feat: update authored pull branches from mobile (Closes #1360)

src/gitea_proxy.py

@@ -173,6 +173,10 @@ class IssueEditConflictError(ValueError):
     """Raised when an issue changed after the editor loaded it."""
 
 
+class PullUpdateConflictError(ValueError):
+    """Raised when Gitea cannot merge a pull request's base into its head."""
+
+
 class IssueDependencyInvalidError(ValueError):
     """Raised when a requested blocker relationship is not valid."""
 
@@ -2089,6 +2093,58 @@ async def reopen_authored_pull(
     )
 
 
+async def update_authored_pull_branch(
+    repository: str, number: int, expected_head_sha: str
+) -> dict:
+    login, pull = await _current_login_and_target(
+        f"repos/{repository}/pulls/{number}"
+    )
+    author = pull.get("user") if isinstance(pull.get("user"), dict) else {}
+    head = pull.get("head") if isinstance(pull.get("head"), dict) else {}
+    if (
+        pull.get("state") != "open"
+        or pull.get("merged") is True
+        or pull.get("draft") is True
+        or author.get("login", "").casefold() != login.casefold()
+        or head.get("sha") != expected_head_sha
+    ):
+        raise IssueNotAvailableError("Pull request state changed")
+    response = await _get_client().post(
+        f"/api/v1/repos/{repository}/pulls/{number}/update",
+        headers=_auth(),
+        params={"style": "merge"},
+    )
+    if response.status_code in {409, 422}:
+        raise PullUpdateConflictError("Pull request has merge conflicts")
+    response.raise_for_status()
+    confirmed_response = await _get_client().get(
+        f"/api/v1/repos/{repository}/pulls/{number}", headers=_auth()
+    )
+    confirmed_response.raise_for_status()
+    confirmed = confirmed_response.json()
+    confirmed_head = confirmed.get("head") if isinstance(confirmed, dict) and isinstance(confirmed.get("head"), dict) else {}
+    new_head_sha = confirmed_head.get("sha")
+    if (
+        not isinstance(confirmed, dict)
+        or confirmed.get("number") != number
+        or confirmed.get("state") != "open"
+        or confirmed.get("merged") is True
+        or not isinstance(new_head_sha, str)
+        or not new_head_sha
+        or new_head_sha == expected_head_sha
+    ):
+        raise ValueError("Gitea did not confirm a new pull request head")
+    return {
+        "repository": repository,
+        "number": number,
+        "title": confirmed.get("title", ""),
+        "previous_head_sha": expected_head_sha,
+        "head_sha": new_head_sha,
+        "state": "open",
+        "draft": confirmed.get("draft") is True,
+    }
+
+
 async def request_assigned_pull_review(
     repository: str, number: int, reviewer: str, expected_head_sha: str
 ) -> dict:

src/main.py

@@ -6721,6 +6721,40 @@ async def reopen_authored_pull(
     )
 
 
+@app.post("/api/v1/repos/{owner}/{repo}/pulls/{number}/update-branch")
+async def update_authored_pull_branch(
+    update: PullReadyRequest,
+    owner: str,
+    repo: str,
+    number: int = PathParam(gt=0),
+):
+    repository = f"{owner}/{repo}"
+    try:
+        result = await asyncio.wait_for(
+            gitea_proxy.update_authored_pull_branch(
+                repository, number, update.expected_head_sha
+            ),
+            timeout=ISSUE_ACTION_TIMEOUT_SECONDS,
+        )
+    except gitea_proxy.IssueNotAvailableError:
+        return JSONResponse(
+            {"error": "The pull request changed. Reload the latest state before updating its branch."},
+            status_code=409,
+        )
+    except gitea_proxy.PullUpdateConflictError:
+        return JSONResponse(
+            {"error": "Automatic branch update is unavailable because the branches have conflicts."},
+            status_code=422,
+        )
+    except Exception:
+        return JSONResponse(
+            {"error": "The branch could not be updated. Please retry."},
+            status_code=503,
+            headers={"Retry-After": "1"},
+        )
+    return JSONResponse(result)
+
+
 @app.get("/api/v1/repos/{owner}/{repo}/pulls/{number}/review-data")
 async def assigned_pull_review_data(
     owner: str, repo: str, number: int = PathParam(gt=0)