/*  $Id$

    Part of XPCE --- The SWI-Prolog GUI toolkit

    Author:        Jan Wielemaker and Anjo Anjewierden
    E-mail:        J.Wielemaker@cs.vu.nl
    WWW:           http://www.swi.psy.uva.nl/projects/xpce/
    Copyright (C): 1985-2010, University of Amsterdam, VU University Amsterdam

    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 (at your option) 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 Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    As a special exception, if you link this library with other files,
    compiled with a Free Software compiler, to produce an executable, this
    library does not by itself cause the resulting executable to be covered
    by the GNU General Public License. This exception does not however
    invalidate any other reasons why the executable file might be covered by
    the GNU General Public License.
*/

:- module(emacs_fundamental_mode, []).
:- use_module(library(pce)).
:- use_module(library(print_text)).
:- require([ append/3
	   , auto_call/1
	   , between/3
	   , chain_list/2
	   , default/3
	   , ignore/1
	   ]).

:- emacs_begin_mode(fundamental, [],	% []: root of the mode hierarchy
		    "Generic PceEmacs editing mode",
	[ prefix		   = key('\\C-h'),
	  insert_file		   = key('\\C-xi'),
	  write_file		   = key('\\C-x\\C-w'),
	  save_and_kill            = key('\\C-x#'),
	  what_cursor_position     = key('\\C-x='),
	  count_lines_region       = key('\\e='),
	  replace	           = key('\\e%'),
	  grab_region              = key('\\ew'),
	  justify_paragraph        = key('\\eQ'),
	  bookmark_line            = key('\\e@'),
	  execute_extended_command = key('\\ex'),
	  write_region		   = key('\\e\\C-w'),
	  compile		   = key('\\C-x\\C-m'),

					% FILE menu
	  show_buffer_menu	   = key('\\C-x\\C-b') + button(file),
	  switch_to_buffer	   = key('\\C-xb') +
				     button(file, @emacs_mode?buffers),
	  -			   = button(file),
	  open			   = key('\\C-x\\C-f') + button(file),
	  new			   = button(file),
	  save_buffer		   = key('\\C-x\\C-s') + button(file),
	  save_as		   = button(file),
	  print			   = button(file),
	  print_selection	   = button(file),
	  -			   = button(file),
	  revert		   = button(file),
	  kill_buffer		   = key('\\C-xk') + button(file),
	  -			   = button(file),
	  ispell		   = button(file),
	  shell			   = button(file),
	  (mode)		   = key('\\em') +
	  			     button(file, @emacs_mode?modes),
	  properties		   = button(file),
	  -			   = button(file),
	  quit			   = key('\\C-x\\C-c') + button(file),

					% EDIT menu
	  undo			   = button(edit),
	  -			   = button(edit),
	  copy			   = button(edit),
	  cut			   = button(edit),
	  paste			   = button(edit),
	  -			   = button(edit),
	  find			   = button(edit),
	  replace		   = button(edit),

					% BROWSER menu
	  split_window		   = key('\\C-x2') + button(browse),
	  only_window              = key('\\C-x1') + button(browse),
	  -			   = button(browse),
	  bookmark_line		   = button(browse),
	  show_bookmarks	   = button(browse),
	  -			   = button(browse),
	  grep			   = button(browse),

					% COMPILE menu
	  compile		   = button(compile),

					% HELP menu
	  help			   = button(help),
	  help_on_mode		   = button(help),
	  customise		   = button(help),
	  -			   = button(help),
	  show_key_bindings	   = key('\\C-hb') + button(help),
	  describe_key		   = key('\\C-hk') + button(help),
	  describe_function	   = key('\\C-hf') + button(help),
	  -			   = button(help),
	  manual_entry		   = button(help),
	  xpce_manual		   = button(help)
	],
	[
	]).

class_variable(grep_command,	string, 'grep -n %s /dev/null',
	       "Command of M-x grep").
class_variable(shell_command,	chain*,
	       when(@pce?window_system == windows,
		    @nil,
		    chain('/bin/sh', '-c')),
	       "Command for running grep, make, etc.").
class_variable(auto_colourise_size_limit, int, 50000,
	       "Auto-colourise if buffer is smaller then this").
class_variable(print_command,	string,
	       [ 'X'('lpr %s'),
		 windows('NOTEPAD.EXE /P %s')
	       ],
	       "Command to print a file").

variable(print_command, name, both,
	 "Command to print a file").
variable(auto_colourise_size_limit,
	 int,
	 both,
	 "Auto-colourise if buffer is smaller then this").

		 /*******************************
		 *	COLOURISE BUFFERS	*
		 *******************************/

idle(M) :->
	"Idle event was received, colour the current element"::
	send(M, auto_colourise_buffer).


new_buffer(M) :->
	"A new buffer is attached"::
	send_super(M, new_buffer),
	send(M, auto_colourise_buffer).


auto_colourise_buffer(M) :->
	"Colourise if shorter then <-auto_colourise_size_limit"::
	get(M, text_buffer, TB),
	get(TB, generation, Generation),
	get(TB, coloured_generation, Coloured),
	(   Coloured \== Generation,
	    get(TB, size, Size),
	    get(M, auto_colourise_size_limit, Limit),
	    Size < Limit,
	    get(M, focus_function, @nil) 	% don't colour in special modes
	->  (	send(M, colourise_buffer)
	    ->	send(TB, coloured_generation, Generation)
	    ;	true
	    )
	;   true
	).


colourisation_up_to_date(M) :->
	"True if the colourisation is up-to-date"::
	get(M, text_buffer, TB),
	get(TB, generation, Generation),
	get(TB, coloured_generation, Coloured),
	Generation == Coloured.


colourise_buffer(M) :->
	"Colour buffer using syntax-rules"::
	send(M, remove_syntax_fragments),
	get(M, text_buffer, TB),
	get(TB, generation, Generation),
	send(TB, coloured_generation, Generation).


remove_syntax_fragments(M,
			From:from=[int], To:to=[int],
			Style:style=[name]) :->
	"Remove all syntax-colouring fragments"::
	remove_condition(From, To, Style, Condition),
	send(M, for_all_fragments,
	     if(Condition, message(@arg1, free))).


:- pce_global(@is_emacs_colour_fragment,
	      new(message(@arg1, instance_of, emacs_colour_fragment))).

remove_condition(@default, @default, @default,
		 @is_emacs_colour_fragment).
remove_condition(From, To, @default,
		 and(message(@arg1, overlap, point(From, To)),
		     @is_emacs_colour_fragment)).
remove_condition(@default, @default, Style,
		 and(@arg1?style == Style,
		     @is_emacs_colour_fragment)).
remove_condition(From, To, Style,
		 and(@arg1?style == Style,
		     message(@arg1, overlap, point(From, To)),
		     @is_emacs_colour_fragment)).


		 /*******************************
		 *	GLOBAL UTILITIES	*
		 *******************************/

quit(M) :->
	"Destroy the editor"::
	ignore(send(M?text_buffer, save_if_modified)),
	send(M, destroy).


		 /*******************************
		 *		REGION		*
		 *******************************/

region(M, Tuple:tuple) :<-
	"Get region start and end (sorted)"::
	get(M, mark, Mark),
	get(M, caret, Caret),
	(   Caret > Mark
	->  new(Tuple, tuple(Mark, Caret))
	;   Mark > Caret
	->  new(Tuple, tuple(Caret, Mark))
	).

line_region(M, F0:[int], T0:[int], Tuple:tuple) :<-
	"Start and end-of region for line-oriented commands"::
	(   F0 == @default,
	    T0 == @default
	->  get(M, region, tuple(From, To))
	;   From = F0,
	    To = T0
	),
	get(M, text_buffer, TB),
	get(TB, scan, From, line, 0, start, S),
	get(TB, scan, To,   line, 0, start, E),
	new(Tuple, tuple(S, E)).

for_lines_in_region(M, From:[int], To:[int], Code:code) :->
	"Run code with @arg1, @arg2 at the start/end of each line"::
	get(M, line_region, From, To, tuple(S, E)),
	for_lines_in_region(M, S, E, Code).

for_lines_in_region(_M, S, E, _Code) :-
	S >= E, !.
for_lines_in_region(M, S, E, Code) :-
	get(M, scan, S, line, 0, EOL),
	send(Code, forward, S, EOL),
	SOL is EOL + 1,
	for_lines_in_region(M, SOL, E, Code).

warn_big_region(M, Action:name, N:int) :->
	"Warn if region exceeds size"::
	get(M, region, tuple(Start, End)),
	(   End - Start > N
	->  send(@display, confirm,
		 'Region is > %d characters; %s?', N, Action)
	;   true
	).

warn_big_paragraph(M, Action:name, N:int) :->
	"Warn if paragraph exceeds size"::
	get(M, caret, Caret),
	get(M, text_buffer, TB),
	get(TB, scan, Caret+1, paragraph, 0, start, SP),
	get(TB, scan, Caret-1, paragraph, 0, end, EP),
	(   EP - SP > N
	->  send(@display, confirm,
		 'Paragraph is > %d characters; %s?', N, Action)
	;   true
	).


		 /*******************************
		 *      DANGEROUS ACTIONS	*
		 *******************************/

upcase_region(M) :->
	"Upcase region, but warn if dangerous"::
	send(M, warn_big_region, upcase, 100),
	send_super(M, upcase_region).

downcase_region(M) :->
	"Downcase region, but warn if dangerous"::
	send(M, warn_big_region, downcase, 100),
	send_super(M, downcase_region).

fill_region(M) :->
	"Fill region, but warn if dangerous"::
	send(M, warn_big_region, fill, 1000),
	send_super(M, fill_region).

justify_paragraph(M) :->
	"Justify paragraph, but warn if dangerous"::
	send(M, warn_big_paragraph, justify, 1000),
	send_super(M, justify_paragraph).

fill_paragraph(M, Arg:[int]) :->
	"Fill paragraph, but warn if dangerous"::
	send(M, warn_big_paragraph, justify, 1000),
	send_super(M, fill_paragraph, Arg).


		 /*******************************
		 *		EDIT		*
		 *******************************/

grab_region(M) :->
	"Copy the current region into the cut-buffer"::
	send(M, kill_or_grab_region, 1).


sort_lines_in_region(M) :->
	"Sort lines in mark ... caret alphabetically"::
	get(M, region, tuple(Start, End)),
	send(M, sort, Start, End).


delete_matching_lines(M, Re:regex) :->
	"Delete lines in (point,end) matching regex"::
	get(M, caret, Caret),
	get(M, text_buffer, TB),
	get(TB, scan, Caret, line, 0, start, SOL),
	send(Re, compile, @on),
	new(Here, number(SOL)),
	repeat,
	    (	get(TB, size, Size),
		get(Here, value, PlHere),
		PlHere >= Size
	    ->	!
	    ;   get(TB, scan, Here, line, 0, end, EOL),
		(   send(Re, search, TB, Here, EOL)
		->  send(TB, delete, Here, EOL+1-Here)
		;   send(Here, value, EOL+1)
		),
		fail
	    ).


/*
delete_rectangle(M) :->
	"Delete rectangular area (mark,caret)"::
	get(M, mark, Mark),
	get(M, column, Mark, MarkColumn),
	get(M, caret, Caret),
	get(M, column, Caret, CaretColumn),
	min(MarkColumn, CaretColumn, FromColumn),
	max(MarkColumn, CaretColumn, ToColumn),

*/

		 /*******************************
		 *	      LOAD/SAVE		*
		 *******************************/

buffers(_M, Buffers:chain) :<-
	"Chain with existing buffers"::
	get(@emacs, buffers, Buffers).

modes(_M, Modes:chain) :<-
	"Chain with defined modes"::
	get(@emacs, modes, Modes).


save_text(M) :->
	"Save buffer as ASCII if it is modified"::
	get(M, text_buffer, TB),
	(   get(TB, modified, @on)
	->  send(M?text_buffer, save),
	    send(M, report, status,
		 'Buffer saved in file `%s''', TB?file?base_name)
	;   send(M, report, status, 'No changes need saving')
	).


save_buffer(M) :->
	"Save buffer if it is modified"::
	send(M, save_text).


save_as(M, File:save_file) :->
	"Equivalent to write_file"::
	send(M, write_file, File).


save_some_buffers(_M, Arg:[int]) :->
	"Save modified buffers. Arg: donot confirm"::
	(   Arg == @default
	->  send(@emacs, save_some_buffers)
	;   send(@emacs, save_some_buffers, @on)
	).


find_file(_M, File:file) :->
	"Find existing file or create new one"::
	new(Buffer, emacs_buffer(File)),
	send(Buffer, open, tab).

new(M, File:save_file) :->
	"Create a new file"::
	send(M, find_file(File)).

open(M, File:file) :->
	"Open existing file (use File/New ... to create a new file)"::
	send(M, find_file(File)).


insert_file(M, File:file) :->
	"Insert file at point"::
	send(M?text_buffer, insert_file, M?caret, File).


write_file(M, File:save_file) :->
	"Write buffer to named file"::
	send(M?text_buffer, save, File).


write_region(M, File:save_file) :->
	"Write current region to file"::
	get(M, region, tuple(Start, End)),
	Length is End - Start,
	send(M?text_buffer, write_region, File, Start, Length).


show_buffer_menu(_M) :->
	"Expose the buffer-menu window"::
	send(@emacs, show_buffer_menu).


switch_to_buffer(_, Buffer:emacs_buffer) :->
	"Switch this window to named buffer"::
	send(Buffer, open, tab).
%	send(M, text_buffer, Buffer).		% Always in same window


kill_buffer(M) :->
	"Kill the current buffer"::
	get(M, text_buffer, Buffer),
	send(Buffer, kill).


		 /*******************************
		 *	     SETTINGS		*
		 *******************************/

comment_column(M, Col:[int]) :->
	"Set comment column to current column"::
	(   Col == @default
	->  get(M, column, Column)
	;   Column = Col
	),
	send(M?editor, comment_column, Column).

encoding(M,
	 Enc:encoding={ascii,iso_latin_1,text,utf8,unicode_be,unicode_le},
	 BOM:'BOM'=bool) :->
	"Set the character encoding for the file"::
	(   get(M, file, File),
	    File \== @nil
	->  send(File, encoding, Enc),
	    send(File, bom, BOM)
	;   send(M, report, warning, "No file")
	).

newline_mode(M, Mode:mode={posix,dos}) :->
	"Set save-mode for newlines"::
	get(M, text_buffer, TB),
	get(TB, file, File),
	send(File, newline_mode, Mode).


		 /*******************************
		 *	       PRINT		*
		 *******************************/

print(M, From:[int], To:[int]) :->
	"Print contents of the buffer"::
	get(M, text_buffer, TB),
	get(M, editor, E),
	(   get(M, file, File),
	    File \== @nil
	->  get(File, absolute_path, Path),
	    prolog_to_os_filename(Path, FileName),
	    (	From \== @default, To \== @default
	    ->	get(M, line_number, From, FL),
		get(M, line_number, To-1, TL),
		format(string(Job), '~w (lines ~w..~w)', [FileName, FL, TL])
	    ;	Job = FileName
	    )
	;   Job = @default
	),
	send(TB, print, From, To,
	     editor := E,
	     job := Job).


print_region(M) :->
	"Print current region"::
	get(M, line_region, tuple(From, To)),
	send(M, print, From, To).


print_selection(M) :->
	"Print the current selection (=region)"::
	send(M, print_region).


		 /*******************************
		 *	    FIND/REPLACE	*
		 *******************************/

:- pce_autoload(editor_find_dialog, library('emacs/find')).

find(M) :->
	"Find in text"::
	get(M, editor, E),
	send(editor_find_dialog(E), open).


replace(M, From:'replace=regex', To:'into=string') :->
	"Query replace regular expression"::
	send(M, query_replace_regex, From, To).


query_replace_regex(M,
		    From:'replace=regex',
		    To:'into=string') :->
	"Query replace regular expression"::
	send(M, internal_mark),
	send(M, attribute, attribute(replace_search_pattern, From)),
	send(M, attribute, attribute(replace_replace_pattern, To)),
	replace_find_and_mark(M),
	send(M, focus_function, '_query_replace_regex').


replace_find_and_mark(M) :-
	get(M, replace_search_pattern, Regex),
	(   send(Regex, search, M?text_buffer, M?caret)
	->  get(Regex, register_start, Start),
	    get(Regex, register_end, End),
	    send(M, selection, Start, End, highlight),
	    send(M, report, status,
		 'Commands: "y" = replace-and-next; "." = replace; "n" = next; "!" = non-interactive; "ESC" = stop')
	;   send(M, report, status, 'Done.'),
	    send(M, replace_end),
	    fail
	).


replace_match(M) :-
	get(M, replace_search_pattern, Regex),
	get(M, replace_replace_pattern, Replace),
	send(Regex, replace, M?text_buffer, Replace),
	get(Regex, register_end, End),
	get(Regex, register_start, Start),
	(   End == Start		% 0-length search string!
	->  send(M, caret, End+1)
	;   send(M, caret, End)
	).


replace_end(M) :->
	send(M, focus_function, @nil),
	get(M, internal_mark, Mark),
	send(M, selection, Mark, @default, inactive).


'_query_replace_regex'(M, Id:event_id) :->
	"Focus function for query_replace_regex"::
	(   Id == 0'y				% replace-and-continue
 	->  replace_match(M),
	    ignore(replace_find_and_mark(M))
	;   Id == 0'.				% replace and done
	->  replace_match(M),
	    send(M, replace_end),
	    send(M, report, status, 'Done.')
	;   Id == 0'n				% donot replace and continue
	->  (   replace_find_and_mark(M)
	    ->	true
	    ;	get(M, focus_function, @nil)
	    )
	;   Id == 27				% exit
	->  send(M, replace_end)
	;   Id == 0'!				% replace no-query
	->  repeat,
		send(M, '_query_replace_regex', 0'y),
		get(M, focus_function, @nil),
	    !
	;   send(M, replace_end),		% anything else: cancel
	    fail
	).


bookmark_line(M) :->
	"Create a mark in the mark-list"::
	get(M, caret, Caret),
	get(M, scan, Caret, line, 0, start, SOL),
	send(@emacs_mark_list, append_hit, M?text_buffer, SOL).


show_bookmarks(_) :->
	"Show PceEmacs bookmarks"::
	send(@emacs, show_bookmarks).


		 /*******************************
		 *	   PROCESS STUFF	*
		 *******************************/

has_processes(M) :->
	"Test if this XPCE version supports processes"::
	(   send(@pce, has_feature, process)
	->  true
	;   send(M, report, error, 'No inferior processes in this OS'),
	    fail
	).

		 /*******************************
		 *	     SPELLING		*
		 *******************************/

:- pce_autoload(ispell, demo(ispell)).

ispell(M) :->
	"Start ispell on this text_buffer"::
	send(M, has_processes),
	new(Ispell, ispell),
	get(M, text_buffer, TB),
	send(Ispell, buffer, TB),
	send(Ispell, label, string('Ispell Emacs buffer %s', TB?name)),
	send(Ispell, open),
	send(Ispell, spell).


		 /*******************************
		 *	  M-x PROCESSING	*
		 *******************************/

command_names(M, Names:chain) :<-
	"Find all send_methods on this mode"::
	get(M, find_all_send_methods, Chain),
	get(Chain, map, @arg1?name, Names).


:- initialization
   (   object(@emacs_mode_command)
   ->  true
   ;   new(@emacs_mode_command,
	   type(emacs_mode_command, value_set,
		quote_function(@current_emacs_mode?command_names),
		@nil))
   ).

execute_extended_command(M,
			 CmdName:command=emacs_mode_command,
			 Times:[int]) :->
	"Prompt for interactive command"::
	send(M, noarg_call, CmdName, Times).


		 /*******************************
		 *	     COMPILE		*
		 *******************************/

split_command_string(String, List) :-
	new(Ch, chain),
	new(Re, regex('[^ ]+')),
	send(Re, for_all, String,
	     message(Ch, append, ?(@arg1, register_value, @arg2, 0, name))),
	chain_list(Ch, List).

compile(M, Command:shell_command=string, Label:[name]) :->
	"Run Unix (compilation) process in buffer"::
	send(M, save_some_buffers),
	send(M, has_processes),
	default(Label, Command, Lbl),
	get(M, directory, Dir),
	new(B, emacs_process_buffer(@default, string('*%s*', Lbl))),
	(   get(B, process, OldP), OldP \== @nil,
	    get(OldP, status, running)
	->  new(D, dialog('Running Process')),
	    send(D, append, label(reporter,
				  'Kill running process and start new one?')),
	    send(D, append, button(kill,
				   and(message(B, process, @nil),
				       message(D, return, ok)))),
	    send(D, append, button(cancel,
				   message(D, return, cancel))),
	    get(D, confirm_centered, Status),
	    send(D, destroy),
	    Status == ok
	;   true
	),
	get(M, shell_command, ShellCommandChain),
	(   ShellCommandChain \== @nil
	->  chain_list(ShellCommandChain, List),
	    append(List, [Command], ArgList),
	    Process =.. [process|ArgList]
	;   split_command_string(Command, Args),
	    Process =.. [process|Args]
	),
	new(P, Process),
	send(P, directory, Dir),
	send(B, clear),
	send(B, format, 'cd %s\n%s\n', Dir?path, Command),
	send(B, directory, Dir),
	send(B, process, P),
	send(B, start_process),
	send(B, open, tab),
	send(B?editors, for_some,
	     and(message(@arg1, report, status, 'Running ...'),
		 message(@arg1, scroll_to, 0),
		 message(@arg1, caret, @default))).


grep(M, GrepArgs:grep_arguments=string) :->
	"Run Unix grep in compilation buffer"::
	get(M, grep_command, GrepCommad),
	send(M, compile,
	     string(GrepCommad, GrepArgs),
	     string('grep %s', GrepArgs)).


shell(M) :->
	"Start interactive shell"::
	send(M, has_processes),
	(   get(@emacs, buffer, '*shell*', Buffer)
	->  send(Buffer, open)
	;   (	get(@pce, environment_variable, 'SHELL', Shell)
	    ->  better_shell(Shell, Shell2),
		Process = process(Shell2, '-i')
	    ;	get(@pce, operating_system, winnt) % TBD: Windows 95-ME
	    ->	Process = process('cmd.exe')
	    ;   Process = process('sh', '-i')
	    ),
	    new(P, Process),
	    get(M, directory, Dir),
	    send(P, directory, Dir),
	    new(B, emacs_process_buffer(P, '*shell*')),
	    send(B, directory, Dir),
	    send(B, start_process),
	    send(B, open, tab)
	).

better_shell('/bin/tcsh', '/bin/csh') :- !.
better_shell(Shell, Shell).

manual_entry(M, Spec:unix_manual_entry_for=name) :->
	"Lookup Unix manual entry"::
	send(M, has_processes),
	new(B, emacs_buffer(@nil, Spec)),
	send(B, (mode), man),
	send(B, open),
	send(B?editors?head, man, Spec).

gdb(M, Cmd:file) :->
	"Run Unix GDB on command"::
	send(M, has_processes),
	new(X, emacs_gdb_buffer(Cmd)),
	get(X, process, Process),
	(   Process \== @nil,
	    get(Process, status, inactive)
	->  get(M, directory, Dir),
	    send(Process, directory, Dir),
	    send(X, directory, Dir)
	;   true
	),
	send(X, start_process),
	send(X, open).

		 /*******************************
		 *	 WYSIWYG (ANNOTATE)	*
		 *******************************/

annotate(M) :->
	"Start annotation buffer from current buffer"::
	get(M, text_buffer, OB),
	get(OB, file, OFile),
	(   OFile == @nil
	->  NFile = @nil,
	    get(OB?name, append, '.ann', BufName)
	;   get(OFile?absolute_path, append, '.ann', NewName),
	    new(NFile, file(NewName)),
	    BufName = @default
	),
	(   send(NFile, exists)
	->  new(B, emacs_annotate_buffer(NFile, BufName))
	;   pce_catch_error(open_file,
			    new(B, emacs_annotate_buffer(NFile, BufName))),
	    send(B, contents, OB?contents)
	),
	send(B, (mode), annotate),
	send(B, open).


		 /*******************************
		 *	  MISCELLENEOUS		*
		 *******************************/

split_window(M) :->
	"Create another window for this buffer"::
	get(M, text_buffer, Buffer),
	get(Buffer, open, window, Frame),
	get(Frame, editor, NewEditor),
	get(M, caret, Here),
	send(NewEditor, caret, Here).

only_window(M) :->
	"Quit other windows on this buffer"::
	get(M, text_buffer, Buffer),
	get(M, editor, Editor),
	send(Buffer?editors, for_all,
	     if(@arg1 \== Editor,
		message(@arg1, quit))).


save_and_kill(M) :->
	"Save, kill window and buffer (return server)"::
	get(M, editor, Editor),
	get(M, text_buffer, TB),
	send(TB, save),
	(   get(Editor, hypered, server, _Server)
	->  send(TB, kill)
	;   send(M, quit)
	).


insert_date(M) :->
	"Insert current date"::
	new(Date, date),
	get(Date, year, Y),
	get(Date, month_name, @on, Mon),
	get(Date, day, D),
	send(M, insert, string('%s %s, %s', Mon, D, Y)).


insert_character_by_code(M, Code:code='0..') :->
	"Insert character by entering numeric value"::
	send(M, insert_self, @default, Code).


what_cursor_position(M) :->
	"Inform user on current position"::
	get(M, caret, Caret),
	get(M, length, Size),
	Proc is (100 * Caret) / Size,
	get(M, column, Caret, Col),
	send(M, report, inform, 'point=%d of %d(%d%%); column=%d',
	     Caret, Size, Proc, Col).


what_line(M) :->
	"Inform user on current line"::
	get(M, line_number, M?caret, CaretLine),
	send(M, report, inform, 'line %d', CaretLine).


goto_line(M, LineNo:int) :->
	"Goto given line-number"::
	send(M, point_to_top_of_file, LineNo).


count_lines_region(M) :->
	"Inform user on # lines in region"::
	get(M, region, tuple(Start, End)),
	get(M, line_number, Start, CaretLine),
	get(M, line_number, End, MarkLine),
	Lines is MarkLine - CaretLine,
	send(M, report, inform, 'Region has %d lines', Lines).


count_chars_region(M) :->
	"Inform user on # characters in region"::
	get(M, region, tuple(Start, End)),
	Chars is End - Start,
	send(M, report, inform, 'Region contains %d characters', Chars).


		 /*******************************
		 *	       HELP		*
		 *******************************/

:- pce_group(help).

help(_) :->
	"Display general help"::
	send(@emacs, help).


customise(_) :->
	"Display customisation help"::
	send(@emacs, customise).


%	->help_on_mode
%
%	See whether there is a file named <Source>.html, where <Source>
%	is the name of the source-file loaded to define the given mode.
%	If so, open it using the users' browser using www_open_url/1.

help_on_mode(M) :->
	"Provide mode-specific help"::
	(   get(M, class, Class),
	    get(Class, source, source_location(File, _)),
	    file_name_extension(FileBase, _, File),
	    absolute_file_name(FileBase,
			       [ extensions([html]),
				 access(read),
				 file_errors(fail)
			       ],
			       HTML)
	->  atom_concat('file:', HTML, URI),
	    www_open_url(URI)
	;   send(M, report, warning, 'No help on mode %s', M?name)
	).


show_key_bindings(M) :->
	"Display window with key-bindings"::
	auto_call(show_key_bindings(M)).


describe_function(M, CmdName:command=emacs_mode_command) :->
	"Give help on command"::
	get(M, send_method, CmdName, tuple(_, Impl)),
	auto_call(help(Impl)).

describe_key(M) :->
	"Read key and write its action"::
	send(M, report, status, 'Describe key: '),
	send(M, focus_function, '_describe_key').

'_describe_key'(M, Ev:event) :->
	"Handle \\C-hk keys"::
	(   get(M, attribute, key_prefix, Prefix)
	->  get(Ev, key, KeyName0),
	    atom_concat(Prefix, KeyName0, KeyName),
	    send(M, delete_attribute, key_prefix)
	;   get(Ev, key, KeyName)
	),
	get(M, bindings, Bindings),
	get(Bindings, function, KeyName, MethodName),
	(   prefix_method(MethodName)
	->  send(M, attribute, key_prefix, KeyName),
	    send(M, report, status, 'Describe key: %s', KeyName)
	;   send(M, focus_function, @nil),
	    (	get(M, send_method, MethodName, tuple(_, Impl))
	    ->  get(Impl, summary, Summary),
		send(M, report, inform, 'Key %s executes %s: "%s"',
		     KeyName, MethodName, Summary)
	    ;	send(M, report, inform, 'Key %s is not bound', KeyName)
	    )
	).

prefix_method(prefix).
prefix_method(prefix_or_cut).
prefix_method(prefix_or_copy).

key_binding_style(M, Style:key_binding_style) :->
	"Switch keyboard accelerator style"::
	send(@pce, key_binding_style, Style),
	send(M, report, status, 'Switched to %s style keys', Style).


		 /*******************************
		 *	       PCE		*
		 *******************************/

xpce_manual(_M) :->
	"Start XPCE manual"::
	auto_call(manpce).

manpce(_M, Class:'behaviour|class*') :->
	"Start XPCE manual on behaviour or class"::
	(   Class == @nil
	->  auto_call(manpce)
	;   auto_call(manpce(Class))
	).


editpce(M, Class:'behaviour|class*') :->
	"Edit XPCE class or class <->method"::
	(   Class == @nil
	->  send(M, report, warning,
		 'Enter "class" or "class->|<-|-selector"')
	;   auto_call(editpce(Class))
	).


tracepce(M, Method:behaviour*) :->
	"Put trace-point on XPCE class <->method"::
	(   Method == @nil
	->  send(M, report, warning,
		 'Enter "class->|<-|-selector"')
	;   auto_call(tracepce(Method))
	).


spypce(M, Method:behaviour*) :->
	"Put spy-point on XPCE class <->method"::
	(   Method == @nil
	->  send(M, report, warning,
		 'Enter "class->|<-|-selector"')
	;   auto_call(spypce(Method))
	).


		 /*******************************
		 *	       DROP		*
		 *******************************/

preview_drop(M, Obj:object*) :->
	"Preview the upcomming drop action"::
	(   Obj == @nil
	->  send(M, report, status, '')
	;   send(Obj, instance_of, file)
	->  send(M, report, status,
		 'Please drop to switch to %s', Obj?absolute_path)
	).


drop_files(M, Files:chain) :->
	"Drop chain of files"::
	send(Files, for_all, message(M, drop, create(file, @arg1))).


drop(M, Obj:object) :->
	"Import source-code from object"::
	(   send(Obj, instance_of, file)
	->  send(M, find_file, Obj)
	;   send(Obj, instance_of, chain)
	->  send(Obj, for_all,
		 if(message(@arg1, instance_of, object),
		    message(M, drop, @arg1)))
	).

:- emacs_end_mode.


		 /*******************************
		 *	      FRAGMENT		*
		 *******************************/

:- pce_begin_class(emacs_colour_fragment, fragment,
		   "Provide colourised region").

variable(severity, {status,warning,error} := status, both, "Message severity").
variable(message,  string*,	     both, "Message displayed").
variable(popup,    popup*,	     both, "Associated popup menu").
variable(context,  any*,	     both, "Popup context argument").

identify(F) :->
	(   get(F, message, Msg),
	    Msg \== @nil
	->  get(F, severity, Severity),
	    (	Severity == status
	    ->	send(F?text_buffer, report, status, Msg)
	    ;	send(F?text_buffer, report, inform,
		     string('%s: %s', F?severity, Msg))
	    )
	;   true
	).

:- pce_end_class.
