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

PAGE = 1000           # the relay's largest page
DEFAULT_LIMIT = 10000  # the relay's default max_pending per source


def _cfg():
    s = json.loads(os.environ.get("INTEGRATION_SECRETS", "{}"))
    base = str(s.get("base_url") or "").strip().rstrip("/")
    if not base.startswith("https://"):
        raise ValueError("base_url must be the relay's https:// address")
    return base, {"Authorization": "Bearer " + str(s.get("read_token") or "").strip(), "Accept": "application/json"}


def _get(path, params):
    base, headers = _cfg()
    url = base + path + "?" + urllib.parse.urlencode({k: v for k, v in params.items() if v not in (None, "")})
    req = urllib.request.Request(url, headers=headers, method="GET")
    with urllib.request.urlopen(req, timeout=60) as r:
        return json.loads(r.read() or b"{}")


def run():
    inp = json.loads(os.environ.get("INTEGRATION_INPUTS", "{}"))
    source = str(inp.get("source") or "").strip()
    if not source:
        raise ValueError("source is required: the relay source id, e.g. r7-acme")
    try:
        limit = int(inp.get("limit") or DEFAULT_LIMIT)
    except (TypeError, ValueError):
        limit = DEFAULT_LIMIT
    since = str(inp.get("since") or "").strip()

    # Every page is read within this one run. The next run's watermark is the
    # instant of this one, so a page left for later would never be asked for.
    messages, after = [], ""
    while True:
        page = _get("/relay/v1/messages", {"source": source, "since": since, "after": after, "limit": PAGE})
        messages.extend(page.get("messages") or [])
        if not page.get("more"):
            break
        after = page.get("next") or ""
        if not after:
            break
        if len(messages) >= limit:
            # Failing keeps the watermark where it is; returning a truncated
            # list would move it past what was never read.
            raise RuntimeError(
                "more than %d messages wait on source %s since %s: raise this command's limit "
                "(nothing was ingested; the next run reads the same window)" % (limit, source, since or "the beginning"))
    print(json.dumps({"messages": messages, "count": len(messages), "source": source, "since": since}))


try:
    run()
except urllib.error.HTTPError as e:
    detail = e.read().decode("utf-8", "replace")
    out = {"error": "HTTP " + str(e.code), "detail": detail}
    if e.code == 401:
        out["hint"] = "The relay refused the read token, or this Riposte's address is not in RELAY_CONSUMER_ALLOW_IPS."
    elif e.code == 404:
        out["hint"] = ("Unknown source on this relay, or this Riposte's address is not allowed by the proxy in front "
                       "of it (it answers 404 to readers it does not know). Run test_connection.")
    print(json.dumps(out))
    sys.exit(1)
except Exception as e:
    print(json.dumps({"error": str(e)}))
    sys.exit(1)