1 files changed, 172 insertions, 2 deletions

diff --git a/src/metadata.rs b/src/metadata.rs
index e88c732..b840633 100644
--- a/src/metadata.rs
+++ b/src/metadata.rs
@@ -1,11 +1,181 @@
-use crate::{Bindings, SubplotError, TemplateSpec, YamlMetadata};
+use crate::{Bindings, SubplotError, TemplateSpec};
 
+use lazy_static::lazy_static;
 use log::trace;
-use std::collections::HashMap;
+use regex::Regex;
+use serde::Deserialize;
+use serde_yaml::Value;
+use std::collections::{BTreeMap, HashMap};
 use std::fmt::Debug;
 use std::ops::Deref;
 use std::path::{Path, PathBuf};
 
+lazy_static! {
+    // Pattern that recognises a YAML block at the beginning of a file.
+    static ref LEADING_YAML_PATTERN: Regex = Regex::new(r"^(?:\S*\n)*(?P<yaml>-{3,}\n([^.].*\n)*\.{3,}\n)(?P<text>(.*\n)*)$").unwrap();
+
+
+    // Pattern that recognises a YAML block at the end of a file.
+    static ref TRAILING_YAML_PATTERN: Regex = Regex::new(r"(?P<text>(.*\n)*)\n*(?P<yaml>-{3,}\n([^.].*\n)*\.{3,}\n)(?:\S*\n)*$").unwrap();
+}
+
+/// Errors from Markdown parsing.
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    #[error(transparent)]
+    Regex(#[from] regex::Error),
+
+    #[error("Markdown doesn't contain a YAML block for document metadata")]
+    NoMetadata,
+
+    #[error(transparent)]
+    Yaml(#[from] serde_yaml::Error),
+}
+
+/// Document metadata.
+///
+/// This is expressed in the Markdown input file as an embedded YAML
+/// block.
+///
+/// Note that this structure needs to be able to capture any metadata
+/// block we can work with, in any input file. By being strict here we
+/// make it easier to tell the user when a metadata block has, say, a
+/// misspelled field.
+#[derive(Debug, Default, Clone, Deserialize)]
+#[serde(deny_unknown_fields)]
+pub struct YamlMetadata {
+    title: String,
+    subtitle: Option<String>,
+    authors: Option<Vec<String>>,
+    date: Option<String>,
+    classes: Option<Vec<String>>,
+    bibliography: Option<Vec<PathBuf>>,
+    markdowns: Vec<PathBuf>,
+    bindings: Option<Vec<PathBuf>>,
+    documentclass: Option<String>,
+    #[serde(default)]
+    impls: BTreeMap<String, Vec<PathBuf>>,
+    pandoc: Option<HashMap<String, Value>>,
+}
+
+impl YamlMetadata {
+    #[cfg(test)]
+    fn new(yaml_text: &str) -> Result<Self, Error> {
+        let meta: Self = serde_yaml::from_str(yaml_text)?;
+        Ok(meta)
+    }
+
+    /// Name of file with the Markdown for the subplot document.
+    pub fn markdown(&self) -> &Path {
+        &self.markdowns[0]
+    }
+
+    /// Title.
+    pub fn title(&self) -> &str {
+        &self.title
+    }
+
+    /// Subtitle.
+    pub fn subtitle(&self) -> Option<&str> {
+        self.subtitle.as_deref()
+    }
+
+    /// Date.
+    pub fn date(&self) -> Option<&str> {
+        self.date.as_deref()
+    }
+
+    /// Authors.
+    pub fn authors(&self) -> Option<&[String]> {
+        self.authors.as_deref()
+    }
+
+    /// Names of bindings files.
+    pub fn bindings_filenames(&self) -> Option<&[PathBuf]> {
+        self.bindings.as_deref()
+    }
+
+    /// Impls section.
+    pub fn impls(&self) -> &BTreeMap<String, Vec<PathBuf>> {
+        &self.impls
+    }
+
+    /// Bibliographies.
+    pub fn bibliographies(&self) -> Option<&[PathBuf]> {
+        self.bibliography.as_deref()
+    }
+
+    /// Classes..
+    pub fn classes(&self) -> Option<&[String]> {
+        self.classes.as_deref()
+    }
+
+    /// Documentclass.
+    pub fn documentclass(&self) -> Option<&str> {
+        self.documentclass.as_deref()
+    }
+
+    /// Pandoc metadata.
+    pub fn pandoc(&self) -> Option<&HashMap<String, Value>> {
+        if let Some(x) = &self.pandoc {
+            Some(x)
+        } else {
+            None
+        }
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::YamlMetadata;
+    use std::path::{Path, PathBuf};
+
+    #[test]
+    fn full_meta() {
+        let meta = YamlMetadata::new(
+            "\
+title: Foo Bar
+date: today
+classes: [json, text]
+impls:
+  python:
+   - foo.py
+   - bar.py
+bibliography:
+- foo.bib
+- bar.bib
+markdowns:
+- test.md
+bindings:
+- foo.yaml
+- bar.yaml
+",
+        )
+        .unwrap();
+        assert_eq!(meta.title, "Foo Bar");
+        assert_eq!(meta.date.unwrap(), "today");
+        assert_eq!(meta.classes.unwrap(), &["json", "text"]);
+        assert_eq!(
+            meta.bibliography.unwrap(),
+            &[path("foo.bib"), path("bar.bib")]
+        );
+        assert_eq!(meta.markdowns, vec![Path::new("test.md")]);
+        assert_eq!(
+            meta.bindings.unwrap(),
+            &[path("foo.yaml"), path("bar.yaml")]
+        );
+        assert!(!meta.impls.is_empty());
+        for (k, v) in meta.impls.iter() {
+            assert_eq!(k, "python");
+            assert_eq!(v, &[path("foo.py"), path("bar.py")]);
+        }
+    }
+
+    fn path(s: &str) -> PathBuf {
+        PathBuf::from(s)
+    }
+}
+
 /// Metadata of a document, as needed by Subplot.
 #[derive(Debug)]
 pub struct Metadata {