"""Authenticated, idempotent HTTP ingestion for user-engine outbox events."""

from __future__ import annotations

import hashlib
import hmac
import json
import os
import sqlite3
from datetime import datetime
from http import HTTPStatus
from typing import Any
from wsgiref.simple_server import make_server

from audit_core.interface import AuditEvent

MAX_BODY_BYTES = 256 * 1024
_SECRET_FRAGMENTS = ("password", "secret", "token", "credential", "private_key")


class SQLiteEventStore:
    def __init__(self, path: str) -> None:
        self.db = sqlite3.connect(path, check_same_thread=False)
        self.db.execute("""
            CREATE TABLE IF NOT EXISTS events (
              event_id TEXT PRIMARY KEY, payload_hash TEXT NOT NULL,
              accepted_at TEXT NOT NULL, record TEXT NOT NULL
            )
        """)
        self.db.commit()

    def accept(self, event: AuditEvent, payload_hash: str) -> tuple[bool, str]:
        existing = self.db.execute(
            "SELECT payload_hash FROM events WHERE event_id = ?", (event.event_id,)
        ).fetchone()
        if existing:
            if existing[0] != payload_hash:
                raise ValueError("event_id_conflict")
            return True, f"audit:{event.event_id}"
        with self.db:
            self.db.execute(
                "INSERT INTO events VALUES (?, ?, ?, ?)",
                (event.event_id, payload_hash, datetime.now().astimezone().isoformat(),
                 json.dumps(event.as_record(), sort_keys=True)),
            )
        return False, f"audit:{event.event_id}"


class IngestionApplication:
    def __init__(self, store: SQLiteEventStore, bearer_token: str) -> None:
        if not bearer_token:
            raise ValueError("bearer token is required")
        self.store = store
        self.token = bearer_token

    def __call__(self, environ, start_response):
        path = environ.get("PATH_INFO", "")
        if path in ("/healthz", "/readyz"):
            return self._json(start_response, HTTPStatus.OK, {"status": "ok"})
        if path != "/v1/events" or environ.get("REQUEST_METHOD") != "POST":
            return self._json(start_response, HTTPStatus.NOT_FOUND, {"error": "not_found"})
        supplied = str(environ.get("HTTP_AUTHORIZATION", ""))
        if not hmac.compare_digest(supplied, f"Bearer {self.token}"):
            return self._json(start_response, HTTPStatus.UNAUTHORIZED, {"error": "unauthorized"})
        try:
            length = int(environ.get("CONTENT_LENGTH") or 0)
            if length <= 0 or length > MAX_BODY_BYTES:
                raise ValueError("invalid_size")
            raw = environ["wsgi.input"].read(length)
            payload = json.loads(raw)
            event = normalize(payload, environ.get("HTTP_IDEMPOTENCY_KEY"))
            duplicate, reference = self.store.accept(
                event, hashlib.sha256(raw).hexdigest()
            )
        except (ValueError, TypeError, KeyError, json.JSONDecodeError) as exc:
            return self._json(start_response, HTTPStatus.BAD_REQUEST, {"error": str(exc)})
        return self._json(start_response, HTTPStatus.OK if duplicate else HTTPStatus.ACCEPTED,
                          {"status": "duplicate" if duplicate else "accepted",
                           "reference": reference})

    @staticmethod
    def _json(start_response, status: HTTPStatus, payload: dict[str, Any]):
        body = json.dumps(payload).encode()
        start_response(f"{status.value} {status.phrase}", [
            ("Content-Type", "application/json"), ("Content-Length", str(len(body)))
        ])
        return [body]


def normalize(payload: dict[str, Any], idempotency_key: str | None) -> AuditEvent:
    required = ("id", "type", "source", "subject", "tenant", "correlation_id", "occurred_at", "data")
    if not isinstance(payload, dict) or any(not payload.get(key) for key in required):
        raise ValueError("invalid_event")
    if idempotency_key != payload["id"]:
        raise ValueError("idempotency_key_mismatch")
    if payload["source"] != "user-engine":
        raise ValueError("source_not_allowed")
    datetime.fromisoformat(str(payload["occurred_at"]).replace("Z", "+00:00"))
    if _contains_secret(payload["data"]):
        raise ValueError("secret_shaped_field")
    return AuditEvent(
        event_id=str(payload["id"]), observed_at=str(payload["occurred_at"]),
        tenant=str(payload["tenant"]), scope="tenant", source="user-engine",
        action=str(payload["type"]), resource=str(payload["subject"]),
        outcome="recorded", actor=None,
        details={"correlation_id": str(payload["correlation_id"]), "data": payload["data"]},
    )


def _contains_secret(value: Any) -> bool:
    if isinstance(value, dict):
        return any(any(fragment in str(key).lower() for fragment in _SECRET_FRAGMENTS)
                   or _contains_secret(item) for key, item in value.items())
    if isinstance(value, list):
        return any(_contains_secret(item) for item in value)
    return False


def main() -> None:
    app = IngestionApplication(
        SQLiteEventStore(os.environ.get("AUDIT_CORE_DATABASE_PATH", "/data/audit-core.db")),
        os.environ["AUDIT_CORE_INGEST_TOKEN"].strip(),
    )
    with make_server(os.environ.get("AUDIT_CORE_HOST", "0.0.0.0"),
                     int(os.environ.get("AUDIT_CORE_HTTP_PORT", "8080")), app) as server:
        server.serve_forever()