/***************************************************************************
 *   SPDX-License-Identifier: GPL-2.0-or-later
 *                                                                         *
 *   SPDX-FileCopyrightText: 2004-2019 Thomas Fischer <fischer@unix-ag.uni-kl.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 2 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 <https://www.gnu.org/licenses/>. *
 ***************************************************************************/

#ifndef KBIBTEX_IO_ENCODER_H
#define KBIBTEX_IO_ENCODER_H

#include <QString>

#ifdef HAVE_KF
#include "kbibtexio_export.h"
#endif // HAVE_KF

/**
 * Base class for that convert between different textual representations
 * for non-ASCII characters. Examples for external textual representations
 * are \"a in LaTeX and &auml; in XML.
 * @author Thomas Fischer <fischer@unix-ag.uni-kl.de>
 */
class KBIBTEXIO_EXPORT Encoder
{
public:
    enum class TargetEncoding {
        RAW, // No processing of data requested or necessary. Use, for example, for verbatim text
        ASCII, // Try to restrict output to ASCII. For example, 'Latin capital A with ring above' may become {\AA} for LaTeX or &#197; for XML output
        UTF8 // Keep Unicode symbols as far as possible. Only 'special' symbols, for example '$' for LaTeX receives special treatment
    };

    static const Encoder &instance();
    virtual ~Encoder();

    /**
     * Decode from external textual representation to internal (UTF-8) representation.
     * @param text text in external textual representation
     * @return text in internal (UTF-8) representation
     */
    virtual QString decode(const QString &text) const;

    /**
     * Encode from internal (UTF-8) representation to external textual representation.
     * Output may be restricted to ASCII (non-ASCII characters will be rewritten depending
     * on concrete Encoder class, for example as '&#228;' as XML or '\"a' for LaTeX)
     * or UTF-8 (all characters allowed, only 'special ones' rewritten, for example
     * '&amp;' for XML and '\&' for LaTeX).
     * @param text in internal (UTF-8) representation
     * @param targetEncoding allow either only ASCII output or UTF-8 output.
     * @return text text in external textual representation
     */
    virtual QString encode(const QString &text, const TargetEncoding targetEncoding) const;

    QString convertToPlainAscii(const QString &input) const;
    static bool containsOnlyAscii(const QString &text);

protected:
    Encoder();

private:
    Q_DISABLE_COPY(Encoder)

    class Private;
    Private *const d;
};

#endif // KBIBTEX_IO_ENCODER_H
