/*************************************************************************
** CMapManager.cpp                                                      **
**                                                                      **
** This file is part of dvisvgm -- a fast DVI to SVG converter          **
** Copyright (C) 2005-2023 Martin Gieseking <martin.gieseking@uos.de>   **
**                                                                      **
** This program 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; either version 3 of       **
** the License, or (at your option) any later version.                  **
**                                                                      **
** This program 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 this program; if not, see <http://www.gnu.org/licenses/>. **
*************************************************************************/

#include <array>
#include <sstream>
#include "CMap.hpp"
#include "CMapManager.hpp"
#include "CMapReader.hpp"
#include "FileFinder.hpp"
#include "Font.hpp"
#include "Message.hpp"

using namespace std;


CMapManager& CMapManager::instance () {
	static CMapManager cmm;
	return cmm;
}


/** Loads a cmap and returns the corresponding object. */
CMap* CMapManager::lookup (const string &name) {
	auto it = _cmaps.find(name);
	if (it != _cmaps.end())
		return it->second.get();

	if (_includedCMaps.find(name) != _includedCMaps.end()) {
		_level = 0;
		throw CMapReaderException("circular reference of CMap " + name);
	}

	unique_ptr<CMap> cmap_ptr;
	if (name == "Identity-H")
		cmap_ptr = util::make_unique<IdentityHCMap>();
	else if (name == "Identity-V")
		cmap_ptr = util::make_unique<IdentityVCMap>();
	else if (name == "unicode")
		cmap_ptr = util::make_unique<UnicodeCMap>();
	if (cmap_ptr) {
		CMap *ret = cmap_ptr.get();
		_cmaps[name] = std::move(cmap_ptr);
		return ret;
	}
	// Load cmap data of file <name> and also process all cmaps referenced by operator "usecmap".
	// This can lead to a sequence of further calls of lookup(). In order to prevent infinite loops
	// due to (disallowed) circular cmap inclusions, we keep track of all cmaps processed during
	// a sequence of inclusions.
	_includedCMaps.insert(name);  // save name of current cmap being processed
	_level++;                     // increase nesting level
	CMap *ret=nullptr;
	try {
		CMapReader reader;
		if (!(cmap_ptr = reader.read(name))) {
			_level = 1;
			Message::wstream(true) << "CMap file '" << name << "' not found\n";
		}
		ret = cmap_ptr.get();
		_cmaps[name] = std::move(cmap_ptr);
	}
	catch (const CMapReaderException &e) {
		Message::estream(true) << "CMap file " << name << ": " << e.what() << "\n";
	}
	if (--_level == 0)            // back again at initial nesting level?
		_includedCMaps.clear();    // => names of included cmaps are no longer needed
	return ret;
}


/** Looks for a base font CMap and a compatible encoding table in a given font. The CMap describe
 *  the mapping from CIDs to character codes where the latter are relative to the encoding table
 *  identified by charmapID.
 *  cmap:X->CID, bfmap:CID->Y, enctable:Y->CharCode
 *  @param[in] font look for available encoding tables in this font
 *  @param[in] cmap take the source registry-ordering pair from this CMap
 *  @param[out] charmapID ID of the compatible character map found in the given font
 *  @return base font CMap that maps from CIDs to character codes */
const CMap* CMapManager::findCompatibleBaseFontMap (const PhysicalFont *font, const CMap *cmap, CharMapID &charmapID) {
	if (!font || !cmap)
		return nullptr;

	struct CharMapIDToEncName {
		CharMapID id;
		const char *encname;
	};
	const array<CharMapIDToEncName, 10> encodings {{
		{CharMapID::WIN_UCS4,         "UCS4"},
		{CharMapID::WIN_UCS2,         "UCS2"},
		{CharMapID::WIN_SHIFTJIS,     "90ms-RKSJ"},
		{CharMapID::WIN_PRC,          "GBK-EUC"},
		{CharMapID::WIN_BIG5,         "ETen-B5"},
		{CharMapID::WIN_WANSUNG,      "KSCms-UHC"},
		{CharMapID::MAC_JAPANESE,     "90pv-RKSJ"},
		{CharMapID::MAC_TRADCHINESE,  "B5pc"},
		{CharMapID::MAC_SIMPLCHINESE, "GBpc-EUC"},
		{CharMapID::MAC_KOREAN,       "KSCpc-EUC"}
	}};

	// get IDs of all available charmaps in font
	vector<CharMapID> charmapIDs;
	font->collectCharMapIDs(charmapIDs);


	// try to find a compatible encoding CMap
	const bool is_unicode_map = cmap->mapsToUnicode();
	const string ro = cmap->getROString();
	for (const CharMapIDToEncName &enc : encodings) {
		for (const CharMapID &id : charmapIDs) {
			if (enc.id == id) {
				string cmapname = ro+"-"+enc.encname;
				if (is_unicode_map || FileFinder::instance().lookup(cmapname, "cmap", false)) {
					charmapID = enc.id;
					return is_unicode_map ? cmap : lookup(cmapname);
				}
			}
		}
	}
	return nullptr;
}

