Bibliography and citations

6 files changed, 501 insertions, 18 deletions

diff --git a/library/src/lib.rs b/library/src/lib.rs
index 5b114d9b..c4a421d2 100644
--- a/library/src/lib.rs
+++ b/library/src/lib.rs
@@ -89,6 +89,8 @@ fn global(math: Module, calc: Module) -> Module {
     global.define("outline", meta::OutlineNode::id());
     global.define("heading", meta::HeadingNode::id());
     global.define("figure", meta::FigureNode::id());
+    global.define("cite", meta::CiteNode::id());
+    global.define("bibliography", meta::BibliographyNode::id());
     global.define("numbering", meta::numbering);
 
     // Symbols.
@@ -179,7 +181,7 @@ fn items() -> LangItems {
         raw: |text, lang, block| {
             let mut node = text::RawNode::new(text).with_block(block);
             if let Some(lang) = lang {
-                node = node.with_lang(Some(lang));
+                node.push_lang(Some(lang));
             }
             node.pack()
         },
@@ -194,6 +196,7 @@ fn items() -> LangItems {
             }
             node.pack()
         },
+        bibliography_keys: meta::BibliographyNode::keys,
         heading: |level, title| meta::HeadingNode::new(title).with_level(level).pack(),
         list_item: |body| layout::ListItem::new(body).pack(),
         enum_item: |number, body| {
diff --git a/library/src/meta/bibliography.rs b/library/src/meta/bibliography.rs
new file mode 100644
index 00000000..a01f9eee
--- /dev/null
+++ b/library/src/meta/bibliography.rs
@@ -0,0 +1,472 @@
+use std::collections::HashMap;
+use std::ffi::OsStr;
+use std::path::Path;
+use std::sync::Arc;
+
+use ecow::EcoVec;
+use hayagriva::io::{BibLaTeXError, YamlBibliographyError};
+use hayagriva::style::{self, Citation, Database, DisplayString, Formatting};
+use typst::font::{FontStyle, FontWeight};
+
+use super::LocalName;
+use crate::layout::{GridNode, ParNode, Sizing, TrackSizings, VNode};
+use crate::meta::HeadingNode;
+use crate::prelude::*;
+use crate::text::{Hyphenate, TextNode};
+
+/// A bibliography / reference listing.
+///
+/// Display: Bibliography
+/// Category: meta
+#[node(Locatable, Synthesize, Show, LocalName)]
+pub struct BibliographyNode {
+    /// Path to a Hayagriva `.yml` or BibLaTeX `.bib` file.
+    #[required]
+    #[parse(
+        let Spanned { v: path, span } =
+            args.expect::<Spanned<EcoString>>("path to bibliography file")?;
+        let path: EcoString = vm.locate(&path).at(span)?.to_string_lossy().into();
+        let _ = load(vm.world(), &path).at(span)?;
+        path
+    )]
+    pub path: EcoString,
+
+    /// The title of the bibliography.
+    ///
+    /// - When set to `{auto}`, an appropriate title for the [text
+    ///   language]($func/text.lang) will be used. This is the default.
+    /// - When set to `{none}`, the bibliography will not have a title.
+    /// - A custom title can be set by passing content.
+    #[default(Some(Smart::Auto))]
+    pub title: Option<Smart<Content>>,
+
+    /// The bibliography style.
+    #[default(BibliographyStyle::Ieee)]
+    pub style: BibliographyStyle,
+}
+
+impl BibliographyNode {
+    /// Find the document's bibliography.
+    pub fn find(introspector: Tracked<Introspector>) -> StrResult<Self> {
+        let mut iter = introspector.locate(Selector::node::<Self>()).into_iter();
+        let Some((_, node)) = iter.next() else {
+            return Err("the document does not contain a bibliography".into());
+        };
+
+        if iter.next().is_some() {
+            Err("multiple bibliographies are not supported")?;
+        }
+
+        Ok(node.to::<Self>().unwrap().clone())
+    }
+
+    /// Whether the bibliography contains the given key.
+    pub fn has(vt: &Vt, key: &str) -> bool {
+        vt.introspector
+            .locate(Selector::node::<Self>())
+            .into_iter()
+            .flat_map(|(_, node)| load(vt.world(), &node.to::<Self>().unwrap().path()))
+            .flatten()
+            .any(|entry| entry.key() == key)
+    }
+
+    /// Find all bibliography keys.
+    pub fn keys(
+        world: Tracked<dyn World>,
+        introspector: Tracked<Introspector>,
+    ) -> Vec<(EcoString, Option<EcoString>)> {
+        Self::find(introspector)
+            .and_then(|node| load(world, &node.path()))
+            .into_iter()
+            .flatten()
+            .map(|entry| {
+                let key = entry.key().into();
+                let detail =
+                    entry.title().map(|title| title.canonical.value.as_str().into());
+                (key, detail)
+            })
+            .collect()
+    }
+}
+
+impl Synthesize for BibliographyNode {
+    fn synthesize(&mut self, _: &Vt, styles: StyleChain) {
+        self.push_style(self.style(styles));
+    }
+}
+
+impl Show for BibliographyNode {
+    fn show(&self, vt: &mut Vt, styles: StyleChain) -> SourceResult<Content> {
+        const COLUMN_GUTTER: Em = Em::new(0.65);
+        const ROW_GUTTER: Em = Em::new(1.0);
+        const INDENT: Em = Em::new(1.5);
+
+        let works = match Works::new(vt) {
+            Ok(works) => works,
+            Err(error) => {
+                if vt.locatable() {
+                    bail!(self.span(), error)
+                } else {
+                    return Ok(TextNode::packed("bibliography"));
+                }
+            }
+        };
+
+        let mut seq = vec![];
+        if let Some(title) = self.title(styles) {
+            let title = title.clone().unwrap_or_else(|| {
+                TextNode::packed(self.local_name(TextNode::lang_in(styles)))
+            });
+
+            seq.push(
+                HeadingNode::new(title)
+                    .with_level(NonZeroUsize::new(1).unwrap())
+                    .with_numbering(None)
+                    .pack(),
+            );
+        }
+
+        if works.references.iter().any(|(prefix, _)| prefix.is_some()) {
+            let mut cells = vec![];
+            for (prefix, reference) in &works.references {
+                cells.push(prefix.clone().unwrap_or_default());
+                cells.push(reference.clone());
+            }
+
+            seq.push(
+                GridNode::new(cells)
+                    .with_columns(TrackSizings(vec![Sizing::Auto; 2]))
+                    .with_column_gutter(TrackSizings(vec![COLUMN_GUTTER.into()]))
+                    .with_row_gutter(TrackSizings(vec![ROW_GUTTER.into()]))
+                    .pack(),
+            );
+        } else {
+            let mut entries = vec![];
+            for (i, (_, reference)) in works.references.iter().enumerate() {
+                if i > 0 {
+                    entries.push(VNode::new(ROW_GUTTER.into()).with_weakness(1).pack());
+                }
+                entries.push(reference.clone());
+            }
+
+            seq.push(
+                Content::sequence(entries)
+                    .styled(ParNode::set_hanging_indent(INDENT.into())),
+            );
+        }
+
+        Ok(Content::sequence(seq))
+    }
+}
+
+impl LocalName for BibliographyNode {
+    fn local_name(&self, lang: Lang) -> &'static str {
+        match lang {
+            Lang::GERMAN => "Bibliographie",
+            Lang::ENGLISH | _ => "Bibliography",
+        }
+    }
+}
+
+/// A bibliography style.
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash, Cast)]
+pub enum BibliographyStyle {
+    /// Follows guidance of the American Psychological Association. Based on the
+    /// 7th edition of the APA Publication Manual.
+    Apa,
+    /// The Chicago Author Date style. Based on the 17th edition of the Chicago
+    /// Manual of Style, Chapter 15.
+    AuthorDate,
+    /// The style of the Institute of Electrical and Electronics Engineers.
+    /// Based on the 2018 IEEE Reference Guide.
+    Ieee,
+    /// Follows guidance of the Modern Language Association. Based on the 8th
+    /// edition of the MLA Handbook.
+    Mla,
+}
+
+impl BibliographyStyle {
+    /// The default citation style for this bibliography style.
+    pub fn default_citation_style(self) -> CitationStyle {
+        match self {
+            Self::Apa => CitationStyle::AuthorDate,
+            Self::AuthorDate => CitationStyle::AuthorDate,
+            Self::Ieee => CitationStyle::Numerical,
+            Self::Mla => CitationStyle::AuthorDate,
+        }
+    }
+}
+
+/// A citation of another work.
+///
+/// Display: Citation
+/// Category: meta
+#[node(Locatable, Synthesize, Show)]
+pub struct CiteNode {
+    /// The citation key.
+    #[required]
+    pub key: EcoString,
+
+    /// A supplement for the citation such as page or chapter number.
+    #[positional]
+    pub supplement: Option<Content>,
+
+    /// The citation style.
+    ///
+    /// When set to `{auto}`, automatically picks the preferred citation style
+    /// for the bibliography's style.
+    pub style: Smart<CitationStyle>,
+}
+
+impl Synthesize for CiteNode {
+    fn synthesize(&mut self, _: &Vt, styles: StyleChain) {
+        self.push_supplement(self.supplement(styles));
+        self.push_style(self.style(styles));
+    }
+}
+
+impl Show for CiteNode {
+    fn show(&self, vt: &mut Vt, _: StyleChain) -> SourceResult<Content> {
+        let id = self.0.stable_id().unwrap();
+        let works = match Works::new(vt) {
+            Ok(works) => works,
+            Err(error) => {
+                if vt.locatable() {
+                    bail!(self.span(), error)
+                } else {
+                    return Ok(TextNode::packed("citation"));
+                }
+            }
+        };
+
+        let Some(citation) = works.citations.get(&id).cloned() else {
+            return Ok(TextNode::packed("citation"));
+        };
+
+        citation
+            .ok_or("bibliography does not contain this key")
+            .at(self.span())
+    }
+}
+
+/// A citation style.
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash, Cast)]
+pub enum CitationStyle {
+    /// IEEE-style numerical reference markers.
+    Numerical,
+    /// A simple alphanumerical style. For example, the output could be Rass97
+    /// or MKG+21.
+    Alphanumerical,
+    /// The Chicago Author Date style. Based on the 17th edition of the Chicago
+    /// Manual of Style, Chapter 15.
+    AuthorDate,
+    /// A Chicago-like author-title format. Results could look like this:
+    /// Prokopov, “It Is Fast or It Is Wrong”.
+    AuthorTitle,
+    /// Citations that just consist of the entry keys.
+    Keys,
+}
+
+/// Fully formatted citations and references.
+pub struct Works {
+    citations: HashMap<StableId, Option<Content>>,
+    references: Vec<(Option<Content>, Content)>,
+}
+
+impl Works {
+    /// Prepare all things need to cite a work or format a bibliography.
+    pub fn new(vt: &Vt) -> StrResult<Arc<Self>> {
+        let bibliography = BibliographyNode::find(vt.introspector)?;
+        let style = bibliography.style(StyleChain::default());
+        let citations = vt
+            .locate_node::<CiteNode>()
+            .map(|(id, node)| {
+                (
+                    id,
+                    node.key(),
+                    node.supplement(StyleChain::default()),
+                    node.style(StyleChain::default())
+                        .unwrap_or(style.default_citation_style()),
+                )
+            })
+            .collect();
+        Ok(create(vt.world(), &bibliography.path(), style, citations))
+    }
+}
+
+/// Generate all citations and the whole bibliography.
+#[comemo::memoize]
+fn create(
+    world: Tracked<dyn World>,
+    path: &str,
+    style: BibliographyStyle,
+    citations: Vec<(StableId, EcoString, Option<Content>, CitationStyle)>,
+) -> Arc<Works> {
+    let entries = load(world, path).unwrap();
+
+    let mut db = Database::new();
+    let mut preliminary = vec![];
+
+    for (id, key, supplement, style) in citations {
+        let entry = entries.iter().find(|entry| entry.key() == key);
+        if let Some(entry) = &entry {
+            db.push(entry);
+        }
+        preliminary.push((id, entry, supplement, style));
+    }
+
+    let mut current = CitationStyle::Numerical;
+    let mut citation_style: Box<dyn style::CitationStyle> =
+        Box::new(style::Numerical::new());
+
+    let citations = preliminary
+        .into_iter()
+        .map(|(id, result, supplement, style)| {
+            let formatted = result.map(|entry| {
+                if style != current {
+                    current = style;
+                    citation_style = match style {
+                        CitationStyle::Numerical => Box::new(style::Numerical::new()),
+                        CitationStyle::Alphanumerical => {
+                            Box::new(style::Alphanumerical::new())
+                        }
+                        CitationStyle::AuthorDate => {
+                            Box::new(style::ChicagoAuthorDate::new())
+                        }
+                        CitationStyle::AuthorTitle => Box::new(style::AuthorTitle::new()),
+                        CitationStyle::Keys => Box::new(style::Keys::new()),
+                    };
+                }
+
+                let citation = db.citation(
+                    &mut *citation_style,
+                    &[Citation {
+                        entry,
+                        supplement: supplement.is_some().then(|| SUPPLEMENT),
+                    }],
+                );
+                let bracketed = citation.display.with_default_brackets(&*citation_style);
+                format_display_string(&bracketed, supplement)
+            });
+            (id, formatted)
+        })
+        .collect();
+
+    let bibliography_style: Box<dyn style::BibliographyStyle> = match style {
+        BibliographyStyle::Apa => Box::new(style::Apa::new()),
+        BibliographyStyle::AuthorDate => Box::new(style::ChicagoAuthorDate::new()),
+        BibliographyStyle::Ieee => Box::new(style::Ieee::new()),
+        BibliographyStyle::Mla => Box::new(style::Mla::new()),
+    };
+
+    let references = db
+        .bibliography(&*bibliography_style, None)
+        .into_iter()
+        .map(|reference| {
+            let prefix = reference.prefix.map(|prefix| {
+                let bracketed = prefix.with_default_brackets(&*citation_style);
+                format_display_string(&bracketed, None)
+            });
+            let reference = format_display_string(&reference.display, None);
+            (prefix, reference)
+        })
+        .collect();
+
+    Arc::new(Works { citations, references })
+}
+
+/// Load bibliography entries from a path.
+#[comemo::memoize]
+fn load(world: Tracked<dyn World>, path: &str) -> StrResult<EcoVec<hayagriva::Entry>> {
+    let path = Path::new(path);
+    let buffer = world.file(path)?;
+    let src = std::str::from_utf8(&buffer).map_err(|_| "file is not valid utf-8")?;
+    let ext = path.extension().and_then(OsStr::to_str).unwrap_or_default();
+    let entries = match ext.to_lowercase().as_str() {
+        "yml" => hayagriva::io::from_yaml_str(src).map_err(format_hayagriva_error)?,
+        "bib" => hayagriva::io::from_biblatex_str(src).map_err(|err| {
+            err.into_iter()
+                .next()
+                .map(|error| format_biblatex_error(src, error))
+                .unwrap_or_else(|| "failed to parse biblatex file".into())
+        })?,
+        _ => return Err("unknown bibliography format".into()),
+    };
+    Ok(entries.into_iter().collect())
+}
+
+/// Format a Hayagriva loading error.
+fn format_hayagriva_error(error: YamlBibliographyError) -> EcoString {
+    eco_format!("{error}")
+}
+
+/// Format a BibLaTeX loading error.
+fn format_biblatex_error(src: &str, error: BibLaTeXError) -> EcoString {
+    let (span, msg) = match error {
+        BibLaTeXError::Parse(error) => (error.span, error.kind.to_string()),
+        BibLaTeXError::Type(error) => (error.span, error.kind.to_string()),
+    };
+    let line = src.get(..span.start).unwrap_or_default().lines().count();
+    eco_format!("failed to parse biblatex file: {msg} in line {line}")
+}
+
+/// Hayagriva only supports strings, but we have a content supplement. To deal
+/// with this, we pass this string to hayagriva instead of our content, find it
+/// in the output and replace it with the content.
+const SUPPLEMENT: &str = "cdc579c45cf3d648905c142c7082683f";
+
+/// Format a display string into content.
+fn format_display_string(
+    string: &DisplayString,
+    mut supplement: Option<Content>,
+) -> Content {
+    let mut stops: Vec<_> = string
+        .formatting
+        .iter()
+        .flat_map(|(range, _)| [range.start, range.end])
+        .collect();
+
+    if let Some(i) = string.value.find(SUPPLEMENT) {
+        stops.push(i);
+        stops.push(i + SUPPLEMENT.len());
+    }
+
+    stops.sort();
+    stops.dedup();
+    stops.push(string.value.len());
+
+    let mut start = 0;
+    let mut seq = vec![];
+    for stop in stops {
+        let segment = string.value.get(start..stop).unwrap_or_default();
+        if segment.is_empty() {
+            continue;
+        }
+
+        let mut styles = StyleMap::new();
+        for (range, fmt) in &string.formatting {
+            if !range.contains(&start) {
+                continue;
+            }
+
+            styles.set(match fmt {
+                Formatting::Bold => TextNode::set_weight(FontWeight::BOLD),
+                Formatting::Italic => TextNode::set_style(FontStyle::Italic),
+                Formatting::NoHyphenation => {
+                    TextNode::set_hyphenate(Hyphenate(Smart::Custom(false)))
+                }
+            });
+        }
+
+        let content = if segment == SUPPLEMENT && supplement.is_some() {
+            supplement.take().unwrap_or_default()
+        } else {
+            TextNode::packed(segment)
+        };
+
+        seq.push(content.styled_with_map(styles));
+        start = stop;
+    }
+
+    Content::sequence(seq)
+}
diff --git a/library/src/meta/heading.rs b/library/src/meta/heading.rs
index 4d1b87e6..48f6e229 100644
--- a/library/src/meta/heading.rs
+++ b/library/src/meta/heading.rs
@@ -145,7 +145,7 @@ impl Finalize for HeadingNode {
     }
 }
 
-/// Counters through headings with different levels.
+/// Counts through headings with different levels.
 pub struct HeadingCounter(Vec<NonZeroUsize>);
 
 impl HeadingCounter {
diff --git a/library/src/meta/mod.rs b/library/src/meta/mod.rs
index 3cde2b8e..ba74dac0 100644
--- a/library/src/meta/mod.rs
+++ b/library/src/meta/mod.rs
@@ -1,5 +1,6 @@
 //! Interaction between document parts.
 
+mod bibliography;
 mod document;
 mod figure;
 mod heading;
@@ -8,6 +9,7 @@ mod numbering;
 mod outline;
 mod reference;
 
+pub use self::bibliography::*;
 pub use self::document::*;
 pub use self::figure::*;
 pub use self::heading::*;
diff --git a/library/src/meta/numbering.rs b/library/src/meta/numbering.rs
index d71fb233..c59766c8 100644
--- a/library/src/meta/numbering.rs
+++ b/library/src/meta/numbering.rs
@@ -65,7 +65,7 @@ pub fn numbering(
     numbering.apply(vm.world(), &numbers)?
 }
 
-/// How to number an enumeration.
+/// How to number a sequence of things.
 #[derive(Debug, Clone, Hash)]
 pub enum Numbering {
     /// A pattern with prefix, numbering, lower / upper case and suffix.
diff --git a/library/src/meta/reference.rs b/library/src/meta/reference.rs
index f63c7e4c..b4cfa049 100644
--- a/library/src/meta/reference.rs
+++ b/library/src/meta/reference.rs
@@ -1,4 +1,4 @@
-use super::{FigureNode, HeadingNode, LocalName, Numbering};
+use super::{BibliographyNode, CiteNode, FigureNode, HeadingNode, LocalName, Numbering};
 use crate::prelude::*;
 use crate::text::TextNode;
 
@@ -35,7 +35,7 @@ use crate::text::TextNode;
 ///
 /// Display: Reference
 /// Category: meta
-#[node(Synthesize, Show)]
+#[node(Show)]
 pub struct RefNode {
     /// The target label that should be referenced.
     #[required]
@@ -60,27 +60,33 @@ pub struct RefNode {
     /// In @intro, we see how to turn
     /// Sections into Chapters.
     /// ```
-
-    /// All elements with the target label in the document.
-    #[synthesized]
-    pub matches: Vec<Content>,
     pub supplement: Smart<Option<Supplement>>,
 }
 
-impl Synthesize for RefNode {
-    fn synthesize(&mut self, vt: &Vt, _: StyleChain) {
-        let matches = vt
+impl Show for RefNode {
+    fn show(&self, vt: &mut Vt, styles: StyleChain) -> SourceResult<Content> {
+        let target = self.target();
+        let supplement = self.supplement(styles);
+
+        let matches: Vec<_> = vt
             .locate(Selector::Label(self.target()))
             .map(|(_, node)| node.clone())
             .collect();
 
-        self.push_matches(matches);
-    }
-}
+        if !vt.locatable() || BibliographyNode::has(vt, &target.0) {
+            if !matches.is_empty() {
+                bail!(self.span(), "label occurs in the document and its bibliography");
+            }
+
+            return Ok(CiteNode::new(target.0)
+                .with_supplement(match supplement {
+                    Smart::Custom(Some(Supplement::Content(content))) => Some(content),
+                    _ => None,
+                })
+                .pack()
+                .spanned(self.span()));
+        }
 
-impl Show for RefNode {
-    fn show(&self, vt: &mut Vt, styles: StyleChain) -> SourceResult<Content> {
-        let matches = self.matches();
         let [target] = matches.as_slice() else {
             if vt.locatable() {
                 bail!(self.span(), if matches.is_empty() {