make it a webapp

src/nightlies.rs

@@ -0,0 +1,66 @@
+use std::collections::HashSet;
+use std::hash::RandomState;
+
+use color_eyre::eyre::Context;
+use color_eyre::Result;
+use tracing::debug;
+
+const EARLIEST_CUTOFF_DATE: &str = "2023-01-01";
+
+/// All nightlies that exist.
+pub struct Nightlies {
+    all: Vec<String>,
+}
+
+impl Nightlies {
+    pub async fn fetch() -> Result<Nightlies> {
+        let manifests = reqwest::get("https://static.rust-lang.org/manifests.txt")
+            .await
+            .wrap_err("fetching https://static.rust-lang.org/manifests.txt")?
+            .text()
+            .await
+            .wrap_err("fetching body of https://static.rust-lang.org/manifests.txt")?;
+        let mut all = nightlies_from_manifest(&manifests)
+            .into_iter()
+            .filter(|date| date.as_str() > EARLIEST_CUTOFF_DATE)
+            .collect::<Vec<_>>();
+        all.sort_by(|a, b| b.cmp(a));
+        debug!("Loaded {} nightlies from the manifest", all.len());
+        Ok(Self { all })
+    }
+
+    pub fn select_latest_to_build(&self, already_finished: &[String]) -> Option<String> {
+        let already_finished = HashSet::<_, RandomState>::from_iter(already_finished.iter());
+
+        self.all
+            .iter()
+            .find(|nightly| !already_finished.contains(nightly))
+            .cloned()
+    }
+}
+
+fn nightlies_from_manifest(manifest: &str) -> Vec<String> {
+    manifest
+        .lines()
+        .filter_map(|line| {
+            let rest = line.strip_prefix("static.rust-lang.org/dist/")?;
+            let date = rest.strip_suffix("/channel-rust-nightly.toml")?;
+
+            Some(date.to_owned())
+        })
+        .collect()
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn manifest_parse() {
+        let test_manifest = "static.rust-lang.org/dist/2024-08-22/channel-rust-nightly.toml
+static.rust-lang.org/dist/2024-08-22/channel-rust-1.81.0-beta.toml
+static.rust-lang.org/dist/2024-08-22/channel-rust-1.81.0-beta.6.toml
+static.rust-lang.org/dist/2024-08-23/channel-rust-nightly.toml";
+
+        let nightlies = super::nightlies_from_manifest(&test_manifest);
+        assert_eq!(nightlies, vec!["2024-08-22", "2024-08-23"]);
+    }
+}