"""CDAPBridge — main class for building CDAP device bridges in Python.

Usage example:

    from betterdesk_cdap import CDAPBridge, gauge, toggle

    bridge = CDAPBridge(
        server="ws://203.0.113.10:21122/cdap",
        auth_method="api_key",
        api_key="your-key",
        device_name="Temperature Sensor",
        device_type="iot",
    )

    temp = bridge.add_widget(gauge("temp", "Temperature", unit="°C", max_val=50))
    heater = bridge.add_widget(toggle("heater", "Heater"))

    @bridge.on_command("heater")
    async def handle_heater(action, value, **kw):
        GPIO.output(HEATER_PIN, value)
        return {"status": "ok"}

    bridge.run()
"""

from __future__ import annotations

import asyncio
import json
import logging
import random
import time
from typing import Any, Callable, Coroutine

import websockets
import websockets.exceptions

from betterdesk_cdap.protocol import Message, auth_payload_api_key, auth_payload_device_token, auth_payload_user_password
from betterdesk_cdap.widgets import Widget

logger = logging.getLogger("betterdesk_cdap")


class CDAPBridge:
    """Python bridge that connects to a BetterDesk CDAP gateway."""

    def __init__(
        self,
        server: str,
        *,
        auth_method: str = "api_key",
        api_key: str = "",
        device_token: str = "",
        username: str = "",
        password: str = "",
        device_id: str = "",
        device_name: str = "Python Bridge",
        device_type: str = "iot",
        vendor: str = "",
        model: str = "",
        firmware: str = "1.0.0",
        tags: list[str] | None = None,
        capabilities: list[str] | None = None,
        heartbeat_sec: int = 15,
        reconnect_sec: int = 5,
        max_reconnect: int = 300,
        # Bridge metadata (optional)
        bridge_name: str = "",
        bridge_protocol: str = "",
        target_host: str = "",
        target_port: int = 0,
    ):
        self.server = server
        self.auth_method = auth_method
        self.api_key = api_key
        self.device_token = device_token
        self.username = username
        self.password = password
        self.device_id = device_id
        self.device_name = device_name
        self.device_type = device_type
        self.vendor = vendor
        self.model = model
        self.firmware = firmware
        self.tags = tags or []
        self.capabilities = capabilities or ["telemetry", "commands"]
        self.heartbeat_sec = max(5, min(300, heartbeat_sec))
        self.reconnect_sec = max(1, reconnect_sec)
        self.max_reconnect = max(reconnect_sec, max_reconnect)

        self.bridge_name = bridge_name
        self.bridge_protocol = bridge_protocol
        self.target_host = target_host
        self.target_port = target_port

        # Internal state
        self._ws: websockets.WebSocketClientProtocol | None = None
        self._widgets: list[Widget] = []
        self._widget_values: dict[str, Any] = {}
        self._command_handlers: dict[str, Callable] = {}
        self._global_command_handler: Callable | None = None
        self._token: str = ""
        self._assigned_device_id: str = ""
        self._role: str = ""
        self._running = False
        self._connected = False

    # ── Widget Registration ───────────────────────────────────────────

    def add_widget(self, widget: Widget) -> Widget:
        """Register a widget for the device manifest."""
        self._widgets.append(widget)
        if widget.value is not None:
            self._widget_values[widget.id] = widget.value
        return widget

    def on_command(self, widget_id: str | None = None):
        """Decorator to register a command handler for a widget (or all widgets)."""
        def decorator(fn: Callable[..., Coroutine]):
            if widget_id:
                self._command_handlers[widget_id] = fn
            else:
                self._global_command_handler = fn
            return fn
        return decorator

    # ── State Updates ─────────────────────────────────────────────────

    async def update_state(self, widget_id: str, value: Any) -> None:
        """Push a single widget state update to the server."""
        self._widget_values[widget_id] = value
        await self._send("state_update", {
            "widget_id": widget_id,
            "value": value,
            "timestamp": time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime()),
        })

    async def bulk_update(self, updates: dict[str, Any]) -> None:
        """Push multiple widget state updates."""
        for wid, val in updates.items():
            self._widget_values[wid] = val
        await self._send("bulk_update", {
            "updates": [
                {"widget_id": wid, "value": val}
                for wid, val in updates.items()
            ],
        })

    # ── Alerts ────────────────────────────────────────────────────────

    async def fire_alert(
        self,
        alert_id: str,
        severity: str = "warning",
        message: str = "",
        data: Any = None,
    ) -> None:
        """Fire an alert to the server."""
        payload: dict[str, Any] = {
            "alert_id": alert_id,
            "severity": severity,
            "message": message,
        }
        if data is not None:
            payload["data"] = data
        await self._send("event", {"event_type": "alert_fire", "data": payload})

    async def resolve_alert(self, alert_id: str) -> None:
        """Resolve a previously fired alert."""
        await self._send("event", {
            "event_type": "alert_resolve",
            "data": {"alert_id": alert_id},
        })

    # ── Logging ───────────────────────────────────────────────────────

    async def send_log(
        self, level: str, message: str, context: Any = None
    ) -> None:
        """Send a log entry to the server."""
        payload: dict[str, Any] = {"level": level, "message": message}
        if context is not None:
            payload["context"] = context
        await self._send("log", payload)

    # ── Lifecycle ─────────────────────────────────────────────────────

    def run(self) -> None:
        """Blocking entry point — connect and run the message loop."""
        asyncio.run(self._run_forever())

    async def _run_forever(self) -> None:
        self._running = True
        delay = self.reconnect_sec

        while self._running:
            try:
                await self._connect_once()
                delay = self.reconnect_sec  # reset on success
            except Exception as exc:
                logger.warning("Connection lost: %s", exc)

            if not self._running:
                break

            jitter = random.uniform(0, delay * 0.25)
            wait = delay + jitter
            logger.info("Reconnecting in %.1fs...", wait)
            await asyncio.sleep(wait)
            delay = min(delay * 2, self.max_reconnect)

    async def _connect_once(self) -> None:
        logger.info("Connecting to %s...", self.server)
        async with websockets.connect(
            self.server,
            max_size=4 * 1024 * 1024,
            open_timeout=30,
        ) as ws:
            self._ws = ws
            await self._authenticate()
            await self._register()
            self._connected = True
            logger.info(
                "Connected as %r (device_id=%s, role=%s)",
                self.device_name,
                self._assigned_device_id,
                self._role,
            )

            heartbeat_task = asyncio.create_task(self._heartbeat_loop())
            try:
                await self._message_loop()
            finally:
                heartbeat_task.cancel()
                self._connected = False
                self._ws = None

    def stop(self) -> None:
        """Signal the bridge to stop."""
        self._running = False

    # ── Authentication ────────────────────────────────────────────────

    async def _authenticate(self) -> None:
        if self.auth_method == "api_key":
            payload = auth_payload_api_key(self.api_key, self.device_id, self.firmware)
        elif self.auth_method == "device_token":
            payload = auth_payload_device_token(self.device_token, self.device_id, self.firmware)
        elif self.auth_method == "user_password":
            payload = auth_payload_user_password(
                self.username, self.password, self.device_id, self.firmware
            )
        else:
            raise ValueError(f"Unknown auth method: {self.auth_method}")

        await self._send("auth", payload)
        msg = await self._recv()
        if msg.type != "auth_result":
            raise RuntimeError(f"Expected auth_result, got {msg.type}")
        if not msg.payload.get("success"):
            raise RuntimeError(f"Auth failed: {msg.payload.get('error', 'unknown')}")

        self._token = msg.payload.get("token", "")
        self._assigned_device_id = msg.payload.get("device_id", "")
        self._role = msg.payload.get("role", "")

    # ── Registration ──────────────────────────────────────────────────

    async def _register(self) -> None:
        manifest = self._build_manifest()
        await self._send("register", {"manifest": manifest})

    def _build_manifest(self) -> dict[str, Any]:
        device: dict[str, Any] = {
            "name": self.device_name,
            "type": self.device_type,
        }
        if self.vendor:
            device["vendor"] = self.vendor
        if self.model:
            device["model"] = self.model
        if self.firmware:
            device["firmware"] = self.firmware
        if self.tags:
            device["tags"] = self.tags

        m: dict[str, Any] = {
            "manifest_version": "1.0",
            "device": device,
            "capabilities": self.capabilities,
            "heartbeat_interval": self.heartbeat_sec,
            "widgets": [w.to_dict() for w in self._widgets],
        }

        if self.bridge_name:
            m["bridge"] = {
                "name": self.bridge_name,
                "version": self.firmware,
                "protocol": self.bridge_protocol,
                "target_host": self.target_host,
                "target_port": self.target_port,
            }

        return m

    # ── Heartbeat ─────────────────────────────────────────────────────

    async def _heartbeat_loop(self) -> None:
        while self._connected:
            try:
                payload: dict[str, Any] = {}
                if self._widget_values:
                    payload["widget_values"] = dict(self._widget_values)
                await self._send("heartbeat", payload)
            except Exception:
                return
            await asyncio.sleep(self.heartbeat_sec)

    # ── Message Loop ──────────────────────────────────────────────────

    async def _message_loop(self) -> None:
        while True:
            msg = await self._recv()
            await self._dispatch(msg)

    async def _dispatch(self, msg: Message) -> None:
        if msg.type == "command":
            await self._handle_command(msg.payload)
        elif msg.type == "ping":
            pass  # heartbeat ACK
        elif msg.type == "error":
            code = msg.payload.get("code", 0)
            error_msg = msg.payload.get("message", "")
            logger.error("Server error %d: %s", code, error_msg)
        elif msg.type == "registered":
            logger.debug("Registration confirmed: %s", msg.payload)
        else:
            logger.debug("Unhandled message type: %s", msg.type)

    async def _handle_command(self, payload: dict[str, Any]) -> None:
        command_id = payload.get("command_id", "")
        widget_id = payload.get("widget_id", "")
        action = payload.get("action", "")
        value = payload.get("value")

        start = time.monotonic()
        handler = self._command_handlers.get(widget_id, self._global_command_handler)

        resp: dict[str, Any] = {"command_id": command_id}
        if handler is None:
            resp["status"] = "error"
            resp["error_message"] = f"No handler for widget {widget_id}"
        else:
            try:
                result = await handler(
                    action=action,
                    value=value,
                    widget_id=widget_id,
                    operator=payload.get("operator", ""),
                    reason=payload.get("reason", ""),
                )
                resp["status"] = "ok"
                resp["result"] = result
                # Auto-update widget value on set
                if action == "set" and value is not None:
                    self._widget_values[widget_id] = value
            except Exception as exc:
                resp["status"] = "error"
                resp["error_message"] = str(exc)

        resp["execution_time_ms"] = int((time.monotonic() - start) * 1000)
        await self._send("command_response", resp)

    # ── Wire I/O ──────────────────────────────────────────────────────

    async def _send(self, msg_type: str, payload: dict[str, Any]) -> None:
        if not self._ws:
            return
        msg = Message(type=msg_type, payload=payload)
        await self._ws.send(msg.to_json())

    async def _recv(self) -> Message:
        if not self._ws:
            raise RuntimeError("Not connected")
        raw = await self._ws.recv()
        return Message.from_json(raw)