import asyncio
import threading
import time
import redis
import pickle
import os
from datetime import datetime, timezone
from zoneinfo import ZoneInfo   # Python 3.9+
from bleak import BleakScanner, BleakClient
from typing import Set, Iterable
from config import *
from sensors import *
from ble import *
from ble_redis import *

# In-memory cache + thread-safe lock
_mac_cache: Set[str] = set()
_lock = threading.Lock()
_sensors_cache = []

# ----------------------------------------------------------------------
# Pickle persistence helpers
# ----------------------------------------------------------------------
STATE_FILE = "scanner_state.pkl"

def save_state() -> None:
    """
    Persist the MAC cache and sensor objects to disk.
    Called automatically after each cache refresh and at program exit.
    """
    with _lock:
        state = {
            "mac_cache": _mac_cache,
            "sensors": _sensors_cache,
        }
    try:
        with open(STATE_FILE, "wb") as f:
            pickle.dump(state, f, protocol=pickle.HIGHEST_PROTOCOL)
        print("[Scanner] State persisted to", STATE_FILE)
    except Exception as exc:
        # Don't crash the app – just log the error
        print("[Scanner] Warning: could not persist state:", exc)

def load_state() -> None:
    """
    Load the MAC cache and sensor objects from disk if the file exists.
    Called automatically on import.
    """
    if not os.path.exists(STATE_FILE):
        return
    try:
        with open(STATE_FILE, "rb") as f:
            state = pickle.load(f)
        with _lock:
            # NOTE: we replace the lists/sets to avoid mutating old references
            _mac_cache.clear()
            _mac_cache.update(state.get("mac_cache", []))
            global _sensors_cache
            _sensors_cache = state.get("sensors", [])
        print("[Scanner] Loaded state from", STATE_FILE)
    except Exception as exc:
        print("[Scanner] Warning: could not load state:", exc)

# Load any persisted state on module import
load_state()

# Redis Functions
r = redis.Redis(host=bind_ip, port=redis_port)

def update_redis(data):
    # push data to redis
    # Publish to the Redis channel that the WS server is listening on
    r.publish('temp_hum', json.dumps(data))
    if debug_output:
        print("=== Stats Redis Update ===")
        print(json.dumps(data, indent=2))
    return True

# this function filters MACs
def _is_match(mac: str, name: str) -> bool:
    """Return True if the MAC starts with the configured prefix and is correct model."""
    if name == "LYWSD03MMC":
        return mac.upper().startswith(MAC_PREFIX.upper())

# this function scans for MACs
async def _scan_once() -> Iterable[str]:
    """Do one scan cycle and return the matching MACs."""
    devices = await BleakScanner.discover(timeout=5.0)  # 5s scan
    return [dev.address for dev in devices if _is_match(dev.address, dev.name)]

# this very important function updates the MAC cache and the sensor objects
def update_cache() -> None:
    """
    Called by the scheduler (in a separate thread).  It runs a tiny
    asyncio event loop to call the Bleak scan, then updates the cache.
    """
    # Run the async scan in a fresh loop; Bleak requires this.
    # Gets the MACs
    print("--- Starting update_cache loop ---")
    new_macs = scan_macs()
    # now that we have MACs, let's get sensor data
    print("Updating sensor data...")
    sensor_data = None
    try:
        sensor_data = sensor_data_query(new_macs)
        # print(sensor_data)
    except Exception as e:
        print(f"Aww fuck, no data :( - {e}")
    # now we update the data in the sensor objects
    print("Sensor data collected:")
    for sensor_datum in sensor_data:
        print(f"MAC - {sensor_datum['name']} | temp - {sensor_datum['temp']} | humidity - {sensor_datum['humidity']}")
        for sensor in _sensors_cache:
            if sensor.name == sensor_datum['name']:
                sensor.add_or_update(key="temp", value=sensor_datum['temp'])
                sensor.add_or_update(key="humidity", value=sensor_datum['humidity'])
    # if redis is enabled, push full details to the redis server
    if enable_redis:
        update_redis(get_sensor_details())
    save_state()

# this helper function scans for MACs
def scan_macs():
    print("Scanning for MACs:")
    new_macs = asyncio.run(_scan_once())
    with _lock:        
        for new_mac in new_macs:
            print(f"{new_mac}")
            new_sensor = Sensor(name=f"{new_mac}")
            if new_mac not in set(_mac_cache):
                _sensors_cache.append(new_sensor)
        _mac_cache.update(new_macs)
    print(f"Found {len(new_macs)} new MACs, total {len(_mac_cache)} MACs in cache.")
    return new_macs

# return just the MACs
def get_cache_snapshot() -> Set[str]:
    """Return a thread-safe snapshot of the current cache."""
    with _lock:
        return set(_mac_cache)

# return sensor data and timestamps, can return int or string
def get_sensor_details(friendly_date = False):
    sensor_list = []
    for sensor in _sensors_cache:
        first_seen = sensor.first_seen
        last_seen = sensor.last_seen
        if friendly_date:
            first_seen = ts_to_pst_string(sensor.first_seen)
            last_seen = ts_to_pst_string(sensor.last_seen)
        # print(f"Summary - {sensor.name}")
        new_sensor = {
            "name": sensor.name,
            "first_seen": first_seen,
            "last_seen": last_seen,
            "comment": sensor.comment,
            "data": sensor.to_dict()

        }
        sensor_list.append(new_sensor)
    result = {
        "sensors": sensor_list
    }
    return result

# return just sensor data without timestamps
def get_sensor_summary():
    sensor_list = []
    for sensor in _sensors_cache:
        # print(f"Summary - {sensor.name}")
        new_sensor = {
            "name": sensor.name,
            "comment": sensor.comment,
            "data": sensor.to_dict(simple_return=True)
        }
        sensor_list.append(new_sensor)
    result = {
        "sensors": sensor_list
    }
    return result

# helper function for ts int to string
def ts_to_pst_string(ts_str):
    utc_dt = datetime.fromtimestamp(ts_str, tz=timezone.utc)
    pacific_dt = utc_dt.astimezone(ZoneInfo("America/Los_Angeles"))
    return pacific_dt.strftime("%Y-%m-%d %H:%M:%S")