/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <https://www.gnu.org/licenses/old-licenses/gpl-2.0>.
 */

/** @file strings_type.h Types related to strings. */

#ifndef STRINGS_TYPE_H
#define STRINGS_TYPE_H

#include "core/convertible_through_base.hpp"
#include "core/enum_type.hpp"
#include "core/strong_typedef_type.hpp"

/**
 * Numeric value that represents a string, independent of the selected language.
 */
typedef uint32_t StringID;
static const StringID INVALID_STRING_ID = 0xFFFF; ///< Constant representing an invalid string (16bit in case it is used in savegames)
static const int MAX_CHAR_LENGTH        = 4;      ///< Max. length of UTF-8 encoded unicode character
static const uint MAX_LANG              = 0x7F;   ///< Maximum number of languages supported by the game, and the NewGRF specs

/** Directions a text can go to */
enum TextDirection : uint8_t {
	TD_LTR, ///< Text is written left-to-right by default
	TD_RTL, ///< Text is written right-to-left by default
};

/** StringTabs to group StringIDs */
enum StringTab : uint8_t {
	/* Tabs 0..1 for regular strings */
	TEXT_TAB_TOWN             =  4,
	TEXT_TAB_INDUSTRY         =  9,
	TEXT_TAB_STATION          = 12,
	TEXT_TAB_SPECIAL          = 14,
	TEXT_TAB_OLD_CUSTOM       = 15,
	TEXT_TAB_VEHICLE          = 16,
	/* Tab 17 for regular strings */
	TEXT_TAB_OLD_NEWGRF       = 26,
	TEXT_TAB_END              = 32, ///< End of language files.
	TEXT_TAB_GAMESCRIPT_START = 32, ///< Start of GameScript supplied strings.
	TEXT_TAB_NEWGRF_START     = 64, ///< Start of NewGRF supplied strings.
};

/** The index/offset of a string within a #StringTab. */
using StringIndexInTab = StrongType::Typedef<uint32_t, struct StringIndexInTabTag, StrongType::Compare, StrongType::Integer>;

/** Number of bits for the StringIndex within a StringTab */
static const uint TAB_SIZE_BITS       = 11;
/** Number of strings per StringTab */
static const uint TAB_SIZE            = 1 << TAB_SIZE_BITS;

/** Number of strings for GameScripts */
static const uint TAB_SIZE_GAMESCRIPT = TAB_SIZE * 32;

/** Number of strings for NewGRFs */
static const uint TAB_SIZE_NEWGRF     = TAB_SIZE * 256;

/** The number of builtin generators for town names. */
static constexpr uint32_t BUILTIN_TOWNNAME_GENERATOR_COUNT = 21;

/** Special strings for town names. The town name is generated dynamically on request. */
static constexpr StringID SPECSTR_TOWNNAME_START = 0x20C0;
static constexpr StringID SPECSTR_TOWNNAME_END = SPECSTR_TOWNNAME_START + BUILTIN_TOWNNAME_GENERATOR_COUNT;

/** Special strings for company names on the form "TownName transport". */
static constexpr StringID SPECSTR_COMPANY_NAME_START = 0x70EA;
static constexpr StringID SPECSTR_COMPANY_NAME_END = SPECSTR_COMPANY_NAME_START + BUILTIN_TOWNNAME_GENERATOR_COUNT;

static constexpr StringID SPECSTR_SILLY_NAME = 0x70E5; ///< Special string for silly company names.
static constexpr StringID SPECSTR_ANDCO_NAME = 0x70E6; ///< Special string for Surname & Co company names.
static constexpr StringID SPECSTR_PRESIDENT_NAME = 0x70E7; ///< Special string for the president's name.

using StringParameterData = std::variant<std::monostate, uint64_t, std::string>;

/** The data required to format and validate a single parameter of a string. */
struct StringParameter {
	StringParameterData data; ///< The data of the parameter.
	char32_t type; ///< The #StringControlCode to interpret this data with when it's the first parameter, otherwise '\0'.

	StringParameter() = default;
	inline StringParameter(StringParameterData &&data) : data(std::move(data)), type(0) {}

	inline StringParameter(const std::monostate &data) : data(data), type(0) {}
	inline StringParameter(uint64_t data) : data(data), type(0) {}

	inline StringParameter(std::string_view data) : data(std::string{data}), type(0) {}
	inline StringParameter(std::string &&data) : data(std::move(data)), type(0) {}
	inline StringParameter(const std::string &data) : data(data), type(0) {}

	inline StringParameter(const ConvertibleThroughBase auto &data) : data(static_cast<uint64_t>(data.base())), type(0) {}

	/**
	 * Create a StringParameter from a scoped enum.
	 * @tparam T the type of the scoped enum.
	 * @param data the scoped enum value.
	 */
	template <typename T> requires is_scoped_enum_v<T>
	inline StringParameter(const T &data) : data(static_cast<uint64_t>(to_underlying(data))), type(0) {}
};

/**
 * Container for an encoded string, created by GetEncodedString.
 */
class EncodedString {
public:
	EncodedString() = default;

	auto operator<=>(const EncodedString &) const = default;

	std::string GetDecodedString() const;
	EncodedString ReplaceParam(size_t param, StringParameter &&value) const;

	inline void clear() { this->string.clear(); }
	inline bool empty() const { return this->string.empty(); }

private:
	std::string string; ///< The encoded string.

	/* An EncodedString can only be created by GetEncodedStringWithArgs(). */
	explicit EncodedString(std::string &&string) : string(std::move(string)) {}

	friend EncodedString GetEncodedStringWithArgs(StringID str, std::span<const StringParameter> params);

	template <typename Tcont, typename Titer>
	friend class EndianBufferWriter;
	friend class EndianBufferReader;
	friend class ScriptText;
};

#endif /* STRINGS_TYPE_H */
