// -*- C++ -*-
/**
 * \file Encoding.h
 * This file is part of LyX, the document processor.
 * Licence details can be found in the file COPYING.
 *
 * \author Lars Gullik Bjønnes
 * \author Jean-Marc Lasgouttes
 *
 * Full author contact details are available in file CREDITS.
 */

#ifndef ENCODING_H
#define ENCODING_H

#include "support/docstring.h"
#include "support/trivstring.h"
#include "support/types.h"

#include <map>
#include <set>
#include <vector>

namespace lyx {

namespace support { class FileName; }

class EncodingException : public std::exception {
public:
	EncodingException(char_type c);
	virtual ~EncodingException() noexcept {}
	virtual const char * what() const noexcept override;

	char_type failed_char;
	int par_id;
	pos_type pos;
};


enum CharInfoFlags {
	///
	CharInfoCombining = 1,
	///
	CharInfoTextFeature = 2,
	///
	CharInfoMathFeature = 4,
	///
	CharInfoForce = 8,
	///
	CharInfoTextNoTermination = 16,
	///
	CharInfoMathNoTermination = 32,
	///
	CharInfoForceSelected = 64,
	///
	CharInfoDeprecated = 128
};


/// Information about a single UCS4 character
class CharInfo {
public:
	CharInfo() : flags_(0) {}
	CharInfo(
		docstring const & textcommand, docstring const & mathcommand,
		std::string const & textpreamble, std::string const & mathpreamble,
		std::string const & tipashortcut, unsigned int flags);
	// we assume that at least one command is nonempty when using unicodesymbols
	bool isUnicodeSymbol() const { return !textcommand_.empty() || !mathcommand_.empty(); }
	/// LaTeX command (text mode) for this character
	docstring const textcommand() const { return textcommand_; }
	/// LaTeX command (math mode) for this character
	docstring mathcommand() const { return mathcommand_; }
	/// Needed LaTeX preamble (or feature) for text mode
	std::string textpreamble() const { return textpreamble_; }
	/// Needed LaTeX preamble (or feature) for math mode
	std::string mathpreamble() const { return mathpreamble_; }
	/// Is this a combining character?
	bool combining() const { return flags_ & CharInfoCombining; }
	/// Is \c textpreamble a feature known by LaTeXFeatures, or a raw LaTeX
	/// command?
	bool textfeature() const { return flags_ & CharInfoTextFeature; }
	/// Is \c mathpreamble a feature known by LaTeXFeatures, or a raw LaTeX
	/// command?
	bool mathfeature() const { return flags_ & CharInfoMathFeature; }
	/// Always force the LaTeX command, even if the encoding contains
	/// this character?
	bool force() const { return flags_ & CharInfoForce; }
	/// Force the LaTeX command for some encodings?
	bool forceselected() const { return flags_ & CharInfoForceSelected; }
	/// Disable LaTeX command => char_type conversion for this deprecated symbol?
	bool deprecated() const { return flags_ & CharInfoDeprecated; }
	/// TIPA shortcut
	std::string const tipashortcut() const { return tipashortcut_; }
	/// \c textcommand needs no termination (such as {} or space).
	bool textnotermination() const { return flags_ & CharInfoTextNoTermination; }
	/// \c mathcommand needs no termination (such as {} or space).
	bool mathnotermination() const { return flags_ & CharInfoMathNoTermination; }
	///
private:
	/// LaTeX command (text mode) for this character
	trivdocstring textcommand_;
	/// LaTeX command (math mode) for this character
	trivdocstring mathcommand_;
	/// Needed LaTeX preamble (or feature) for text mode
	trivstring textpreamble_;
	/// Needed LaTeX preamble (or feature) for math mode
	trivstring mathpreamble_;
	/// TIPA shortcut
	trivstring tipashortcut_;
	/// feature flags
	unsigned int flags_;
};


/**
 * An encoding as defined in lib/encodings.
 * All const methods are thread-safe, so the caller does not need any locking.
 * This property must be kept when changing the class.
 */
class Encoding {
public:
	/// Which LaTeX package handles this encoding?
	enum Package {
		none = 1,
		inputenc = 2,
		CJK = 4,
		japanese = 8
	};
	/// Represent any of the above packages
	static int const any;
	///
	Encoding() : fixedwidth_(true), unsafe_(false), forced_(nullptr),
	             start_encodable_(0), package_(none), complete_(false) {}
	///
	Encoding(std::string const & n, std::string const & l,
		 std::string const & g, std::string const & i,
		 bool f, bool u, Package p);
	///
	void init() const;
	///
	std::string const name() const { return name_; }
	///
	std::string const latexName() const { return latexName_; }
	///
	std::string const guiName() const { return guiName_; }
	///
	std::string const iconvName() const { return iconvName_; }
	///
	bool hasFixedWidth() const { return fixedwidth_; }
	///
	bool unsafe() const { return unsafe_; }
	/// \p c is representable in this encoding without a LaTeX macro
	bool encodable(char_type c) const;
	/**
	 * Convert \p c to something that LaTeX can understand.
	 * This is either the character itself (if it is representable
	 * in this encoding), or a LaTeX macro.
	 * If the character is not representable in this encoding, but no
	 * LaTeX macro is known, a warning is given of lyxerr, and the
	 * character is returned.
	 * \return the converted character and a flag indicating whether
	 * the command needs to be terminated by {} or a space.
	 */
	std::pair<docstring, bool> latexChar(char_type c) const;
	/**
	 * Convert \p input to something that LaTeX can understand.
	 * This is either the string itself (if it is representable
	 * in this encoding), or a LaTeX macro.
	 * If a character is not representable in this encoding, but no
	 * LaTeX macro is known, a warning is given of lyxerr, and the
	 * character is returned in the second string of the pair and
	 * omitted in the first.
	 * \p dryrun specifies whether the string is used within source
	 * preview (which yields a special warning).
	 */
	std::pair<docstring, docstring> latexString(docstring const & input,
						    bool dryrun = false) const;
	/// Which LaTeX package handles this encoding?
	Package package() const { return package_; }
	/// A list of all characters usable in this encoding
	std::vector<char_type> symbolsList() const;
private:
	/**
	 * Do we have to output this character as LaTeX command in any case?
	 * This is true if the "force" flag is set.
	 * We need this if the inputencoding does not support a certain glyph.
	 */
	bool isForced(char_type c) const;
	///
	trivstring name_;
	///
	trivstring latexName_;
	///
	trivstring guiName_;
	///
	trivstring iconvName_;
	/// Is this a fixed width encoding?
	bool fixedwidth_;
	/// Is this encoding TeX unsafe, e.g. control characters like {, }
	/// and \\ may appear in high bytes?
	bool unsafe_;
	///
	typedef std::set<char_type> CharSet;
	/// Set of UCS4 characters that we can encode (for singlebyte
	/// encodings only)
	CharSet encodable_;
	/// Set of UCS4 characters that we can't encode
	CharSet const * forced_;
	/// All code points below this are encodable. This helps us to avoid
	/// lokup of ASCII characters in encodable_ and gives about 1 sec
	/// speedup on export of the Userguide.
	char_type start_encodable_;
	/// Which LaTeX package handles this encoding?
	Package package_;
	/**
	 * If this is true the stored information about the encoding covers
	 * all encodable characters. We set this to false initially so that
	 * we only need to query iconv for the actually used encodings.
	 * This is needed especially for the multibyte encodings, if we
	 * complete all encoding info on startup it takes 2-3 minutes.
	 */
	bool complete_;
};

class Encodings {
public:
	///
	typedef std::set<char_type> MathCommandSet;
	///
	typedef std::set<char_type> TextCommandSet;
	///
	typedef std::set<char_type> MathSymbolSet;
	///
	typedef std::map<trivstring, Encoding> EncodingList;
	/// iterator to iterate over all encodings.
	/// We hide the fact that our encoding list is implemented as a map.
	class const_iterator : public EncodingList::const_iterator {
		typedef EncodingList::const_iterator base;
	public:
		const_iterator() : base() {}
		const_iterator(base const & b) : base(b) {}
		Encoding const & operator*() const { return base::operator*().second; }
		Encoding const * operator->() const { return &(base::operator*().second); }
	};
	///
	Encodings();
	/// Read the encodings.
	/// \param encfile encodings definition file
	/// \param symbolsfile unicode->LaTeX mapping file
	void read(support::FileName const & encfile,
		  support::FileName const & symbolsfile);
	/// Get encoding from LyX name \p name
	Encoding const *
	fromLyXName(std::string const & name, bool allowUnsafe = false) const;
	/// Get encoding from LaTeX name \p name and package \p package
	Encoding const * fromLaTeXName(std::string const & name,
		int package = Encoding::any, bool allowUnsafe = false) const;
	/// Get encoding from iconv name \p name and package \p package
	Encoding const * fromIconvName(std::string const & name,
		int package = Encoding::any, bool allowUnsafe = false) const;

	///
	const_iterator begin() const { return encodinglist.begin(); }
	///
	const_iterator end() const { return encodinglist.end(); }

	/// Accessor for the unicode information table.
	static CharInfo const & unicodeCharInfo(char_type c);
	/// Is this a combining char?
	static bool isCombiningChar(char_type c);
	/// Return the TIPA shortcut
	static std::string const TIPAShortcut(char_type c);
	/**
	 * Test, if \p c is a supported Greek or Cyrillic letter.
	 * Return script macro name or empty string.
	 */
	static std::string const isKnownScriptChar(char_type const c);
	/// Does \p fontenc support characters in \p script?
	static bool fontencSupportsScript(std::string const & fontenc,
									  std::string const & script);
	/**
	 * Do we have to display in italics this character when in mathmode?
	 * This is true if the "mathalpha" flag is set. We use this for
	 * letters and accented characters that are output as math commands.
	 */
	static bool isMathAlpha(char_type c);
	/**
	 * Do we have to wrap in \text this character when in mathmode?
	 * This is true if \p c is not ascii and the "mathalpha" flag is not
	 * set and a mathcommand is not defined in the unicodesymbols file.
	 */
	static bool isUnicodeTextOnly(char_type c);
	/**
	 * Register \p c as a mathmode command.
	 */
	static void addMathCmd(char_type c) { mathcmd.insert(c); }
	/**
	 * Register \p c as a textmode command.
	 */
	static void addTextCmd(char_type c) { textcmd.insert(c); }
	/**
	 * Register \p c as a mathmode symbol.
	 */
	static void addMathSym(char_type c) { mathsym.insert(c); }
	/**
	 * Tell whether \p c is registered as a mathmode command.
	 */
	static bool isMathCmd(char_type c) { return mathcmd.count(c); }
	/**
	 * Tell whether \p c is registered as a textmode command.
	 */
	static bool isTextCmd(char_type c) { return textcmd.count(c); }
	/**
	 * Tell whether \p c is registered as a mathmode symbol.
	 */
	static bool isMathSym(char_type c) { return mathsym.count(c); }
	/**
	 * If \p c cannot be encoded in the given \p encoding, convert
	 * it to something that LaTeX can understand in mathmode.
	 * \p needsTermination indicates whether the command needs to be
	 * terminated by {} or a space.
	 * \return whether \p command is a mathmode command
	 */
	static bool latexMathChar(char_type c, bool mathmode,
			Encoding const * encoding, docstring & command,
			bool & needsTermination);
	/**
	 * Convert the LaTeX command in \p cmd to the corresponding unicode
	 * point and set \p combining to true if it is a combining symbol.
	 * \p needsTermination indicates whether the command needs to be
	 * terminated by {} or a space.
	 */
	static char_type fromLaTeXCommand(docstring const & cmd, int cmdtype,
			bool & combining, bool & needsTermination,
			std::set<std::string> * req = nullptr);
	///
	enum LatexCmd {
		///
		MATH_CMD = 1,
		///
		TEXT_CMD = 2
	};
	/**
	 * Convert the LaTeX commands in \p cmd and \return a docstring
	 * of corresponding unicode points. The conversion stops at the
	 * first command which could not be converted, and the remaining
	 * unconverted commands are returned in \p rem.
	 * The \p cmdtype parameter can be used to limit recognized
	 * commands to math or text mode commands only.
	 * \p needsTermination indicates whether the command needs to be
	 * terminated by {} or a space.
	 */
	static docstring fromLaTeXCommand(docstring const & cmd, int cmdtype,
			bool & needsTermination, docstring & rem,
			std::set<std::string> * req = nullptr);

protected:
	///
	EncodingList encodinglist;
	///
	static MathCommandSet mathcmd;
	///
	static TextCommandSet textcmd;
	///
	static MathSymbolSet mathsym;
};

extern Encodings encodings;


} // namespace lyx

#endif
