Add /gh-changes-since endpoint

Author: Urgau

src/gh_changes_since.rs

@@ -0,0 +1,76 @@
+use std::sync::Arc;
+
+use anyhow::Context as _;
+use axum::{
+    extract::{Path, State},
+    response::{IntoResponse, Redirect, Response},
+};
+use hyper::StatusCode;
+
+use crate::{github, handlers::Context, utils::AppError};
+
+/// Redirects to either `/gh-range-diff` (when the base changed) or to GitHub's compare
+/// page (when the base is the same).
+///
+/// Takes an PR number and an `oldbase..oldhead` representing the range we are starting from.
+pub async fn gh_changes_since(
+    Path((owner, repo, pr_num, oldbasehead)): Path<(String, String, u64, String)>,
+    State(ctx): State<Arc<Context>>,
+) -> axum::response::Result<Response, AppError> {
+    let Some((oldbase, oldhead)) = oldbasehead.split_once("..") else {
+        return Ok((
+            StatusCode::BAD_REQUEST,
+            format!("`{oldbasehead}` is not in the form `base..head`"),
+        )
+            .into_response());
+    };
+
+    let repos = ctx
+        .team
+        .repos()
+        .await
+        .context("unable to retrieve team repos")?;
+
+    // Verify that the request org is part of the Rust project
+    let Some(repos) = repos.repos.get(&owner) else {
+        return Ok((
+            StatusCode::BAD_REQUEST,
+            format!("organization `{owner}` is not part of the Rust Project team repos"),
+        )
+            .into_response());
+    };
+
+    // Verify that the request repo is part of the Rust project
+    if !repos.iter().any(|r| r.name == repo) {
+        return Ok((
+            StatusCode::BAD_REQUEST,
+            format!("repository `{owner}` is not part of the Rust Project team repos"),
+        )
+            .into_response());
+    }
+
+    let issue_repo = github::IssueRepository {
+        organization: owner.to_string(),
+        repository: repo.to_string(),
+    };
+
+    let pr = ctx.github.pull_request(&issue_repo, pr_num).await?;
+
+    let newbase = &pr.base.as_ref().context("no base")?.sha;
+    let newhead = &pr.head.as_ref().context("no head")?.sha;
+
+    // Has the base changed?
+    if oldbase == newbase {
+        // No, redirect to GitHub native compare page
+        return Ok(Redirect::to(&format!(
+            "https://github.com/{owner}/{repo}/compare/{oldhead}..{newhead}"
+        ))
+        .into_response());
+    }
+
+    // Yes, use our Github range-diff instead
+    Ok(Redirect::to(&format!(
+        "/gh-range-diff/{owner}/{repo}/{oldbase}..{oldhead}/{newbase}..{newhead}"
+    ))
+    .into_response())
+}

src/github.rs

@@ -270,6 +270,16 @@ impl GithubClient {
             .await
             .context("failed to retrive the compare")
     }
+
+    pub async fn pull_request(&self, repo: &IssueRepository, pr_num: u64) -> anyhow::Result<Issue> {
+        let url = format!("{}/pulls/{pr_num}", repo.url(&self));
+        let mut pr: Issue = self
+            .json(self.get(&url))
+            .await
+            .with_context(|| format!("{repo} failed to get pr {pr_num}"))?;
+        pr.pull_request = Some(PullRequestDetails::new());
+        Ok(pr)
+    }
 }
 
 #[derive(Debug, serde::Serialize)]
@@ -1982,13 +1992,15 @@ impl Repository {
     }
 
     pub async fn get_pr(&self, client: &GithubClient, pr_num: u64) -> anyhow::Result<Issue> {
-        let url = format!("{}/pulls/{pr_num}", self.url(client));
-        let mut pr: Issue = client
-            .json(client.get(&url))
+        client
+            .pull_request(
+                &IssueRepository {
+                    organization: self.owner().to_string(),
+                    repository: self.name().to_string(),
+                },
+                pr_num,
+            )
             .await
-            .with_context(|| format!("{} failed to get pr {pr_num}", self.full_name))?;
-        pr.pull_request = Some(PullRequestDetails::new());
-        Ok(pr)
     }
 
     /// Fetches information about merge conflicts on open PRs.

src/lib.rs

@@ -6,6 +6,7 @@ pub mod bors;
 mod changelogs;
 mod config;
 pub mod db;
+pub mod gh_changes_since;
 pub mod gh_range_diff;
 pub mod gha_logs;
 pub mod github;

src/main.rs

@@ -193,6 +193,10 @@ async fn run_server(addr: SocketAddr) -> anyhow::Result<()> {
             "/gh-range-diff/{owner}/{repo}/{oldbasehead}/{newbasehead}",
             get(triagebot::gh_range_diff::gh_ranges_diff),
         )
+        .route(
+            "/gh-changes-since/{owner}/{repo}/{pr}/{oldbasehead}",
+            get(triagebot::gh_changes_since::gh_changes_since),
+        )
         .nest("/agenda", agenda)
         .route("/bors-commit-list", get(triagebot::bors::bors_commit_list))
         .route(