do semver magic

src/main.rs

@@ -1,7 +1,11 @@
 use std::fs;
 
-use color_eyre::{eyre::WrapErr, Result};
-use tracing::{debug, info, metadata::LevelFilter};
+use color_eyre::{
+    eyre::{bail, WrapErr},
+    Result,
+};
+use semver_rs::{Range, Version};
+use tracing::{debug, info, metadata::LevelFilter, warn};
 use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt, EnvFilter, Registry};
 
 use crate::{download::NpmClient, manifest::PackageJson};
@@ -22,19 +26,36 @@ fn main() -> Result<()> {
 
     let client = NpmClient::new();
 
-    for (name, _) in &manifest.dependencies.unwrap() {
-        look_at_package(name, &client)?;
+    for (name, requested_version) in &manifest.dependencies.unwrap() {
+        look_at_package(name, requested_version, &client).wrap_err(format!("package {name}"))?;
     }
 
     Ok(())
 }
 
 #[tracing::instrument(skip(client))]
-fn look_at_package(name: &str, client: &NpmClient) -> Result<()> {
+fn look_at_package(name: &str, requested_version: &str, client: &NpmClient) -> Result<()> {
+    let requested = Range::new(requested_version).parse()?;
+
     let meta = client.inspect_package(name)?;
 
-    for version in meta.versions.keys() {
-        info!(%version);
+    info!(versions = ?meta.versions.keys());
+
+    let mut versions = meta
+        .versions
+        .keys()
+        .map(|v| Ok((v, Version::new(v).parse()?)))
+        .collect::<Result<Vec<_>, semver_rs::Error>>()?;
+
+    versions.sort_by(|a, b| b.cmp(a));
+
+    let chosen = versions.iter().find(|(_, version)| requested.test(version));
+
+    match chosen {
+        Some((version, _)) => {
+            info!(?version, "Found version")
+        }
+        None => bail!("could not find matching version for '{requested_version}'"),
     }
 
     Ok(())