text: /*
   * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
   *
   * 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 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, write to the Free Software
   * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
   */
  
  FILE_LICENCE ( GPL2_OR_LATER );
  
  #include <assert.h>
  #include <string.h>
  #include <ipxe/keys.h>
  #include <ipxe/editstring.h>
  
  /** @file
   *
   * Editable strings
   *
   */
  
  static void insert_delete ( struct edit_string *string, size_t delete_len,
                              const char *insert_text ) 
  			    __attribute__ (( nonnull (1) ));
  static void insert_character ( struct edit_string *string,
                                 unsigned int character ) __nonnull;
  static void delete_character ( struct edit_string *string ) __nonnull;
  static void backspace ( struct edit_string *string ) __nonnull;
  static void kill_sol ( struct edit_string *string ) __nonnull;
  static void kill_eol ( struct edit_string *string ) __nonnull;
  
  /**
   * Insert and/or delete text within an editable string
   *
   * @v string		Editable string
   * @v delete_len	Length of text to delete from current cursor position
   * @v insert_text	Text to insert at current cursor position, or NULL
   */
  static void insert_delete ( struct edit_string *string, size_t delete_len,
  			    const char *insert_text ) {
  	size_t old_len, max_delete_len, insert_len, max_insert_len, new_len;
  
  	/* Calculate lengths */
  	old_len = strlen ( string->buf );
  	assert ( string->cursor <= old_len );
  	max_delete_len = ( old_len - string->cursor );
  	if ( delete_len > max_delete_len )
  		delete_len = max_delete_len;
  	insert_len = ( insert_text ? strlen ( insert_text ) : 0 );
  	max_insert_len = ( ( string->len - 1 ) - ( old_len - delete_len ) );
  	if ( insert_len > max_insert_len )
  		insert_len = max_insert_len;
  	new_len = ( old_len - delete_len + insert_len );
  
  	/* Fill in edit history */
  	string->mod_start = string->cursor;
  	string->mod_end = ( ( new_len > old_len ) ? new_len : old_len );
  
  	/* Move data following the cursor */
  	memmove ( ( string->buf + string->cursor + insert_len ),
  		  ( string->buf + string->cursor + delete_len ),
  		  ( max_delete_len + 1 - delete_len ) );
  
  	/* Copy inserted text to cursor position */
  	memcpy ( ( string->buf + string->cursor ), insert_text, insert_len );
  	string->cursor += insert_len;
  }
  
  /**
   * Insert character at current cursor position
   *
   * @v string		Editable string
   * @v character		Character to insert
   */
  static void insert_character ( struct edit_string *string,
  			      unsigned int character ) {
  	char insert_text[2] = { character, '\0' };
  	insert_delete ( string, 0, insert_text );
  }
  
  /**
   * Delete character at current cursor position
   *
   * @v string		Editable string
   */
  static void delete_character ( struct edit_string *string ) {
  	insert_delete ( string, 1, NULL );
  }
  
  /**
   * Delete character to left of current cursor position
   *
   * @v string		Editable string
   */
  static void backspace ( struct edit_string *string ) {
  	if ( string->cursor > 0 ) {
  		string->cursor--;
  		delete_character ( string );
  	}
  }
  
  /**
   * Delete to start of line
   *
   * @v string           Editable string
   */
  static void kill_sol ( struct edit_string *string ) {
  	size_t old_cursor = string->cursor;
  	string->cursor = 0;
  	insert_delete ( string, old_cursor, NULL );
  }
  
  /**
   * Delete to end of line
   *
   * @v string		Editable string
   */
  static void kill_eol ( struct edit_string *string ) {
  	insert_delete ( string, ~( ( size_t ) 0 ), NULL );
  }
  
  /**
   * Replace editable string
   *
   * @v string		Editable string
   * @v replacement	Replacement string
   */
  void replace_string ( struct edit_string *string, const char *replacement ) {
  	string->cursor = 0;
  	insert_delete ( string, ~( ( size_t ) 0 ), replacement );
  }
  
  /**
   * Edit editable string
   *
   * @v string		Editable string
   * @v key		Key pressed by user
   * @ret key		Key returned to application, or zero
   *
   * Handles keypresses and updates the content of the editable string.
   * Basic line editing facilities (delete/insert/cursor) are supported.
   * If edit_string() understands and uses the keypress it will return
   * zero, otherwise it will return the original key.
   *
   * This function does not update the display in any way.
   *
   * The string's edit history will be updated to allow the caller to
   * efficiently bring the display into sync with the string content.
   */
  int edit_string ( struct edit_string *string, int key ) {
  	int retval = 0;
  	size_t len = strlen ( string->buf );
  
  	/* Prepare edit history */
  	string->last_cursor = string->cursor;
  	string->mod_start = string->cursor;
  	string->mod_end = string->cursor;
  
  	/* Interpret key */
  	if ( ( key >= 0x20 ) && ( key <= 0x7e ) ) {
  		/* Printable character; insert at current position */
  		insert_character ( string, key );
  	} else switch ( key ) {
  	case KEY_BACKSPACE:
  		/* Backspace */
  		backspace ( string );
  		break;
  	case KEY_DC:
  	case CTRL_D:
  		/* Delete character */
  		delete_character ( string );
  		break;
  	case CTRL_U:
  		/* Delete to start of line */
  		kill_sol ( string );
  		break;
  	case CTRL_K:
  		/* Delete to end of line */
  		kill_eol ( string );
  		break;
  	case KEY_HOME:
  	case CTRL_A:
  		/* Start of line */
  		string->cursor = 0;
  		break;
  	case KEY_END:
  	case CTRL_E:
  		/* End of line */
  		string->cursor = len;
  		break;
  	case KEY_LEFT:
  	case CTRL_B:
  		/* Cursor left */
  		if ( string->cursor > 0 )
  			string->cursor--;
  		break;
  	case KEY_RIGHT:
  	case CTRL_F:
  		/* Cursor right */
  		if ( string->cursor < len )
  			string->cursor++;
  		break;
  	default:
  		retval = key;
  		break;
  	}
  
  	return retval;
  }
  