feat: add latest field to package metadata (#45)

Fixes denoland/registry3#645

api/src/ids.rs

@@ -349,7 +349,7 @@ impl serde::Serialize for ScopedPackageName {
 /// A package version, like '1.2.3' or '0.0.0-foo'. The version is not prefixed
 /// with a v.
 /// The version must be a valid semver version.
-#[derive(Clone, PartialEq, Eq, Hash)]
+#[derive(Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
 pub struct Version(pub deno_semver::Version);
 
 impl Version {

api/src/metadata.rs

@@ -30,6 +30,7 @@ use std::collections::HashMap;
 pub struct PackageMetadata {
   pub scope: ScopeName,
   pub name: PackageName,
+  pub latest: Option<Version>,
   pub versions: HashMap<Version, PackageMetadataVersion>,
 }
 
@@ -39,10 +40,16 @@ impl PackageMetadata {
     scope: &ScopeName,
     package_name: &PackageName,
   ) -> anyhow::Result<Self> {
-    let versions = db.list_package_versions(scope, package_name).await?;
+    let mut versions = db.list_package_versions(scope, package_name).await?;
+    versions.sort_by(|(a, _), (b, _)| b.version.cmp(&a.version));
+    let latest = versions
+      .iter()
+      .find(|(v, _)| !v.is_yanked && v.version.0.pre.is_empty())
+      .map(|(v, _)| v.version.clone());
     let mut out = Self {
       scope: scope.to_owned(),
       name: package_name.to_owned(),
+      latest,
       versions: HashMap::new(),
     };
     for (version, _) in versions {

api/src/publish.rs

@@ -764,6 +764,7 @@ pub mod tests {
       serde_json::from_slice(&json).unwrap()
     };
     assert_eq!(package_metadata.name, package_name);
+    assert_eq!(package_metadata.latest, Some(version));
     assert_eq!(package_metadata.versions.len(), 1);
   }