rfc-app/backend/app/gitea.py

"""Thin HTTP client for the Gitea REST API.

Read operations live here and are called from any module that needs them
(reconciler, super-draft body fetch, webhook handler). Write operations
also live here but are not called directly from outside this module —
they are wrapped by `bot.py` per §1, so that every commit, branch, and
PR carries the §6.5 On-behalf-of trailer and a row in the actions log.

This split keeps the chokepoint legible: anything that wants to read
imports from here; anything that wants to write imports from `bot.py`
and never reaches around it.
"""
from __future__ import annotations

import asyncio
import base64
import logging
from typing import Any

import httpx

from .config import Config

log = logging.getLogger(__name__)


class GiteaError(Exception):
    def __init__(self, status: int, detail: str):
        super().__init__(f"Gitea {status}: {detail}")
        self.status = status
        self.detail = detail


class Gitea:
    def __init__(self, config: Config):
        self._config = config
        self._client = httpx.AsyncClient(
            base_url=f"{config.gitea_url}/api/v1",
            headers={
                "Authorization": f"token {config.gitea_bot_token}",
                "Accept": "application/json",
            },
            timeout=30.0,
        )

    async def close(self) -> None:
        await self._client.aclose()

    async def _request(self, method: str, path: str, **kwargs: Any) -> httpx.Response:
        resp = await self._client.request(method, path, **kwargs)
        if resp.status_code >= 400:
            try:
                detail = resp.json().get("message", resp.text)
            except Exception:
                detail = resp.text
            raise GiteaError(resp.status_code, detail)
        return resp

    # ----- Repo lifecycle -----

    async def get_repo(self, owner: str, repo: str) -> dict | None:
        try:
            resp = await self._request("GET", f"/repos/{owner}/{repo}")
            return resp.json()
        except GiteaError as e:
            if e.status == 404:
                return None
            raise

    async def create_org_repo(self, org: str, name: str, *, description: str = "", private: bool = False) -> dict:
        resp = await self._request(
            "POST",
            f"/orgs/{org}/repos",
            json={
                "name": name,
                "description": description,
                "private": private,
                "auto_init": False,
            },
        )
        return resp.json()

    async def delete_repo(self, owner: str, repo: str) -> None:
        await self._request("DELETE", f"/repos/{owner}/{repo}")

    # ----- Branches -----

    async def get_branch(self, owner: str, repo: str, branch: str) -> dict | None:
        try:
            resp = await self._request("GET", f"/repos/{owner}/{repo}/branches/{branch}")
            return resp.json()
        except GiteaError as e:
            if e.status == 404:
                return None
            raise

    async def list_branches(self, owner: str, repo: str) -> list[dict]:
        resp = await self._request("GET", f"/repos/{owner}/{repo}/branches", params={"limit": 50})
        return resp.json()

    async def create_branch(self, owner: str, repo: str, new_branch: str, from_branch: str = "main") -> dict:
        resp = await self._request(
            "POST",
            f"/repos/{owner}/{repo}/branches",
            json={"new_branch_name": new_branch, "old_branch_name": from_branch},
        )
        return resp.json()

    async def delete_branch(self, owner: str, repo: str, branch: str) -> None:
        await self._request("DELETE", f"/repos/{owner}/{repo}/branches/{branch}")

    # ----- File contents -----

    async def get_contents(self, owner: str, repo: str, path: str, ref: str = "main") -> dict | None:
        try:
            resp = await self._request(
                "GET",
                f"/repos/{owner}/{repo}/contents/{path}",
                params={"ref": ref},
            )
            return resp.json()
        except GiteaError as e:
            if e.status == 404:
                return None
            raise

    async def list_dir(self, owner: str, repo: str, path: str = "", ref: str = "main") -> list[dict]:
        try:
            resp = await self._request(
                "GET",
                f"/repos/{owner}/{repo}/contents/{path}",
                params={"ref": ref},
            )
        except GiteaError as e:
            if e.status == 404:
                return []
            raise
        data = resp.json()
        return data if isinstance(data, list) else [data]

    async def read_file(self, owner: str, repo: str, path: str, ref: str = "main") -> tuple[str, str] | None:
        """Return (content, sha) or None if the file is missing."""
        item = await self.get_contents(owner, repo, path, ref)
        if not item or item.get("type") != "file":
            return None
        return base64.b64decode(item["content"]).decode("utf-8"), item["sha"]

    async def create_file(
        self,
        owner: str,
        repo: str,
        path: str,
        *,
        content: str,
        message: str,
        branch: str,
        author_name: str | None = None,
        author_email: str | None = None,
    ) -> dict:
        body: dict[str, Any] = {
            "message": message,
            "content": base64.b64encode(content.encode("utf-8")).decode("ascii"),
            "branch": branch,
        }
        if author_name and author_email:
            body["author"] = {"name": author_name, "email": author_email}
            body["committer"] = {"name": author_name, "email": author_email}
        resp = await self._request("POST", f"/repos/{owner}/{repo}/contents/{path}", json=body)
        return resp.json()

    async def update_file(
        self,
        owner: str,
        repo: str,
        path: str,
        *,
        content: str,
        sha: str,
        message: str,
        branch: str,
        author_name: str | None = None,
        author_email: str | None = None,
    ) -> dict:
        body: dict[str, Any] = {
            "message": message,
            "content": base64.b64encode(content.encode("utf-8")).decode("ascii"),
            "sha": sha,
            "branch": branch,
        }
        if author_name and author_email:
            body["author"] = {"name": author_name, "email": author_email}
            body["committer"] = {"name": author_name, "email": author_email}
        resp = await self._request("PUT", f"/repos/{owner}/{repo}/contents/{path}", json=body)
        return resp.json()

    # ----- Pull requests -----

    async def list_pulls(self, owner: str, repo: str, state: str = "open") -> list[dict]:
        resp = await self._request(
            "GET",
            f"/repos/{owner}/{repo}/pulls",
            params={"state": state, "limit": 50},
        )
        return resp.json()

    async def get_pull(self, owner: str, repo: str, number: int) -> dict | None:
        try:
            resp = await self._request("GET", f"/repos/{owner}/{repo}/pulls/{number}")
            return resp.json()
        except GiteaError as e:
            if e.status == 404:
                return None
            raise

    async def create_pull(
        self,
        owner: str,
        repo: str,
        *,
        title: str,
        body: str,
        head: str,
        base: str = "main",
    ) -> dict:
        resp = await self._request(
            "POST",
            f"/repos/{owner}/{repo}/pulls",
            json={"title": title, "body": body, "head": head, "base": base},
        )
        return resp.json()

    async def merge_pull(
        self,
        owner: str,
        repo: str,
        number: int,
        *,
        merge_message_title: str,
        merge_message_body: str,
        style: str = "merge",
    ) -> None:
        # Per §10.5: no-fast-forward merge commit. We pass Do='merge' so
        # Gitea produces a merge commit rather than a fast-forward.
        await self._request(
            "POST",
            f"/repos/{owner}/{repo}/pulls/{number}/merge",
            json={
                "Do": style,
                "MergeTitleField": merge_message_title,
                "MergeMessageField": merge_message_body,
            },
        )

    async def wait_for_mergeable(
        self,
        owner: str,
        repo: str,
        number: int,
        *,
        timeout_seconds: float = 30.0,
        poll_interval_seconds: float = 0.5,
    ) -> bool:
        """Block until Gitea finishes computing the PR's mergeability,
        or the timeout expires.

        Gitea computes the `mergeable` field in a background job after a
        PR is opened or its head commit changes. Until that job finishes,
        `mergeable` is `null` and `POST /pulls/{n}/merge` rejects with
        `405 "Please try again later"`. Callers about to merge should
        wait here first so the merge call doesn't race the computation.

        Returns the final `mergeable` value (True / False). Raises
        TimeoutError if the field never becomes non-null within the
        budget — the caller can then surface a retryable error to the
        operator instead of silently failing the merge step.
        """
        deadline = asyncio.get_event_loop().time() + timeout_seconds
        while True:
            pr = await self.get_pull(owner, repo, number)
            if pr is not None:
                mergeable = pr.get("mergeable")
                if mergeable is not None:
                    return bool(mergeable)
            if asyncio.get_event_loop().time() >= deadline:
                raise TimeoutError(
                    f"Gitea did not compute mergeability for "
                    f"{owner}/{repo}#{number} within {timeout_seconds:.1f}s"
                )
            await asyncio.sleep(poll_interval_seconds)

    async def close_pull(self, owner: str, repo: str, number: int) -> None:
        await self._request(
            "PATCH",
            f"/repos/{owner}/{repo}/issues/{number}",
            json={"state": "closed"},
        )

    async def create_issue_comment(self, owner: str, repo: str, number: int, body: str) -> dict:
        resp = await self._request(
            "POST",
            f"/repos/{owner}/{repo}/issues/{number}/comments",
            json={"body": body},
        )
        return resp.json()

    # ----- Webhooks -----

    async def ensure_webhook(self, owner: str, repo: str, *, url: str, secret: str, events: list[str]) -> dict:
        existing = (await self._request("GET", f"/repos/{owner}/{repo}/hooks")).json()
        for hook in existing:
            if hook.get("config", {}).get("url") == url:
                return hook
        resp = await self._request(
            "POST",
            f"/repos/{owner}/{repo}/hooks",
            json={
                "type": "gitea",
                "active": True,
                "events": events,
                "config": {
                    "url": url,
                    "content_type": "json",
                    "secret": secret,
                },
            },
        )
        return resp.json()