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use std::collections::{HashMap, HashSet};
use pdf_writer::writers::Destination;
use pdf_writer::{Ref, Str};
use typst_library::diag::SourceResult;
use typst_library::foundations::{Label, NativeElement};
use typst_library::introspection::Location;
use typst_library::layout::Abs;
use typst_library::model::HeadingElem;
use crate::{AbsExt, PdfChunk, Renumber, StrExt, WithGlobalRefs};
/// A list of destinations in the PDF document (a specific point on a specific
/// page), that have a name associated with them.
///
/// Typst creates a named destination for each heading in the document, that
/// will then be written in the document catalog. PDF readers can then display
/// them to show a clickable outline of the document.
#[derive(Default)]
pub struct NamedDestinations {
/// A map between elements and their associated labels
pub loc_to_dest: HashMap<Location, Label>,
/// A sorted list of all named destinations.
pub dests: Vec<(Label, Ref)>,
}
impl Renumber for NamedDestinations {
fn renumber(&mut self, offset: i32) {
for (_, reference) in &mut self.dests {
reference.renumber(offset);
}
}
}
/// Fills in the map and vector for named destinations and writes the indirect
/// destination objects.
pub fn write_named_destinations(
context: &WithGlobalRefs,
) -> SourceResult<(PdfChunk, NamedDestinations)> {
let mut chunk = PdfChunk::new();
let mut out = NamedDestinations::default();
let mut seen = HashSet::new();
// Find all headings that have a label and are the first among other
// headings with the same label.
let mut matches: Vec<_> = context
.document
.introspector
.query(&HeadingElem::elem().select())
.iter()
.filter_map(|elem| elem.location().zip(elem.label()))
.filter(|&(_, label)| seen.insert(label))
.collect();
// Named destinations must be sorted by key.
matches.sort_by_key(|&(_, label)| label.resolve());
for (loc, label) in matches {
// Don't encode named destinations that would exceed the limit. Those
// will instead be encoded as normal links.
if label.resolve().len() > Str::PDFA_LIMIT {
continue;
}
let pos = context.document.introspector.position(loc);
let index = pos.page.get() - 1;
let y = (pos.point.y - Abs::pt(10.0)).max(Abs::zero());
if let Some((Some(page), Some(page_ref))) =
context.pages.get(index).zip(context.globals.pages.get(index))
{
let dest_ref = chunk.alloc();
let x = pos.point.x.to_f32();
let y = (page.content.size.y - y).to_f32();
out.dests.push((label, dest_ref));
out.loc_to_dest.insert(loc, label);
chunk
.indirect(dest_ref)
.start::<Destination>()
.page(*page_ref)
.xyz(x, y, None);
}
}
Ok((chunk, out))
}
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