/*  $Id$

    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-prolog.org/projects/xpce/
    Copyright (C): 1985-2011, 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  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_buffer, []).
:- use_module(library(pce)).
:- require([ between/3
	   , default/3
	   , ignore/1
	   ]).

:- pce_begin_class(emacs_buffer(file, name), text_buffer).

variable(name,		  name,		get,  "Name of this buffer").
variable(directory,	  directory,	both, "Associated CWD").
variable(file,		  file*,	get,  "Associated file").
variable(prompt_reload,	  bool := @on,  both, "Prompt before reloading").
variable(mode,		  name,		get,  "Major mode of operation").
variable(time_stamp,	  date*,	get,  "Time-stamp for file").
variable(ensure_newline,  bool := @on,	both, "Add newline when done").
variable(ensure_no_whitespace_errors,
			  bool,		both, "Remove trailing whitespace when done").
variable(tab_width,	  int := 8,	both, "Width of a tab").
variable(auto_save_mode,  bool,		both, "Auto-save?").
variable(auto_save_count, number,	get,  "Auto-save at expiration").
variable(saved_caret,	  int,		both, "Saved caret on last quit").
variable(saved_fill,	  bool := @off,	both, "Saved fill_mode on quit").
variable(margin_width,	  '0..' := 0,	get,  "Margin width of editors").
variable(coloured_generation,
	 int := -1,
	 both,
	 "Last generation of the text-buffer that was coloured").
variable(xref_generation,
	 int := -1,
	 both,
	 "Last generation we analysed").

class_variable(undo_buffer_size,      int, 40000).
class_variable(ensure_no_whitespace_errors, bool, @on).
class_variable(newline_existing_file, {posix,dos,detect}, detect).
class_variable(newline_new_file,      {posix,dos},        posix).
:- if(current_prolog_flag(windows, true)).
class_variable(newline_new_file,      {posix,dos},        dos).
class_variable(unicode_encoding,      {utf8,unicode_le,unicode_be}, unicode_le).
:- else.
class_variable(newline_new_file,      {posix,dos},        posix).
class_variable(unicode_encoding,      {utf8,unicode_le,unicode_be}, utf8).
:- endif.

initialise(B, File:file*, Name:[name]) :->
	"Create from file and name"::
	send(B, send_super, initialise),
	send(B, saved_caret, 0),

	(   File == @nil
	->  send(B, undo_buffer_size, 0),
	    send(B, auto_save_mode, @off),
	    default(Name, '*scratch*', BufBaseName),
	    (	BufBaseName == '*scratch*'
	    ->	send(B, slot, mode, prolog),
		scratch_text(Text),
		send(B, insert, 0, Text),
		send(B, saved_caret, B?size)
	    ;	send(B, slot, mode, fundamental)
	    ),
	    send(B, directory, directory('.'))
	;   send(File, absolute_path),
	    get(File, base_name, FileBaseName),
	    default(Name, FileBaseName, BufBaseName),
	    send(B, file, File),
	    send(B, auto_save_mode, @on),
	    send(@emacs_base_names, append, FileBaseName, B),
	    send(B, determine_initial_mode),
	    (	object(@emacs_mark_list)
	    ->	ignore(send(@emacs_mark_list, loaded_buffer, B))
	    ;	true
	    )
	),

	send(B, init_mode_defaults),
	send(B, slot, auto_save_count, number(300)),
	send(B, name, BufBaseName).


unlink(B) :->
	"Remove from buffer-list and base_name table"::
	send(@emacs_buffers, delete, B?name),
	(   get(B, file, File), File \== @nil
	->  send(@emacs_base_names, delete, File?base_name, B)
	;   true
	),
	send(B, send_super, unlink).

report(B,
       Kind:kind={status,inform,progress,done,warning,error,fatal},
       Format:format=[char_array],
       Argv:any ...) :->
	"Report to associated editors"::
	get(B, editors, Editors),
	Message =.. [message, @arg1, report, Kind, Format | Argv],
	send(Editors, for_all, Message).


scratch_text('% This buffer is for notes you don\'t want to save.\n\c
	      % If you want to create a file, visit that file with C-x C-f,\n\c
	      % then enter the text in that file\'s own buffer.\n\n').

:- pce_global(@emacs_interpreter_regex,
	      new(regex('#!(\\S+)\\s'))).
:- pce_global(@emacs_mode_regex,	% -*- Mode -*-
					% -*- mode: Mode; ... -*-
	      new(regex('.*-\\*-\\s*([Mm]ode:\\s*(\\w+);.*-\\*-|(\\w+)\\s*-\\*-)'))).


% ->determine_initial_mode uses the following steps:
%
%   1. If the file is a loaded file, it is a Prolog file
%   2. The Emacs magic sequences -*- Mode -*- or -*- mode: Mode; ... -*-
%   3. Try @emacs_content_mode_list
%   4. Try #! interpreter (PrologScript)
%   5. Try the file-name

determine_initial_mode(B) :->
	"Determine initial mode"::
	(   get(B, file, File), File \== @nil,
	    get(File, name, FileName),
	    absolute_file_name(FileName, FilePath),
	    source_file(FilePath),
	    \+ source_file_property(FilePath, derived_from(_,_))
	->  send(B, slot, mode, prolog)
	;   send(@emacs_mode_regex, match, B),
	    member(Reg, [2,3]),
	    get(@emacs_mode_regex, register_value, B, Reg, Mode0),
	    get(Mode0?downcase, value, Mode),
	    get(@pce, convert, Mode, emacs_mode, _ModeObject)
	->  send(B, slot, mode, Mode)
	;   content_from_mode(B, Mode)
	->  send(B, slot, mode, Mode)
	;   (   send(@emacs_interpreter_regex, match, B),
		get(@emacs_interpreter_regex, register_value, B, 1, Match),
		To = @emacs_interpreter_mode_list
	    ;   get(B, file, File),
		get(File, base_name, Match),
		To = @emacs_mode_list
	    ),
	    get(To?members, find,
		message(@arg1?name, match, Match), Att)
	->  send(B, slot, mode, Att?value)
	;   send(B, slot, mode, @emacs_default_mode)
	),
	send(B, set_temp_file).

set_temp_file(B) :->
	"Clear ->prompt_reload if this is a temp file"::
	get(B, file, File),
	(   no_backup(File)
	->  send(B, prompt_reload, @off)
	;   true
	).


%%	content_from_mode(+Buffer, -Mode) is semidet.
%
%	Search Buffer with the patterns from @emacs_content_mode_list

content_from_mode(B, Mode) :-
	get(@emacs_content_mode_list?members, find,
	     message(@arg1?name?first, search, B,
		     0, @arg1?name?second),
	    Att),
	get(Att, value, Mode).


attach(B, E:editor) :->
	"A new editor is attached.  Prepare it"::
	get(B, editors, Editors),
	(   send(Editors, empty)
	->  get(B, saved_caret, Caret),
	    get(B, saved_fill, Fill),
	    get(B, tab_width, TabWidth)
	;   get(Editors?head, caret, Caret),
	    get(Editors?head, fill_mode, Fill),
	    get(Editors?head, tab_distance, TabWidth)
	),
	get(B, margin_width, MW),
	send(B, send_super, attach, E),
	send(E, caret, Caret),
	send(E, fill_mode, Fill),
	send(E, margin_width, MW),
	send(E, tab_distance, TabWidth).


detach(B, E:editor) :->
	"An editor is detached"::
	get(B, editors, Editors),
	(   get(Editors, size, 1)
	->  send(B, saved_caret, E?caret),
	    send(B, saved_fill, E?fill_mode)
	;   true
	),
	send(B, send_super, detach, E).


name(B, Name:name) :->
	"Rename buffer to name"::
	get(B, name, OldName),
	(   Name == OldName
	->  true
	;   (   get(@emacs_buffers, member, Name, _)
	    ->  between(2, 1000000, N),
		get(Name, append, string('<%d>', N), BufName),
	        \+ get(@emacs_buffers, member, BufName, _),
		!
	    ;   BufName = Name
	    ),
	    send(B, slot, name, BufName),
	    (	OldName \== @nil,
	        get(@emacs_buffers, member, OldName, DictItem)
	    ->  send(DictItem, key, BufName)
	    ;	send(@emacs_buffers, append, dict_item(BufName, @default, B))
	    ),
	    send(B, update_label),
	    send(B?editors, for_some, message(@arg1?frame, label, BufName))
	).


lookup(_Ctx, File:file*, Name:[name], Buffer:emacs_buffer) :<-
	"Lookup in name and file-table"::
	(   Name \== @default,
	    get(@emacs_buffers, member, Name, DictItem),
	    get(DictItem, object, Buffer)
	->  true
	;   File \== @nil,
	    get(@emacs_base_names, member, File?base_name, Chain),
	    get(Chain, find, message(@arg1?file, same, File), Buffer)
	;   File \== @nil,
	    send(File, exists),
	    send(File, check_object),
	    get(File, object, Buffer),
	    send(Buffer, instance_of, emacs_buffer),
	    get(Buffer, name, BufName),
	    send(Buffer, slot, name, ''),
	    send(Buffer, name, BufName),
	    send(Buffer, slot, file, File),
	    send(@emacs_base_names, append, File?base_name, Buffer),
	    send(Buffer, reset_undo),
	    send(Buffer, modified, @off),
	    send(Buffer, slot, time_stamp, File?time),
	    send(Buffer, loaded)
	).


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

file(B, File:file) :->
	"Switch to indicated file"::
	send(B, clear),
	(   send(directory(File?name), exists)
	->  send(File, error, open_file, read, 'is a directory')
	;   send(File, exists)
	->  get(B, newline_existing_file, OpenMode),
	    send(File, newline_mode, OpenMode),
	    ignore(send(B, insert_file, 0, File)),
	    send(B, reset_undo),
	    send(B, modified, @off),
	    send(B, slot, time_stamp, File?time)
	;   send(B, reset_undo),
	    send(B, modified, @off),
	    get(B, newline_new_file, Mode),
	    send(File, newline_mode, Mode)
	),
	send(B, slot, file, File),
	new(F2, file(File?absolute_path)),
	send(B, directory, F2?directory_name).


save(B, File:[file]) :->
	"->do_save and update time_stamp"::
	(   File == @default
	->  get(B, file, SaveFile),
	    (	SaveFile == @nil
	    ->	send(B, report, error, 'No file associated to this buffer'),
		fail
	    ;	true
	    )
	;   SaveFile = File,
	    (	get(B, file, OldFile), OldFile \== @nil
	    ->	send(@emacs_base_names, delete, OldFile?base_name, B)
	    ;	true
	    ),
	    send(File, absolute_path),
	    get(File, base_name, BaseName),
	    send(B, slot, file, File),
	    send(B, directory, File?directory_name),
	    send(B, name, BaseName),
	    send(@emacs_base_names, append, File?base_name, B)
	),
	(   get(B, ensure_newline, @on)
	->  send(B, complete_last_line)
	;   true
	),
	(   get(B, ensure_no_whitespace_errors, @on)
	->  send(B, fix_whitespace_errors)
	;   true
	),
	(   no_backup(SaveFile)
	->  true
	;   ignore(send(SaveFile, backup))
	),
	send(B, do_save, SaveFile),
	send(B, slot, time_stamp, SaveFile?time),
	(   object(@emacs_mark_list)
	->  ignore(send(@emacs_mark_list, saved_buffer, B))
	;   true
	).

no_backup(File) :-
	get(@emacs_no_backup_list, find,
	    message(@arg1, match, File?name), _).


complete_last_line(B) :->
	"Add \\n if needed"::
	get(B, size, Size),
	(   (   Size == 0
	    ;   get(B, character, Size-1, 10)
	    )
	->  true
	;   send(B, append, string('\n'))
	).

fix_whitespace_errors(B) :->
	"Remove trailing spaces and tabs from lines"::
	new(Count, number(0)),
	send(B, fix_trailing_space_errors, Count),
	send(B, fix_space_tab_errors, Count),
	(   get(Count, value, 0)
	->  true
	;   send(B, report, status,
		 'Fixed %d whitespace errors', Count)
	).

fix_trailing_space_errors(B, Count:number) :->
	"Remove trailing spaces and tabs from lines"::
	new(Re, regex('[ \t]+\n')),
	send(Re, for_all, B,
	     and(message(@arg1, replace, @arg2, '\n'),
		 message(Count, plus, 1))).

fix_space_tab_errors(B, Count:number) :->
	"Replace space+tab sequences"::
	new(Re, regex(' +\t')),
	send(Re, for_all, B,
	     and(message(B, fix_space_tab, Re),
		 message(Count, plus, 1))).

fix_space_tab(B, Re:regex) :->
	"Fix matched spaces followed by tab"::
	(   get(B?editors, head, E)
	->  get(Re, register_start, 0, Start),
	    get(Re, register_end, 0, End),
	    get(E, column, Start, StartCol),
	    get(E, column, End, EndCol),
	    get(E, tab_distance, TD),
	    tabs(StartCol, EndCol, TD, Tabs),
	    tab_atom(Tabs, Atom),
	    send(Re, replace, B, Atom)
	;   true
	).

tabs(SC, EC, _, 0) :-
	SC >= EC, !.
tabs(SC, EC, TD, N) :-
	SC2 is ((SC+TD)//TD)*TD,
	tabs(SC2, EC, TD, N0),
	N is N0+1.

tab_atom(N, Atom) :-
	length(List, N),
	maplist(=(0'\t), List),
	atom_codes(Atom, List).


do_save(B, SaveFile:file, Start:[int], Length:[int]) :->
	"Do the actual saving"::
	get(B, unicode_encoding, FallBackEncoding),
	(   pce_catch_error(io_error,
			    send_super(B, save, SaveFile, Start, Length))
	->  true
	;   get(SaveFile, name, FileName),
	    \+ access_file(FileName, write)
	->  send(B, report, error, 'Cannot write %s (permission denied)', FileName),
	    fail
	;   get(SaveFile, encoding, Encoding),
	    Encoding \== FallBackEncoding
	->  send(SaveFile, encoding, FallBackEncoding),
	    send(SaveFile, bom, @on),
	    send_super(B, save, SaveFile, Start, Length),
	    once(user_encoding(FallBackEncoding, UserEnc)),
	    send(B, report, warning,
		 'Could not save using default locale; saved using %s', UserEnc)
	;   send_super(B, save, SaveFile, Start, Length)
	).

user_encoding(utf8, 'UTF-8').
user_encoding(unicode_le, 'UTF-16 (little endian)').
user_encoding(unicode_be, 'UTF-16 (big endian)').
user_encoding(Enc, Enc).


write_region(B, File:file, Start:int, Length:int) :->
	"Wrote region to file (start, length)"::
	send(B, do_save, File, Start, Length).


save_if_modified(B, Confirm:[bool]) :->
	"Save if associated with a file and modified"::
	(   get(B, modified, @on),
	    get(B, file, File), File \== @nil
	->  (	(   Confirm == @off
		;   send(@display, confirm,
			 '%s is modified.  Save?', File?name)
		)
	    ->	send(B, save)
	    ;	fail
	    )
	;   true
	).


		 /*******************************
		 *	     AUTO-SAVE		*
		 *******************************/

check_auto_save(B) :->
	"Check whether to auto_save"::
	(   get(B, modified, @on),
	    get(B, auto_save_count, C),
	    send(C, minus, 1),
	    send(C, equal, 0),
	    get(B, auto_save_mode, @on)
	->  send(B, auto_save)
	;   true
	).


auto_save_file(B, F:file) :<-
	get(B, file, File), File \== @nil,
	get(File, backup_file_name, '#', Name),
	new(F, file(Name)).


auto_save(B) :->
	"Auto-save the buffer (when file)"::
	(   get(B, auto_save_file, File)
	->  send(B, report, status, 'Auto saving ...'),
	    send(@display, flush),
	    ignore(send(B, send_super, save, File, 0, B?size)),
	    send(B?auto_save_count, value, 300),
	    send(B, report, status, 'Auto saving ... done')
	;   true
	).


delete_auto_save_file(B) :->
	"Delete the autosave-file if present"::
	(   get(B, auto_save_file, File)
	->  ignore(send(File, remove))
	;   true
	).


		 /*******************************
		 *	      KILL		*
		 *******************************/

kill(B) :->
	"->save_if_modified and ->free"::
	(   get(B, modified, @off)
	->  send(B, free)
	;   get(B, file, File), File \== @nil, \+ get(B, size, 0)
	->  new(D, dialog('Kill modified buffer?')),
	    send(D, append, new(L, label(reporter))),
	    send(L, format, 'Buffer %s is modified', B?name),
	    send(D, append,
		 button('save & kill', message(D, return, save_and_kill))),
	    send(D, append,
		 button(kill, message(D, return, kill))),
	    send(D, append,
		 button(cancel, message(D, return, cancel))),
	    get(D, confirm_centered, Rval),
	    send(D, destroy),
	    (	Rval == save_and_kill
	    ->	send(B, save),
		send(B, free)
	    ;	Rval == kill
	    ->	send(B, free)
	    ;	fail
	    )
	;   send(B, free)
	).


revert(B) :->
	"Reload associated file"::
	get(B, file, File),
	(   File == @nil
	->  send(B, report, warning, 'No file'),
	    fail
	;   new(Carets, chain),
	    get(B, editors, Editors),
	    send(Editors, for_all, message(Carets, append, @arg1?caret)),
	    new(@emacs_reverting, object), % avoid trap
	    send(B, file, File),
	    send(Editors, for_all,
		 and(message(@arg1, caret, Carets?head),
		     message(Carets, delete_head))),
	    (	get(Editors, head, First)
	    ->	send(First?mode, auto_colourise_buffer)
	    ;	true
	    ),
	    free(@emacs_reverting),
	    send(B, report, status, 'Reloaded %s', File?absolute_path)
	).


		 /*******************************
		 *          NAME/LABEL		*
		 *******************************/

update_label(B) :->
	"Update label in the buffer-menu"::
	get(B, name, Name),
	(   Name \== @nil
	->  get(@emacs_buffers, member, Name, DictItem),
	    (   get(B, modified, @on)
	    ->  send(DictItem, label, string('%s\t**', Name)),
		new(EditorLabel, string('%s [modified]', Name))
	    ;   send(DictItem, label, Name),
		EditorLabel = Name
	    ),
	    send(B?editors, for_all,
		 message(@arg1, label, EditorLabel))
	;   true
	).


		 /*******************************
		 *	      MARGINS		*
		 *******************************/

margin_width(B, W:'0..') :->
	"Set width of the margin for associated editors"::
	send(B, slot, margin_width, W),
	send(B?editors, for_all,
	     message(@arg1, margin_width, W)).


		 /*******************************
		 *           MODIFIED		*
		 *******************************/

modified(B, Val:bool) :->
	"Check the file; mark buffer-menu"::
	send_super(B, modified, Val),
	(   Val == @on
	->  send(B, check_modified_file)
	;   send(B, delete_auto_save_file)
	),
	send(B, update_label).


check_modified_file(B, Frame:frame=[frame], Confirm:confirm=[bool]) :->
	"Check if file has been modified after buffer"::
	(   get(B, file, File),
	    File \== @nil,
	    send(File, exists),
	    get(B, time_stamp, Stamp),
	    get(File, time, FileStamp),
	    \+ send(Stamp, equal, FileStamp),
	    \+ object(@emacs_reverting)
	->  (   confirm_reload(B, Frame, Confirm, File)
	    ->	send(B, revert)
	    ;	true
	    )
	;   true
	).

confirm_reload(_, _, @off, _) :- !.
confirm_reload(B, _, @default, _) :-
	get(B, prompt_reload, @off), !,
	send(B, saved_caret, 0),
	send(B?editors, for_all, message(@arg1, caret, 0)).
confirm_reload(_, Frame, _, File) :-
	new(D, dialog('Modified file')),
	send(D, append,
	     label(title,  string('File %N was modified', File))),
	send(D, append,
	     button(reload_file, message(D, return, reload_file))),
	send(D, append,
	     button(edit_buffer, message(D, return, edit_buffer))),
	(   Frame \== @default
	->  EmacsFrame = Frame
	;   get(@emacs, current_frame, EmacsFrame)
	->  true
	;   EmacsFrame = @nil
	),
	(   EmacsFrame \== @default
	->  get(EmacsFrame?area, center, Position),
	    send(D, transient_for, EmacsFrame)
	;   Position = @default
	),
	get(D, confirm_centered, Position, RVal),
	send(D, destroy),
	RVal == reload_file.


		 /*******************************
		 *          OPEN WINDOW		*
		 *******************************/

open(B, How:[{here,tab,window}], Frame:emacs_frame) :<-
	"Create window for buffer"::
	(   How == window
	->  send(new(Frame, emacs_frame(B)), open)
	;   How == tab,
	    get(@emacs, current_frame, Frame)
	->  send(Frame, tab, B, @on),
	    send(Frame, expose)
	;   get(@emacs, current_frame, Frame)
	->  send(Frame, buffer, B),
	    send(Frame, expose)
	;   send(new(Frame, emacs_frame(B)), open)
	),
	send(B, check_modified_file, Frame).

open(B, How:[{here,tab,window}]) :->
	"Create window for buffer"::
	get(B, open, How, _).


		 /*******************************
		 *	      MODE		*
		 *******************************/

mode(B, Mode:name) :->
	"Switch to named mode"::
	(   get(B, mode, Mode)
	->  true
	;   send(B, slot, mode, Mode),
	    send(B, init_mode_defaults),
	    send(B?editors, for_some, message(@arg1, mode, Mode))
	).

init_mode_defaults(B) :->
	"Initialise defaults from the current mode"::
	get(B, mode, ModeName),
	atomic_list_concat([emacs_, ModeName, '_mode'], ClassName),
	get(@pce, convert, ClassName, class, ModeClass),
	(   copy_class_var(Name),
	    get(ModeClass, class_variable, Name, CV),
	    get(CV, value, Value),
	    send(B, Name, Value),
	    fail
	;   true
	).

copy_class_var(indent_tabs).
copy_class_var(tab_width).


		 /*******************************
		 *       LANGUAGE SUPPORT	*
		 *******************************/

%	emacs_buffer<-name_and_arity returns the name and arity if the
%	caret is in the functor of the term.  If the arity cannot be
%	determined, arity is returned as @default.

name_and_arity(TB, Pos:int, Tuple:tuple) :<-
	"Find name and arity of term at position"::
	(   get(TB, character, Pos, C0)
	;   get(TB, character, Pos-1, C0)
	),
	send(TB?syntax, has_syntax, C0, word), !,
	get(TB, scan, Pos, word, 0, start, P1),
	get(TB, scan, P1, word, 0, end, P2),
	get(TB, contents, P1, P2-P1, NameString),
	(   get(TB, character, P2, 0'()
	->  P4 is P2 + 1,
	    (	count_args(TB, P4, 0, 0, Arity)
	    ->	true
	    ;	Arity = @default
	    )
	;   Arity = 0
	),
	new(Tuple, tuple(NameString?value, Arity)).


count_args(TB, Here, _, _, _) :-
	get(TB, size, Here), !,
	fail.
count_args(_TB, _Here, 20, _, _) :-
	!,
	fail.
count_args(TB, Here, NAT, A0, A) :-
	get(TB, scan, Here, term, 1, EndTerm),
	get(TB, skip_comment, EndTerm, Next),
	(   get(TB, character, Next, 0'))
	->  A is A0 + 1
	;   get(TB, character, Next, 0',)
	->  A1 is A0 + 1,
	    count_args(TB, EndTerm, 0, A1, A)
	;   NNAT is NAT + 1,
	    count_args(TB, EndTerm, NNAT, A0, A)
	).

:- pce_end_class.


