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/cloud-platform"
COMPUTE = "https://compute.googleapis.com/compute/v1"


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


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


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, url, cfg, body=None, params=None):
    q = {k: str(v) for k, v in (params or {}).items() if v not in (None, "")}
    if q:
        url += ("&" if "?" in url else "?") + urllib.parse.urlencode(q)
    data = json.dumps(body).encode("utf-8") if body is not None else None
    headers = {"Accept": "application/json", "Authorization": "Bearer " + _token(cfg)}
    if data is not None:
        headers["Content-Type"] = "application/json"
    req = urllib.request.Request(url, data=data, 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)


proj = lambda cfg: str(cfg.get("project_id", ""))


def _csv(v):
    return [s.strip() for s in str(v).split(",") if s.strip()]


def main(cfg, inputs):
    name = inputs.get("name")
    if not name:
        raise Exception("name is required")
    network = inputs.get("network") or "default"
    direction = inputs.get("direction") or "INGRESS"
    action = inputs.get("action") or "deny"
    protocol = inputs.get("protocol") or "all"
    ports = _csv(inputs.get("ports", ""))
    ranges = _csv(inputs.get("ranges", ""))
    priority = inputs.get("priority", 1000)
    target_tags = _csv(inputs.get("target_tags", ""))

    rule_entry = {"IPProtocol": protocol or "all"}
    if ports:
        rule_entry["ports"] = ports

    key = "allowed" if action == "allow" else "denied"

    body = {
        "name": name,
        "network": "global/networks/" + (network or "default"),
        "direction": direction or "INGRESS",
        "priority": int(priority),
        key: [rule_entry],
    }

    ranges_list = ranges or ["0.0.0.0/0"]
    if (direction or "INGRESS") == "EGRESS":
        body["destinationRanges"] = ranges_list
    else:
        body["sourceRanges"] = ranges_list

    if target_tags:
        body["targetTags"] = target_tags

    url = COMPUTE + "/projects/{}/global/firewalls".format(proj(cfg))
    return api("POST", url, cfg, body=body)


_run(main)