"""Liest den Gitea-Actions-Event-Kontext (GitHub-kompatible Env-Vars).

Gitea spiegelt die GITHUB_*-Variablen: GITHUB_REPOSITORY (owner/repo),
GITHUB_EVENT_PATH (JSON des auslösenden Events), GITHUB_EVENT_NAME.
"""
import json
import os


def repo_slug():
    """(owner, repo) aus GITHUB_REPOSITORY."""
    full = os.environ.get("GITHUB_REPOSITORY", "")
    if "/" not in full:
        raise SystemExit("[context] GITHUB_REPOSITORY fehlt oder ist ungültig.")
    owner, repo = full.split("/", 1)
    return owner, repo


def event():
    """Geparstes Event-JSON (oder {} wenn nicht vorhanden)."""
    path = os.environ.get("GITHUB_EVENT_PATH", "")
    if path and os.path.exists(path):
        with open(path, encoding="utf-8") as fh:
            return json.load(fh)
    return {}


def pull_request():
    """PR-Infos aus dem Event oder None, wenn das Event kein PR ist.

    Liefert dict: index, title, body, author, base_ref, head_sha.
    """
    pr = event().get("pull_request")
    if not pr:
        return None
    return {
        "index": pr.get("number"),
        "title": pr.get("title", ""),
        "body": pr.get("body", "") or "",
        "author": (pr.get("user") or {}).get("login", ""),
        "base_ref": (pr.get("base") or {}).get("ref", ""),
        "head_sha": (pr.get("head") or {}).get("sha", ""),
    }