/*
    Nested list helper
    SPDX-FileCopyrightText: 2008 Stephen Kelly <steveire@gmail.com>

    SPDX-License-Identifier: LGPL-2.1-or-later
*/

#ifndef NESTEDLISTHELPER_H
#define NESTEDLISTHELPER_H

//@cond PRIVATE

class QTextEdit;

class QKeyEvent;
class QDropEvent;
class QTextCursor;
class QTextList;
class QTextBlock;

/**
 *
 * @short Helper class for automatic handling of nested lists in a text edit
 *
 *
 * @author Stephen Kelly
 * @since 4.1
 * @internal
 */
class NestedListHelper
{
public:

    /**
     * Create a helper
     *
     * @param te The text edit object to handle lists in.
     */
    explicit NestedListHelper(QTextEdit *te);

    /**
     * Destructor
     */
    ~NestedListHelper();

    /**
     *
     * Handles a key press before it is processed by the text edit widget.
     *
     * This includes:
     *   1. Backspace at the beginning of a line decreases nesting level
     *   2. Return at the empty list element decreases nesting level
     *   3. Tab at the beginning of a line OR with a multi-line selection
     * increases nesting level
     *
     * @param event The event to be handled
     * @return Whether the event was completely handled by this method.
     */
    bool handleKeyPressEvent(QKeyEvent *event);

    bool handleAfterDropEvent(QDropEvent *event);

    /**
     * Changes the indent (nesting level) on a current list item or selection
     * by the value @p delta (typically, +1 or -1)
     */
    void changeIndent(int delta);

    /**
     * Changes the style of the current list or creates a new list with
     * the specified style.
     *
     * @param styleIndex The QTextListStyle of the list.
     */
    void handleOnBulletType(int styleIndex);

    /**
     * @brief Check whether the current item in the list may be indented.
     *
     * An list item must have an item above it on the same or greater level
     * if it can be indented.
     *
     * Also, a block which is currently part of a list can be indented.
     *
     * @sa canDedent
     *
     * @return Whether the item can be indented.
     */
    bool canIndent() const;

    /**
     * \brief Check whether the current item in the list may be dedented.
     *
     * An item may be dedented if it is part of a list.
     * The next item must be at the same or lesser level.
     *
     * @sa canIndent
     *
     * @return Whether the item can be dedented.
     */
    bool canDedent() const;

private:
    QTextCursor topOfSelection() const;
    QTextCursor bottomOfSelection() const;
    void processList(QTextList *list);
    void reformatList(QTextBlock block);
    void reformatList();

    QTextEdit *textEdit = nullptr;
};

//@endcond

#endif
