import base64, json, os, sys, urllib.parse, urllib.request, urllib.error


def _cfg():
    return json.loads(os.environ.get("INTEGRATION_SECRETS", "{}"))


def _headers(cfg):
    h = {"Accept": "application/json", "Content-Type": "application/json"}
    if str(cfg.get("auth_type") or "basic").lower() == "oauth":
        data = urllib.parse.urlencode({
            "grant_type": "password",
            "client_id": cfg.get("client_id", ""),
            "client_secret": cfg.get("client_secret", ""),
            "username": cfg.get("username", ""),
            "password": cfg.get("password", ""),
        }).encode("utf-8")
        req = urllib.request.Request(
            cfg.get("url", "").rstrip("/") + "/oauth_token.do", data=data,
            headers={"Content-Type": "application/x-www-form-urlencoded", "Accept": "application/json"}, method="POST")
        with urllib.request.urlopen(req, timeout=60) as r:
            tok = json.loads(r.read())
        if not tok.get("access_token"):
            raise Exception("OAuth token request failed: " + json.dumps(tok))
        h["Authorization"] = "Bearer " + tok["access_token"]
    else:
        cred = (cfg.get("username", "") + ":" + cfg.get("password", "")).encode("utf-8")
        h["Authorization"] = "Basic " + base64.b64encode(cred).decode("ascii")
    return h


def request(method, path, params=None, body=None, root="/api/now", versioned=True):
    cfg = _cfg()
    v = str(cfg.get("api_version") or "").strip().strip("/")
    url = cfg.get("url", "").rstrip("/") + root + ("/" + v if v and versioned else "") + path
    q = {k: str(x) for k, x in (params or {}).items() if x not in (None, "")}
    if q:
        url += "?" + urllib.parse.urlencode(q)
    data = json.dumps(body).encode("utf-8") if body is not None else None
    req = urllib.request.Request(url, data=data, headers=_headers(cfg), method=method)
    with urllib.request.urlopen(req, timeout=90) as r:
        raw = r.read()
        return json.loads(raw) if raw else {}


def relation_params(inputs):
    fields = str(inputs.get("fields") or "")
    if fields:
        parts = [p.strip() for p in fields.split(",") if p.strip()]
        for required in ("sys_id", "name"):
            if required not in parts:
                parts.append(required)
        fields = ",".join(parts)
    return {
        "sysparm_fields": fields or None,
        "sysparm_relation_limit": int(inputs.get("relation_limit") or 50),
        "sysparm_relation_offset": int(inputs.get("relation_offset") or 0),
    }


def parse_relations(s):
    if s in (None, ""):
        return None
    rel = json.loads(s) if isinstance(s, str) else s
    if not isinstance(rel, list):
        raise Exception("relations must be a JSON array of {type, target} objects")
    return rel


def main():
    inputs = json.loads(os.environ.get("INTEGRATION_INPUTS", "{}"))
    ci_class = str(inputs.get("class") or "")
    sys_id = str(inputs.get("sys_id") or "")
    if not ci_class or not sys_id:
        raise Exception("class and sys_id are required")
    body = {"source": str(inputs.get("source") or "ServiceNow")}
    inbound = parse_relations(inputs.get("inbound_relations"))
    if inbound is not None:
        body["inbound_relations"] = inbound
    outbound = parse_relations(inputs.get("outbound_relations"))
    if outbound is not None:
        body["outbound_relations"] = outbound
    if "inbound_relations" not in body and "outbound_relations" not in body:
        raise Exception("inbound_relations or outbound_relations is required")
    path = "/cmdb/instance/" + urllib.parse.quote(ci_class) + "/" + urllib.parse.quote(sys_id) + "/relation"
    print(json.dumps(request("POST", path, params=relation_params(inputs), body=body)))


try:
    main()
except urllib.error.HTTPError as e:
    print(json.dumps({"error": "HTTP " + str(e.code), "detail": e.read().decode("utf-8", "replace")}))
    sys.exit(1)
except Exception as e:
    print(json.dumps({"error": str(e)}))
    sys.exit(1)