->info("Pausing node");

		return 0;
	}

	/** Resumes operation of a node. */
	virtual
	int resume()
	{
		return 0;
	}

	/** Restarts operation of a node. */
	virtual
	int restart();

	/** Receive multiple messages at once.
	 *
	 * This callback is optional. It will only be called if non-null.
	 *
	 * Messages are received with a single recvmsg() syscall by
	 * using gathering techniques (struct iovec).
	 * The messages will be stored in a circular buffer / array @p m.
	 * Indexes used to address @p m will wrap around after len messages.
	 * Some node-types might only support to receive one message at a time.
	 *
	 * @param smps		An array of pointers to memory blocks where the function should store received samples.
	 * @param cnt		The number of samples that are allocated by the calling function.
	 * @return		    The number of messages actually received.
	 */
	int read(struct Sample * smps[], unsigned cnt);

	/** Send multiple messages in a single datagram / packet.
	 *
	 * This callback is optional. It will only be called if non-null.
	 *
	 * Messages are sent with a single sendmsg() syscall by
	 * using gathering techniques (struct iovec).
	 * The messages have to be stored in a circular buffer / array m.
	 * So the indexes will wrap around after len.
	 *
	 * @param smps		An array of pointers to memory blocks where samples read from.
	 * @param cnt		The number of samples that are allocated by the calling function.
	 * @return		    The number of messages actually sent.
	 */
	int write(struct Sample * smps[], unsigned cnt);

	/** Reverse local and remote socket address. */
	virtual
	int reverse()
	{
		return -1;
	}

	/** Get a list of file descriptors on which the path should poll
	 *  to detect the availability of new samples which can be read.
	 */
	virtual
	std::vector<int> getPollFDs()
	{
		return {};
	}

	/** Get a list of socket file descriptors which are used by the node
	 * To perform network IO. We use those to selectively apply network emulation
	 */
	virtual
	std::vector<int> getNetemFDs()
	{
		return {};
	}

	/** Get the memory type which this node-type expects.
	 *
	 * This is useful for special node-types like Infiniband, GPUs & FPGAs
	 * which require DMA-backed memory.
	 */
	virtual
	struct villas::node::memory::Type * getMemoryType()
	{
		return villas::node::memory::default_type;
	}

	/** Get the factory which was used to construct this node. */
	villas::node::NodeFactory * getFactory() const
	{
		return factory;
	}

	/** Return a pointer to a string which should be used to print this node.
	 *
	 * @param n A pointer to the node structure.
	 */
	std::string getNameShort() const
	{
		return name_short;
	}

	/** Return a pointer to a string which should be used to print this node. */
	const std::string & getName() const
	{
		return name_long;
	}

	/** Get the full name including type and details of the node. */
	const std::string & getNameFull();

	/** Just get the config details of this node as a string */
	virtual
	const std::string & getDetails()
	{
		static std::string empty;
		return empty;
	}

	/** Return a pointer to a string which should be used to print this node.
	 *
	 * @param n A pointer to the node structure.
	 */
	const std::string & getNameLong();

	/** Return a list of signals which are sent to this node.
	 *
	 * This list is derived from the path which uses the node as destination.
	 */
	SignalList::Ptr getOutputSignals(bool after_hooks = true) const;
	SignalList::Ptr getInputSignals(bool after_hooks = true) const;

	/** Get the number of input signals (received by this node) */
	unsigned getInputSignalsMaxCount() const;

	/** Get the number of output signals (send out via this node) */
	unsigned getOutputSignalsMaxCount() const;

	void swapSignals();

	/** Get the node configuration as JSON. */
	json_t * getConfig()
	{
		return config;
	}

	/** Get the state of this node. */
	enum State getState() const
	{
		return state;
	}

	/** Set the state of this node. */
	void setState(enum State s)
	{
		state = s;
	}

	/** Get the UUID of this node. */
	const uuid_t & getUuid() const
	{
		return uuid;
	}

	std::shared_ptr<Stats> getStats()
	{
		return stats;
	}

	void setStats(std::shared_ptr<Stats> sts)
	{
		stats = sts;
	}

	void setEnabled(bool en)
	{
		enabled = en;
	}

	/** Custom formatter for spdlog */
	template<typename OStream>
	friend OStream &operator<<(OStream &os, const Node &n)
	{
		os << n.getName();

		return os;
	}

	json_t * toJson() const;

	static
	bool isValidName(const std::string &name);

	bool isEnabled() const
	{
		return enabled;
	}
};

class NodeFactory : public villas::plugin::Plugin {

	friend Node;

protected:
	virtual
	void init(Node *n)
	{
		n->logger = getLogger();
		n->factory = this;

		n->name_long = fmt::format(CLR_RED("{}") "(" CLR_YEL("{}") ")", n->name_short, getName());

		instances.push_back(n);
	}

	State state;

public:
	enum class Flags {
		SUPPORTS_POLL  		= (1 << 0),
		SUPPORTS_READ  		= (1 << 1),
		SUPPORTS_WRITE 		= (1 << 2),
		REQUIRES_WEB   		= (1 << 3),
		PROVIDES_SIGNALS	= (1 << 4),
		INTERNAL		= (1 << 5),
		HIDDEN			= (1 << 6)
	};

	NodeList instances;

	NodeFactory() :
		Plugin()
	{
		state = State::INITIALIZED;
	}

	virtual
	Node * make(const uuid_t &id = {}, const std::string &nme = "") = 0;

	static
	Node * make(json_t *json, const uuid_t &id, const std::string &name = "");

	static
	Node * make(const std::string &type, const uuid_t &id = {}, const std::string &name = "");

	virtual
	std::string getType() const
	{
		return "node";
	}

	/** Custom formatter for spdlog */
	template<typename OStream>
	friend OStream &operator<<(OStream &os, const NodeFactory &f)
	{
		os << f.getName();

		return os;
	}

	virtual
	int getFlags() const
	{
		return 0;
	}

	virtual
	int getVectorize() const
	{
		return 0;
	}

	bool isInternal() const
	{
		return getFlags() & (int) Flags::INTERNAL;
	}

	bool isHidden() const
	{
		return isInternal() || getFlags() & (int) Flags::HIDDEN;
	}

	virtual
	int start(SuperNode *sn);

	virtual
	int stop();

	State getState() const
	{
		return state;
	}
};

template<typename T, const char *name, const char *desc, int flags = 0, int vectorize = 0>
class NodePlugin : public NodeFactory {

public:
	virtual
	Node * make(const uuid_t &id = {}, const std::string &nme = "")
	{
		T* n = new T(id, nme);

		init(n);

		return n;
	}

	virtual
	int getFlags() const
	{
		return flags;
	}

	virtual
	int getVectorize() const
	{
		return vectorize;
	}

	virtual
	std::string getName() const
	{
		return name;
	}

	virtual
	std::string getDescription() const
	{
		return desc;
	}
};

} /* namespace node */
} /* namespace villas */