//
// Copyright 2001-2023 by Bill Spitzak and others.
//
// Original code Copyright Mark Edel.  Permission to distribute under
// the LGPL for the FLTK library granted by Mark Edel.
//
// This library is free software. Distribution and use rights are outlined in
// the file "COPYING" which should have been included with this file.  If this
// file is missing or damaged, see the license at:
//
//     https://www.fltk.org/COPYING.php
//
// Please see the following page on how to report bugs and issues:
//
//     https://www.fltk.org/bugs.php
//

#include <stdio.h>
#include <stdlib.h>
#include "flstring.h"
#include <ctype.h>
#include <FL/Fl.H>
#include <FL/Fl_Window.H>
#include <FL/Fl_Text_Editor.H>
#include "Fl_Screen_Driver.H"
#include <FL/fl_ask.H>

/* Keyboard Control Matrix

key\modifier   plain  Ctrl   Alt  Meta
  left          1/1  13/9   0/13  0/9
  right         2/2  14/10  0/14  0/10
  up            3/19 21/7   0/15  0/17
  down          4/20 22/8   0/16  0/18
  home          9/5  17/0   0/0   0/0
  end          10/6  18/0   0/0   0/0
  page up      11/7  23/0   0/11  0/0
  page down    12/8  24/0   0/12  0/0
    (FLTK action / OS X action)
    (adding the shift key extends the selection, all other combinations are no-op)

  0: no-op
  1: move cursor to the left, at line beginning wrap to end of prev line, at doc start no-op
  2: move cursor to the right, at line end move to beginning of the next line, at doc end no-op
  3: move cursor up, at doc top no-op
  4: move cursor down, at doc bottom no-op
  5: scroll display to top of text (cursor unchanged)
  6: scroll display to end of text (cursor unchanged)
  7: scroll text down one page (cursor unchanged)
  8: scroll text up one page (cursor unchanged)
  9: move cursor to beginning of line
 10: move cursor to end of line
 11: move cursor up one page and scroll down
 12: move cursor down one page and scroll up
 13: move to the beginning of the word or the previous word
 14: move to the end of the word or the next word
 15: if start of line: start of prev line, else start of this line
 16: if end of line: end of next line, else end of this line
 17: move cursor to the beginning of the document
 18: move cursor to the end of the document
 19: move cursor up, at doc top: home, at doc start: no-op)
 20: move cursor down, at doc bot: end, at doc end: no-op)
 21: scroll text down one line (cursor unchanged)
 22: scroll text up one line (cursor unchanged)
 23: move cursor to the beginning of the top of the screen
 24: move cursor to the beginning of the bottom of the window
*/

/**  The constructor creates a new text editor widget.*/
Fl_Text_Editor::Fl_Text_Editor(int X, int Y, int W, int H,  const char* l)
    : Fl_Text_Display(X, Y, W, H, l) {
  mCursorOn = 1;
  insert_mode_ = 1;
  key_bindings = 0;
  set_flag(MAC_USE_ACCENTS_MENU);
  set_flag(NEEDS_KEYBOARD);

  // handle the default key bindings
  add_default_key_bindings(&key_bindings);

  // handle everything else
  default_key_function(kf_default);
}

#ifndef FL_DOXYGEN
Fl_Text_Editor::Key_Binding* Fl_Text_Editor::global_key_bindings = 0;
#endif

// These are the default key bindings every widget should start with
static struct {
  int key;
  int state;
  Fl_Text_Editor::Key_Func func;
} default_key_bindings[] = {
  { FL_Escape,    FL_TEXT_EDITOR_ANY_STATE, Fl_Text_Editor::kf_ignore     },
  { FL_Enter,     FL_TEXT_EDITOR_ANY_STATE, Fl_Text_Editor::kf_enter      },
  { FL_KP_Enter,  FL_TEXT_EDITOR_ANY_STATE, Fl_Text_Editor::kf_enter      },
  { FL_BackSpace, FL_TEXT_EDITOR_ANY_STATE, Fl_Text_Editor::kf_backspace  },
  { FL_Insert,    FL_TEXT_EDITOR_ANY_STATE, Fl_Text_Editor::kf_insert     },
  { FL_Delete,    FL_TEXT_EDITOR_ANY_STATE, Fl_Text_Editor::kf_delete     },
  { FL_Home,      0,                        Fl_Text_Editor::kf_move       },
  { FL_End,       0,                        Fl_Text_Editor::kf_move       },
  { FL_Left,      0,                        Fl_Text_Editor::kf_move       },
  { FL_Up,        0,                        Fl_Text_Editor::kf_move       },
  { FL_Right,     0,                        Fl_Text_Editor::kf_move       },
  { FL_Down,      0,                        Fl_Text_Editor::kf_move       },
  { FL_Page_Up,   0,                        Fl_Text_Editor::kf_move       },
  { FL_Page_Down, 0,                        Fl_Text_Editor::kf_move       },
  { FL_Home,      FL_SHIFT,                 Fl_Text_Editor::kf_shift_move },
  { FL_End,       FL_SHIFT,                 Fl_Text_Editor::kf_shift_move },
  { FL_Left,      FL_SHIFT,                 Fl_Text_Editor::kf_shift_move },
  { FL_Up,        FL_SHIFT,                 Fl_Text_Editor::kf_shift_move },
  { FL_Right,     FL_SHIFT,                 Fl_Text_Editor::kf_shift_move },
  { FL_Down,      FL_SHIFT,                 Fl_Text_Editor::kf_shift_move },
  { FL_Page_Up,   FL_SHIFT,                 Fl_Text_Editor::kf_shift_move },
  { FL_Page_Down, FL_SHIFT,                 Fl_Text_Editor::kf_shift_move },
  { FL_Home,      FL_CTRL,                  Fl_Text_Editor::kf_ctrl_move  },
  { FL_End,       FL_CTRL,                  Fl_Text_Editor::kf_ctrl_move  },
  { FL_Left,      FL_CTRL,                  Fl_Text_Editor::kf_ctrl_move  },
  { FL_Up,        FL_CTRL,                  Fl_Text_Editor::kf_ctrl_move  },
  { FL_Right,     FL_CTRL,                  Fl_Text_Editor::kf_ctrl_move  },
  { FL_Down,      FL_CTRL,                  Fl_Text_Editor::kf_ctrl_move  },
  { FL_Page_Up,   FL_CTRL,                  Fl_Text_Editor::kf_ctrl_move  },
  { FL_Page_Down, FL_CTRL,                  Fl_Text_Editor::kf_ctrl_move  },
  { FL_Home,      FL_CTRL|FL_SHIFT,         Fl_Text_Editor::kf_c_s_move   },
  { FL_End,       FL_CTRL|FL_SHIFT,         Fl_Text_Editor::kf_c_s_move   },
  { FL_Left,      FL_CTRL|FL_SHIFT,         Fl_Text_Editor::kf_c_s_move   },
  { FL_Up,        FL_CTRL|FL_SHIFT,         Fl_Text_Editor::kf_c_s_move   },
  { FL_Right,     FL_CTRL|FL_SHIFT,         Fl_Text_Editor::kf_c_s_move   },
  { FL_Down,      FL_CTRL|FL_SHIFT,         Fl_Text_Editor::kf_c_s_move   },
  { FL_Page_Up,   FL_CTRL|FL_SHIFT,         Fl_Text_Editor::kf_c_s_move   },
  { FL_Page_Down, FL_CTRL|FL_SHIFT,         Fl_Text_Editor::kf_c_s_move   },
//{ FL_Clear,     0,                        Fl_Text_Editor::delete_to_eol },
  { 'z',          FL_CTRL,                  Fl_Text_Editor::kf_undo       },
  { 'z',          FL_CTRL|FL_SHIFT,         Fl_Text_Editor::kf_redo       }, // Windows screen driver also defines Ctrl-Y
  { '/',          FL_CTRL,                  Fl_Text_Editor::kf_undo       }, // Emacs
  { '?',          FL_CTRL,                  Fl_Text_Editor::kf_redo       }, // Emacs
  { 'x',          FL_CTRL,                  Fl_Text_Editor::kf_cut        },
  { FL_Delete,    FL_SHIFT,                 Fl_Text_Editor::kf_cut        },
  { 'c',          FL_CTRL,                  Fl_Text_Editor::kf_copy       },
  { FL_Insert,    FL_CTRL,                  Fl_Text_Editor::kf_copy       },
  { 'v',          FL_CTRL,                  Fl_Text_Editor::kf_paste      },
  { FL_Insert,    FL_SHIFT,                 Fl_Text_Editor::kf_paste      },
  { 'a',          FL_CTRL,                  Fl_Text_Editor::kf_select_all },
  { 0,            0,                        0                             }
};

/**  Adds all of the default editor key bindings to the specified key binding list.*/
void Fl_Text_Editor::add_default_key_bindings(Key_Binding** list) {
  for (int i = 0; default_key_bindings[i].key; i++) {
    add_key_binding(default_key_bindings[i].key,
                    default_key_bindings[i].state,
                    default_key_bindings[i].func,
                    list);
  }
  Key_Binding *extra_key_bindings = Fl::screen_driver()->text_editor_extra_key_bindings;
  if (extra_key_bindings) { // add platform-specific key bindings, if any
    for (int i = 0; extra_key_bindings[i].key; i++) {
      add_key_binding(extra_key_bindings[i].key,
                      extra_key_bindings[i].state,
                      extra_key_bindings[i].function,
                      list);
    }
  }
}

/**  Returns the function associated with a key binding.*/
Fl_Text_Editor::Key_Func Fl_Text_Editor::bound_key_function(int key, int state, Key_Binding* list) const {
  Key_Binding* cur;
  for (cur = list; cur; cur = cur->next)
    if (cur->key == key)
      if (cur->state == FL_TEXT_EDITOR_ANY_STATE || cur->state == state)
        break;
  if (!cur) return 0;
  return cur->function;
}

/**  Removes all of the key bindings associated with the text editor or list.*/
void Fl_Text_Editor::remove_all_key_bindings(Key_Binding** list) {
  Key_Binding *cur, *next;
  for (cur = *list; cur; cur = next) {
    next = cur->next;
    delete cur;
  }
  *list = 0;
}

/** Removes the key binding associated with the key \p key of state \p state
    from the Key_Binding list \p list.

    This can be used in derived classes to remove global key bindings
    by using the global (static) Key_Binding list
    Fl_Text_Editor::global_key_bindings.
*/
void Fl_Text_Editor::remove_key_binding(int key, int state, Key_Binding** list) {
  Key_Binding *cur, *last = 0;
  for (cur = *list; cur; last = cur, cur = cur->next)
    if (cur->key == key && cur->state == state) break;
  if (!cur) return;
  if (last) last->next = cur->next;
  else *list = cur->next;
  delete cur;
}

/** Adds a \p key of state \p state with the function \p function to an
    arbitrary key binding list \p list.

    This can be used in derived classes to add global key bindings
    by using the global (static) Key_Binding list
    Fl_Text_Editor::global_key_bindings.
*/
void Fl_Text_Editor::add_key_binding(int key, int state, Key_Func function,
                                Key_Binding** list) {
  Key_Binding* kb = new Key_Binding;
  kb->key = key;
  kb->state = state;
  kb->function = function;
  kb->next = *list;
  *list = kb;
}

////////////////////////////////////////////////////////////////

static void kill_selection(Fl_Text_Editor* e) {
  if (e->buffer()->selected()) {
    e->insert_position(e->buffer()->primary_selection()->start());
    e->buffer()->remove_selection();
  }
}

/** Inserts the text associated with key \p 'c' in editor \p 'e'.
    Honors the current selection and insert/overstrike mode.
*/
int Fl_Text_Editor::kf_default(int c, Fl_Text_Editor* e) {
  // FIXME: this function is a mess! Fix this!
  if (!c || (!(c > 0 && c < 127 && isprint(c)) && c != '\t')) return 0;
  char s[2] = "\0";
  s[0] = (char)c;
  kill_selection(e);
  if (e->insert_mode()) e->insert(s);
  else e->overstrike(s);
  e->show_insert_position();
  e->set_changed();
  if (e->when()&FL_WHEN_CHANGED) e->do_callback(FL_REASON_CHANGED);
  return 1;
}

/** Ignores the key \p 'c' in editor \p 'e'.
    This method can be used as a keyboard binding to disable a key
    that might otherwise be handled or entered as text.

    An example would be disabling FL_Escape, so that it isn't added
    to the buffer when invoked by the user.
*/
int Fl_Text_Editor::kf_ignore(int, Fl_Text_Editor*) {
  return 0; // don't handle
}

/** Does a backspace for key \p 'c' in the current buffer of editor \p 'e'.
    Any current selection is deleted.
    Otherwise, the character left is deleted and the cursor moved.
    The key value \p 'c' is currently unused.
*/
int Fl_Text_Editor::kf_backspace(int, Fl_Text_Editor* e) {
  if (!e->buffer()->selected() && e->move_left()) {
    int p1 = e->insert_position();
    int p2 = e->buffer()->next_char(p1);
    e->buffer()->select(p1, p2);
  }
  kill_selection(e);
  e->show_insert_position();
  e->set_changed();
  if (e->when()&FL_WHEN_CHANGED) e->do_callback(FL_REASON_CHANGED);
  return 1;
}

/** Inserts a newline for key \p 'c' at the current cursor position in editor \p 'e'.
    The key value \p 'c' is currently unused.
*/
int Fl_Text_Editor::kf_enter(int, Fl_Text_Editor* e) {
  kill_selection(e);
  e->insert("\n");
  e->show_insert_position();
  e->set_changed();
  if (e->when()&FL_WHEN_CHANGED) e->do_callback(FL_REASON_CHANGED);
  return 1;
}

extern int fl_text_drag_prepare(int pos, int key, Fl_Text_Display* d);
extern void fl_text_drag_me(int pos, Fl_Text_Display* d);
/** Moves the text cursor in the direction indicated by key \p 'c' in editor \p 'e'.
    Supported values for 'c' are currently:
    \code
        FL_Home      -- moves the cursor to the beginning of the current line
        FL_End       -- moves the cursor to the end of the current line
        FL_Left      -- moves the cursor left one character
        FL_Right     -- moves the cursor right one character
        FL_Up        -- moves the cursor up one line
        FL_Down      -- moves the cursor down one line
        FL_Page_Up   -- moves the cursor up one page
        FL_Page_Down -- moves the cursor down one page
    \endcode
*/
int Fl_Text_Editor::kf_move(int c, Fl_Text_Editor* e) {
  int i;
  int selected = e->buffer()->selected();
  if (!selected)
    e->dragPos = e->insert_position();
  e->buffer()->unselect();
  Fl::copy("", 0, 0);
  switch (c) {
  case FL_Home:
      e->insert_position(e->line_start(e->insert_position()));
      break;
    case FL_End:
      e->insert_position(e->line_end(e->insert_position(), false));
      break;
    case FL_Left:
      e->move_left();
      break;
    case FL_Right:
      e->move_right();
      break;
    case FL_Up:
      e->move_up();
      break;
    case FL_Down:
      e->move_down();
      break;
    case FL_Page_Up:
      for (i = 0; i < e->mNVisibleLines - 1; i++) e->move_up();
      break;
    case FL_Page_Down:
      for (i = 0; i < e->mNVisibleLines - 1; i++) e->move_down();
      break;
  }
  e->show_insert_position();
  return 1;
}

/** Extends the current selection in the direction of key \p 'c' in editor \p 'e'.
    \see kf_move()
*/
int Fl_Text_Editor::kf_shift_move(int c, Fl_Text_Editor* e) {
  fl_text_drag_prepare(-1, c, e);
  kf_move(c, e);
  fl_text_drag_me(e->insert_position(), e);
  char *copy = e->buffer()->selection_text();
  if (copy) {
    Fl::copy(copy, (int) strlen(copy), 0);
    free(copy);
    }
  return 1;
}

/** Moves the current text cursor in the direction indicated by control key \p 'c' in editor \p 'e'.
    Supported values for 'c' are currently:
    \code
        FL_Home      -- moves the cursor to the beginning of the document
        FL_End       -- moves the cursor to the end of the document
        FL_Left      -- moves the cursor left one word
        FL_Right     -- moves the cursor right one word
        FL_Up        -- scrolls up one line, without moving cursor
        FL_Down      -- scrolls down one line, without moving cursor
        FL_Page_Up   -- moves the cursor to the beginning of the top line on the current page
        FL_Page_Down -- moves the cursor to the beginning of the last line on the current page
    \endcode
*/
int Fl_Text_Editor::kf_ctrl_move(int c, Fl_Text_Editor* e) {
  if (!e->buffer()->selected())
    e->dragPos = e->insert_position();
  if (c != FL_Up && c != FL_Down) {
    e->buffer()->unselect();
    Fl::copy("", 0, 0);
    e->show_insert_position();
  }
  switch (c) {
    case FL_Home:
      e->insert_position(0);
      e->scroll(0, 0);
      break;
    case FL_End:
      e->insert_position(e->buffer()->length());
      e->scroll(e->count_lines(0, e->buffer()->length(), 1), 0);
      break;
    case FL_Left:
      e->previous_word();
      break;
    case FL_Right:
      e->next_word();
      break;
    case FL_Up:
      e->scroll(e->mTopLineNum-1, e->mHorizOffset);
      break;
    case FL_Down:
      e->scroll(e->mTopLineNum+1, e->mHorizOffset);
      break;
    case FL_Page_Up:
      e->insert_position(e->mLineStarts[0]);
      break;
    case FL_Page_Down:
      e->insert_position(e->mLineStarts[e->mNVisibleLines-2]);
      break;
  }
  return 1;
}

/** Moves the current text cursor in the direction indicated by meta key \p 'c' in editor \p 'e'.
    Supported values for 'c' are currently:
    \code
        FL_Up        -- moves cursor to the beginning of the current document
        FL_Down      -- moves cursor to the end of the current document
        FL_Left      -- moves the cursor to the beginning of the current line
        FL_Right     -- moves the cursor to the end of the current line
    \endcode
*/
int Fl_Text_Editor::kf_meta_move(int c, Fl_Text_Editor* e) {
  if (!e->buffer()->selected())
    e->dragPos = e->insert_position();
  if (c != FL_Up && c != FL_Down) {
    e->buffer()->unselect();
    Fl::copy("", 0, 0);
    e->show_insert_position();
  }
  switch (c) {
    case FL_Up:                         // top of buffer
      e->insert_position(0);
      e->scroll(0, 0);
      break;
    case FL_Down:                       // end of buffer
      e->insert_position(e->buffer()->length());
      e->scroll(e->count_lines(0, e->buffer()->length(), 1), 0);
      break;
    case FL_Left:                       // beginning of line
      kf_move(FL_Home, e);
      break;
    case FL_Right:                      // end of line
      kf_move(FL_End, e);
      break;
  }
  return 1;
}

/** Extends the current selection in the direction indicated by meta key \p 'c' in editor \p 'e'.
    \see kf_meta_move().
*/
int Fl_Text_Editor::kf_m_s_move(int c, Fl_Text_Editor* e) {
  fl_text_drag_prepare(-1, c, e);
  kf_meta_move(c, e);
  fl_text_drag_me(e->insert_position(), e);
  return 1;
}

/** Extends the current selection in the direction indicated by control key \p 'c' in editor \p 'e'.
    \see kf_ctrl_move().
*/
int Fl_Text_Editor::kf_c_s_move(int c, Fl_Text_Editor* e) {
  fl_text_drag_prepare(-1, c, e);
  kf_ctrl_move(c, e);
  fl_text_drag_me(e->insert_position(), e);
  return 1;
}

/** Moves the text cursor to the beginning of the current line in editor \p 'e'.
    Same as kf_move(FL_Home, e).
    The key value \p 'c' is currently unused.
*/
int Fl_Text_Editor::kf_home(int, Fl_Text_Editor* e) {
    return kf_move(FL_Home, e);
}

/** Moves the text cursor to the end of the current line in editor \p 'e'.
    Same as kf_move(FL_End, e).
    The key value \p 'c' is currently unused.
*/
int Fl_Text_Editor::kf_end(int, Fl_Text_Editor* e) {
  return kf_move(FL_End, e);
}

/** Moves the text cursor one character to the left in editor \p 'e'.
    Same as kf_move(FL_Left, e).
    The key value \p 'c' is currently unused.
*/
int Fl_Text_Editor::kf_left(int, Fl_Text_Editor* e) {
  return kf_move(FL_Left, e);
}

/** Moves the text cursor one line up for editor \p 'e'.
    Same as kf_move(FL_Up, e).
    The key value \p 'c' is currently unused.
*/
int Fl_Text_Editor::kf_up(int, Fl_Text_Editor* e) {
  return kf_move(FL_Up, e);
}

/** Moves the text cursor one character to the right for editor \p 'e'.
    Same as kf_move(FL_Right, e).
    The key value \p 'c' is currently unused.
*/
int Fl_Text_Editor::kf_right(int, Fl_Text_Editor* e) {
  return kf_move(FL_Right, e);
}

/** Moves the text cursor one line down for editor \p 'e'.
    Same as kf_move(FL_Down, e).
    The key value \p 'c' is currently unused.
*/
int Fl_Text_Editor::kf_down(int, Fl_Text_Editor* e) {
  return kf_move(FL_Down, e);
}

/** Moves the text cursor up one page for editor \p 'e'.
    Same as kf_move(FL_Page_Up, e).
    The key value \p 'c' is currently unused.
*/
int Fl_Text_Editor::kf_page_up(int, Fl_Text_Editor* e) {
  return kf_move(FL_Page_Up, e);
}

/** Moves the text cursor down one page for editor \p 'e'.
    Same as kf_move(FL_Page_Down, e).
    The key value \p 'c' is currently unused.
*/
int Fl_Text_Editor::kf_page_down(int, Fl_Text_Editor* e) {
  return kf_move(FL_Page_Down, e);
}

/** Toggles the insert mode for editor \p 'e'.
    The key value \p 'c' is currently unused.
*/
int Fl_Text_Editor::kf_insert(int, Fl_Text_Editor* e) {
  e->insert_mode(e->insert_mode() ? 0 : 1);
  return 1;
}

/** Does a delete of selected text or the current character in the current buffer of editor \p 'e'.
    The key value \p 'c' is currently unused.
*/
int Fl_Text_Editor::kf_delete(int, Fl_Text_Editor* e) {
  if (!e->buffer()->selected()) {
    int p1 = e->insert_position();
    int p2 = e->buffer()->next_char(p1);
    e->buffer()->select(p1, p2);
  }

  kill_selection(e);
  e->show_insert_position();
  e->set_changed();
  if (e->when()&FL_WHEN_CHANGED) e->do_callback(FL_REASON_CHANGED);
  return 1;
}

/** Does a copy of selected text or the current character in the current buffer of editor \p 'e'.
    The key value \p 'c' is currently unused.
*/
int Fl_Text_Editor::kf_copy(int, Fl_Text_Editor* e) {
  if (!e->buffer()->selected()) return 1;
  const char *copy = e->buffer()->selection_text();
  if (*copy) Fl::copy(copy, (int) strlen(copy), 1);
  free((void*)copy);
  e->show_insert_position();
  return 1;
}

/** Does a cut of selected text in the current buffer of editor \p 'e'.
    The key value \p 'c' is currently unused.
*/
int Fl_Text_Editor::kf_cut(int c, Fl_Text_Editor* e) {
  kf_copy(c, e);
  kill_selection(e);
  e->set_changed();
  if (e->when()&FL_WHEN_CHANGED) e->do_callback(FL_REASON_CHANGED);
  return 1;
}

/** Does a paste of selected text in the current buffer of editor \p 'e'.
    Any current selection is replaced with the pasted content.
    The key value \p 'c' is currently unused.
*/
int Fl_Text_Editor::kf_paste(int, Fl_Text_Editor* e) {
  kill_selection(e);
  Fl::paste(*e, 1);
  e->show_insert_position();
  e->set_changed();
  if (e->when()&FL_WHEN_CHANGED) e->do_callback(FL_REASON_CHANGED);
  return 1;
}

/** Selects all text in the current buffer in editor \p 'e'.
    The key value \p 'c' is currently unused.
*/
int Fl_Text_Editor::kf_select_all(int, Fl_Text_Editor* e) {
  e->buffer()->select(0, e->buffer()->length());
  const char *copy = e->buffer()->selection_text();
  if (*copy) Fl::copy(copy, (int) strlen(copy), 0);
  free((void*)copy);
  return 1;
}

/** Undo last edit in the current buffer of editor \p 'e'.
 Also deselects previous selection.
 The key value \p 'c' is currently unused.
 */
int Fl_Text_Editor::kf_undo(int , Fl_Text_Editor* e) {
  e->buffer()->unselect();
  Fl::copy("", 0, 0);
  int crsr = e->insert_position();
  int ret = e->buffer()->undo(&crsr);
  e->insert_position(crsr);
  e->show_insert_position();
  e->set_changed();
  if (e->when()&FL_WHEN_CHANGED) e->do_callback();
  return ret;
}

/** Redo last undo action.
 Also deselects previous selection.
 The key value \p 'c' is currently unused.
 */
int Fl_Text_Editor::kf_redo(int , Fl_Text_Editor* e) {
  e->buffer()->unselect();
  Fl::copy("", 0, 0);
  int crsr = e->insert_position();
  int ret = e->buffer()->redo(&crsr);
  e->insert_position(crsr);
  e->show_insert_position();
  e->set_changed();
  if (e->when()&FL_WHEN_CHANGED) e->do_callback();
  return ret;
}

/** Handles a key press in the editor */
int Fl_Text_Editor::handle_key() {
  // Call FLTK's rules to try to turn this into a printing character.
  // This uses the right-hand ctrl key as a "compose prefix" and returns
  // the changes that should be made to the text, as a number of
  // bytes to delete and a string to insert:
  int del = 0;
  if (Fl::compose(del)) {
    if (del) {
      // del is a number of bytes
      int dp = insert_position() - del;
      if ( dp < 0 ) dp = 0;
      buffer()->select(dp, insert_position());
    }
    kill_selection(this);
    if (Fl::event_length()) {
      if (insert_mode()) insert(Fl::event_text());
      else overstrike(Fl::event_text());
    }
    if (Fl::screen_driver()->has_marked_text() && Fl::compose_state) {
      int pos = this->insert_position();
      this->buffer()->select(pos - Fl::compose_state, pos);
    }
    show_insert_position();
    set_changed();
    if (when()&FL_WHEN_CHANGED) do_callback(FL_REASON_CHANGED);
    return 1;
  }

  int key = Fl::event_key(), state = Fl::event_state(), c = Fl::event_text()[0];
  state &= FL_SHIFT|FL_CTRL|FL_ALT|FL_META; // only care about these states
  Key_Func f;
  f = bound_key_function(key, state, global_key_bindings);
  if (!f) f = bound_key_function(key, state, key_bindings);
  if (f == kf_undo || f == kf_redo) {
    // never propagate undo and redo up to another widget
    if (!f(key, this)) fl_beep();
    return 1;
  } else if (f){
    return f(key, this);
  }
  if (default_key_function_ && !state) return default_key_function_(c, this);
  return 0;
}

/** does or does not a callback according to changed() and when() settings */
void Fl_Text_Editor::maybe_do_callback(Fl_Callback_Reason reason) {
//  printf("Fl_Text_Editor::maybe_do_callback()\n");
//  printf("changed()=%d, when()=%x\n", changed(), when());
  if (changed() || (when()&FL_WHEN_NOT_CHANGED))
    do_callback(reason);
}

int Fl_Text_Editor::handle(int event) {
  static int dndCursorPos;

  if (!buffer()) return 0;

  switch (event) {
    case FL_FOCUS:
      show_cursor(mCursorOn); // redraws the cursor
      if (buffer()->selected()) redraw(); // Redraw selections...
      Fl::focus(this);
      return 1;

    case FL_UNFOCUS:
      show_cursor(mCursorOn); // redraws the cursor
      if (Fl::screen_driver()->has_marked_text() && buffer()->selected() && Fl::compose_state) {
        int pos = insert_position();
        buffer()->select(pos, pos);
        fl_reset_spot();
      }
      if (buffer()->selected()) redraw(); // Redraw selections...
      // FALLTHROUGH
    case FL_HIDE:
      if (when() & FL_WHEN_RELEASE) maybe_do_callback(FL_REASON_LOST_FOCUS);
      return 1;

    case FL_KEYBOARD:
      if (active_r() && window() && this == Fl::belowmouse())
        window()->cursor(FL_CURSOR_NONE);
      return handle_key();

    case FL_PASTE:
      if (!Fl::event_text()) {
        fl_beep();
        return 1;
      }
      buffer()->remove_selection();
      if (insert_mode()) insert(Fl::event_text());
      else overstrike(Fl::event_text());
      show_insert_position();
      set_changed();
      if (when()&FL_WHEN_CHANGED) do_callback(FL_REASON_CHANGED);
      return 1;

    case FL_ENTER:
// MRS: Windows only?  Need to test!
//  case FL_MOVE:
      show_cursor(mCursorOn);
      return 1;

    case FL_PUSH:
      if (Fl::event_button() == 2) {
        // don't let the text_display see this event
        if (Fl_Group::handle(event)) return 1;
        dragType = DRAG_NONE;
        if(buffer()->selected()) {
          buffer()->unselect();
        }
        int pos = xy_to_position(Fl::event_x(), Fl::event_y(), CURSOR_POS);
        insert_position(pos);
        Fl::paste(*this, 0);
        Fl::focus(this);
        set_changed();
        if (when()&FL_WHEN_CHANGED) do_callback(FL_REASON_CHANGED);
        return 1;
      }

      if (Fl::event_button() == FL_RIGHT_MOUSE) {
        if (active_r() && window()) {
          if (Fl::event_inside(text_area.x, text_area.y, text_area.w,
                               text_area.h)) window()->cursor(FL_CURSOR_INSERT);
          else window()->cursor(FL_CURSOR_DEFAULT);
        }
        if (Fl::focus() != this) {
          Fl::focus(this);
          handle(FL_FOCUS);
        }
        switch (handle_rmb(0)) {
          case 1: kf_cut(0, this); break;
          case 2: kf_copy(0, this); break;
          case 3: kf_paste(0, this); break;
        }
        return 1;
      }

      break;

    case FL_SHORTCUT:
      if (!(shortcut() ? Fl::test_shortcut(shortcut()) : test_shortcut()))
        return 0;
      if (Fl::visible_focus() && handle(FL_FOCUS)) {
        Fl::focus(this);
        return 1;
      }
      break;

      // Handle drag'n'drop attempt by the user. This is a simplified
      // implementation which allows dnd operations onto the scroll bars.
    case FL_DND_ENTER: // save the current cursor position
      if (Fl::visible_focus() && handle(FL_FOCUS))
        Fl::focus(this);
      show_cursor(mCursorOn);
      dndCursorPos = insert_position();
      /* fall through */
    case FL_DND_DRAG: // show a temporary insertion cursor
      insert_position(xy_to_position(Fl::event_x(), Fl::event_y(), CURSOR_POS));
      return 1;
    case FL_DND_LEAVE: // restore original cursor
      insert_position(dndCursorPos);
      return 1;
    case FL_DND_RELEASE: // keep insertion cursor and wait for the FL_PASTE event
      if (!dragging) buffer()->unselect(); // FL_PASTE must not destroy current selection if drag comes from outside
      return 1;
  }

  return Fl_Text_Display::handle(event);
}

/**
Enables or disables Tab key focus navigation.

When disabled (default), tab characters are inserted into
Fl_Text_Editor. Only the mouse can change focus.  This behavior is
desireable when Fl_Text_Editor is used, e.g. in a source code editor.

When enabled, Tab navigates focus to the next widget, and Shift-Tab
navigates focus to the previous widget. This behavior is desireable
when Fl_Text_Editor is used e.g. in a database input form.

Currently, this method is implemented as a convenience method
that adjusts the key bindings for the Tab key. This implementation
detail may change in the future. Know that changing the editor's
key bindings for Tab and Shift-Tab may affect tab navigation.

\param [in] val If \p val is 0, Tab inserts a tab character (default).<br>
                If \p val is 1, Tab navigates widget focus.

\see tab_nav(), Fl::OPTION_ARROW_FOCUS.
\version 1.3.4 ABI feature
*/
void Fl_Text_Editor::tab_nav(int val) {
  if ( val )
    add_key_binding(FL_Tab, 0, kf_ignore);
  else
    remove_key_binding(FL_Tab, 0);
}

/**
Check if Tab focus navigation is enabled.

If disabled (default), hitting Tab inserts a tab character into the
editor buffer.

If enabled, hitting Tab navigates focus to the next widget,
and Shift-Tab navigates focus to the previous widget.

\returns        if Tab inserts tab characters or moves the focus
\retval 0       Tab inserts tab characters (default)
\retval 1       Tab navigation is enabled.

\see tab_nav(int), Fl::OPTION_ARROW_FOCUS.
\version 1.3.4 ABI feature
*/
int Fl_Text_Editor::tab_nav() const {
  return (bound_key_function(FL_Tab,0)==kf_ignore) ? 1 : 0;
}
