feat(fastapi): add /pkgbase/{name}/merge (post)

Changes:

- `via` is not required in FastAPI. We deduce the involved
  requests via their PackageBaseName / MergeBaseName columns
  and set them to Accepted when merged.
- When erroneous input is given, the error is now presented
  on the merge page instead of sending the user to the pkgbase
  page.

Signed-off-by: Kevin Morris <kevr@0cost.org>

aurweb/routers/packages.py

@@ -13,7 +13,7 @@ from aurweb import db, defaults, l10n, logging, models, util
 from aurweb.auth import auth_required
 from aurweb.models.package_request import ACCEPTED_ID, PENDING_ID, REJECTED_ID
 from aurweb.models.relation_type import CONFLICTS_ID
-from aurweb.models.request_type import DELETION_ID
+from aurweb.models.request_type import DELETION_ID, MERGE, MERGE_ID
 from aurweb.packages.search import PackageSearch
 from aurweb.packages.util import get_pkg_or_base, get_pkgbase_comment, query_notified, query_voted
 from aurweb.scripts import notify, popupdate
@@ -1053,6 +1053,7 @@ async def pkgbase_delete_post(request: Request, name: str,
         return render_template(request, "packages/delete.html", context,
                                status_code=HTTPStatus.BAD_REQUEST)
 
+    # Obtain deletion locks and delete the packages.
     packages = pkgbase.packages.all()
     for package in packages:
         delete_package(request.user, package)
@@ -1343,3 +1344,137 @@ async def pkgbase_merge_get(request: Request, name: str,
 
     return render_template(request, "pkgbase/merge.html", context,
                            status_code=status_code)
+
+
+def pkgbase_merge_instance(request: Request, pkgbase: models.PackageBase,
+                           target: models.PackageBase):
+    pkgbasename = str(pkgbase.Name)
+
+    # Collect requests related to this merge.
+    query = pkgbase.requests.filter(
+        models.PackageRequest.ReqTypeID == MERGE_ID
+    )
+
+    requests = query.filter(
+        models.PackageRequest.MergeBaseName == target.Name).all()
+    reject_requests = query.filter(
+        models.PackageRequest.MergeBaseName != target.Name).all()
+
+    notifs = []  # Used to keep track of notifications over the function.
+    closure_comment = (f"Merged into package base {target.Name} by "
+                       f"{request.user.Username}.")
+    rejected_closure_comment = ("Rejected because another merge request "
+                                "for the same package base was accepted.")
+    conn = db.ConnectionExecutor(db.get_engine().raw_connection())
+    if not requests:
+        # If there are no requests, create one owned by request.user.
+        with db.begin():
+            pkgreq = db.create(models.PackageRequest,
+                               ReqTypeID=MERGE_ID,
+                               User=request.user,
+                               PackageBase=pkgbase,
+                               PackageBaseName=pkgbasename,
+                               MergeBaseName=target.Name,
+                               Comments="Generated by aurweb.",
+                               Status=ACCEPTED_ID,
+                               ClosureComment=closure_comment)
+            requests.append(pkgreq)
+
+        # Add a notification about the opening to our notifs array.
+        notif = notify.RequestOpenNotification(
+            conn, request.user.ID, pkgreq.ID, MERGE,
+            pkgbase.ID, merge_into=target.Name)
+        notifs.append(notif)
+
+        with db.begin():
+            # Merge pkgbase's comments, notifications and votes into target.
+            for comment in pkgbase.comments:
+                comment.PackageBase = target
+            for notif in pkgbase.notifications:
+                notif.PackageBase = target
+            for vote in pkgbase.package_votes:
+                vote.PackageBase = target
+
+        with db.begin():
+            # Delete pkgbase and its packages now that everything's merged.
+            for pkg in pkgbase.packages:
+                db.session.delete(pkg)
+            db.session.delete(pkgbase)
+
+            # Accept merge requests related to this pkgbase and target.
+            for pkgreq in requests:
+                pkgreq.Status = ACCEPTED_ID
+                pkgreq.ClosureComment = closure_comment
+                pkgreq.Closer = request.user
+
+            for pkgreq in reject_requests:
+                pkgreq.Status = REJECTED_ID
+                pkgreq.ClosureComment = rejected_closure_comment
+                pkgreq.Closer = request.user
+
+    all_requests = requests + reject_requests
+    for pkgreq in all_requests:
+        # Create notifications for request closure.
+        notif = notify.RequestCloseNotification(
+            conn, request.user.ID, pkgreq.ID, pkgreq.status_display())
+        notifs.append(notif)
+
+    conn.close()
+
+    # Log this out for accountability purposes.
+    logger.info(f"Trusted User '{request.user.Username}' merged "
+                f"'{pkgbasename}' into '{target.Name}'.")
+
+    # Send our notifications array.
+    util.apply_all(notifs, lambda n: n.send())
+
+
+@router.post("/pkgbase/{name}/merge")
+@auth_required(redirect="/pkgbase/{name}/merge")
+async def pkgbase_merge_post(request: Request, name: str,
+                             into: str = Form(default=str()),
+                             confirm: bool = Form(default=False),
+                             next: str = Form(default=str())):
+
+    pkgbase = get_pkg_or_base(name, models.PackageBase)
+    context = await make_variable_context(request, "Package Merging")
+    context["pkgbase"] = pkgbase
+
+    # TODO: Lookup errors from credential instead of hardcoding them.
+    if not request.user.has_credential("CRED_PKGBASE_MERGE"):
+        context["errors"] = [
+            "Only Trusted Users and Developers can merge packages."]
+        return render_template(request, "pkgbase/merge.html", context,
+                               status_code=HTTPStatus.UNAUTHORIZED)
+
+    if not confirm:
+        context["errors"] = ["The selected packages have not been deleted, "
+                             "check the confirmation checkbox."]
+        return render_template(request, "pkgbase/merge.html", context,
+                               status_code=HTTPStatus.BAD_REQUEST)
+
+    try:
+        target = get_pkg_or_base(into, models.PackageBase)
+    except HTTPException:
+        context["errors"] = [
+            "Cannot find package to merge votes and comments into."]
+        return render_template(request, "pkgbase/merge.html", context,
+                               status_code=HTTPStatus.BAD_REQUEST)
+
+    if pkgbase == target:
+        context["errors"] = ["Cannot merge a package base with itself."]
+        return render_template(request, "pkgbase/merge.html", context,
+                               status_code=HTTPStatus.BAD_REQUEST)
+
+    # Merge pkgbase into target.
+    pkgbase_merge_instance(request, pkgbase, target)
+
+    # Run popupdate on the target.
+    conn = db.ConnectionExecutor(db.get_engine().raw_connection())
+    popupdate.run_single(conn, target)
+
+    if not next:
+        next = f"/pkgbase/{target.Name}"
+
+    # Redirect to the newly merged into package.
+    return RedirectResponse(next, status_code=HTTPStatus.SEE_OTHER)