text: /**
   * @file text_editor.c
   * @author CuBeatSystems
   * @author Shinichiro Nakamura
   * @copyright
   * ===============================================================
   * Natural Tiny Shell (NT-Shell) Version 0.3.1
   * ===============================================================
   * Copyright (c) 2010-2016 Shinichiro Nakamura
   *
   * Permission is hereby granted, free of charge, to any person
   * obtaining a copy of this software and associated documentation
   * files (the "Software"), to deal in the Software without
   * restriction, including without limitation the rights to use,
   * copy, modify, merge, publish, distribute, sublicense, and/or
   * sell copies of the Software, and to permit persons to whom the
   * Software is furnished to do so, subject to the following
   * conditions:
   *
   * The above copyright notice and this permission notice shall be
   * included in all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
   * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
   * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
   * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
   * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
   * OTHER DEALINGS IN THE SOFTWARE.
   */
  
  #include "text_editor.h"
  
  /**
   * @brief Initialize the text editor module.
   *
   * @param p A pointer to the text editor handler.
   */
  void text_editor_init(text_editor_t *p)
  {
      p->pos = 0;
      p->len = 0;
      p->buffer[p->len] = '\0';
  }
  
  /**
   * @brief Insert a character.
   *
   * @param p A pointer to the text editor handler.
   * @param c A character.
   */
  int text_editor_insert(text_editor_t *p, char c)
  {
      if (p->len < (int)sizeof(p->buffer) - 1) {
          int n = p->len - p->pos + 1;
          int i;
          char *src = p->buffer + p->len + 0;
          char *des = p->buffer + p->len + 1;
          for (i = 0; i < n; i++) {
              *des = *src;
              des--;
              src--;
          }
  
          p->buffer[p->pos] = c;
          p->pos++;
          p->len++;
          p->buffer[p->len] = '\0';
          return 1;
      }
      return 0;
  }
  
  /**
   * @brief Delete a character.
   *
   * @param p A pointer to the text editor handler.
   */
  int text_editor_backspace(text_editor_t *p)
  {
      if (0 < p->pos) {
          int n = p->len - p->pos;
          int i;
          char *src = p->buffer + p->pos - 0;
          char *des = p->buffer + p->pos - 1;
          p->pos--;
          p->len--;
          for (i = 0; i < n; i++) {
              *des = *src;
              des++;
              src++;
          }
          *(p->buffer + p->len) = '\0';
          return 1;
      }
      return 0;
  }
  
  /**
   * @brief Delete a character.
   *
   * @param p A pointer to the text editor handler.
   */
  int text_editor_delete(text_editor_t *p)
  {
      if (p->pos < p->len) {
          int n = p->len - p->pos - 1;
          int i;
          char *src = p->buffer + p->pos + 1;
          char *des = p->buffer + p->pos + 0;
          p->len--;
          for (i = 0; i < n; i++) {
              *des = *src;
              des++;
              src++;
          }
          *(p->buffer + p->len) = '\0';
          return 1;
      }
      return 0;
  }
  
  /**
   * @brief Get the cursor position.
   *
   * @param p A pointer to the text editor handler.
   */
  int text_editor_cursor_get_position(text_editor_t *p)
  {
      return p->pos;
  }
  
  /**
   * @brief Move to the cursor to the head of the line.
   *
   * @param p A pointer to the text editor handler.
   */
  int text_editor_cursor_head(text_editor_t *p)
  {
      if (0 < p->pos) {
          p->pos = 0;
          return 1;
      }
      return 0;
  }
  
  /**
   * @brief Move to the cursor to the tail of the line.
   *
   * @param p A pointer to the text editor handler.
   */
  int text_editor_cursor_tail(text_editor_t *p)
  {
      if (p->pos < p->len) {
          p->pos = p->len;
          return 1;
      }
      return 0;
  }
  
  /**
   * @brief Move to the cursor to left.
   *
   * @param p A pointer to the text editor handler.
   */
  int text_editor_cursor_left(text_editor_t *p)
  {
      if (0 < p->pos) {
          p->pos--;
          return 1;
      }
      return 0;
  }
  
  /**
   * @brief Move to the cursor to right.
   *
   * @param p A pointer to the text editor handler.
   */
  int text_editor_cursor_right(text_editor_t *p)
  {
      if (p->pos < p->len) {
          p->pos++;
          return 1;
      }
      return 0;
  }
  
  /**
   * @brief Set the edit line.
   *
   * @param p A pointer to the text editor handler.
   * @param buf A text string.
   */
  int text_editor_set_text(text_editor_t *p, char *buf)
  {
      char *src = buf;
      char *des = p->buffer;
      int n = 0;
      while (*src) {
          *des = *src;
          des++;
          src++;
          n++;
          if ((int)sizeof(p->buffer) <= n - 1) {
              break;
          }
      }
      *des = '\0';
      p->len = n;
      p->pos = p->len;
      return n;
  }
  
  /**
   * @brief Get the edit line.
   *
   * @param p A pointer to the text editor handler.
   * @param buf A text string.
   * @param siz Size of the text string buffer.
   */
  int text_editor_get_text(text_editor_t *p, char *buf, int siz)
  {
      char *src = p->buffer;
      char *des = buf;
      int n = 0;
      while (*src) {
          *des++ = *src++;
          n++;
          if (siz <= n) {
              break;
          }
      }
      *des = '\0';
      return n;
  }
  
  /**
   * @brief Clear the text string.
   *
   * @param p A pointer to the text editor handler.
   */
  void text_editor_clear(text_editor_t *p)
  {
      p->pos = 0;
      p->len = 0;
      p->buffer[p->len] = '\0';
  }
  