/*
 *
 * (C) 2003-2022 Anope Team
 * Contact us at team@anope.org
 *
 * Please read COPYING and README for further details.
 *
 * Based on the original code of Epona by Lara.
 * Based on the original code of Services by Andy Church.
 */

#ifndef SERIALIZE_H
#define SERIALIZE_H

#include <sstream>

#include "anope.h"
#include "base.h"

namespace Serialize
{
	class Data
	{
	 public:
		enum Type
		{
			DT_TEXT,
			DT_INT
		};

		virtual ~Data() { }

		virtual std::iostream& operator[](const Anope::string &key) = 0;
		virtual std::set<Anope::string> KeySet() const { throw CoreException("Not supported"); }
		virtual size_t Hash() const { throw CoreException("Not supported"); }

		virtual void SetType(const Anope::string &key, Type t) { }
		virtual Type GetType(const Anope::string &key) const { return DT_TEXT; }
	};

	extern void RegisterTypes();
	extern void CheckTypes();

	class Type;
	template<typename T> class Checker;
	template<typename T> class Reference;
}

/** A serializable object. Serializable objects can be serialized into
 * abstract data types (Serialize::Data), and then reconstructed or
 * updated later at any time.
 */
class CoreExport Serializable : public virtual Base
{
 private:
	/* A list of every serializable item in Anope.
	 * Some of these are static and constructed at runtime,
	 * so this list must be on the heap, as it is not always
	 * constructed before other objects are if it isn't.
	 */
	static std::list<Serializable *> *SerializableItems;
	friend class Serialize::Type;
	/* The type of item this object is */
	Serialize::Type *s_type;
	/* Iterator into serializable_items */
	std::list<Serializable *>::iterator s_iter;
	/* The hash of the last serialized form of this object committed to the database */
	size_t last_commit;
	/* The last time this object was committed to the database */
	time_t last_commit_time;

 protected:
	Serializable(const Anope::string &serialize_type);
	Serializable(const Serializable &);

	Serializable &operator=(const Serializable &);

 public:
	virtual ~Serializable();

	/* Unique ID (per type, not globally) for this object */
	uint64_t id;

	/* Only used by redis, to ignore updates */
	unsigned short redis_ignore;

	/** Marks the object as potentially being updated "soon".
	 */
	void QueueUpdate();

	bool IsCached(Serialize::Data &);
	void UpdateCache(Serialize::Data &);

	bool IsTSCached();
	void UpdateTS();

	/** Get the type of serializable object this is
	 * @return The serializable object type
	 */
	Serialize::Type* GetSerializableType() const { return this->s_type; }

	virtual void Serialize(Serialize::Data &data) const = 0;

	static const std::list<Serializable *> &GetItems();
};

/* A serializable type. There should be one of these classes for each type
 * of class that inherits from Serializable. Used for unserializing objects
 * of this type, as it requires a function pointer to a static member function.
 */
class CoreExport Serialize::Type : public Base
{
	typedef Serializable* (*unserialize_func)(Serializable *obj, Serialize::Data &);

	static std::vector<Anope::string> TypeOrder;
	static std::map<Anope::string, Serialize::Type *> Types;

	/* The name of this type, should be a class name */
	Anope::string name;
	unserialize_func unserialize;
	/* Owner of this type. Used for placing objects of this type in separate databases
	 * based on what module, if any, owns it.
	 */
	Module *owner;

	/* The timestamp for this type. All objects of this type are as up to date as
	 * this timestamp. if curtime == timestamp then we have the most up to date
	 * version of every object of this type.
	 */
	time_t timestamp;

 public:
	/* Map of Serializable::id to Serializable objects */
	std::map<uint64_t, Serializable *> objects;

	/** Creates a new serializable type
	 * @param n Type name
	 * @param f Func to unserialize objects
	 * @param owner Owner of this type. Leave NULL for the core.
	 */
	Type(const Anope::string &n, unserialize_func f, Module *owner = NULL);
	~Type();

	/** Gets the name for this type
	 * @return The name, eg "NickAlias"
	 */
	const Anope::string &GetName() { return this->name; }

	/** Unserialized an object.
	 * @param obj NULL if this object doesn't yet exist. If this isn't NULL, instead
	 * update the contents of this object.
	 * @param data The data to unserialize
	 * @return The unserialized object. If obj != NULL this should be obj.
	 */
	Serializable *Unserialize(Serializable *obj, Serialize::Data &data);

	/** Check if this object type has any pending changes and update them.
	 */
	void Check();

	/** Gets the timestamp for the object type. That is, the time we know
	 * all objects of this type are updated at least to.
	 */
	time_t GetTimestamp() const;

	/** Bumps object type timestamp to current time
	 */
	void UpdateTimestamp();

	Module* GetOwner() const { return this->owner; }

	static Serialize::Type *Find(const Anope::string &name);

	static const std::vector<Anope::string> &GetTypeOrder();

	static const std::map<Anope::string, Serialize::Type *>& GetTypes();
};

/** Should be used to hold lists and other objects of a specific type,
 * but not a specific object. Used for ensuring that any access to
 * this object type is always up to date. These are usually constructed
 * at run time, before main is called, so no types are registered. This
 * is why there are static Serialize::Type* variables in every function.
 */
template<typename T>
class Serialize::Checker
{
	Anope::string name;
	T obj;
	mutable ::Reference<Serialize::Type> type;

	inline void Check() const
	{
		if (!type)
			type = Serialize::Type::Find(this->name);
		if (type)
			type->Check();
	}

 public:
	Checker(const Anope::string &n) : name(n), type(NULL) { }

	inline const T* operator->() const
	{
		this->Check();
		return &this->obj;
	}
	inline T* operator->()
	{
		this->Check();
		return &this->obj;
	}

	inline const T& operator*() const
	{
		this->Check();
		return this->obj;
	}
	inline T& operator*()
	{
		this->Check();
		return this->obj;
	}

	inline operator const T&() const
	{
		this->Check();
		return this->obj;
	}
	inline operator T&()
	{
		this->Check();
		return this->obj;
	}
};

/** Used to hold references to serializable objects. Reference should always be
 * used when holding references to serializable objects for extended periods of time
 * to ensure that the object it refers to it always up to date. This also behaves like
 * Reference in that it will invalidate itself if the object it refers to is
 * destructed.
 */
template<typename T>
class Serialize::Reference : public ReferenceBase
{
 protected:
	T *ref;

 public:
	Reference() : ref(NULL)
	{
	}

	Reference(T *obj) : ref(obj)
	{
		if (obj)
			obj->AddReference(this);
	}

	Reference(const Reference<T> &other) : ReferenceBase(other), ref(other.ref)
	{
		if (ref && !invalid)
			this->ref->AddReference(this);
	}

	~Reference()
	{
		if (ref && !invalid)
			this->ref->DelReference(this);
	}

	inline Reference<T>& operator=(const Reference<T> &other)
	{
		if (this != &other)
		{
			if (ref && !invalid)
				this->ref->DelReference(this);

			this->ref = other.ref;
			this->invalid = other.invalid;

			if (ref && !invalid)
				this->ref->AddReference(this);
		}
		return *this;
	}

	inline operator bool() const
	{
		if (!this->invalid)
			return this->ref != NULL;
		return false;
	}

	inline operator T*() const
	{
		if (!this->invalid)
		{
			if (this->ref)
				// This can invalidate me
				this->ref->QueueUpdate();
			if (!this->invalid)
				return this->ref;
		}
		return NULL;
	}

	inline T* operator*() const
	{
		if (!this->invalid)
		{
			if (this->ref)
				// This can invalidate me
				this->ref->QueueUpdate();
			if (!this->invalid)
				return this->ref;
		}
		return NULL;
	}

	inline T* operator->() const
	{
		if (!this->invalid)
		{
			if (this->ref)
				// This can invalidate me
				this->ref->QueueUpdate();
			if (!this->invalid)
				return this->ref;
		}
		return NULL;
	}
};

#endif // SERIALIZE_H