/*  This file is part of the Kate project.
 *
 *  Copyright (C) 2010 Christoph Cullmann <cullmann@kde.org>
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Library General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library 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
 *  Library General Public License for more details.
 *
 *  You should have received a copy of the GNU Library General Public License
 *  along with this library; see the file COPYING.LIB.  If not, write to
 *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 *  Boston, MA 02110-1301, USA.
 */

#ifndef KATE_TEXTBUFFER_H
#define KATE_TEXTBUFFER_H

#include <QtCore/QObject>
#include <QtCore/QString>
#include <QtCore/QVector>
#include <QtCore/QSet>
#include <QtCore/QTextCodec>

#include <ktexteditor/document.h>

#include "katedocument.h"
#include "katepartinterfaces_export.h"
#include "katetextblock.h"
#include "katetextcursor.h"
#include "katetextrange.h"
#include "katetexthistory.h"

namespace Kate {

/**
 * Class representing a text buffer.
 * The interface is line based, internally the text will be stored in blocks of text lines.
 */
class KATEPARTINTERFACES_EXPORT TextBuffer : public QObject {
  friend class TextCursor;
  friend class TextRange;
  friend class TextBlock;

  Q_OBJECT

  public:
    /**
     * End of line mode
     */
    enum EndOfLineMode {
        eolUnknown = -1
      , eolUnix = 0
      , eolDos = 1
      , eolMac = 2
    };

    /**
     * Construct an empty text buffer.
     * Empty means one empty line in one block.
     * @param parent parent qobject
     * @param blockSize block size in lines the buffer should try to hold, default 64 lines
     */
    TextBuffer (KateDocument *parent, int blockSize = 64);

    /**
     * Destruct the text buffer
     * Virtual, we allow inheritance
     */
    virtual ~TextBuffer ();

    /**
     * Clears the buffer, reverts to initial empty state.
     * Empty means one empty line in one block.
     * Virtual, can be overwritten.
     */
    virtual void clear ();

    /**
     * Set fallback codec for this buffer to use for load.
     * @param codec fallback QTextCodec to use for encoding
     */
    void setFallbackTextCodec (QTextCodec *codec) { m_fallbackTextCodec = codec; }

    /**
     * Get fallback codec for this buffer
     * @return currently in use fallback codec of this buffer
     */
    QTextCodec *fallbackTextCodec () const { return m_fallbackTextCodec; }

    /**
     * Set codec for this buffer to use for load/save.
     * Loading might overwrite this, if it encounters problems and finds a better codec.
     * Might change BOM setting.
     * @param codec QTextCodec to use for encoding
     */
    void setTextCodec (QTextCodec *codec);

    /**
     * Get codec for this buffer
     * @return currently in use codec of this buffer
     */
    QTextCodec *textCodec () const { return m_textCodec; }

    /**
     * Generate byte order mark on save.
     * Loading might overwrite this setting, if there is a BOM found inside the file.
     * @param generateByteOrderMark should BOM be generated?
     */
    void setGenerateByteOrderMark (bool generateByteOrderMark) { m_generateByteOrderMark = generateByteOrderMark; }

    /**
     * Generate byte order mark on save?
     * @return should BOM be generated?
     */
    bool generateByteOrderMark () const { return m_generateByteOrderMark; }

    /**
     * Set end of line mode for this buffer, not allowed to be set to unknown.
     * Loading might overwrite this setting, if there is a eol found inside the file.
     * @param endOfLineMode new eol mode
     */
    void setEndOfLineMode (EndOfLineMode endOfLineMode) { Q_ASSERT (endOfLineMode != eolUnknown); m_endOfLineMode = endOfLineMode; }

    /**
     * Get end of line mode
     * @return end of line mode
     */
    EndOfLineMode endOfLineMode () const { return m_endOfLineMode; }

    /**
     * Set whether to insert a newline character on save at the end of the file
     * @param newlineAtEof should newline be added if non-existing
     */
    void setNewLineAtEof(bool newlineAtEof) { m_newLineAtEof = newlineAtEof; }

    /**
     * Set line length limit
     * @param lineLengthLimit new line length limit
     */
    void setLineLengthLimit (int lineLengthLimit) { m_lineLengthLimit = lineLengthLimit; }

    /**
     * Load the given file. This will first clear the buffer and then load the file.
     * Even on error during loading the buffer will still be cleared.
     * Before calling this, setTextCodec must have been used to set codec!
     * @param filename file to open
     * @param encodingErrors were there problems occurred while decoding the file?
     * @param tooLongLinesWrapped were too long lines found and wrapped?
     * @param enforceTextCodec enforce to use only the set text codec
     * @return success, the file got loaded, perhaps with encoding errors
     * Virtual, can be overwritten.
     */
    virtual bool load (const QString &filename, bool &encodingErrors, bool &tooLongLinesWrapped, bool enforceTextCodec);

    /**
     * Save the current buffer content to the given file.
     * Before calling this, setTextCodec and setFallbackTextCodec must have been used to set codec!
     * @param filename file to save
     * @return success
     * Virtual, can be overwritten.
     */
    virtual bool save (const QString &filename);

    /**
     * Lines currently stored in this buffer.
     * This is never 0, even clear will let one empty line remain.
     */
    int lines () const { Q_ASSERT (m_lines > 0); return m_lines; }

    /**
     * Revision of this buffer. Is set to 0 on construction, clear() (load will trigger clear()).
     * Is incremented on each change to the buffer.
     * @return current revision
     */
    qint64 revision () const { return m_revision; }

    /**
     * Retrieve a text line.
     * @param line wanted line number
     * @return text line
     */
    TextLine line (int line) const;

    /**
     * Retrieve text of complete buffer.
     * @return text for this buffer, lines separated by '\n'
     */
    QString text () const;

    /**
     * Start an editing transaction, the wrapLine/unwrapLine/insertText and removeText functions
     * are only to be allowed to be called inside a editing transaction.
     * Editing transactions can stack. The number startEdit and endEdit calls must match.
     * @return returns true, if no transaction was already running
     * Virtual, can be overwritten.
     */
    virtual bool startEditing ();

    /**
     * Finish an editing transaction. Only allowed to be called if editing transaction is started.
     * @return returns true, if this finished last running transaction
     * Virtual, can be overwritten.
     */
    virtual bool finishEditing ();

    /**
     * Query the number of editing transactions running atm.
     * @return number of running transactions
     */
    int editingTransactions () const { return m_editingTransactions; }

    /**
     * Query the revsion of this buffer before the ongoing editing transactions.
     * @return revision of buffer before current editing transaction altered it
     */
    qint64 editingLastRevision () const { return m_editingLastRevision; }

    /**
     * Query the number of lines of this buffer before the ongoing editing transactions.
     * @return number of lines of buffer before current editing transaction altered it
     */
    int editingLastLines () const { return m_editingLastLines; }

    /**
     * Query information from the last editing transaction: was the content of the buffer changed?
     * This is checked by comparing the editingLastRevision() with the current revision().
     * @return content of buffer was changed in last transaction?
     */
    bool editingChangedBuffer () const { return editingLastRevision() != revision(); }

    /**
     * Query information from the last editing transaction: was the number of lines of the buffer changed?
     * This is checked by comparing the editingLastLines() with the current lines().
     * @return content of buffer was changed in last transaction?
     */
    bool editingChangedNumberOfLines () const { return editingLastLines() != lines(); }

    /**
     * Get minimal line number changed by last editing transaction
     * @return maximal line number changed by last editing transaction, or -1, if none changed
     */
    int editingMinimalLineChanged () const { return m_editingMinimalLineChanged; }

    /**
     * Get maximal line number changed by last editing transaction
     * @return maximal line number changed by last editing transaction, or -1, if none changed
     */
    int editingMaximalLineChanged () const { return m_editingMaximalLineChanged; }

    /**
     * Wrap line at given cursor position.
     * @param position line/column as cursor where to wrap
     * Virtual, can be overwritten.
     */
    virtual void wrapLine (const KTextEditor::Cursor &position);

    /**
     * Unwrap given line.
     * @param line line to unwrap
     * Virtual, can be overwritten.
     */
    virtual void unwrapLine (int line);

    /**
     * Insert text at given cursor position. Does nothing if text is empty, beside some consistency checks.
     * @param position position where to insert text
     * @param text text to insert
     * Virtual, can be overwritten.
     */
    virtual void insertText (const KTextEditor::Cursor &position, const QString &text);

    /**
     * Remove text at given range. Does nothing if range is empty, beside some consistency checks.
     * @param range range of text to remove, must be on one line only.
     * Virtual, can be overwritten.
     */
    virtual void removeText (const KTextEditor::Range &range);

    /**
     * TextHistory of this buffer
     * @return text history for this buffer
     */
    TextHistory &history () { return m_history; }

  Q_SIGNALS:
    /**
     * Buffer got cleared. This is emitted when constructor or load have called clear() internally,
     * or when the user of the buffer has called clear() itself.
     */
    void cleared ();

    /**
     * Buffer loaded successfully a file
     * @param filename file which was loaded
     * @param encodingErrors were there problems occurred while decoding the file?
     */
    void loaded (const QString &filename, bool encodingErrors);

    /**
     * Buffer saved successfully a file
     * @param filename file which was saved
     */
    void saved (const QString &filename);

    /**
     * Editing transaction has started.
     */
    void editingStarted ();

    /**
     * Editing transaction has finished.
     */
    void editingFinished ();

    /**
     * A line got wrapped.
     * @param position position where the wrap occurred
     */
    void lineWrapped (const KTextEditor::Cursor &position);

    /**
     * A line got unwrapped.
     * @param line line where the unwrap occurred
     */
    void lineUnwrapped (int line);

    /**
     * Text got inserted.
     * @param position position where the insertion occurred
     * @param text inserted text
     */
    void textInserted (const KTextEditor::Cursor &position, const QString &text);

    /**
     * Text got removed.
     * @param range range where the removal occurred
     * @param text removed text
     */
    void textRemoved (const KTextEditor::Range &range, const QString &text);

  private:
    /**
     * Find block containing given line.
     * @param line we want to find block for this line
     * @return index of found block
     */
    int blockForLine (int line) const;

    /**
     * Fix start lines of all blocks after the given one
     * @param startBlock index of block from which we start to fix
     */
    void fixStartLines (int startBlock);

    /**
     * Balance the given block. Look if it is too small or too large.
     * @param index block to balance
     */
    void balanceBlock (int index);

    /**
     * Block for given index in block list.
     * @param index block index
     * @return block matching this index
     */
    TextBlock *blockForIndex (int index) { return m_blocks[index]; }

    /**
     * A range changed, notify the views, in case of attributes or feedback.
     * @param view which view is affected? 0 for all views
     * @param startLine start line of change
     * @param endLine end line of change
     * @param rangeWithAttribute attribute changed or is active, this will perhaps lead to repaints
     */
    void notifyAboutRangeChange (KTextEditor::View *view, int startLine, int endLine, bool rangeWithAttribute);

    /**
     * Mark all modified lines as lines saved on disk (modified line system).
     */
    void markModifiedLinesAsSaved();

  public:
    /**
     * Gets the document to which this buffer is bound.
     * \return a pointer to the document
     */
    KateDocument *document () const { return m_document; }

    /**
     * Debug output, print whole buffer content with line numbers and line length
     * @param title title for this output
     */
    void debugPrint (const QString &title) const;

    /**
     * Return the ranges which affect the given line.
     * @param line line to look at
     * @param view only return ranges associated with given view
     * @param rangesWithAttributeOnly only return ranges which have a attribute set
     * @return list of ranges affecting this line
     */
    QList<TextRange *> rangesForLine (int line, KTextEditor::View *view, bool rangesWithAttributeOnly) const;

    /**
     * Check if the given range pointer is still valid.
     * @return range pointer still belongs to range for this buffer
     */
    bool rangePointerValid (TextRange *range) const { return m_ranges.contains (range); }

    /**
     * Invalidate all ranges in this buffer.
     */
    void invalidateRanges();

  //
  // sha1 checksum handling
  //
  public:
    /**
    * sha1 digest of the document on disk, set either through file loading
    * in openFile() or in KateDocument::saveFile()
    * @return sha1 digest for this document
    */
    const QByteArray &digest () const;

    /**
    * Set the sha1sum of this buffer. Make sure this checksum is up-to-date
    * when reading digest().
    * @param sha1sum sha1 digest for the document on disk
    */
    void setDigest (const QByteArray & sha1sum);

  private:
    QByteArray m_digest;

  private:
    /**
     * parent document
     */
    KateDocument *m_document;

    /**
     * text history
     */
    TextHistory m_history;

    /**
     * block size in lines the buffer will try to hold
     */
    const int m_blockSize;

    /**
     * List of blocks which contain the lines of this buffer
     */
    QVector<TextBlock *> m_blocks;

    /**
     * Number of lines in buffer
     */
    int m_lines;

    /**
     * Last used block in the buffer. Is used for speeding up blockForLine.
     * May contain invalid index, must be checked before using.
     */
    mutable int m_lastUsedBlock;

    /**
     * Revision of the buffer.
     */
    qint64 m_revision;

    /**
     * Current number of running edit transactions
     */
    int m_editingTransactions;

    /**
     * Revision remembered at start of current editing transaction
     */
    qint64 m_editingLastRevision;

    /**
     * Number of lines remembered at start of current editing transaction
     */
    int m_editingLastLines;

    /**
     * minimal line number changed by last editing transaction
     */
    int m_editingMinimalLineChanged;

    /**
     * maximal line number changed by last editing transaction
     */
    int m_editingMaximalLineChanged;

    /**
     * Set of invalid cursors for this whole buffer.
     * Valid cursors are inside the block the belong to.
     */
    QSet<TextCursor *> m_invalidCursors;

    /**
     * Set of ranges of this whole buffer.
     */
    QSet<TextRange *> m_ranges;

    /**
     * Fallback text codec to use
     */
    QTextCodec *m_fallbackTextCodec;

    /**
     * Text codec to use
     */
    QTextCodec *m_textCodec;

    /**
     * Should byte order mark be created?
     */
    bool m_generateByteOrderMark;

    /**
     * End of line mode, default is Unix
     */
    EndOfLineMode m_endOfLineMode;

    /**
     * Insert newline character at the end of the file?
     */
    bool m_newLineAtEof;

    /**
     * Limit for line length, longer lines will be wrapped on load
     */
    int m_lineLengthLimit;
};

}

#endif