/***************************************************************************
 * Copyright (c) 2024 Microsoft Corporation 
 * 
 * This program and the accompanying materials are made available under the
 * terms of the MIT License which is available at
 * https://opensource.org/licenses/MIT.
 * 
 * SPDX-License-Identifier: MIT
 **************************************************************************/


/**************************************************************************/
/**************************************************************************/
/**                                                                       */
/** GUIX Component                                                        */
/**                                                                       */
/**   Multi Line Text Input Management (Multi Line Text Input)            */
/**                                                                       */
/**************************************************************************/

#define GX_SOURCE_CODE


/* Include necessary system files.  */

#include "gx_api.h"
#include "gx_system.h"
#include "gx_window.h"
#include "gx_scrollbar.h"
#include "gx_multi_line_text_input.h"
#include "gx_multi_line_text_view.h"
#include "gx_text_input_cursor.h"
#include "gx_utility.h"
#include "gx_widget.h"

/**************************************************************************/
/*                                                                        */
/*  FUNCTION                                               RELEASE        */
/*                                                                        */
/*    _gx_multi_line_text_input_mark_previous             PORTABLE C      */
/*                                                           6.1.7        */
/*  AUTHOR                                                                */
/*                                                                        */
/*    Kenneth Maxwell, Microsoft Corporation                              */
/*                                                                        */
/*  DESCRIPTION                                                           */
/*                                                                        */
/*    This function moves highlight text end mark one character left.     */
/*                                                                        */
/*  INPUT                                                                 */
/*                                                                        */
/*    text_input                        Multi line text input             */
/*                                        control block                   */
/*                                                                        */
/*  OUTPUT                                                                */
/*                                                                        */
/*    None                                                                */
/*                                                                        */
/*  CALLS                                                                 */
/*                                                                        */
/*    _gx_text_input_cursor_dirty_rectangle_get                           */
/*                                          Get cursor rectangle          */
/*    _gx_multi_line_text_input_cursor_pos_update                         */
/*                                          Calculate cursor position     */
/*                                            according to insert index   */
/*    _gx_system_dirty_partial_add          Add one dirty area to         */
/*                                            dirty list                  */
/*    _gx_system_dirty_mark                 Mark widget area dirty        */
/*    _gx_utility_utf8_string_character_get Parses utf8 string to         */
/*                                            multi-byte glyph            */
/*    _gx_utility_string_length_check       Test string length            */
/*                                                                        */
/*  CALLED BY                                                             */
/*                                                                        */
/*    _gx_multi_line_text_input_keydown_process                           */
/*                                                                        */
/*  RELEASE HISTORY                                                       */
/*                                                                        */
/*    DATE              NAME                      DESCRIPTION             */
/*                                                                        */
/*  05-19-2020     Kenneth Maxwell          Initial Version 6.0           */
/*  09-30-2020     Kenneth Maxwell          Modified comment(s),          */
/*                                            resulting in version 6.1    */
/*  06-02-2021     Kenneth Maxwell          Modified comment(s),          */
/*                                            removed unused variable     */
/*                                            assignment,                 */
/*                                            resulting in version 6.1.7  */
/*                                                                        */
/**************************************************************************/
UINT _gx_multi_line_text_input_mark_previous(GX_MULTI_LINE_TEXT_INPUT *text_input)
{
GX_TEXT_INPUT_CURSOR *cursor_ptr = &text_input -> gx_multi_line_text_input_cursor_instance;
GX_CONST GX_CHAR     *string;
INT                   old_shift;
GX_RECTANGLE          cur_rect;
UINT                  glyph_len = 1;
UINT                  cursor_line;
GX_POINT              start_pos;
GX_POINT              end_pos;
UINT                  start_mark = text_input -> gx_multi_line_text_input_start_mark;
UINT                  end_mark = text_input -> gx_multi_line_text_input_end_mark;

    if (start_mark == end_mark)
    {
        start_mark = text_input -> gx_multi_line_text_input_text_insert_position;
        end_mark = text_input -> gx_multi_line_text_input_text_insert_position;

        text_input -> gx_multi_line_text_input_start_mark = start_mark;
        text_input -> gx_multi_line_text_input_end_mark = end_mark;
    }

    if (end_mark > 0)
    {
        cursor_line = (UINT)(text_input -> gx_multi_line_text_input_text_cursor_line - 1);
        cursor_line = (UINT)(cursor_line - text_input -> gx_multi_line_text_view_first_cache_line);

#ifdef GX_UTF8_SUPPORT
        _gx_utility_utf8_string_backward_character_length_get(&text_input -> gx_multi_line_text_view_text,
                                                              (INT)(end_mark - 1), &glyph_len);
#endif
        string = &text_input -> gx_multi_line_text_view_text.gx_string_ptr[end_mark - glyph_len];

        if (string[0] == GX_KEY_CARRIAGE_RETURN || string[0] == GX_KEY_LINE_FEED)
        {
            glyph_len = text_input -> gx_multi_line_text_input_new_line_character_size;
        }

        text_input -> gx_multi_line_text_input_end_mark -= glyph_len;

        /* Record scroll shift before recalculate cursor position. */
        old_shift = text_input -> gx_multi_line_text_view_text_scroll_shift;

        start_pos = cursor_ptr -> gx_text_input_cursor_pos;

        text_input -> gx_multi_line_text_input_text_insert_position = text_input -> gx_multi_line_text_input_end_mark;

        _gx_multi_line_text_input_cursor_pos_update(text_input, GX_TRUE);

        /* Dirty mark. */
        if (old_shift == text_input -> gx_multi_line_text_view_text_scroll_shift)
        {
            end_pos = cursor_ptr -> gx_text_input_cursor_pos;

            _gx_multi_line_text_input_text_rectangle_get(text_input, start_pos, end_pos, &cur_rect);

            /* Mark highlight area as dirty. */
            _gx_system_dirty_partial_add((GX_WIDGET *)text_input, &cur_rect);
        }
        else
        {
            _gx_system_dirty_mark((GX_WIDGET *)text_input);
        }
    }
    return GX_SUCCESS;
}