From 254998a56180556f507e2ca7b2a93d126c8f8f28 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ludovic=20Court=C3=A8s?= <ludo@gnu.org>
Date: Tue, 27 May 2025 11:44:19 +0200
Subject: [PATCH] forgejo: Support deletion of branches when a pull request is
 closed.

---
 guix-data-service/forgejo.scm                | 22 +++++++++++++++++++-
 guix-data-service/web/forgejo/controller.scm |  2 +-
 tests/forgejo.scm                            |  8 ++++++-
 3 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/guix-data-service/forgejo.scm b/guix-data-service/forgejo.scm
index 5649a6b..f149529 100644
--- a/guix-data-service/forgejo.scm
+++ b/guix-data-service/forgejo.scm
@@ -43,7 +43,8 @@
             forgejo-pull-request-draft?
             forgejo-pull-request-body
 
-            enqueue-job-for-pull-request))
+            enqueue-job-for-pull-request
+            mark-pull-request-branch-for-deletion))
 
 ;; The JSON data structures below were copied from Cuirass.
 
@@ -125,3 +126,22 @@
 
         (enqueue-load-new-guix-revision-job conn repository-id
                                             commit label))))
+
+(define (mark-pull-request-branch-for-deletion conn pull-request)
+  "Mark the branch associated with @var{pull-request}, a pull request being
+closed, for deletion."
+  (let* ((url (forgejo-pull-request-url pull-request))
+         (repository-id (git-repository-url->git-repository-id
+                         conn url #:create-if-missing? #f)))
+    (when repository-id
+      (let* ((date (time-utc->date (current-time time-utc)))
+             (reference (forgejo-pull-request-head pull-request))
+             (branch (forgejo-repository-reference-ref reference))
+             (branch-id (git-branch-for-repository-and-name
+                         conn repository-id branch)))
+        (when branch-id
+          ;; Insert a commit entry with the empty string: this is interpreted
+          ;; as BRANCH-ID being a candidate for deletion.
+          (format #t "marking pull request branch ~s of ~s for deletion~%"
+                  branch url)
+          (insert-git-commit-entry conn branch-id "" date))))))
diff --git a/guix-data-service/web/forgejo/controller.scm b/guix-data-service/web/forgejo/controller.scm
index b77efd1..28df2f6 100644
--- a/guix-data-service/web/forgejo/controller.scm
+++ b/guix-data-service/web/forgejo/controller.scm
@@ -74,7 +74,7 @@
                       ('synchronized              ;pull request is updated
                        (enqueue-job-for-pull-request conn pull-request))
                       ('closed                    ;closed or merged
-                       #f)
+                       (mark-pull-request-branch-for-deletion conn pull-request))
                       (_                          ;other action
                        (render-json '((error . "unknown action"))
                                     #:code 404)))))))
diff --git a/tests/forgejo.scm b/tests/forgejo.scm
index 5c41aad..3716c48 100644
--- a/tests/forgejo.scm
+++ b/tests/forgejo.scm
@@ -127,7 +127,13 @@
           (enqueue-job-for-pull-request conn pull)))
 
       (test-assert "git-commit-exists?, new commit"
-        (git-commit-exists? conn pull-request-new-commit)))
+        (git-commit-exists? conn pull-request-new-commit))
+
+      (test-assert "mark-pull-request-branch-for-deletion"
+        (let* ((event (json->forgejo-pull-request-event
+                       pull-request-event-json))
+               (pull (forgejo-pull-request-event-pull-request event)))
+          (mark-pull-request-branch-for-deletion conn pull))))
 
     #:always-rollback? #t)))