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

    Author:        Jan Wielemaker and Anjo Anjewierden
    E-mail:        J.Wielemaker@vu.nl
    WWW:           http://www.swi-prolog.org/projects/xpce/
    Copyright (c)  1996-2014, University of Amsterdam
                              VU University Amsterdam
    All rights reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions
    are met:

    1. Redistributions of source code must retain the above copyright
       notice, this list of conditions and the following disclaimer.

    2. Redistributions in binary form must reproduce the above copyright
       notice, this list of conditions and the following disclaimer in
       the documentation and/or other materials provided with the
       distribution.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
    POSSIBILITY OF SUCH DAMAGE.
*/

:- module(pui_help,
          [ prolog_help/0,
            prolog_help/1,
            prolog_apropos/1,
            prolog_help_topic/1,
            prolog_explain/1
          ]).

/** <module> XPCE-based graphical frontend for online help

This module is normally hooked into help/1 by the module swi_hooks.pl.
*/

:- use_module(library(pce)).
:- use_module(library(persistent_frame)).
:- pce_autoload(toc_window, library(pce_toc)).
:- use_module(library(helpidx)).
:- require([ start_emacs/0
           , absolute_file_name/3
           , append/3
           , atom_length/2
           , between/3
           , chain_list/2
           , atomic_list_concat/2
           , atomic_list_concat/3
           , default/3
           , explain/2
           , forall/2
           , ignore/1
           , maplist/3
           , member/2
           , send_list/3
           , term_to_atom/2
           , (volatile)/1
           ]).

resource(manual,        image,  image('16x16/manual.xpm')).
resource(book,          image,  image('16x16/book2.xpm')).
resource(cfunction,     image,  image('16x16/funcdoc.xpm')).
resource(predicate,     image,  image('16x16/preddoc.xpm')).


                 /*******************************
                 *            TOPLEVEL          *
                 *******************************/

%!  prolog_help is det.
%
%   Open SWI-Prolog graphical reference manual.

prolog_help :-
    section(S, 'Getting started quickly', _, _),
    atomic_list_concat(S, -, Id),
    term_to_atom(Spec, Id),
    prolog_help(Spec).


%!  prolog_help(+Topic) is semidet.
%
%   Open SWI-Prolog graphical reference manual   on  Topic. Fails if
%   Topic is not in the manual.

prolog_help(Topic) :-
    in_pce_thread(prolog_help_sync(Topic)).

prolog_help_sync(Topic) :-
    help_atom(Topic, Atom),
    (   atomic(Atom)
    ->  once(manual_range(Atom, _)),
        send(@pui_help_window, give_help, Atom)
    ;   get(@pui_help_window, member, pui_editor, Editor),
        send(Editor, clear),
        forall(member(A, Atom),
               send(@pui_help_window, give_help, A, @off, @off)),
        send(Editor, home)
    ),
    send(@pui_help_window?frame, expose).


%!  prolog_apropos(+Keyword) is det.
%
%   Do a keyword search on the manual through the object summaries.

prolog_apropos(Keywd) :-
    in_pce_thread(prolog_apropos_sync(Keywd)).

prolog_apropos_sync(Keywd) :-
    send(@pui_help_window, apropos, Keywd),
    send(@pui_help_window?frame, expose).

%!  prolog_explain(+Term) is det.
%
%   Provide all information Prolog knows about Term.


prolog_explain(Term) :-
    in_pce_thread(prolog_explain_sync(Term)).

prolog_explain_sync(Term) :-
    term_to_atom(Term, Atom),
    send(@pui_help_window, explain, Atom),
    send(@pui_help_window?frame, expose).


                 /*******************************
                 *          MAIN WINDOW         *
                 *******************************/

:- pce_global(@pui_help_window, make_pui_help_window).

make_pui_help_window(W) :-
    send(new(W, pui_manual), open).

:- pce_begin_class(pui_manual, persistent_frame,
                   "Frame for Prolog help").

variable(history, chain, get, "History list").

initialise(F) :->
    send(F, send_super, initialise, 'SWI-Prolog help'),
    send(F, append, new(MBD, dialog)),
    send(MBD, name, menu_bar_dialog),
    send(new(E, pui_editor), below, MBD),
    send(new(dialog), below, E),
    send(F, slot, history, new(chain)),
    send(F, fill_menu_bar),
    send(F, fill_dialog),
    send(F, table_of_contents).

give_help(F, What:name, Clear:[bool], ScrollToStart:[bool]) :->
    get(F, display, Display),
    send(Display, busy_cursor),
    get(F, member, pui_editor, Editor),
    ignore(send(Editor, give_help, What, Clear, ScrollToStart)),
    send(Display, busy_cursor, @nil).

apropos(F, Atom:name) :->
    "Search summary descriptions"::
    send(F, add_history, string('apropos:%s', Atom)),
    get(F, member, pui_editor, Editor),
    give_apropos(Editor, Atom).

explain(F, Text:name) :->
    "Explain what we know about of term"::
    send(F, add_history, string('explain:%s', Text)),
    get(F, member, pui_editor, Editor),
    send(Editor, editable, @on),
    do_explain_text(Editor, Text),
    send(Editor, editable, @off).

go(F, What:name) :->
    "Handle Go menu (history)"::
    (   sub_atom(What, 0, _, A, 'apropos:')
    ->  sub_atom(What, _, A, 0, For),
        send(F, apropos, For)
    ;   sub_atom(What, 0, _, A, 'explain:')
    ->  sub_atom(What, _, A, 0, For),
        send(F, explain, For)
    ;   send(F, give_help, What)
    ).

about(_F) :->
    send(@display, inform,
         '%s\n\n%s\n%s',
         'SWI-Prolog manual browser version 3.0',
         'Jan Wielemaker',
         'E-mail: jan@swi-prolog.org').

fill_menu_bar(F) :->
    get(F, member, menu_bar_dialog, D),
    send(D, gap, size(0, 0)),
    send(D, pen, 0),
                                    % the menu-bar
    send(D, append, new(MB, menu_bar)),
    send(MB, append, new(File, popup(file))),
    send(MB, append, new(Settings, popup(settings))),
    send(MB, append, new(Hist, popup(go, message(F, go, @arg1)))),
    send(MB, append, new(Help, popup(help))),

    send_list(File, append,
              [ menu_item(exit,
                          message(F, destroy))
              ]),

    send_list(Settings, append,
              [ menu_item('User init file ...',
                          message(F, edit_preferences, prolog))
              ]),

    send(Hist, update_message,
         message(F, fill_history_popup, @receiver)),

    send_list(Help, append,
              [ menu_item(about,
                          message(F, about),
                          end_group := @on),

                menu_item('Package documentation ...',
                          message(F, open_package_doc)),
                menu_item('SWI-Prolog WWW home (on www) ...',
                          message(F, open_url, pl)),
                menu_item('SWI-Prolog FAQ (on www) ...',
                          message(F, open_url, pl_faq)),
                menu_item('SWI-Prolog Quick Start (on www) ...',
                          message(F, open_url, pl_quick)),
                menu_item('SWI-Prolog Manual (on www) ...',
                          message(F, open_url, pl_man)),
                menu_item('SWI-Prolog Mailing list (on www) ...',
                          message(F, open_url, pl_mail)),
                menu_item('SWI-Prolog Download (on www) ...',
                          message(F, open_url, pl_download),
                          end_group := @on),

                menu_item('XPCE (GUI) Manual ...',
                          message(@prolog, manpce)),
                menu_item('XPCE User Guide (on www) ...',
                          message(F, open_url, xpce_man),
                          end_group := @on),

                menu_item('SWI-Prolog bug report (on www) ...',
                          message(F, open_url, pl_bugs)),
                gap,
                menu_item('Donate to SWI-Prolog (on www) ...',
                          message(F, open_url, pl_donate))

              ]).


open_url(F, Id) :->
    "Open WWW browser on url with given id"::
    send(F, report, progress, 'Starting browser ...'),
    Spec =.. [Id, '.'],
    www_open_url(Spec),
    send(F, report, done).


open_package_doc(_F) :->
    (   absolute_file_name(swi('doc/packages/index.html'),
                           [ access(read),
                             file_errors(fail)
                           ],
                           Page)
    ->  atom_concat('file://', Page, URL),
        www_open_url(URL)
    ;   send(@display, inform,
             'Package documentation is not installed.  You may\n \c
                  wish to view it on http://www.swi-prolog.org')
    ).


edit_preferences(_F, Which:name) :->
    "Edit preferences"::
    prolog_edit_preferences(Which).


fill_dialog(F) :->
    get(F, member, dialog, D),
                                    % the other items
    new(TI, text_item(on, '')),
    setof(Name, prolog_help_topic(Name), Names),
    chain_list(ValueSet, Names),
    send(TI, value_set, ValueSet),
    send(D, append, button(help,
                           message(F, give_help, TI?selection))),
    send(D, append, button(search,
                           message(F, apropos, TI?selection)),
         right),
    send(D, append, button(explain,
                           message(F, explain, TI?selection)),
         right),
    send(D, append, TI, right),
    send(D, append, label(reporter), right),
    send(D, default_button, help).

prolog_help_topic(Name) :-
    predicate(Name, _, _, _, _).
prolog_help_topic(Name) :-
    function(Name, _, _).


add_history(F, What:name) :->
    get(F, history, Chain),
    send(Chain, delete_all, What),
    send(Chain, prepend, What).

fill_history_popup(F, P:popup) :->
    send(P, clear),
    send(F?history, for_all,
         message(@prolog, append_history_menu_item, P, @arg1)).

append_history_menu_item(Popup, What) :-
    atom_codes(What, S),
    phrase(section(Section), S),
    section(Section, Title, _, _),
    !,
    send(Popup, append, menu_item(What, @default, Title)).
append_history_menu_item(Popup, What) :-
    sub_atom(What, 0, _, A, 'apropos:'),
    !,
    sub_atom(What, _, A, 0, For),
    send(Popup, append, menu_item(What, @default,
                                  string('Search %s', For))).
append_history_menu_item(Popup, What) :-
    sub_atom(What, 0, _, A, 'explain:'),
    !,
    sub_atom(What, _, A, 0, For),
    send(Popup, append, menu_item(What, @default,
                                  string('Explain %s', For))).
append_history_menu_item(Popup, What) :-
    send(Popup, append, menu_item(What, @default, What)).

table_of_contents(F) :->
    (   get(F, member, pui_toc, _)
    ->  true
    ;   get(F, member, pui_editor, Editor),
        new(PT, pui_toc),
        send(PT, left, Editor?tile),
        send(PT, expand_node, manual)
    ).

:- pce_end_class.


                 /*******************************
                 *        THE HELP EDITOR       *
                 *******************************/

:- pce_begin_class(pui_editor, view,
                   "Editor for PUI help text").

variable(displayed_ranges, prolog, get, "Currently displayed ranges").

initialise(V) :->
    send_super(V, initialise),
    get(V, editor, Editor),
    send(V, setup_isearch),
    send(Editor?text_cursor, displayed, @off),
    get(Editor, image, Image),
    send(Editor, style, button,    style(bold := @on,
                                         colour := forestgreen)),
    send(Editor, style, title,     style(font := bold)),
    send(Editor, style, section,   style(font := boldlarge)),
    send(Editor, style, bold,      style(bold := @on)),
    send(Editor, style, underline, style(underline := @on)),
    send(Image, wrap, none),
    send(Image, recogniser,
         click_gesture(left, '', single,
                       and(message(V?display, busy_cursor),
                           if(message(V, jump, ?(Image, index, @event))),
                           message(V?display, busy_cursor, @nil)))).

setup_isearch(V) :->
    get(V, editor, Editor),
    send(Editor, send_method,
         send_method(insert_self, vector('[int]', '[char]'),
                     if(@receiver?editable == @on,
                        message(@receiver, send_class, insert_self,
                                @arg1, @arg2),
                        and(message(@receiver, isearch_forward),
                            message(@receiver, '_start_isearch',@arg2))))),
    send(V?editor, send_method,
         send_method('_isearch', vector(event_id),
                     if(@arg1 == 13,
                        and(message(@receiver, caret,
                                    @receiver?selection_end),
                            message(@receiver, '_changed_region',
                                    @receiver?selection_start,
                                    @receiver?selection_end),
                            message(@receiver, focus_function, @nil)),
                        message(@receiver, send_class, '_isearch',
                                @arg1)))).


displayed_ranges(V, Displayed:prolog) :->
    send(V, slot, displayed_ranges, Displayed),
    (   get(V?frame, member, pui_toc, TocTree)
    ->  send(TocTree, select_range, Displayed)
    ;   true
    ).

clear(V) :->
    send_super(V, clear),
    send(V, displayed_ranges, []).

give_help(V, What:name,
     Clear:[bool], ScrollToStart:[bool],
     FailOnError:fail_on_error=[bool]) :->
    "Display help message"::
    send(V, editable, @on),
    (   manual_range(What, Ranges)
    ->  (   Clear == @off
        ->  true
        ;   send(V, clear)
        ),
        manual_file(ManFile),
        new(F, file(ManFile, binary)),
        get(V, caret, Start),
        send(F, open, read),
        append_ranges(V, F, Ranges),
        send(F, close),
        get(V, caret, End),
        send(V, markup, Start, End),
        get(V, text_buffer, TB),
        mark_titles(TB, Start, End),
        send(V?frame, add_history, What),
        (   ScrollToStart \== @off
        ->  send(V, caret, Start),
            send(V, scroll_to, Start)
        ;   true
        ),
        send(V, displayed_ranges, Ranges)
    ;   FailOnError == @on
    ->  fail
    ;   (   Clear == @off
        ->  true
        ;   send(V, clear)
        ),
        send(V, format, 'Could not find help for "%s".\n', What),
        send(V, caret, 0)
    ),
    send(V, editable, @off).

%!  append_ranges(+View, +File, +Ranges) is det.
%
%   Note that the file is opened in binary mode to allow seeking. We
%   must delete \r from the input   to  compensate for Windows cr/lf
%   line ends. This is all ok as long  as the contents of the manual
%   file is ISO Latin 1.

append_ranges(V, F, [H|T]) :-
    !,
    append_ranges(V, F, H),
    append_ranges(V, F, T).
append_ranges(_, _, []) :- !.
append_ranges(V, F, FromLine-ToLine) :-
    line_start(FromLine, From),
    line_start(ToLine, To),
    send(F, seek, From),
    get(F, read, To-From, Text),
    send(Text, translate, 13, @nil),
    send(V, insert, Text),
    send(V, insert, @pui_ff),
    send(V, newline).

home(V, Where:[int]) :->
    default(Where, 0, Caret),
    send(V, scroll_to, Caret),
    send(V, caret, Caret).


                 /*******************************
                 *             TITLES           *
                 *******************************/

:- pce_global(@pui_ff, new(string('\f'))).

mark_titles(_, From, To) :-
    From >= To,
    !.
mark_titles(TB, From, To) :-
    get(TB, character, From, 12),
    !,
    send(TB, delete, From, 1),
    (   between(1, 3, L),
        get(TB, scan, From, line, L, start, I2),
        get(TB, character, I2, C2),
        C2 > 32
    ->  mark_titles(TB, I2, To)
    ;   true
    ).
mark_titles(TB, From, To) :-
    get(TB, scan, From, line, 0, end, EL),
%   Len is EL - From,
%!  new(_, fragment(TB, From, Len, title)),
    (   get(TB, find, EL, @pui_ff, 1, start, Idx)
    ->  mark_titles(TB, Idx, To)
    ;   true
    ).

                 /*******************************
                 *     CROSS-REFERENCE LINKS    *
                 *******************************/

:- volatile
    regex_db/2.
:- dynamic
    regex_db/2.

:- pce_global(@ul_regex, new(regex('.\b(.)'))).

%       Bug: send(regex('((.)x\\2)+$'), match, axbaxa) succeeds!
%       Bug reproduces in TCL.  Submitted to Tcl bugtracking system.

regex(bold,       '((.)\b\\2)+').
regex(underline,  '(_\b(.))+').
regex(predicate,  '(\\w+)/(\\d+)').
regex(predicate2, '\\w+/\\[\\d+[-,]\\d+\\]').
regex(function,   'PL_\\w+\\(\\)').
regex(section,    '([Ss]ection|[Cc]hapter)\\s+\\d+(\\.\\d+)*').
regex(location,   '([a-zA-Z]:)?(/[-_a-zA-Z0-9~+=.]*)+:\\d+').
regex(clause,     '\\d+-th clause of \\w+:[^\n]+/\\d+').
regex(method,     '\\w+(->|<-)\\w+').

regex_object(Id, Re) :-
    regex_db(Id, Re),
    !.
regex_object(Id, Re) :-
    regex(Id, Pattern),
    new(Re, regex(Pattern)),
    send(Re, compile, @on),
    send(Re, lock_object, @on),
    assert(regex_db(Id, Re)).

markup(V, From:int, To:int) :->
    get(V, text_buffer, TB),
    (   regex(Id, _),
        regex_object(Id, Re),
        send(Re, for_all, TB,
             message(V, mark_fragment, @arg1),
             From, To),
        fail
    ;   true
    ).

mark_fragment(V, Re:regex) :->
    (   documented(Re, V, Type)
    ->  get(Re, register_start, Start),
        get(Re, register_size, Len),
        new(_F, fragment(V, Start, Len, Type))
    ;   true
    ).

font_style(bold, bold).
font_style(underline, underline).

documented(Re, V, button) :-
    regex_db(predicate, Re),
    !,
    get(V, text_buffer, TB),
    get(Re, register_value, TB, 1, name, Name),
    get(Re, register_value, TB, 2, int,  Arity),
    predicate(Name, Arity, _, _, _).
documented(Re, V, Style) :-
    regex_db(Style0, Re),
    font_style(Style0, Style),
    !,
    get(V, text_buffer, TB),
    get(Re, register_value, TB, 0, String),
    send(@ul_regex, for_all, String,
         message(@ul_regex, replace, String, '\\1')),
    send(Re, replace, TB, String).
documented(_, _, button).

jump(V, Caret:[int]) :->
    "Jump to current fragment"::
    (   Caret == @default
    ->  get(V, caret, C)
    ;   C = Caret
    ),
    get(V, find_fragment, message(@arg1, overlap, C), Fragment),
    get(Fragment, string, JumpTo),
    (   send(V, give_help, JumpTo, fail_on_error := @on)
    ->  true
    ;   get(JumpTo, value, Atom),
        try_to_edit(Atom)
    ).

insert_section(V, Text) :->
    get(V, caret, Caret),
    (   Caret == 0
    ->  Begin = Caret
    ;   send(V, newline, 2),
        get(V, caret, Begin)
    ),
    send(V, insert, Text),
    get(V, caret, NewCaret),
    new(_, fragment(V, Begin, NewCaret-Begin, section)),
    send(V, newline, 2).

drop(V, Id:name) :->
    send(V, give_help, Id, fail_on_error := @on).

:- pce_end_class.


                 /*******************************
                 *       MANUAL UTILITIES       *
                 *******************************/

%!  manual_file(-File)
%
%   Find the database file of the manual.  If the manual cannot be
%   found, display an error message.

manual_file(File) :-
    absolute_file_name(library('MANUAL'), File,
                       [access(read)]),
    !.
manual_file(_File) :-
    send(@nil, report, error, 'Can''t find manual database MANUAL'),
    fail.

%!  line_start(Line, Start) is det.
%
%   True if Start is the byte position at which Line starts.

:- dynamic
    start_of_line/2.

line_start(Line, Start) :-
    start_of_line(Line, Start),
    !.
line_start(Line, Start) :-
    line_index,
    start_of_line(Line, Start).


%!  line_index
%
%   Create index holding the byte positions for the line starts

line_index :-
    start_of_line(_,_),
    !.
line_index :-
    manual_file(File),
    open(File, read, Stream, [type(binary)]),
    call_cleanup(line_index(Stream, 1), close(Stream)).

line_index(Stream, LineNo) :-
    byte_count(Stream, ByteNo),
    assert(start_of_line(LineNo, ByteNo)),
    (   at_end_of_stream(Stream)
    ->  true
    ;   LineNo2 is LineNo+1,
        skip(Stream, 10),
        line_index(Stream, LineNo2)
    ).


                 /*******************************
                 *     ATOMIC SPECIFICATIONS    *
                 *******************************/

%!  manual_range(+What, -Range:From-To) is nondet.
%
%   Find the character range for the given help topic, which is of
%   the form
%
%           * name/arity
%           * function()
%           * n.m..

manual_range(What, Ranges) :-
    atom_codes(What, S),
    phrase(manual_spec(Ranges), S).

manual_spec(From-To) -->
    name_and_arity(Name, SArity),
    { predicate(Name, Arity, _Summary, From, To),
      (   var(SArity)
      ->  var(Arity)
      ;   SArity = Arity
      )
    }.
manual_spec(From-To) -->
    pl_function(Name),
    !,
    { function(Name, From, To)
    }.
manual_spec(From-To) -->
    (   "section",
        blanks
    ->  {true}
    ;   {true}
    ),
    section(SN),
    { section(SN, _Summary, From, To)
    }.
manual_spec(Ranges) -->
    word(S),
    { atom_codes(Name, S),
      findall(From-To, predicate(Name, _, _, From, To), Ranges),
      Ranges \== []
    }.
manual_spec(Ranges) -->
    [C1|CT],
    "/[",
    word(_),
    { atom_codes(Name, [C1|CT]),
      findall(From-To, predicate(Name, _, _, From, To), Ranges),
      Ranges \== []
    }.

section([S0|ST]) -->
    integer(S0),
    subsections(ST).

subsections([S0|ST]) -->
    section_separator,
    integer(S0),
    !,
    subsections(ST).
subsections([]) -->
    [].

section_separator -->
    ".",
    !.
section_separator -->
    "-",
    !.

name_and_arity(Name, Arity) -->
    string(NameCodes),
    "/",
    (   integer(Arity)
    ->  []
    ;   "_"
    ),
    !,
    { atom_codes(Name, NameCodes)
    }.

pl_function(Name) -->
    identifier(S),
    "()",
    !,
    { atom_codes(Name, S)
    }.
pl_function(Name) -->
    "PL_",
    identifier(S),
    !,
    { append("PL_", S, Chars),
      atom_codes(Name, Chars)
    }.


string([]) -->
    [].
string([H|T]) -->
    [H],
    string(T).

word([C0|CT]) -->
    [C0],
    { C0 > 0' },
    !,
    word(CT).
word([]) -->
    [].

identifier([C0|CT]) -->
    alnum(C0),
    !,
    identifier(CT).
identifier([]) -->
    [].

blanks -->
    blank,
    !,
    blanks.
blanks -->
    [].

blank -->
    [C],
    { C =< 32 }.

integer(N) -->
    digit(D0),
    digits(DT),
    { number_chars(N, [D0|DT])
    }.

digits([D0|DT]) -->
    digit(D0),
    !,
    digits(DT).
digits([]) -->
    [].

digit(D) -->
    [D],
    { between(0'0, 0'9, D)
    }.

alnum(C) -->
    [C],
    { between(0'a, 0'z, C)
    ; between(0'A, 0'Z, C)
    ; between(0'0, 0'9, C)
    ; C = 0'_
    }.


help_atom(Name/Arity, Atom) :-
    !,
    (   var(Arity)
    ->  atom_concat(Name, '/_', Atom)
    ;   atomic_list_concat([Name, /, Arity], Atom)
    ).
help_atom(S1-S0, Atom) :-
    !,
    help_atom(S1, A0),
    atomic_list_concat([A0, '.', S0], Atom).
help_atom(C, C) :-
    integer(C),
    !.
help_atom(F, F) :-
    atom(F),
    sub_atom(F, 0, _, _, 'PL_'),
    !.
help_atom(Name, List) :-
    findall(Name/Arity, predicate(Name, Arity, _, _, _), Preds),
    Preds \== [],
    maplist(help_atom, Preds, List).

                 /*******************************
                 *           APROSPOS           *
                 *******************************/

give_apropos(V, Atom) :-
    send(V, clear),
    send(V, editable, @on),
    ignore(predicate_apropos(V, Atom)),
    ignore(function_apropos(V, Atom)),
    ignore(section_apropos(V, Atom)),
    send(V, editable, @off),
    send(V, home).

apropos_predicate(Pattern, Name, Arity, Summary) :-
    predicate(Name, Arity, Summary, _, _),
    (   apropos_match(Pattern, Name)
    ->  true
    ;   apropos_match(Pattern, Summary)
    ).

predicate_apropos(V, Pattern) :-
    setof(triple(Name, Arity, Summary),
          apropos_predicate(Pattern, Name, Arity, Summary),
          Names),
    send(V, insert_section,
         string('Predicates from "%s":', Pattern)),
    forall(member(triple(Name, Arity, Summary), Names),
           (   help_atom(Name/Arity, Jump),
               append_apropos(V, Jump, Summary)
           )).

function_apropos(V, Pattern) :-
    findall(Name, (function(Name, _, _),
                   apropos_match(Pattern, Name)), Names),
    Names \= [],
    send(V, insert_section,
         string('Foreign language interface functions from "%s":', Pattern)),
    forall(member(Name, Names),
           (   atom_concat(Name, '()', Jump),
               append_apropos(V, Jump, 'Interface Function')
           )).


section_apropos(V, Pattern) :-
    findall(Index-Name, (section(Index, Name, _, _),
                         apropos_match(Pattern, Name)), Names),
    Names \== [],
    send(V, insert_section,
         string('Sections from "%s":', Pattern)),
    forall(member(Index-Title, Names),
           (   atomic_list_concat(Index, '.', Jump),
               append_apropos(V, Jump, Title)
           )).

append_apropos(V, Jump, Summary) :-
    get(V, caret, Caret),
    send(V, format, '%-30s%s\n', Jump, Summary),
    atom_length(Jump, Len),
    new(_, fragment(V, Caret, Len, button)).

apropos_match(Needle, Haystack) :-
    sub_atom_icasechk(Haystack, _, Needle).


                 /*******************************
                 *             EXPLAIN          *
                 *******************************/

do_explain_text(V, Text) :-
    catch(term_to_atom(Term, Text), _, fail),
    !,
    do_explain(V, Term).
do_explain_text(V, Text) :-
    send(V, clear),
    send(V, insert_section, string('Explanation for "%s"', Text)),
    send(V, format,
         '"%s" is not correct Prolog syntax.', Text).

do_explain(V, Term) :-
    send(V, clear),
    term_to_atom(Term, Atom),
    send(V, insert_section, string('Explanation for "%s"', Atom)),
    findall(Explanation, explain(Term, Explanation), Explanations),
    get(V, caret, Start),
    forall(member(E, Explanations),
           (   send(V, insert, string(E)),
               send(V, newline)
           )),
    get(V, caret, End),
    send(V, markup, Start, End),
    send(V, caret, 0),
    send(V, scroll_to, 0).


                 /*******************************
                 *          EDIT/SOURCE         *
                 *******************************/

try_to_edit(Spec) :-
    atom_codes(Spec, S),
    phrase(source(File, Line), S),
    !,
    start_emacs,
    send(@emacs, goto_source_location, source_location(File, Line)).

source(File, Line) -->                  % path:line
    string(FileCodes),
    ":",
    integer(Line),
    !,
    { atom_codes(File, FileCodes)
    }.
source(File, Line) -->                  % n-th clause of module:name/arity
    integer(NClause),
    "-th clause of ",
    string(MCodes), ":",
    string(NCodes), "/",
    integer(Arity),
    { atom_codes(Name, NCodes),
      atom_codes(Module, MCodes),
      functor(Head, Name, Arity),
      nth_clause(Module:Head, NClause, CRef),
      clause_property(CRef, file(File)),
      clause_property(CRef, line_count(Line))
    }.
source(File, Line) -->                  % XPCE method
    blanks,
    identifier(ClassChars),
    blanks,
    (   "->"
    ->  { Method = '->'(Class, Selector)
        }
    ;   "<-",
        { Method = '<-'(Class, Selector)
        }
    ),
    identifier(SelectorChars),
    { atom_codes(Class, ClassChars),
      atom_codes(Selector, SelectorChars),
      pce_edit:method(Method, Obj),
      get(Obj, source, Location),
      Location \== @nil,
      get(Location, file_name, File),
      get(Location, line_no, Line)
    }.


                 /*******************************
                 *       TABLE-OF-CONTENTS      *
                 *******************************/

:- pce_begin_class(pui_toc, toc_window,
                   "Prolog manual table-of-contents").

initialise(PT) :->
    send(PT, send_super, initialise),
    send(PT, root,
         toc_folder('Manual', manual, resource(manual), resource(book))).


                 /*******************************
                 *             OPEN             *
                 *******************************/

select_node(PT, Id:name) :->
    "Show selected section"::
    send(PT?frame, give_help, Id).


                 /*******************************
                 *            EXPAND            *
                 *******************************/

expand_node(PT, Node:any) :->
    expand_node(PT, Node),
    send(PT, send_super, expand_node, Node).

expand_node(PT, manual) :-
    !,
    forall(section([N], _, _, _),
           send(PT, son, manual, pui_section_node([N]))).
expand_node(PT, Section) :-
    atom_codes(Section, S),
    phrase(section(List), S),
    subsection(List, I),
    forall(section(I, _, _, _),
           send(PT, son, Section, pui_section_node(I))),
    forall(predicate_in_section(List, Name/Arity),
           send(PT, son, Section, pui_predicate_node(Name, Arity))),
    forall(function_in_section(List, Name),
           send(PT, son, Section, pui_function_node(Name))).

can_expand(Section) :-
    subsection(Section, Sub),
    section(Sub, _, _, _),
    !.
can_expand(Section) :-
    plain_predicate_in_section(Section, _),
    !.
can_expand(Section) :-
    plain_function_in_section(Section, _),
    !.


plain_predicate_in_section(Section, Name/Arity) :-
    section(Section, _, SFrom, STo),
    predicate(Name, Arity, _, PFrom, PTo),
    PFrom > SFrom,
    PTo < STo.

predicate_in_section(Section, Pred) :-
    plain_predicate_in_section(Section, Pred),
    \+ (subsection(Section, Sub),
        plain_predicate_in_section(Sub, Pred)).

plain_function_in_section(Section, Name) :-
    section(Section, _, SFrom, STo),
    function(Name, PFrom, PTo),
    PFrom > SFrom,
    PTo < STo.

function_in_section(Section, Func) :-
    plain_function_in_section(Section, Func),
    \+ (subsection(Section, Sub),
        plain_function_in_section(Sub, Func)).

subsection(Sec, Sub) :-
    append(Sec, [_], Sub).

select_range(PT, Ranges:prolog) :->
    "Select selections in range"::
    (   Ranges == []
    ->  send(PT, selection, @nil)
    ;   get(PT, node, manual, Root),
        send(Root, collapsed, @off),
        send(Root?sons, for_all,
             message(@arg1, select_range, prolog(Ranges))),
        get(PT, selection, Nodes),
        send(PT, normalise, Nodes, y)
    ).

in_range(F-T, Node, How) :-
    get(Node, start, S),
    get(Node, end, E),
    \+  (   F>=E
        ;   T=<S
        ),
    (   S>=F,E=<T
    ->  How = all
    ;   How = partial
    ).
in_range([H|_], Node, How) :-
    in_range(H, Node, How).
in_range([_|T], Node, How) :-
    in_range(T, Node, How).


:- pce_end_class.

:- pce_begin_class(pui_section_node, toc_folder,
                   "Represent section of the manual").

variable(start, int, get, "Start index").
variable(end,   int, get, "End index").

initialise(N, Index:prolog) :->
    section(Index, Title, Start, End),
    (   can_expand(Index)
    ->  CanExpand = @on
    ;   CanExpand = @off
    ),
    atomic_list_concat(Index, '.', Id),
    send_super(N, initialise, Title?capitalise, Id,
               resource(manual), resource(book),
               CanExpand),
    (   font(Index, Font)
    ->  send(N, font, Font)
    ;   true
    ),
    send(N, slot, start, Start),
    send(N, slot, end, End).

font([_], bold).

select_range(N, Ranges:prolog) :->
    "Select nodes in given ranges"::
    (   in_range(Ranges, N, all)
    ->  send(N, selected, @on)
    ;   in_range(Ranges, N, partial)
    ->  send(N, collapsed, @off),
        send(N?sons, for_all,
             message(@arg1, select_range, prolog(Ranges)))
    ;   true
    ).

:- pce_end_class(pui_section_node).


:- pce_begin_class(pui_predicate_node, toc_file,
                   "Represent a single predicate").

variable(start, int, get, "Start index").
variable(end,   int, get, "End index").

initialise(N, Name:name, Arity:prolog) :->
    predicate(Name, SArity, _Summary, Start, End),
    SArity =@= Arity,
    help_atom(Name/Arity, Id),
    send_super(N, initialise, Id, Id, resource(predicate)),
    send(N, slot, start, Start),
    send(N, slot, end, End).

select_range(N, Ranges:prolog) :->
    "Select nodes in given ranges"::
    (   in_range(Ranges, N, _)
    ->  send(N, selected, @on)
    ;   true
    ).

:- pce_end_class.


:- pce_begin_class(pui_function_node, toc_file,
                   "Represent a single C-function").

variable(start, int, get, "Start index").
variable(end,   int, get, "End index").

initialise(N, Name:name) :->
    function(Name, Start, End),
    send_super(N, initialise, Name, Name, resource(cfunction)),
    send(N, slot, start, Start),
    send(N, slot, end, End).

select_range(N, Ranges:prolog) :->
    "Select nodes in given ranges"::
    (   in_range(Ranges, N, _)
    ->  send(N, selected, @on)
    ;   true
    ).

:- pce_end_class.


