/*  $Id$

    Part of SWI-Prolog

    Author:        Jan Wielemaker
    E-mail:        jan@swi.psy.uva.nl
    WWW:           http://www.swi-prolog.org
    Copyright (C): 1985-2002, University of 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(prolog_edit,
	  [ edit/1,			% +Spec
	    edit/0
	  ]).
:- use_module(library(lists), [append/3, member/2, nth1/3]).
:- use_module(library(make), [make/0]).
:- set_prolog_flag(generate_debug_info, false).

/** <module> Editor interface

This module implements the generic editor  interface. It consists of two
extensible parts with little  in  between.   The  first  part deals with
translating the input into source-location, and the second with starting
an editor.
*/

:- multifile
	locate/3,			% +Partial, -FullSpec, -Location
	locate/2,			% +FullSpec, -Location
	select_location/3,		% +Pairs, +Spec, -Location
	edit_source/1,			% +Location
	edit_command/2,			% +Editor, -Command
	load/0.				% provides load-hooks

%%	edit(+Spec)
%
%	Edit indicated object.

edit(Spec) :-
	var(Spec), !,
	throw(error(instantiation_error, _)).
edit(Spec) :-
	load_extensions,
	findall(Location-FullSpec,
		locate(Spec, FullSpec, Location),
		Pairs0),
	merge_locations(Pairs0, Pairs),
	do_select_location(Pairs, Spec, Location),
	do_edit_source(Location).

%%	edit
%
%	Edit associated or script file.  This is the Prolog file opened
%	by double-clicking or the file loaded using
%
%	==
%	% pl -s file.pl
%	==

edit :-
	'$option'(script_file, OsFiles),
	OsFiles = [OsFile], !,
	prolog_to_os_filename(File, OsFile),
	edit(file(File)).
edit :-
	current_prolog_flag(associated_file, File), !,
	edit(file(File)).
edit :-
	throw(error(context_error(edit, no_default_file), _)).


		 /*******************************
		 *	      LOCATE		*
		 *******************************/

%%	locate(+Spec, -FullSpec, -Location)

locate(Path, file(Path), [file(Path)]) :-
	atom(Path),
	exists_file(Path),
	\+ exists_directory(Path).
locate(FileBase, file(File), [file(File)]) :-
	atom(FileBase),
	absolute_file_name(FileBase,
			   [ file_type(prolog),
			     access(read),
			     file_errors(fail)
			   ],
			   File),
	\+ exists_directory(File).
locate(FileSpec, file(File), [file(File)]) :-
	catch(absolute_file_name(FileSpec,
				 [ file_type(prolog),
				   access(read),
				   file_errors(fail)
				 ],
				 File),
	      _, fail).
locate(FileBase, source_file(Path), [file(Path)]) :-
	atom(FileBase),
	source_file(Path),
	file_base_name(Path, File),
	file_name_extension(FileBase, pl, File).
locate(Name, FullSpec, Location) :-
	atom(Name),
	locate(Name/_, FullSpec, Location).
locate(Name/Arity, Module:Name/Arity, Location) :-
	locate(Module:Name/Arity, Location).
locate(Name//DCGArity, FullSpec, Location) :-
	(   integer(DCGArity)
	->  Arity is DCGArity+2,
	    locate(Name/Arity, FullSpec, Location)
	;   locate(Name/_, FullSpec, Location) % demand arity >= 2
	).
locate(Name/Arity, library(File), [file(PlPath)]) :-
	atom(Name),
	'$in_library'(Name, Arity, Path),
	(   absolute_file_name(library(.),
			       [ file_type(directory),
				 solutions(all)
			       ],
			       Dir),
	    atom_concat(Dir, File0, Path),
	    atom_concat(/, File, File0)
	->  absolute_file_name(Path,
			       [ file_type(prolog),
				 access(read),
				 file_errors(fail)
			       ],
			       PlPath)
	;   fail
	).
locate(Module:Name, Module:Name/Arity, Location) :-
	locate(Module:Name/Arity, Location).
locate(Module:Head, Module:Name/Arity, Location) :-
	callable(Head),
	functor(Head, Name, Arity),
	locate(Module:Name/Arity, Location).
locate(Spec, module(Spec), Location) :-
	locate(module(Spec), Location).
locate(Spec, Spec, Location) :-
	locate(Spec, Location).

%%	locate(+Spec, -Location)
%
%	Locate object from the specified location.

locate(file(File, line(Line)), [file(File), line(Line)]).
locate(file(File), [file(File)]).
locate(Module:Name/Arity, [file(File), line(Line)]) :-
	(   nonvar(Arity)
	->  functor(Head, Name, Arity)
	;   true
	),
	(   (   var(Module)
	    ;	var(Name)
	    )
	->  NonImport = true
	;   NonImport = false
	),
	current_predicate(Name, Module:Head),
	\+ (   NonImport == true,
	       Module \== system,
	       predicate_property(Module:Head, imported_from(_))
	   ),
	functor(Head, Name, Arity),	% bind arity
	predicate_property(Module:Head, file(File)),
	predicate_property(Module:Head, line_count(Line)).
locate(module(Module), [file(Path)|Rest]) :-
	atom(Module),
	module_property(Module, file(Path)),
	(   module_property(Module, line_count(Line))
	->  Rest = [line(Line)]
	;   Rest = []
	).
locate(clause(Ref), [file(File), line(Line)]) :-
	clause_property(Ref, file(File)),
	clause_property(Ref, line_count(Line)).
locate(clause(Ref, _PC), [file(File), line(Line)]) :- % TBD: use clause
	clause_property(Ref, file(File)),
	clause_property(Ref, line_count(Line)).


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

%%	do_edit_source(+Location)
%
%	Actually call the editor to edit Location, a list of Name(Value)
%	that contains file(File) and may contain line(Line). First the
%	multifile hook edit_source/1 is called. If this fails the system
%	checks for XPCE and the prolog-flag editor. If the latter is
%	built_in or pce_emacs, it will start PceEmacs.
%
%	Finally, it will get the editor to use from the prolog-flag
%	editor and use edit_command/2 to determine how this editor
%	should be called.

do_edit_source(Location) :-		% hook
	edit_source(Location), !.
do_edit_source(Location) :-		% PceEmacs
	current_prolog_flag(editor, Editor),
	pceemacs(Editor),
	current_prolog_flag(gui, true), !,
	memberchk(file(File), Location),
	(   memberchk(line(Line), Location)
	->  Goal = in_pce_thread(emacs(File:Line))
	;   Goal = in_pce_thread(emacs(File))
	),
	Goal.
do_edit_source(Location) :-		% External editor
	external_edit_command(Location, Command),
	print_message(informational, edit(waiting_for_editor)),
	(   catch(shell(Command), E,
		  (print_message(warning, E),
		   fail))
	->  print_message(informational, edit(make)),
	    make
	;   print_message(informational, edit(canceled))
	).

external_edit_command(Location, Command) :-
	memberchk(file(File), Location),
	memberchk(line(Line), Location),
	editor(Editor),
	file_base_name(Editor, EditorFile),
	file_name_extension(Base, _, EditorFile),
	edit_command(Base, Cmd),
	prolog_to_os_filename(File, OsFile),
	atom_codes(Cmd, S0),
	substitute("%e", Editor, S0, S1),
	substitute("%f", OsFile, S1, S2),
	substitute("%d", Line,   S2, S), !,
	atom_codes(Command, S).
external_edit_command(Location, Command) :-
	memberchk(file(File), Location),
	editor(Editor),
	file_base_name(Editor, EditorFile),
	file_name_extension(Base, _, EditorFile),
	edit_command(Base, Cmd),
	prolog_to_os_filename(File, OsFile),
	atom_codes(Cmd, S0),
	substitute("%e", Editor, S0, S1),
	substitute("%f", OsFile, S1, S),
	\+ substitute("%d", 1, S, _), !,
	atom_codes(Command, S).
external_edit_command(Location, Command) :-
	memberchk(file(File), Location),
	editor(Editor),
	atomic_list_concat(['"', Editor, '" "', File, '"'], Command).

pceemacs(pce_emacs).
pceemacs(built_in).

%%	editor(-Editor)
%
%	Determine the external editor to run.

editor(Editor) :-			% $EDITOR
	current_prolog_flag(editor, Editor),
	(   sub_atom(Editor, 0, _, _, $)
	->  sub_atom(Editor, 1, _, 0, Var),
	    catch(getenv(Var, Editor), _, fail), !
	;   Editor == default
	->  catch(getenv('EDITOR', Editor), _, fail), !
	;   \+ pceemacs(Editor)
	->  !
	).
editor(Editor) :-			% User defaults
	getenv('EDITOR', Editor), !.
editor(vi) :-				% Platform defaults
	current_prolog_flag(unix, true), !.
editor(notepad) :-
	current_prolog_flag(windows, true), !.
editor(_) :-				% No luck
	throw(error(existence_error(editor), _)).

%%	edit_command(+Editor, -Command)
%
%	This predicate should specify the shell-command called to invoke
%	the user's editor. The following substitutions will be made:
%
%		| %e | Path name of the editor		  |
%		| %f | Path name of the file to be edited |
%		| %d | Line number of the target	  |


edit_command(vi,	  '%e +%d ''%f''').
edit_command(vi,	  '%e ''%f''').
edit_command(emacs,	  '%e +%d ''%f''').
edit_command(emacs,	  '%e ''%f''').
edit_command(notepad,     '"%e" "%f"').
edit_command(wordpad,     '"%e" "%f"').
edit_command(uedit32,     '%e "%f/%d/0"').	% ultraedit (www.ultraedit.com)
edit_command(edit,        '%e %f:%d').		% private stuff
edit_command(edit,        '%e %f').

edit_command(emacsclient, Command) :- edit_command(emacs, Command).
edit_command(vim,         Command) :- edit_command(vi,    Command).

substitute(From, ToAtom, Old, New) :-
	name(ToAtom, To),
	append(Pre, S0, Old),
	append(From, Post, S0) ->
	append(Pre, To, S1),
	append(S1, Post, New), !.
substitute(_, _, Old, Old).


		 /*******************************
		 *	      SELECT		*
		 *******************************/

merge_locations(Pairs0, Pairs) :-
	keysort(Pairs0, Pairs1),
	merge_locations2(Pairs1, Pairs).

merge_locations2([], []).
merge_locations2([H0|T0], [H|T]) :-
	remove_same_location(H0, H, T0, T1),
	merge_locations2(T1, T).

remove_same_location(Pair0, H, [Pair1|T0], L) :-
	merge_locations(Pair0, Pair1, Pair2), !,
	remove_same_location(Pair2, H, T0, L).
remove_same_location(H, H, L, L).

merge_locations(Loc1-Spec1, Loc2-Spec2, Loc-Spec) :-
	same_location(Loc1, Loc2, Loc), !,
	(   merge_specs(Spec1, Spec2, Spec)
	;   merge_specs(Spec2, Spec1, Spec)
	;   Spec = Spec1
	), !.
merge_locations([file(X)]-_, Loc-Spec, Loc-Spec) :-
	memberchk(file(X), Loc),
	memberchk(line(_), Loc).

same_location(L, L, L).
same_location([file(F1)], [file(F2)], [file(F)]) :-
	best_same_file(F1, F2, F).
same_location([file(F1),line(L)], [file(F2)], [file(F),line(L)]) :-
	best_same_file(F1, F2, F).
same_location([file(F1)], [file(F2),line(L)], [file(F),line(L)]) :-
	best_same_file(F1, F2, F).

best_same_file(F1, F2, F) :-
	catch(same_file(F1, F2), _, fail), !,
	atom_length(F1, L1),
	atom_length(F2, L2),
	(   L1 < L2
	->  F = F1
	;   F = F2
	).

merge_specs(source_file(Path), _, source_file(Path)).

%%	select_location(+Pairs, +UserSpec, -Location)

do_select_location(Pairs, Spec, Location) :-
	select_location(Pairs, Spec, Location), !, 		% HOOK
	Location \== [].
do_select_location([], Spec, _) :- !,
	print_message(warning, edit(not_found(Spec))),
	fail.
do_select_location([Location-_Spec], _, Location) :- !.
do_select_location(Pairs, _, Location) :-
	print_message(help, edit(select)),
	list_pairs(Pairs, 0, N),
	print_message(help, edit(prompt_select)),
	read_number(N, I),
	nth1(I, Pairs, Location-_Spec), !.

list_pairs([], N, N).
list_pairs([H|T], N0, N) :-
	NN is N0 + 1,
	list_pair(H, NN),
	list_pairs(T, NN, N).

list_pair(Pair, N) :-
	print_message(help, edit(target(Pair, N))).


read_number(Max, X) :-
	Max < 10, !,
	get_single_char(C),
	between(0'0, 0'9, C),
	X is C - 0'0.
read_number(_, X) :-
	read_line(Chars),
	name(X, Chars),
	integer(X).

read_line(Chars) :-
	get0(user_input, C0),
	read_line(C0, Chars).

read_line(10, []) :- !.
read_line(-1, []) :- !.
read_line(C, [C|T]) :-
	get0(user_input, C1),
	read_line(C1, T).


		 /*******************************
		 *	       MESSAGES		*
		 *******************************/

:- multifile
	prolog:message/3.

prolog:message(edit(not_found(Spec))) -->
	[ 'Cannot find anything to edit from "~p"'-[Spec] ],
	(   { atom(Spec) }
	->  [ nl, '    Use edit(file(~q)) to create a new file'-[Spec] ]
	;   []
	).
prolog:message(edit(select)) -->
	[ 'Please select item to edit:', nl, nl ].
prolog:message(edit(prompt_select)) -->
	[ nl, 'Your choice? ', flush ].
prolog:message(edit(target(Location-Spec, N))) -->
	[ '~t~d~3| '-[N]],
	edit_specifier(Spec),
	[ '~t~32|' ],
	edit_location(Location).
prolog:message(edit(waiting_for_editor)) -->
	[ 'Waiting for editor ... ', flush ].
prolog:message(edit(make)) -->
	[ 'Running make to reload modified files' ].
prolog:message(edit(canceled)) -->
	[ 'Editor returned failure; skipped make/0 to reload files' ].

edit_specifier(Module:Name/Arity) -->
	[ '~w:~w/~w'-[Module, Name, Arity] ].
edit_specifier(file(_Path)) -->
	[ '<file>' ].
edit_specifier(source_file(_Path)) -->
	[ '<loaded file>' ].
edit_specifier(Term) -->
	[ '~p'-[Term] ].

edit_location(Location) -->
	{ memberchk(file(File), Location),
	  memberchk(line(Line), Location),
	  short_filename(File, Spec)
	}, !,
	[ '~q:~d'-[Spec, Line] ].
edit_location(Location) -->
	{ memberchk(file(File), Location),
	  short_filename(File, Spec)
	}, !,
	[ '~q'-[Spec] ].

short_filename(Path, Spec) :-
	absolute_file_name('', Here),
	atom_concat(Here, Local0, Path), !,
	remove_leading_slash(Local0, Spec).
short_filename(Path, Spec) :-
	findall(LenAlias, aliased_path(Path, LenAlias), Keyed),
	keysort(Keyed, [_-Spec|_]).
short_filename(Path, Path).

aliased_path(Path, Len-Spec) :-
	setof(Alias, file_alias_path(Alias), Aliases),
	member(Alias, Aliases),
	Alias \== autoload,		% confusing and covered by something else
	Term =.. [Alias, '.'],
	absolute_file_name(Term,
			   [ file_type(directory),
			     file_errors(fail),
			     solutions(all)
			   ], Prefix),
	atom_concat(Prefix, Local0, Path),
	remove_leading_slash(Local0, Local),
	atom_length(Local, Len),
	Spec =.. [Alias, Local].

file_alias_path(Alias) :-
	user:file_search_path(Alias, _).

remove_leading_slash(Path, Local) :-
	atom_concat(/, Local, Path), !.
remove_leading_slash(Path, Path).


		 /*******************************
		 *	  LOAD EXTENSIONS	*
		 *******************************/

load_extensions :-
	load,
	fail.
load_extensions.

:- load_extensions.
