add support for thumbnails

content/programming/unreal-engine/fixes.tree

@@ -1,5 +1,6 @@
 %% title = "new in Unreal Engine 5.4: data validation quick fixes"
-   thumbnail = "01HP1G5WC29GP4KQY1NV1F1RR1"
+   thumbnail.id = "01HP1G5WC29GP4KQY1NV1F1RR1"
+   thumbnail.alt = "a screenshot with a validation error in it; beneath the error there's a hint that it may be fixed automatically, coupled with a link you can click on to fix the issue"
 
 % id = "01HP1FESY3H9K1QVSM1XMNC8NS"
 - a few days ago I got a really cool change into Unreal, which allows you to add quick fixes to any data validation warning/error you emit:

crates/treehouse/src/cli/generate.rs

@@ -24,7 +24,7 @@ use crate::{
         tree::branches_to_html,
     },
     state::Source,
-    tree::{attributes::RootAttributes, SemaRoots},
+    tree::SemaRoots,
 };
 
 use crate::state::{FileId, Treehouse};
@@ -107,7 +107,11 @@ impl Generator {
         Ok(())
     }
 
-    fn parse_trees(&self, paths: &Paths<'_>) -> anyhow::Result<(Treehouse, Vec<ParsedTree>)> {
+    fn parse_trees(
+        &self,
+        config: &Config,
+        paths: &Paths<'_>,
+    ) -> anyhow::Result<(Treehouse, Vec<ParsedTree>)> {
         let mut treehouse = Treehouse::new();
         let mut parsed_trees = vec![];
 
@@ -148,7 +152,7 @@ impl Generator {
             );
 
             if let Ok(roots) = parse_tree_with_diagnostics(&mut treehouse, file_id) {
-                let roots = SemaRoots::from_roots(&mut treehouse, file_id, roots);
+                let roots = SemaRoots::from_roots(&mut treehouse, config, file_id, roots);
                 treehouse.roots.insert(tree_path.clone(), roots);
                 parsed_trees.push(ParsedTree {
                     tree_path,
@@ -197,11 +201,18 @@ impl Generator {
             #[derive(Serialize)]
             pub struct Page {
                 pub title: String,
+                pub thumbnail: Option<Thumbnail>,
                 pub breadcrumbs: String,
                 pub tree_path: Option<String>,
                 pub tree: String,
             }
 
+            #[derive(Serialize)]
+            pub struct Thumbnail {
+                pub url: String,
+                pub alt: Option<String>,
+            }
+
             #[derive(Serialize)]
             pub struct TemplateData<'a> {
                 pub config: &'a Config,
@@ -211,6 +222,22 @@ impl Generator {
                 config,
                 page: Page {
                     title: roots.attributes.title.clone(),
+                    thumbnail: roots
+                        .attributes
+                        .thumbnail
+                        .as_ref()
+                        .map(|thumbnail| Thumbnail {
+                            url: format!(
+                                "{}/static/pic/{}",
+                                config.site,
+                                config
+                                    .pics
+                                    .get(&thumbnail.id)
+                                    .map(|x| &**x)
+                                    .unwrap_or("404.png")
+                            ),
+                            alt: thumbnail.alt.clone(),
+                        }),
                     breadcrumbs,
                     tree_path: treehouse
                         .tree_path(parsed_tree.file_id)
@@ -268,7 +295,7 @@ pub fn generate(paths: &Paths<'_>) -> anyhow::Result<Treehouse> {
     info!("parsing tree");
     let mut generator = Generator::default();
     generator.add_directory_rec(paths.content_dir)?;
-    let (mut treehouse, parsed_trees) = generator.parse_trees(paths)?;
+    let (mut treehouse, parsed_trees) = generator.parse_trees(&config, paths)?;
 
     info!("generating navigation map");
     let navigation_map = build_navigation_map(&treehouse, "index");

crates/treehouse/src/tree/attributes.rs

@@ -15,7 +15,18 @@ pub struct RootAttributes {
 
     /// ID of picture attached to the page, to be used as a thumbnail.
     #[serde(default)]
-    pub thumbnail: Option<String>,
+    pub thumbnail: Option<Picture>,
+}
+
+/// A picture reference.
+#[derive(Debug, Default, Clone, PartialEq, Eq, Deserialize, Serialize)]
+pub struct Picture {
+    /// ID of the picture.
+    pub id: String,
+
+    /// Optional alt text.
+    #[serde(default)]
+    pub alt: Option<String>,
 }
 
 /// Branch attributes.

crates/treehouse/src/tree/mod.rs

@@ -9,6 +9,7 @@ use treehouse_format::{
 };
 
 use crate::{
+    config::Config,
     state::{toml_error_to_diagnostic, FileId, Source, TomlError, Treehouse},
     tree::attributes::{Attributes, Content},
 };
@@ -42,9 +43,14 @@ pub struct SemaRoots {
 }
 
 impl SemaRoots {
-    pub fn from_roots(treehouse: &mut Treehouse, file_id: FileId, roots: Roots) -> Self {
+    pub fn from_roots(
+        treehouse: &mut Treehouse,
+        config: &Config,
+        file_id: FileId,
+        roots: Roots,
+    ) -> Self {
         Self {
-            attributes: Self::parse_attributes(treehouse, file_id, &roots),
+            attributes: Self::parse_attributes(treehouse, config, file_id, &roots),
             branches: roots
                 .branches
                 .into_iter()
@@ -55,6 +61,7 @@ impl SemaRoots {
 
     fn parse_attributes(
         treehouse: &mut Treehouse,
+        config: &Config,
         file_id: FileId,
         roots: &Roots,
     ) -> RootAttributes {
@@ -88,6 +95,44 @@ impl SemaRoots {
             }
         }
 
+        if let Some(thumbnail) = &attributes.thumbnail {
+            if thumbnail.alt.is_none() {
+                treehouse.diagnostics.push(Diagnostic {
+                    severity: Severity::Warning,
+                    code: Some("sema".into()),
+                    message: "thumbnail without alt text".into(),
+                    labels: vec![Label {
+                        style: LabelStyle::Primary,
+                        file_id,
+                        range: roots.attributes.as_ref().unwrap().percent.clone(),
+                        message: "".into(),
+                    }],
+                    notes: vec![
+                        "note: alt text is important for people using screen readers".into(),
+                        "help: add alt text using the thumbnail.alt key".into(),
+                    ],
+                })
+            }
+
+            if !config.pics.contains_key(&thumbnail.id) {
+                treehouse.diagnostics.push(Diagnostic {
+                    severity: Severity::Warning,
+                    code: Some("sema".into()),
+                    message: format!(
+                        "thumbnail picture with id '{}' does not exist",
+                        thumbnail.id
+                    ),
+                    labels: vec![Label {
+                        style: LabelStyle::Primary,
+                        file_id,
+                        range: roots.attributes.as_ref().unwrap().percent.clone(),
+                        message: "".into(),
+                    }],
+                    notes: vec!["note: check your id for typos".into()],
+                })
+            }
+        }
+
         attributes
     }
 }

template/tree.hbs

@@ -18,6 +18,10 @@
     It just needs to be a string replacement.
     --}}
     <!-- treehouse-ca37057a-cff5-45b3-8415-3b02dbf6c799-per-branch-metadata -->
+    {{#if page.thumbnail}}
+    <meta property="og:image" content="{{ page.thumbnail.url }}">
+    <meta property="og:image:alt" content="{{ page.thumbnail.alt }}">
+    {{/if}}
 
     <link rel="stylesheet" href="{{ config.site }}/static/css/main.css">
     <link rel="stylesheet" href="{{ config.site }}/static/css/tree.css">