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

    Author:        Jan Wielemaker and Anjo Anjewierden
    E-mail:        jan@swi.psy.uva.nl
    WWW:           http://www.swi.psy.uva.nl/projects/xpce/
    Copyright (c)  2000-2015, University of 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(browser_classes, []).
:- use_module(library(pce)).
:- use_module(doc(util)).
:- use_module(doc(emit)).
:- use_module(doc(vfont)).

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Support classes for the html rendering package.  Defines the classes:

        # pbox
        Refinement of class parbox with event-handling, etc.

        # button_box
        hbox for labeling buttons

        # anchor_box
        hbox for labeling anchors

        # bullet_list
        lbox for dealing with bulletted lists (<UL>)

        # enum_list
        lbox for dealing with ordered lists (<OL>)

        # definition_list
        lbox for dealing with definition lists <DL>

        # doc_mode
        Style and font handling
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

                 /*******************************
                 *             PBOX             *
                 *******************************/

:- pce_begin_class(pbox, parbox, "Refined parbox for viewer").

class_variable(auto_crop, bool, @on).

:- pce_global(@pbox_recogniser,
              new(click_gesture(left, '', single,
                                message(@receiver, clicked, @event)))).

event(PB, Ev:event) :->
    (   send_super(PB, event, Ev)
    ;   send(@pbox_recogniser, event, Ev)
    ;   send(Ev, is_a, loc_move),
        send(PB, show_location, Ev)
    ).

clicked(PB, Ev:event) :->
    get(PB, locate_event, Ev, Index),
    (   get(PB, box, Index, Box),
        get(Box, attribute, footnote, Footnote)
    ->  send(PB, show_note, Footnote)
    ;   find_button(PB, Index, Button),
        get(Button, message, Message),
        send(Message, forward, Button)
    ->  true
    ;   debugging(parbox),
        get(PB, box_area, Index, area(X,Y,W,H)),
        send(PB, display, box(W, H), point(X, Y))
    ).

find_button(PB, Index, Button) :-
    find_button(PB, Index, Index, 100, Button).

find_button(PB, Index0, Index, _, CB) :-
    get(PB, box, Index, CB),
    send(CB, instance_of, button_box),
    get(CB, hypered, open, OB),
    get(PB?content, index, OB, OpenIndex),
    OpenIndex =< Index0,
    !.
find_button(PB, Index0, Index, MaxDist, CB) :-
    Index1 is Index+1,
    Index0+MaxDist > Index,
    find_button(PB, Index0, Index1, MaxDist, CB).

show_note(_, Note:graphical) :->
    get(Note, size, Size),
    send(Note, lock_object, @on),
    new(W, window('Footnote', size := Size)),
    send(W, kind, popup),
    send(W, display, Note),
    send(W, recogniser,
         new(C, click_gesture(left, '', single,
                              message(W, free)))),
    send(W, focus, W, C, @nil, @nil),
    get(@event, position, @display, Pos),
    send(W, open, Pos, @on).

:- dynamic
    showing/1.              % actually we should use the frame for this

show_location(PB, Ev:event) :->
    get(PB, locate_event, Ev, Index),
    (   find_button(PB, Index, Button),
        get(Button, balloon, Text),
        Text \== @nil
    ->  true
    ;   Text = ''
    ),
    (   showing(Text)
    ->  true
    ;   retractall(showing(_)),
        assert(showing(Text)),
        send(PB, report, status, Text)
    ).

anchor(PB, Anchor:name, Reply:tuple) :<-
    "Find tuple(Box, Index) defining this anchor"::
    get(PB, find,
        and(message(@arg1, instance_of, anchor_box),
            @arg1?identifier == Anchor),
        Reply).

url(PB, URL:name) :<-
    "Represented URL"::
    get(PB, window, Window),
    catch(get(Window, url, URL), _, fail).

show(PB, Content:prolog, Mode:mode=[doc_mode]) :->
    "Render list of commands in this box"::
    (   Mode == @default
    ->  new(M, doc_mode)
    ;   M = Mode
    ),
    (   Content = element(_,_,_)
    ->  emit([Content], PB, M)
    ;   emit(Content, PB, M)
    ).
%       send(PB, compute).

:- pce_end_class.

                 /*******************************
                 *            BUTTON            *
                 *******************************/

:- pce_begin_class(button_box, hbox,
                   "Open/close buttons").

variable(message,       code*,   both, "Message executed on click").
variable(balloon,       string*, both, "Message displayed when hooveing").

initialise(B, Message:code*, Balloon:[string]*) :->
    default(Balloon, @nil, Text),
    send_super(B, initialise),
    send(B, message, Message),
    send(B, balloon, Text).

:- pce_end_class.

:- pce_begin_class(anchor_box, hbox,
                   "End-point of a link").

variable(identifier,    name*,  get, "Identifier (label)").

initialise(B, Id:any) :->
    send_super(B, initialise),
    send(B, slot, identifier, Id).

:- pce_end_class.


                 /*******************************
                 *          BULLET LIST         *
                 *******************************/

:- pce_begin_class(bullet_list, lbox, "TeX bulletlist environment").

class_variable(item_sep, '0..', 0).

new_label(_, Label:graphical) :<-
    new(Label, circle(8)),
    send(Label, fill_pattern, @black_image).

make_item(BL, Item:prolog, Mode:mode, PB:parbox) :<-
    "Create a new item"::
    (   Item == []
    ->  Label = @default
    ;   get(BL, label_width, LW),
        new(Label, pbox(LW, right)),
        get(Mode, clone, Clone),
        emit(Item, Label, Clone)
    ),
    get(Mode, alignment, Align),
    send(BL, append, Label, new(PB, pbox(0, Align))).

:- pce_end_class.


                 /*******************************
                 *           ENUMERATE          *
                 *******************************/

:- pce_begin_class(enum_list, lbox, "TeX enumerate environment").

variable(index,         int := 0,       both, "Current index").

new_label(EN, Label:graphical) :<-
    get(EN, index, I0),
    I is I0 + 1,
    send(EN, index, I),
    new(Label, text(I, right, normal)).

make_item(BL, Item:prolog, Mode:mode, PB:parbox) :<-
    "Create a new item"::
    (   Item == []
    ->  Label = @default
    ;   get(BL, label_width, LW),
        new(Label, pbox(LW, right)),
        get(Mode, clone, Clone),
        emit(Item, Label, Clone)
    ),
    get(Mode, alignment, Align),
    send(BL, append, Label, new(PB, pbox(0, Align))).

:- pce_end_class.


                 /*******************************
                 *          DESCRIPTION         *
                 *******************************/

:- pce_begin_class(definition_list, lbox, "HTML <DL> element").

make_item(DL, Item:prolog, Mode:mode, PB:parbox) :<-
    "Create a new item"::
    get(Mode, alignment, Align),
    get(DL, item_width, IW),
    send(DL, append, @default, new(PB, pbox(IW, Align))),
    get(DL, left_margin, LM),
    send(PB, append, hbox(-LM)),
    get(Mode, clone, Clone),
    append(Item, [@br], Label),
    emit([\setfont(weight, bold) | Label], PB, Clone).

:- pce_end_class.


                 /*******************************
                 *        CLASS DOC-MODE        *
                 *******************************/

:- pce_begin_class(doc_mode, object, "Parameters of rendering engine").

variable(style,         style,    get,  "Basic text style").
variable(parsep,        hbox,     get,  "Amount to skip for paragraph").
variable(parindent,     hbox,     get,  "Indentation for paragraph").
variable(alignment,     name,     both, "Default paragraph alignment").
variable(vfont,         vfont,    get,  "Virtual font").
variable(space,         hbox,     get,  "Space in current font").
variable(base_url,      name:='', both, "Reference URL").
variable(ignore_blanks, [name],   both, "How to handle blanks").
variable(space_mode,    {preserve,canonical}, both, "How to handle blanks").
variable(link_colour,   colour,   both, "Colour for hyperlinks").

class_variable(alignment, name, justify).

initialise(M) :->
    send_super(M, initialise),
    send(M, slot, vfont, new(VFont, vfont)),
    send(M, slot, link_colour, colour(dark_green)),
    send(M, slot, style, style(font := VFont?font)),
    send(M, slot, ignore_blanks, @default),
    send(M, set_font, family, helvetica),
    send(M, slot, parsep, hbox(0,8)),       % vertical skip
    send(M, slot, parindent, hbox(0,0)),    % horizontal skip
    send(M, space_mode, canonical).

set_font(M, Att:name, Val:any) :->
    "Set a font attribute"::
    get(M, vfont, VFont),
    send(VFont, Att, Val),
    get(VFont, font, Font),
    send(M?style, font, Font),
    get(Font, advance, ' ', SW),
    get(Font, ascent, Ascent),
    get(Font, descent, Descent),
    send(M, slot, space, hbox(SW, Ascent, Descent, @space_rubber)).

colour(M, Colour:colour) :->
    "Set text-foreground colour"::
    send(M?style, colour, Colour).

underline(M, OnOff:bool) :->
    "Set text underline"::
    send(M?style, underline, OnOff).

:- pce_end_class.