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

import jwt

TOKEN_URL = "https://oauth2.googleapis.com/token"
SCOPE = "https://www.googleapis.com/auth/chronicle-backstory"


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


def _inputs():
    return json.loads(os.environ.get("INTEGRATION_INPUTS", "{}"))


def _base(cfg):
    return (str(cfg.get("base_url") or "https://backstory.googleapis.com")).rstrip("/")


def _token(cfg):
    raw = cfg.get("service_account_json", "")
    sa = json.loads(raw) if isinstance(raw, str) else raw
    if not sa.get("client_email") or not sa.get("private_key"):
        raise Exception("service_account_json must contain client_email and private_key")
    now = int(time.time())
    aud = sa.get("token_uri") or TOKEN_URL
    payload = {"iss": sa["client_email"], "scope": SCOPE, "aud": aud, "iat": now, "exp": now + 3600}
    assertion = jwt.encode(payload, sa["private_key"], algorithm="RS256")
    data = urllib.parse.urlencode({
        "grant_type": "urn:ietf:params:oauth:grant-type:jwt-bearer",
        "assertion": assertion,
    }).encode("utf-8")
    req = urllib.request.Request(aud, data=data,
                                 headers={"Content-Type": "application/x-www-form-urlencoded"}, method="POST")
    with urllib.request.urlopen(req, timeout=60) as r:
        tok = json.loads(r.read())
    if not tok.get("access_token"):
        raise Exception("Token request failed: " + json.dumps(tok))
    return tok["access_token"]


def api(method, path, cfg, params=None):
    url = _base(cfg) + path
    if params:
        clean = {k: v for k, v in params.items() if v not in (None, "")}
        if clean:
            url += "?" + urllib.parse.urlencode(clean)
    headers = {"Accept": "application/json", "Authorization": "Bearer " + _token(cfg)}
    req = urllib.request.Request(url, headers=headers, method=method)
    with urllib.request.urlopen(req, timeout=90) as r:
        raw = r.read()
        return json.loads(raw) if raw else {}


def _run(fn):
    try:
        print(json.dumps(fn(_cfg(), _inputs())))
    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)


def main(cfg, inputs):
    start_time = inputs.get("start_time")
    if not start_time:
        raise Exception("start_time is required")
    end_time = inputs.get("end_time")
    if not end_time:
        raise Exception("end_time is required")
    page_size = inputs.get("page_size")
    params = {
        "start_time": start_time,
        "end_time": end_time,
        "page_size": int(page_size or 100),
    }
    return api("GET", "/v1/alert/listalerts", cfg, params)


_run(main)
