#!/usr/bin/env python3
"""
fps_test.py - Misst Frame-Rate, Framegroesse und Durchsatz einer MJPEG-Quelle.

Nuetzlich zum Diagnostizieren der ESP32-CAM (WLAN-/Bandbreiten-Engpass):
ein flüssiger Stream + zuverlaessige Zaehlung braucht ausreichend FPS.

Beispiele:
    python3 fps_test.py                      # misst die App-Pipeline (/webcam_feed)
    python3 fps_test.py --cam                 # misst die Kamera direkt (CAMERA_URL aus .env)
    python3 fps_test.py http://192.168.10.99:81/stream
    python3 fps_test.py --app -t 20           # App-Stream, 20 Sekunden messen
"""
import argparse
import os
import sys
import time

import requests

try:
    from dotenv import load_dotenv
    load_dotenv()
except ImportError:
    pass

APP_URL = "http://localhost:8080/webcam_feed"
CAM_URL = os.environ.get("CAMERA_URL", "http://192.168.10.99:81/stream")

SOI = b"\xff\xd8"   # JPEG Start-of-Image
EOI = b"\xff\xd9"   # JPEG End-of-Image


def measure(url: str, seconds: float) -> int:
    print(f"Messe {seconds:.0f}s an: {url}\n", flush=True)
    try:
        resp = requests.get(url, stream=True, timeout=(5, 10))
        resp.raise_for_status()
    except requests.RequestException as exc:
        print(f"FEHLER: {exc}")
        return 1

    buf = b""
    frames = 0
    total_bytes = 0
    sizes = []
    t0 = time.time()
    try:
        for chunk in resp.iter_content(chunk_size=16384):
            buf += chunk
            total_bytes += len(chunk)
            while True:
                s = buf.find(SOI)
                e = buf.find(EOI, s + 2)
                if s == -1 or e == -1:
                    break
                sizes.append(e + 2 - s)
                buf = buf[e + 2:]
                frames += 1
            if time.time() - t0 >= seconds:
                break
    except requests.RequestException as exc:
        print(f"Stream-Abbruch nach {frames} Frames: {exc}")
    finally:
        resp.close()

    dt = time.time() - t0
    if not frames:
        print("Keine vollstaendigen Frames empfangen.")
        return 1

    fps = frames / dt
    avg_kb = sum(sizes) / len(sizes) / 1024
    min_kb = min(sizes) / 1024
    max_kb = max(sizes) / 1024
    kbs = total_bytes / dt / 1024
    mbit = total_bytes * 8 / dt / 1e6

    print(f"  Frames        : {frames} in {dt:.1f}s")
    print(f"  FPS           : {fps:.1f}")
    print(f"  Framegroesse  : Ø {avg_kb:.0f} KB  (min {min_kb:.0f} / max {max_kb:.0f})")
    print(f"  Durchsatz     : {kbs:.0f} KB/s  ({mbit:.2f} Mbit/s)")

    print("\n  Einschaetzung :", end=" ")
    if fps >= 10:
        print("fluessig - gut fuer Zaehlung. ✓")
    elif fps >= 5:
        print("brauchbar, aber schnelle Fahrzeuge koennen rutschen.")
    else:
        print("zu niedrig - WLAN-Signal/Framegroesse pruefen (kleinere Quality, naeher zum AP).")
    if mbit < 2 and avg_kb > 40:
        print("  Hinweis       : grosse Frames + wenig Bandbreite -> Quality-Zahl hoeher setzen ODER WLAN verbessern.")
    return 0


def main() -> int:
    p = argparse.ArgumentParser(description="Misst FPS/Durchsatz einer MJPEG-Quelle.")
    p.add_argument("url", nargs="?", help="MJPEG-URL (Default: App-Stream)")
    p.add_argument("--app", action="store_true", help=f"App-Pipeline messen ({APP_URL})")
    p.add_argument("--cam", action="store_true", help=f"Kamera direkt messen (CAMERA_URL: {CAM_URL})")
    p.add_argument("-t", "--seconds", type=float, default=10, help="Messdauer in Sekunden (Default 10)")
    args = p.parse_args()

    if args.url:
        url = args.url
    elif args.cam:
        url = CAM_URL
    else:
        url = APP_URL
    return measure(url, args.seconds)


if __name__ == "__main__":
    sys.exit(main())