vcmi/lib/JsonNode.h

/*
 * JsonNode.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 "GameConstants.h"
#include "filesystem/ResourcePath.h"

VCMI_LIB_NAMESPACE_BEGIN

class JsonNode;
using JsonMap = std::map<std::string, JsonNode>;
using JsonVector = std::vector<JsonNode>;

struct Bonus;
class CSelector;
class CAddInfo;
class ILimiter;

class DLL_LINKAGE JsonNode
{
public:
	enum class JsonType
	{
		DATA_NULL,
		DATA_BOOL,
		DATA_FLOAT,
		DATA_STRING,
		DATA_VECTOR,
		DATA_STRUCT,
		DATA_INTEGER
	};

private:
	using JsonData = std::variant<std::monostate, bool, double, std::string, JsonVector, JsonMap, si64>;

	JsonData data;

public:
	/// free to use metadata fields
	std::string meta;
	// meta-flags like override
	std::vector<std::string> flags;

	//Create empty node
	JsonNode(JsonType Type = JsonType::DATA_NULL);
	//Create tree from Json-formatted input
	explicit JsonNode(const char * data, size_t datasize);
	explicit JsonNode(const std::byte * data, size_t datasize);
	//Create tree from JSON file
	explicit JsonNode(const JsonPath & fileURI);
	explicit JsonNode(const std::string & modName, const JsonPath & fileURI);
	explicit JsonNode(const JsonPath & fileURI, bool & isValidSyntax);

	bool operator == (const JsonNode &other) const;
	bool operator != (const JsonNode &other) const;

	void setMeta(const std::string & metadata, bool recursive = true);

	/// Convert node to another type. Converting to nullptr will clear all data
	void setType(JsonType Type);
	JsonType getType() const;

	bool isNull() const;
	bool isNumber() const;
	bool isString() const;
	bool isVector() const;
	bool isStruct() const;
	/// true if node contains not-null data that cannot be extended via merging
	/// used for generating common base node from multiple nodes (e.g. bonuses)
	bool containsBaseData() const;
	bool isCompact() const;
	/// removes all data from node and sets type to null
	void clear();

	/// returns bool or bool equivalent of string value if 'success' is true, or false otherwise
	bool TryBoolFromString(bool & success) const;

	/// non-const accessors, node will change type on type mismatch
	bool & Bool();
	double & Float();
	si64 & Integer();
	std::string & String();
	JsonVector & Vector();
	JsonMap & Struct();

	/// const accessors, will cause assertion failure on type mismatch
	bool Bool() const;
	///float and integer allowed
	double Float() const;
	///only integer allowed
	si64 Integer() const;
	const std::string & String() const;
	const JsonVector & Vector() const;
	const JsonMap & Struct() const;

	/// returns resolved "json pointer" (string in format "/path/to/node")
	const JsonNode & resolvePointer(const std::string & jsonPointer) const;
	JsonNode & resolvePointer(const std::string & jsonPointer);

	/// convert json tree into specified type. Json tree must have same type as Type
	/// Valid types: bool, string, any numeric, map and vector
	/// example: convertTo< std::map< std::vector<int> > >();
	template<typename Type>
	Type convertTo() const;

	//operator [], for structs only - get child node by name
	JsonNode & operator[](const std::string & child);
	const JsonNode & operator[](const std::string & child) const;

	JsonNode & operator[](size_t child);
	const JsonNode & operator[](size_t  child) const;

	std::string toJson(bool compact = false) const;
	std::vector<std::byte> toBytes(bool compact = false) const;

	template <typename Handler> void serialize(Handler &h)
	{
		h & meta;
		h & flags;
		h & data;
	}
};

namespace JsonUtils
{
	DLL_LINKAGE std::shared_ptr<Bonus> parseBonus(const JsonVector & ability_vec);
	DLL_LINKAGE std::shared_ptr<Bonus> parseBonus(const JsonNode & ability);
	DLL_LINKAGE std::shared_ptr<Bonus> parseBuildingBonus(const JsonNode & ability, const FactionID & faction, const BuildingID & building, const std::string & description);
	DLL_LINKAGE bool parseBonus(const JsonNode & ability, Bonus * placement);
	DLL_LINKAGE std::shared_ptr<ILimiter> parseLimiter(const JsonNode & limiter);
	DLL_LINKAGE CSelector parseSelector(const JsonNode &ability);
	DLL_LINKAGE void resolveAddInfo(CAddInfo & var, const JsonNode & node);

	/**
	 * @brief recursively merges source into dest, replacing identical fields
	 * struct : recursively calls this function
	 * arrays : each entry will be merged recursively
	 * values : value in source will replace value in dest
	 * null   : if value in source is present but set to null it will delete entry in dest
	 * @note this function will destroy data in source
	 */
	DLL_LINKAGE void merge(JsonNode & dest, JsonNode & source, bool ignoreOverride = false, bool copyMeta = false);

	/**
	 * @brief recursively merges source into dest, replacing identical fields
	 * struct : recursively calls this function
	 * arrays : each entry will be merged recursively
	 * values : value in source will replace value in dest
	 * null   : if value in source is present but set to null it will delete entry in dest
	 * @note this function will preserve data stored in source by creating copy
	 */
	DLL_LINKAGE void mergeCopy(JsonNode & dest, JsonNode source, bool ignoreOverride = false, bool copyMeta = false);

	/** @brief recursively merges descendant into copy of base node
	* Result emulates inheritance semantic
	*/
	DLL_LINKAGE void inherit(JsonNode & descendant, const JsonNode & base);

	/**
	 * @brief construct node representing the common structure of input nodes
	 * @param pruneEmpty - omit common properties whose intersection is empty
	 * different types: null
	 * struct: recursive intersect on common properties
	 * other: input if equal, null otherwise
	 */
	DLL_LINKAGE JsonNode intersect(const JsonNode & a, const JsonNode & b, bool pruneEmpty = true);
	DLL_LINKAGE JsonNode intersect(const std::vector<JsonNode> & nodes, bool pruneEmpty = true);

	/**
	 * @brief construct node representing the difference "node - base"
	 * merging difference with base gives node
	 */
	DLL_LINKAGE JsonNode difference(const JsonNode & node, const JsonNode & base);

	/**
	 * @brief generate one Json structure from multiple files
	 * @param files - list of filenames with parts of json structure
	 */
	DLL_LINKAGE JsonNode assembleFromFiles(const std::vector<std::string> & files);
	DLL_LINKAGE JsonNode assembleFromFiles(const std::vector<std::string> & files, bool & isValid);

	/// This version loads all files with same name (overridden by mods)
	DLL_LINKAGE JsonNode assembleFromFiles(const std::string & filename);

	/**
	 * @brief removes all nodes that are identical to default entry in schema
	 * @param node - JsonNode to minimize
	 * @param schemaName - name of schema to use
	 * @note for minimizing data must be valid against given schema
	 */
	DLL_LINKAGE void minimize(JsonNode & node, const std::string & schemaName);
	/// opposed to minimize, adds all missing, required entries that have default value
	DLL_LINKAGE void maximize(JsonNode & node, const std::string & schemaName);

	/**
	* @brief validate node against specified schema
	* @param node - JsonNode to check
	* @param schemaName - name of schema to use
	* @param dataName - some way to identify data (printed in console in case of errors)
	* @returns true if data in node fully compilant with schema
	*/
	DLL_LINKAGE bool validate(const JsonNode & node, const std::string & schemaName, const std::string & dataName);

	/// get schema by json URI: vcmi:<name of file in schemas directory>#<entry in file, optional>
	/// example: schema "vcmi:settings" is used to check user settings
	DLL_LINKAGE const JsonNode & getSchema(const std::string & URI);

	/// for easy construction of JsonNodes; helps with inserting primitives into vector node
	DLL_LINKAGE JsonNode boolNode(bool value);
	DLL_LINKAGE JsonNode floatNode(double value);
	DLL_LINKAGE JsonNode stringNode(const std::string & value);
	DLL_LINKAGE JsonNode intNode(si64 value);
}

namespace JsonDetail
{
	// conversion helpers for JsonNode::convertTo (partial template function instantiation is illegal in c++)

	template <typename T, int arithm>
	struct JsonConvImpl;

	template <typename T>
	struct JsonConvImpl<T, 1>
	{
		static T convertImpl(const JsonNode & node)
		{
			return T((int)node.Float());
		}
	};

	template <typename T>
	struct JsonConvImpl<T, 0>
	{
		static T convertImpl(const JsonNode & node)
		{
			return T(node.Float());
		}
	};

	template<typename Type>
	struct JsonConverter
	{
		static Type convert(const JsonNode & node)
		{
			///this should be triggered only for numeric types and enums
			static_assert(std::is_arithmetic_v<Type> || std::is_enum_v<Type> || std::is_class_v<Type>, "Unsupported type for JsonNode::convertTo()!");
			return JsonConvImpl<Type, std::is_enum_v<Type> || std::is_class_v<Type> >::convertImpl(node);

		}
	};

	template<typename Type>
	struct JsonConverter<std::map<std::string, Type> >
	{
		static std::map<std::string, Type> convert(const JsonNode & node)
		{
			std::map<std::string, Type> ret;
			for (const JsonMap::value_type & entry : node.Struct())
			{
				ret.insert(entry.first, entry.second.convertTo<Type>());
			}
			return ret;
		}
	};

	template<typename Type>
	struct JsonConverter<std::set<Type> >
	{
		static std::set<Type> convert(const JsonNode & node)
		{
			std::set<Type> ret;
			for(const JsonVector::value_type & entry : node.Vector())
			{
				ret.insert(entry.convertTo<Type>());
			}
			return ret;
		}
	};

	template<typename Type>
	struct JsonConverter<std::vector<Type> >
	{
		static std::vector<Type> convert(const JsonNode & node)
		{
			std::vector<Type> ret;
			for (const JsonVector::value_type & entry: node.Vector())
			{
				ret.push_back(entry.convertTo<Type>());
			}
			return ret;
		}
	};

	template<>
	struct JsonConverter<std::string>
	{
		static std::string convert(const JsonNode & node)
		{
			return node.String();
		}
	};

	template<>
	struct JsonConverter<bool>
	{
		static bool convert(const JsonNode & node)
		{
			return node.Bool();
		}
	};
}

template<typename Type>
Type JsonNode::convertTo() const
{
	return JsonDetail::JsonConverter<Type>::convert(*this);
}

VCMI_LIB_NAMESPACE_END