#!/usr/bin/env python3
import cv2
import numpy as np
import subprocess
import os
import json
import time
import requests
import logging
import sys
import argparse

# ==================================================
# Logging
# ==================================================
LOG_LEVEL = os.environ.get("LOG_LEVEL", "INFO").upper()
LOG_FILE = os.environ.get("LOG_FILE")  # optional

handlers = [logging.StreamHandler(sys.stdout)]
if LOG_FILE:
    handlers.append(logging.FileHandler(LOG_FILE))

logging.basicConfig(
    level=LOG_LEVEL,
    format="%(asctime)s | %(levelname)-8s | %(message)s",
    handlers=handlers,
)

log = logging.getLogger("desk_presence")

# ==================================================
# Arguments
# ==================================================
parser = argparse.ArgumentParser(description="Desk presence detection")
parser.add_argument(
    "--vflip",
    action="store_true",
    help="Flip captured image vertically before processing",
)
args = parser.parse_args()
VFLIP = args.vflip

if VFLIP:
    log.info("Vertical flip enabled")

# ==================================================
# Camera
# ==================================================
CAMERA = "/dev/video0"
TMP_IMG = "/tmp/desk_current.jpg"
PREV_IMG = "/tmp/desk_prev.jpg"

# ==================================================
# State files
# ==================================================
STATE_FILE = "/tmp/desk_presence_score.json"
HA_STATE_FILE = "/tmp/desk_presence_last_ha.json"
LIGHT_COOLDOWN_FILE = "/tmp/desk_light_cooldown.json"

# ==================================================
# Haar cascade
# ==================================================
FACE_CASCADE = cv2.CascadeClassifier("cascades/haarcascade_frontalface_default.xml")
if FACE_CASCADE.empty():
    raise RuntimeError("Failed to load Haar cascade")

# ==================================================
# Home Assistant
# ==================================================
HA_URL = os.environ.get("HA_URL", "http://192.168.0.202:8123")
HA_ENTITY_ID = os.environ.get("HA_ENTITY_ID", "binary_sensor.desk_presence_vision")
HA_TOKEN = os.environ.get("HA_TOKEN")

if not HA_TOKEN:
    raise RuntimeError("HA_TOKEN environment variable not set")

# ==================================================
# Presence logic
# ==================================================
MAX_SCORE = 5
FACE_BOOST = 2
MOTION_BOOST = 1
DECAY = 1

MOTION_AREA_THRESHOLD = 3500
LIGHT_COOLDOWN_SECONDS = 15

SCORE_DELAYS = {
    0: 5,
    1: 10,
    2: 20,
    3: 20,
    4: 20,
    5: 20,
}


# ==================================================
# Helpers
# ==================================================
def safe_delete(path):
    try:
        if os.path.exists(path):
            os.remove(path)
            log.debug("Deleted %s", path)
    except Exception:
        log.exception("Failed to delete %s", path)


def capture():
    log.debug("Capturing frame from %s", CAMERA)
    subprocess.run(
        [
            "ffmpeg",
            "-loglevel",
            "error",
            "-f",
            "v4l2",
            "-i",
            CAMERA,
            "-frames:v",
            "1",
            TMP_IMG,
        ],
        check=True,
    )


def load_json(path, default):
    if not os.path.exists(path):
        return default
    try:
        return json.load(open(path))
    except Exception:
        log.warning("Failed to load JSON from %s", path)
        return default


def save_json(path, data):
    try:
        json.dump(data, open(path, "w"))
    except Exception:
        log.exception("Failed to save JSON to %s", path)


# ==================================================
# Presence score
# ==================================================
def load_score():
    return load_json(STATE_FILE, {}).get("score", 0)


def save_score(score):
    save_json(STATE_FILE, {"score": score})


# ==================================================
# Home Assistant state
# ==================================================
def load_last_ha_state():
    return load_json(HA_STATE_FILE, {}).get("state")


def save_last_ha_state(state):
    save_json(HA_STATE_FILE, {"state": state})


def record_light_off_event():
    log.debug("Recording light-off cooldown event")
    save_json(LIGHT_COOLDOWN_FILE, {"ts": time.time()})


def ignore_motion_due_to_light():
    data = load_json(LIGHT_COOLDOWN_FILE, {})
    ts = data.get("ts", 0)
    return (time.time() - ts) < LIGHT_COOLDOWN_SECONDS


def send_to_ha(present):
    new_state = "on" if present else "off"
    last_state = load_last_ha_state()

    if new_state == last_state:
        log.debug("HA state unchanged (%s)", new_state)
        return

    log.info("Sending HA state: %s", new_state)

    try:
        r = requests.post(
            f"{HA_URL}/api/states/{HA_ENTITY_ID}",
            headers={
                "Authorization": f"Bearer {HA_TOKEN}",
                "Content-Type": "application/json",
            },
            json={
                "state": new_state,
                "attributes": {
                    "friendly_name": "Desk Presence (Vision)",
                    "source": "snapshot_camera",
                },
            },
            timeout=5,
        )

        if r.status_code in (200, 201):
            log.info("HA state updated successfully")
            save_last_ha_state(new_state)
            if new_state == "off":
                record_light_off_event()
        else:
            log.error(
                "HA update failed (%s): %s",
                r.status_code,
                r.text,
            )

    except Exception:
        log.exception("Failed to send update to Home Assistant")


# ==================================================
# Detection
# ==================================================
def detect_face(gray):
    faces = FACE_CASCADE.detectMultiScale(
        gray,
        scaleFactor=1.2,
        minNeighbors=4,
        minSize=(60, 60),
    )
    return len(faces) > 0


def detect_motion(gray):
    light_cooldown = ignore_motion_due_to_light()

    # If no previous frame exists, initialize it
    if not os.path.exists(PREV_IMG):
        cv2.imwrite(PREV_IMG, gray)
        log.debug("Initialized previous frame")
        return False

    prev = cv2.imread(PREV_IMG, cv2.IMREAD_GRAYSCALE)

    # Always update PREV_IMG so state stays aligned
    cv2.imwrite(PREV_IMG, gray)

    # If we're in light cooldown, ignore motion but accept the frame
    if light_cooldown:
        log.debug("Ignoring motion due to light cooldown (state synced)")
        return False

    diff = cv2.absdiff(prev, gray)
    mean_diff = np.mean(diff)

    if mean_diff > 60:
        log.debug("Ignoring global brightness change (mean=%.2f)", mean_diff)
        return False

    _, thresh = cv2.threshold(diff, 30, 255, cv2.THRESH_BINARY)
    kernel = np.ones((5, 5), np.uint8)
    thresh = cv2.morphologyEx(thresh, cv2.MORPH_OPEN, kernel)

    contours, _ = cv2.findContours(thresh, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)

    max_area = max((cv2.contourArea(c) for c in contours), default=0)
    log.debug("Motion max contour area: %d", max_area)

    return max_area > MOTION_AREA_THRESHOLD


def get_delay(score):
    return SCORE_DELAYS.get(score, 30)


# ==================================================
# Main loop
# ==================================================
def main_loop():
    log.info("Snapshot desk presence started")

    while True:
        try:
            capture()

            frame = cv2.imread(TMP_IMG)
            if frame is None:
                log.warning("Failed to read captured frame")
                time.sleep(30)
                continue

            if VFLIP:
                frame = cv2.flip(frame, 0)

            gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

            face = detect_face(gray)
            motion = detect_motion(gray)

            log.debug(
                "Detection | face=%s motion=%s",
                face,
                motion,
            )

            score = load_score()
            old_score = score

            if face:
                score += FACE_BOOST
            elif motion:
                score += MOTION_BOOST
            else:
                score -= DECAY

            score = max(0, min(MAX_SCORE, score))

            if score != old_score:
                log.info("Score changed %d → %d", old_score, score)

            save_score(score)
            send_to_ha(score > 0)

        except Exception:
            log.exception("Unhandled error in main loop")
            time.sleep(30)

        finally:
            safe_delete(TMP_IMG)

        time.sleep(get_delay(score))


if __name__ == "__main__":
    main_loop()