"""Stage 2 Borealis Engine application factory.

Stage 1 introduced the structural skeleton for the Engine runtime.  Stage 2
builds upon that foundation by centralising configuration handling and logging
initialisation so the Engine mirrors the legacy server's start-up behaviour.
The factory delegates configuration resolution to :mod:`Data.Engine.config`
and emits structured logs to ``Logs/Server/server.log`` to align with the
project's operational practices.
"""
from __future__ import annotations

import logging
import ssl
import sys
from dataclasses import dataclass
from pathlib import Path
from typing import Any, Mapping, Optional, Sequence, Tuple

import eventlet
from flask import Flask, request
from flask_cors import CORS
from flask_socketio import SocketIO
from werkzeug.middleware.proxy_fix import ProxyFix

# Eventlet ensures Socket.IO long-polling and WebSocket support parity with the
# legacy server. We keep thread pools enabled for compatibility with blocking
# filesystem/database operations.
eventlet.monkey_patch(thread=False)

try:  # pragma: no-cover - defensive import mirroring the legacy runtime.
    from eventlet.wsgi import HttpProtocol  # type: ignore
except Exception:  # pragma: no-cover - the Engine should still operate without it.
    HttpProtocol = None  # type: ignore[assignment]
else:
    _original_handle_one_request = HttpProtocol.handle_one_request

    def _quiet_tls_http_mismatch(self):  # type: ignore[override]
        """Mirror the legacy suppression of noisy TLS handshake errors."""

        def _close_connection_quietly():
            try:
                self.close_connection = True  # type: ignore[attr-defined]
            except Exception:
                pass
            try:
                conn = getattr(self, "socket", None) or getattr(self, "connection", None)
                if conn:
                    conn.close()
            except Exception:
                pass

        try:
            return _original_handle_one_request(self)
        except ssl.SSLError as exc:  # type: ignore[arg-type]
            reason = getattr(exc, "reason", "")
            reason_text = str(reason).lower() if reason else ""
            message = " ".join(str(arg) for arg in exc.args if arg).lower()
            if (
                "http_request" in message
                or reason_text == "http request"
                or "unknown ca" in message
                or reason_text == "unknown ca"
                or "unknown_ca" in message
            ):
                _close_connection_quietly()
                return None
            raise
        except ssl.SSLEOFError:
            _close_connection_quietly()
            return None
        except ConnectionAbortedError:
            _close_connection_quietly()
            return None

    HttpProtocol.handle_one_request = _quiet_tls_http_mismatch  # type: ignore[assignment]


# Ensure the legacy ``Modules`` package is importable when running from the
# Engine deployment directory.
_ENGINE_DIR = Path(__file__).resolve().parent
_SEARCH_ROOTS = [
    _ENGINE_DIR.parent / "Server",
    _ENGINE_DIR.parent.parent / "Data" / "Server",
]
for root in _SEARCH_ROOTS:
    modules_dir = root / "Modules"
    if modules_dir.is_dir():
        root_str = str(root)
        if root_str not in sys.path:
            sys.path.insert(0, root_str)

from .config import EngineSettings, initialise_engine_logger, load_runtime_config


@dataclass
class EngineContext:
    """Shared handles that Engine services will consume."""

    database_path: str
    logger: logging.Logger
    scheduler: Any
    tls_cert_path: Optional[str]
    tls_key_path: Optional[str]
    tls_bundle_path: Optional[str]
    config: Mapping[str, Any]
    api_groups: Sequence[str]


__all__ = ["EngineContext", "create_app", "register_engine_api"]


def _build_engine_context(settings: EngineSettings, logger: logging.Logger) -> EngineContext:
    return EngineContext(
        database_path=settings.database_path,
        logger=logger,
        scheduler=None,
        tls_cert_path=settings.tls_cert_path,
        tls_key_path=settings.tls_key_path,
        tls_bundle_path=settings.tls_bundle_path,
        config=settings.as_dict(),
        api_groups=settings.api_groups,
    )


def _attach_transition_logging(app: Flask, context: EngineContext, logger: logging.Logger) -> None:
    tracked = {group.strip().lower() for group in context.api_groups if group}
    if not tracked:
        tracked = {"tokens", "enrollment"}

    existing = getattr(app, "_engine_api_tracked_blueprints", set())
    if existing:
        tracked.update(existing)
    setattr(app, "_engine_api_tracked_blueprints", tracked)

    if getattr(app, "_engine_api_logging_installed", False):
        return

    @app.before_request
    def _log_engine_api_bridge() -> None:  # pragma: no cover - integration behaviour exercised in higher-level tests
        blueprint = (request.blueprint or "").lower()
        if blueprint and blueprint in getattr(app, "_engine_api_tracked_blueprints", tracked):
            logger.info(
                "Engine handling API request via legacy bridge: %s %s",
                request.method,
                request.path,
            )

    setattr(app, "_engine_api_logging_installed", True)


def create_app(config: Optional[Mapping[str, Any]] = None) -> Tuple[Flask, SocketIO, EngineContext]:
    """Create the Stage 2 Engine Flask application."""

    settings: EngineSettings = load_runtime_config(config)
    logger = initialise_engine_logger(settings)

    static_folder = settings.static_folder
    app = Flask(__name__, static_folder=static_folder, static_url_path="")
    app.wsgi_app = ProxyFix(app.wsgi_app, x_proto=1, x_host=1)

    cors_origins = settings.cors_origins
    if cors_origins:
        CORS(app, supports_credentials=True, origins=cors_origins)
    else:
        CORS(app, supports_credentials=True)

    app.secret_key = settings.secret_key

    app.config.update(settings.to_flask_config())

    socketio = SocketIO(
        app,
        cors_allowed_origins="*",
        async_mode="eventlet",
        engineio_options={
            "max_http_buffer_size": 100_000_000,
            "max_websocket_message_size": 100_000_000,
        },
    )

    context = _build_engine_context(settings, logger)

    from .services import API, WebSocket, WebUI  # Local import to avoid circular deps during bootstrap

    API.register_api(app, context)
    WebUI.register_web_ui(app, context)
    WebSocket.register_realtime(socketio, context)

    logger.debug("Engine application factory completed initialisation.")

    return app, socketio, context


def register_engine_api(app: Flask, *, config: Optional[Mapping[str, Any]] = None) -> EngineContext:
    """Register Engine-managed API blueprints onto an existing Flask app."""

    settings: EngineSettings = load_runtime_config(config)
    logger = initialise_engine_logger(settings)
    context = _build_engine_context(settings, logger)

    from .services import API  # Local import avoids circular dependency at module import time

    API.register_api(app, context)
    _attach_transition_logging(app, context, logger)

    groups_display = ", ".join(context.api_groups) if context.api_groups else "none"
    logger.info("Engine API delegation activated for groups: %s", groups_display)

    return context