% pdflink.w
%
% Copyright 2009-2012 Taco Hoekwater <taco@@luatex.org>
%
% This file is part of LuaTeX.
%
% LuaTeX 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.
%
% LuaTeX 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 Lesser General Public
% License for more details.
%
% You should have received a copy of the GNU General Public License along
% with LuaTeX; if not, see <http://www.gnu.org/licenses/>.

@ @c

#include "ptexlib.h"

@ To implement nested link annotations, we need a stack to hold copy of
|pdf_start_link_node|'s that are being written out, together with their box
nesting level.

@c
void push_link_level(PDF pdf, halfword p)
{
    if (pdf->link_stack_ptr >= pdf_max_link_level)
        overflow("pdf link stack size", pdf_max_link_level);
    pdf->link_stack_ptr++;
    pdf->link_stack[pdf->link_stack_ptr].nesting_level = cur_s;
    pdf->link_stack[pdf->link_stack_ptr].link_node = copy_node_list(p);
    pdf->link_stack[pdf->link_stack_ptr].ref_link_node = p;
}

@ @c
void pop_link_level(PDF pdf)
{
    flush_node_list(pdf->link_stack[pdf->link_stack_ptr].link_node);
    pdf->link_stack_ptr--;
}

@ @c
void do_link(PDF pdf, halfword p, halfword parent_box, scaledpos cur)
{
    scaled_whd alt_rule;
    int k;
    if (type(p) == vlist_node)
        normal_error("pdf backend", "'startlink' ended up in vlist");
    if (global_shipping_mode == SHIPPING_FORM)
        normal_error("pdf backend", "link annotations cannot be inside an xform");
    if (is_obj_scheduled(pdf, pdf_link_objnum(p)))
        pdf_link_objnum(p) = pdf_create_obj(pdf, obj_type_others, 0);
    push_link_level(pdf, p);
    alt_rule.wd = width(p);
    alt_rule.ht = height(p);
    alt_rule.dp = depth(p);
    set_rect_dimens(pdf, p, parent_box, cur, alt_rule, pdf_link_margin);
    obj_annot_ptr(pdf, pdf_link_objnum(p)) = p; /* the reference for the pdf annot object must be set here */
    k = pdf_link_objnum(p);
    set_obj_scheduled(pdf, pdf_link_objnum(p));
    addto_page_resources(pdf, obj_type_link, k);
}

@ @c
void end_link(PDF pdf, halfword p)
{
    halfword q;
    scaledpos pos = pdf->posstruct->pos;
    if (type(p) == vlist_node)
        normal_error("pdf backend","'endlink' ended up in vlist");
    if (pdf->link_stack_ptr < 1)
        normal_error("pdf backend","pdf link_stack empty, 'endlink' used without 'startlink'");
    if (pdf->link_stack[pdf->link_stack_ptr].nesting_level != cur_s)
        normal_error("pdf backend","'endlink' ended up in different nesting level than 'startlink'");
    /*
        NOTA BENE: test for running link must be done on |link_node| and not
        |ref_link_node|, as |ref_link_node| can be set by |do_link| or
        |append_link| already
    */
    if (is_running(width(pdf->link_stack[pdf->link_stack_ptr].link_node))) {
        q = pdf->link_stack[pdf->link_stack_ptr].ref_link_node;
        if (global_shipping_mode == SHIPPING_PAGE && matrixused()) {
            matrixrecalculate(pos.h + pdf_link_margin);
            pdf_ann_left(q) = getllx() - pdf_link_margin;
            pdf_ann_top(q) = getlly() - pdf_link_margin;
            pdf_ann_right(q) = geturx() + pdf_link_margin;
            pdf_ann_bottom(q) = getury() + pdf_link_margin;
        } else {
            switch (pdf->posstruct->dir) {
                case dir_TLT:
                    pdf_ann_right(q) = pos.h + pdf_link_margin;
                    break;
                case dir_TRT:
                    pdf_ann_left(q) = pos.h - pdf_link_margin;
                    break;
                case dir_LTL:
                case dir_RTT:
                    pdf_ann_bottom(q) = pos.v - pdf_link_margin;
                    break;
                default:
                    pdf_ann_right(q) = pos.h + pdf_link_margin;
                    formatted_warning("pdf backend","forcing bad dir %i to TLT in link",pdf->posstruct->dir);
            }
        }
    }
    pop_link_level(pdf);
}

@ For ``running'' annotations we must append a new node when the end of
annotation is in other box than its start. The new created node is identical to
corresponding whatsit node representing the start of annotation, but its |info|
field is |max_halfword|. We set |info| field just before destroying the node, in
order to use |flush_node_list| to do the job.

@ Append a new pdf annot to |pdf_link_list|.

@c
void append_link(PDF pdf, halfword parent_box, scaledpos cur, small_number i)
{
    halfword p;
    int k;
    scaled_whd alt_rule;
    p = copy_node(pdf->link_stack[(int) i].link_node);
    pdf->link_stack[(int) i].ref_link_node = p;
    subtype(p) = pdf_link_data_node;    /* this node is not a normal link node */
    alt_rule.wd = width(p);
    alt_rule.ht = height(p);
    alt_rule.dp = depth(p);
    set_rect_dimens(pdf, p, parent_box, cur, alt_rule, pdf_link_margin);
    k = pdf_create_obj(pdf, obj_type_others, 0);
    obj_annot_ptr(pdf, k) = p;
    set_obj_scheduled(pdf, pdf_link_objnum(p));
    addto_page_resources(pdf, obj_type_link, k);
}

@ @c
void scan_startlink(PDF pdf)
{
    int k;
    halfword r;
    if (abs(cur_list.mode_field) == vmode)
        normal_error("pdf backend", "startlink cannot be used in vertical mode");
    k = pdf_create_obj(pdf, obj_type_others, 0);
    new_annot_whatsit(pdf_start_link_node);
    set_pdf_link_attr(cur_list.tail_field, null);
    if (scan_keyword("attr")) {
        scan_toks(false, true);
        set_pdf_link_attr(cur_list.tail_field, def_ref);
    }
    r = scan_action(pdf);
    set_pdf_link_action(cur_list.tail_field, r);
    set_pdf_link_objnum(cur_list.tail_field, k);
    pdf_last_link = k;
    /*
        NOTA BENE: although it is possible to set |obj_annot_ptr(k) := tail|
        here, it is not safe if nodes are later copied/destroyed/moved; a better
        place to do this is inside |do_link|, when the whatsit node is written
        out
    */
}