/*
 * CModHandler.h, part of VCMI engine
 *
 * Authors: listed in file AUTHORS in main folder
 *
 * License: GNU General Public License v2.0 or later
 * Full text of license available in license.txt file, in main folder
 *
 */
#pragma once

#include "JsonNode.h"
#include "CModVersion.h"

#ifdef __UCLIBC__
#undef major
#undef minor
#undef patch
#endif

VCMI_LIB_NAMESPACE_BEGIN

class CModHandler;
class CModIndentifier;
class CModInfo;
class JsonNode;
class IHandlerBase;

/// class that stores all object identifiers strings and maps them to numeric ID's
/// if possible, objects ID's should be in format <type>.<name>, camelCase e.g. "creature.grandElf"
class DLL_LINKAGE CIdentifierStorage
{
	enum ELoadingState
	{
		LOADING,
		FINALIZING,
		FINISHED
	};

	struct ObjectCallback // entry created on ID request
	{
		std::string localScope;  /// scope from which this ID was requested
		std::string remoteScope; /// scope in which this object must be found
		std::string type;        /// type, e.g. creature, faction, hero, etc
		std::string name;        /// string ID
		std::function<void(si32)> callback;
		bool optional;

		/// Builds callback from identifier in form "targetMod:type.name"
		static ObjectCallback fromNameWithType(const std::string & scope, const std::string & fullName, const std::function<void(si32)> & callback, bool optional);

		/// Builds callback from identifier in form "targetMod:name"
		static ObjectCallback fromNameAndType(const std::string & scope, const std::string & type, const std::string & fullName, const std::function<void(si32)> & callback, bool optional);

	private:
		ObjectCallback() = default;
	};

	struct ObjectData // entry created on ID registration
	{
		si32 id;
		std::string scope; /// scope in which this ID located

		bool operator==(const ObjectData & other) const
		{
			return id == other.id && scope == other.scope;
		}

		template <typename Handler> void serialize(Handler &h, const int version)
		{
			h & id;
			h & scope;
		}
	};

	std::multimap<std::string, ObjectData> registeredObjects;
	std::vector<ObjectCallback> scheduledRequests;

	ELoadingState state;

	/// Check if identifier can be valid (camelCase, point as separator)
	static void checkIdentifier(std::string & ID);

	void requestIdentifier(ObjectCallback callback);
	bool resolveIdentifier(const ObjectCallback & callback);
	std::vector<ObjectData> getPossibleIdentifiers(const ObjectCallback & callback);
public:
	CIdentifierStorage();
	virtual ~CIdentifierStorage() = default;
	/// request identifier for specific object name.
	/// Function callback will be called during ID resolution phase of loading
	void requestIdentifier(const std::string & scope, const std::string & type, const std::string & name, const std::function<void(si32)> & callback);
	///fullName = [remoteScope:]type.name
	void requestIdentifier(const std::string & scope, const std::string & fullName, const std::function<void(si32)> & callback);
	void requestIdentifier(const std::string & type, const JsonNode & name, const std::function<void(si32)> & callback);
	void requestIdentifier(const JsonNode & name, const std::function<void(si32)> & callback);

	/// try to request ID. If ID with such name won't be loaded, callback function will not be called
	void tryRequestIdentifier(const std::string & scope, const std::string & type, const std::string & name, const std::function<void(si32)> & callback);
	void tryRequestIdentifier(const std::string & type, const JsonNode & name, const std::function<void(si32)> & callback);

	/// get identifier immediately. If identifier is not know and not silent call will result in error message
	std::optional<si32> getIdentifier(const std::string & scope, const std::string & type, const std::string & name, bool silent = false);
	std::optional<si32> getIdentifier(const std::string & type, const JsonNode & name, bool silent = false);
	std::optional<si32> getIdentifier(const JsonNode & name, bool silent = false);
	std::optional<si32> getIdentifier(const std::string & scope, const std::string & fullName, bool silent = false);

	/// registers new object
	void registerObject(const std::string & scope, const std::string & type, const std::string & name, si32 identifier);

	/// called at the very end of loading to check for any missing ID's
	void finalize();

	template <typename Handler> void serialize(Handler &h, const int version)
	{
		h & registeredObjects;
		h & state;
	}
};

/// internal type to handle loading of one data type (e.g. artifacts, creatures)
class DLL_LINKAGE ContentTypeHandler
{
public:
	struct ModInfo
	{
		/// mod data from this mod and for this mod
		JsonNode modData;
		/// mod data for this mod from other mods (patches)
		JsonNode patches;
	};
	/// handler to which all data will be loaded
	IHandlerBase * handler;
	std::string objectName;

	/// contains all loaded H3 data
	std::vector<JsonNode> originalData;
	std::map<std::string, ModInfo> modData;

	ContentTypeHandler(IHandlerBase * handler, const std::string & objectName);

	/// local version of methods in ContentHandler
	/// returns true if loading was successful
	bool preloadModData(const std::string & modName, const std::vector<std::string> & fileList, bool validate);
	bool loadMod(const std::string & modName, bool validate);
	void loadCustom();
	void afterLoadFinalization();
};

/// class used to load all game data into handlers. Used only during loading
class DLL_LINKAGE CContentHandler
{
	/// preloads all data from fileList as data from modName.
	bool preloadModData(const std::string & modName, JsonNode modConfig, bool validate);

	/// actually loads data in mod
	bool loadMod(const std::string & modName, bool validate);

	std::map<std::string, ContentTypeHandler> handlers;

public:
	void init();

	/// preloads all data from fileList as data from modName.
	void preloadData(CModInfo & mod);

	/// actually loads data in mod
	void load(CModInfo & mod);

	void loadCustom();

	/// all data was loaded, time for final validation / integration
	void afterLoadFinalization();

	const ContentTypeHandler & operator[] (const std::string & name) const;
};

using TModID = std::string;

class DLL_LINKAGE CModInfo
{
	/// cached result of checkModGameplayAffecting() call
	/// Do not serialize - depends on local mod version, not server/save mod version
	mutable std::optional<bool> modGameplayAffecting;

public:
	enum EValidationStatus
	{
		PENDING,
		FAILED,
		PASSED
	};

	/// identifier, identical to name of folder with mod
	std::string identifier;

	/// human-readable strings
	std::string name;
	std::string description;
	
	/// version of the mod
	CModVersion version;

	/// Base language of mod, all mod strings are assumed to be in this language
	std::string baseLanguage;
	
	/// vcmi versions compatible with the mod

	CModVersion vcmiCompatibleMin, vcmiCompatibleMax;

	/// list of mods that should be loaded before this one
	std::set <TModID> dependencies;

	/// list of mods that can't be used in the same time as this one
	std::set <TModID> conflicts;

	/// CRC-32 checksum of the mod
	ui32 checksum;

	EValidationStatus validation;

	JsonNode config;

	CModInfo();
	CModInfo(const std::string & identifier, const JsonNode & local, const JsonNode & config);

	JsonNode saveLocalData() const;
	void updateChecksum(ui32 newChecksum);

	/// return true if this mod can affect gameplay, e.g. adds or modifies any game objects
	bool checkModGameplayAffecting() const;

	bool isEnabled() const;
	void setEnabled(bool on);

	static std::string getModDir(const std::string & name);
	static std::string getModFile(const std::string & name);

private:
	/// true if mod is enabled by user, e.g. in Launcher UI
	bool explicitlyEnabled;

	/// true if mod can be loaded - compatible and has no missing deps
	bool implicitlyEnabled;

	void loadLocalData(const JsonNode & data);
};

class DLL_LINKAGE CModHandler
{
	std::map <TModID, CModInfo> allMods;
	std::vector <TModID> activeMods;//active mods, in order in which they were loaded
	CModInfo coreMod;

	bool hasCircularDependency(const TModID & mod, std::set<TModID> currentList = std::set<TModID>()) const;

	/**
	* 1. Set apart mods with resolved dependencies from mods which have unresolved dependencies
	* 2. Sort resolved mods using topological algorithm
	* 3. Log all problem mods and their unresolved dependencies
	*
	* @param modsToResolve list of valid mod IDs (checkDependencies returned true - TODO: Clarify it.)
	* @return a vector of the topologically sorted resolved mods: child nodes (dependent mods) have greater index than parents
	*/
	std::vector <TModID> validateAndSortDependencies(std::vector <TModID> modsToResolve) const;

	std::vector<std::string> getModList(const std::string & path) const;
	void loadMods(const std::string & path, const std::string & parent, const JsonNode & modSettings, bool enableMods);
	void loadOneMod(std::string modName, const std::string & parent, const JsonNode & modSettings, bool enableMods);
	void loadTranslation(const TModID & modName);

	bool validateTranslations(TModID modName) const;
public:

	/// returns true if scope is reserved for internal use and can not be used by mods
	static bool isScopeReserved(const TModID & scope);

	/// reserved scope name for referencing built-in (e.g. H3) objects
	static const TModID & scopeBuiltin();

	/// reserved scope name for accessing objects from any loaded mod
	static const TModID & scopeGame();

	/// reserved scope name for accessing object for map loading
	static const TModID & scopeMap();

	class DLL_LINKAGE Incompatibility: public std::exception
	{
	public:
		using StringPair = std::pair<const std::string, const std::string>;
		using ModList = std::list<StringPair>;
		
		Incompatibility(ModList && _missingMods):
			missingMods(std::move(_missingMods))
		{
			std::ostringstream _ss;
			for(const auto & m : missingMods)
				_ss << m.first << ' ' << m.second << std::endl;
			message = _ss.str();
		}
		
		const char * what() const noexcept override
		{
			return message.c_str();
		}
		
	private:
		//list of mods required to load the game
		// first: mod name
		// second: mod version
		const ModList missingMods;
		std::string message;
	};

	CIdentifierStorage identifiers;

	std::shared_ptr<CContentHandler> content; //(!)Do not serialize

	/// receives list of available mods and trying to load mod.json from all of them
	void initializeConfig();
	void loadMods(bool onlyEssential = false);
	void loadModFilesystems();

	/// returns ID of mod that provides selected file resource
	TModID findResourceOrigin(const ResourceID & name);

	std::string getModLanguage(const TModID & modId) const;

	std::set<TModID> getModDependencies(const TModID & modId, bool & isModFound) const;

	/// returns list of all (active) mods
	std::vector<std::string> getAllMods();
	std::vector<std::string> getActiveMods();
	
	const CModInfo & getModInfo(const TModID & modId) const;

	/// load content from all available mods
	void load();
	void afterLoad(bool onlyEssential);

	CModHandler();
	virtual ~CModHandler() = default;

	static std::string normalizeIdentifier(const std::string & scope, const std::string & remoteScope, const std::string & identifier);

	static void parseIdentifier(const std::string & fullIdentifier, std::string & scope, std::string & type, std::string & identifier);

	static std::string makeFullIdentifier(const std::string & scope, const std::string & type, const std::string & identifier);

	template <typename Handler> void serialize(Handler &h, const int version)
	{
		if(h.saving)
		{
			h & activeMods;
			for(const auto & m : activeMods)
				h & allMods[m].version;
		}
		else
		{
			loadMods();
			std::vector<TModID> saveActiveMods;
			std::vector<TModID> newActiveMods;
			h & saveActiveMods;
			
			Incompatibility::ModList missingMods;

			for(const auto & m : activeMods)
			{
				if (vstd::contains(saveActiveMods, m))
					continue;

				auto & modInfo = allMods.at(m);
				if(modInfo.checkModGameplayAffecting())
					missingMods.emplace_back(m, modInfo.version.toString());
			}

			for(const auto & m : saveActiveMods)
			{
				CModVersion mver;
				h & mver;

				if (allMods.count(m) == 0)
				{
					missingMods.emplace_back(m, mver.toString());
					continue;
				}

				auto & modInfo = allMods.at(m);

				bool modAffectsGameplay = modInfo.checkModGameplayAffecting();
				bool modVersionCompatible = modInfo.version.isNull() || mver.isNull() || modInfo.version.compatible(mver);
				bool modEnabledLocally = vstd::contains(activeMods, m);
				bool modCanBeEnabled = modEnabledLocally && modVersionCompatible;

				allMods[m].setEnabled(modCanBeEnabled);

				if (modCanBeEnabled)
					newActiveMods.push_back(m);

				if (!modCanBeEnabled && modAffectsGameplay)
					missingMods.emplace_back(m, mver.toString());
			}
			
			if(!missingMods.empty())
				throw Incompatibility(std::move(missingMods));
			
			std::swap(activeMods, newActiveMods);
		}

		h & identifiers;
	}
};

VCMI_LIB_NAMESPACE_END