vendor assets with versionning

src/assets.rs

@@ -0,0 +1,79 @@
+use std::collections::HashMap;
+use std::sync::LazyLock;
+
+use sha2::{Digest, Sha256};
+
+/// A single static asset: its embedded bytes and a content hash used to
+/// version its URL.
+pub struct StaticAsset {
+    pub data: &'static [u8],
+    pub hash: String,
+}
+
+/// A registry of the app's static assets, keyed by filename. Each asset's
+/// content hash is computed once on first use and cached, so the versioned URL
+/// changes automatically whenever the underlying file changes.
+pub struct StaticAssetStore {
+    assets: HashMap<&'static str, StaticAsset>,
+}
+
+impl StaticAssetStore {
+    fn new(entries: &[(&'static str, &'static [u8])]) -> Self {
+        let assets = entries
+            .iter()
+            .map(|(name, data)| {
+                let hash = content_hash(data);
+                (*name, StaticAsset { data, hash })
+            })
+            .collect();
+        Self { assets }
+    }
+
+    /// Looks up an asset by its filename (e.g. `"style.css"`).
+    pub fn get(&self, name: &str) -> Option<&StaticAsset> {
+        self.assets.get(name)
+    }
+
+    /// Returns the versioned URL for an asset, e.g. `/static/style.css?v=<hash>`.
+    pub fn url(&self, name: &str) -> Option<String> {
+        self.assets
+            .get(name)
+            .map(|asset| format!("/static/{name}?v={}", asset.hash))
+    }
+}
+
+fn content_hash(data: &[u8]) -> String {
+    let mut hasher = Sha256::new();
+    hasher.update(data);
+    hex::encode(hasher.finalize())
+}
+
+/// Constructs a `StaticAssetStore` from `name => path` pairs, embedding each
+/// file's bytes at compile time via `include_bytes!`.
+macro_rules! static_assets {
+    ($($name:literal => $path:literal),* $(,)?) => {
+        StaticAssetStore::new(&[
+            $(($name, include_bytes!($path))),*
+        ])
+    };
+}
+
+/// The app's static assets, loaded once on first use.
+pub static STORE: LazyLock<StaticAssetStore> = LazyLock::new(|| {
+    static_assets! {
+        "style.css" => "../static/style.css",
+        "passkey-login.js" => "../static/passkey-login.js",
+        "passkey-register.js" => "../static/passkey-register.js",
+        "password-toggle.js" => "../static/password-toggle.js",
+        "htmx.min.js" => "../static/htmx.min.js",
+        "htmx-ws.min.js" => "../static/htmx-ws.min.js",
+    }
+});
+
+/// Returns the versioned URL for a known asset, panicking if the name isn't
+/// registered (a programmer error, since these are compile-time constants).
+pub fn url(name: &str) -> String {
+    STORE
+        .url(name)
+        .unwrap_or_else(|| panic!("unknown static asset: {name}"))
+}