import cv2
import os
import time
import threading
import numpy as np
from datetime import datetime
from flask import Flask, Response, render_template, jsonify, send_from_directory
from dotenv import load_dotenv
from ultralytics import YOLO

load_dotenv(override=True)

app = Flask(__name__)

# ---------------------------------------------------------------------------
# Configuration
# ---------------------------------------------------------------------------
USERNAME = os.getenv("username")
PASSWORD = os.getenv("password")
RTSP_URL = (
    f"rtsp://{USERNAME}:{PASSWORD}@192.168.6.36:554"
    "/cam/realmonitor?channel=1&subtype=0"
)

PROXIMITY_PX = 200        # max pixel distance to consider two people "together"
GROUP_TIME_THRESHOLD = 20  # seconds before an alert fires
ALERT_COOLDOWN = 60        # seconds between successive alerts
MIN_GROUP_SIZE = 2
YOLO_CONF = 0.5

# ---------------------------------------------------------------------------
# Shared state (protected by lock)
# ---------------------------------------------------------------------------
lock = threading.Lock()
state = {
    "frame": None,
    "people_count": 0,
    "groups": [],
    "alert_active": False,
    "alerts": [],
    "fps": 0,
    "stream_status": "connecting",
}

# ---------------------------------------------------------------------------
# YOLO model (downloaded on first run)
# ---------------------------------------------------------------------------
model = YOLO("yolov8n.pt")

# Group tracking
_group_trackers: dict = {}
_next_group_id = 0
_last_alert_time = 0.0


# ---------------------------------------------------------------------------
# Detection helpers
# ---------------------------------------------------------------------------

def _centroids(boxes):
    """Return list of (cx, cy) from xyxy boxes."""
    return [((b[0] + b[2]) / 2, (b[1] + b[3]) / 2) for b in boxes]


def _find_groups(centroids, threshold):
    """BFS clustering — returns list of index-lists with >= MIN_GROUP_SIZE."""
    n = len(centroids)
    if n < MIN_GROUP_SIZE:
        return []

    visited = set()
    groups = []

    for i in range(n):
        if i in visited:
            continue
        cluster = [i]
        visited.add(i)
        queue = [i]
        while queue:
            cur = queue.pop(0)
            for j in range(n):
                if j in visited:
                    continue
                dx = centroids[cur][0] - centroids[j][0]
                dy = centroids[cur][1] - centroids[j][1]
                if (dx * dx + dy * dy) ** 0.5 < threshold:
                    cluster.append(j)
                    visited.add(j)
                    queue.append(j)
        if len(cluster) >= MIN_GROUP_SIZE:
            groups.append(cluster)

    return groups


def _group_centroid(centroids, indices):
    xs = [centroids[i][0] for i in indices]
    ys = [centroids[i][1] for i in indices]
    return (sum(xs) / len(xs), sum(ys) / len(ys))


# ---------------------------------------------------------------------------
# Main processing loop (runs in background thread)
# ---------------------------------------------------------------------------

def _process_stream():
    global _group_trackers, _next_group_id, _last_alert_time

    cap = cv2.VideoCapture(RTSP_URL)
    if not cap.isOpened():
        with lock:
            state["stream_status"] = "error"
        print(f"[ERROR] Cannot open RTSP stream: {RTSP_URL}")
        return

    with lock:
        state["stream_status"] = "live"

    prev_time = time.time()

    while True:
        ret, frame = cap.read()
        if not ret:
            with lock:
                state["stream_status"] = "reconnecting"
            cap.release()
            time.sleep(2)
            cap = cv2.VideoCapture(RTSP_URL)
            if cap.isOpened():
                with lock:
                    state["stream_status"] = "live"
            continue

        now = time.time()
        fps = 1.0 / max(now - prev_time, 1e-6)
        prev_time = now

        # --- YOLO inference (person = class 0) ---
        results = model(frame, classes=[0], verbose=False, conf=YOLO_CONF)

        person_boxes = []
        for r in results:
            for box in r.boxes:
                x1, y1, x2, y2 = box.xyxy[0].cpu().numpy()
                conf = float(box.conf[0])
                person_boxes.append((float(x1), float(y1), float(x2), float(y2), conf))

        centroids = _centroids([(b[0], b[1], b[2], b[3]) for b in person_boxes])
        current_groups = _find_groups(centroids, PROXIMITY_PX)

        # --- Match current groups to tracked groups ---
        matched_ids: set = set()
        frame_group_data = []

        for grp_indices in current_groups:
            gc = _group_centroid(centroids, grp_indices)

            best_id, best_dist = None, float("inf")
            for gid, gdata in _group_trackers.items():
                if gid in matched_ids:
                    continue
                dx = gc[0] - gdata["centroid"][0]
                dy = gc[1] - gdata["centroid"][1]
                dist = (dx * dx + dy * dy) ** 0.5
                if dist < PROXIMITY_PX * 2 and dist < best_dist:
                    best_dist = dist
                    best_id = gid

            if best_id is not None:
                _group_trackers[best_id]["centroid"] = gc
                _group_trackers[best_id]["last_seen"] = now
                _group_trackers[best_id]["member_count"] = len(grp_indices)
                matched_ids.add(best_id)
                frame_group_data.append((best_id, grp_indices, gc))
            else:
                gid = _next_group_id
                _next_group_id += 1
                _group_trackers[gid] = {
                    "centroid": gc,
                    "first_seen": now,
                    "last_seen": now,
                    "member_count": len(grp_indices),
                    "alerted": False,
                }
                frame_group_data.append((gid, grp_indices, gc))

        # Remove stale groups (not seen for > 3 s)
        stale = [gid for gid, gd in _group_trackers.items() if now - gd["last_seen"] > 3]
        for gid in stale:
            del _group_trackers[gid]

        # --- Alert logic ---
        alert_this_frame = False
        for gid, gdata in _group_trackers.items():
            duration = gdata["last_seen"] - gdata["first_seen"]
            if duration >= GROUP_TIME_THRESHOLD and not gdata["alerted"]:
                if now - _last_alert_time >= ALERT_COOLDOWN:
                    gdata["alerted"] = True
                    alert_this_frame = True
                    _last_alert_time = now

                    os.makedirs("alerts", exist_ok=True)
                    ts = datetime.now().strftime("%Y%m%d_%H%M%S")
                    alert_path = f"alerts/alert_{ts}.jpg"
                    cv2.imwrite(alert_path, frame)

                    alert_info = {
                        "time": datetime.now().strftime("%Y-%m-%d %H:%M:%S"),
                        "people": gdata["member_count"],
                        "duration": round(duration, 1),
                        "image": alert_path,
                    }
                    with lock:
                        state["alerts"].insert(0, alert_info)
                        state["alerts"] = state["alerts"][:50]

        # --- Draw overlays ---
        display = frame.copy()

        for x1, y1, x2, y2, conf in person_boxes:
            cv2.rectangle(display, (int(x1), int(y1)), (int(x2), int(y2)), (0, 255, 0), 2)
            cv2.putText(
                display, f"{conf:.0%}",
                (int(x1), int(y1) - 6),
                cv2.FONT_HERSHEY_SIMPLEX, 0.5, (0, 255, 0), 2,
            )

        for gid, grp_indices, gc in frame_group_data:
            gdata = _group_trackers.get(gid)
            if gdata is None:
                continue
            duration = gdata["last_seen"] - gdata["first_seen"]
            radius = int(PROXIMITY_PX * 0.6)
            is_alert = duration >= GROUP_TIME_THRESHOLD
            color = (0, 0, 255) if is_alert else (0, 165, 255)

            cv2.circle(display, (int(gc[0]), int(gc[1])), radius, color, 2)
            label = f"Group: {len(grp_indices)} | {duration:.0f}s"
            cv2.putText(
                display, label,
                (int(gc[0]) - 70, int(gc[1]) - radius - 10),
                cv2.FONT_HERSHEY_SIMPLEX, 0.55, color, 2,
            )
            if is_alert:
                cv2.putText(
                    display, "ALERT",
                    (int(gc[0]) - 35, int(gc[1]) + radius + 25),
                    cv2.FONT_HERSHEY_SIMPLEX, 0.8, (0, 0, 255), 3,
                )

        # --- Update shared state ---
        groups_json = []
        for gid, gi, gc in frame_group_data:
            gdata = _group_trackers.get(gid)
            if gdata:
                groups_json.append({
                    "id": gid,
                    "count": len(gi),
                    "duration": round(gdata["last_seen"] - gdata["first_seen"], 1),
                })

        with lock:
            state["frame"] = display
            state["people_count"] = len(person_boxes)
            state["groups"] = groups_json
            state["alert_active"] = alert_this_frame or any(
                (gd["last_seen"] - gd["first_seen"]) >= GROUP_TIME_THRESHOLD
                for gd in _group_trackers.values()
            )
            state["fps"] = round(fps, 1)


# ---------------------------------------------------------------------------
# MJPEG generator
# ---------------------------------------------------------------------------

def _generate_frames():
    while True:
        with lock:
            frame = state["frame"]
        if frame is not None:
            ok, buf = cv2.imencode(".jpg", frame, [cv2.IMWRITE_JPEG_QUALITY, 80])
            if ok:
                yield (
                    b"--frame\r\n"
                    b"Content-Type: image/jpeg\r\n\r\n" + buf.tobytes() + b"\r\n"
                )
        time.sleep(0.033)


# ---------------------------------------------------------------------------
# Routes
# ---------------------------------------------------------------------------

@app.route("/")
def dashboard():
    return render_template("dashboard.html")


@app.route("/video_feed")
def video_feed():
    return Response(
        _generate_frames(),
        mimetype="multipart/x-mixed-replace; boundary=frame",
    )


@app.route("/api/status")
def api_status():
    with lock:
        return jsonify({
            "people_count": state["people_count"],
            "groups": state["groups"],
            "alert_active": state["alert_active"],
            "alerts": state["alerts"][:20],
            "fps": state["fps"],
            "stream_status": state["stream_status"],
        })


@app.route("/alerts/<path:filename>")
def serve_alert_image(filename):
    return send_from_directory("alerts", filename)


# ---------------------------------------------------------------------------
# Entry point
# ---------------------------------------------------------------------------

if __name__ == "__main__":
    threading.Thread(target=_process_stream, daemon=True).start()
    print(f"\n  Surveillance Dashboard → http://localhost:5000\n")
    app.run(host="0.0.0.0", port=5000, debug=False, threaded=True)