# SPDX-License-Identifier: MIT
# Copyright (C) Intel Corporation
#
# Motion Detection: DLStreamer pipeline sample.
# See README.md for prerequisites and inputs. Run: python3 dlstreamer_sample.py

import gi

gi.require_version("Gst", "1.0")
from gi.repository import Gst

import numpy as np

Gst.init([])

# Import cv2 after Gst.init to avoid GStreamer re-initialization conflicts.
import cv2

INPUT_VIDEO = "test_video.mp4"
MIN_AREA = 500

# Decode with the DLStreamer/GStreamer stack and hand BGR frames to OpenCV.
pipeline_str = (
    f"filesrc location={INPUT_VIDEO} ! decodebin3 ! videoconvert ! "
    "video/x-raw,format=BGR ! "
    "appsink name=sink emit-signals=false sync=false"
)
pipeline = Gst.parse_launch(pipeline_str)
sink = pipeline.get_by_name("sink")
pipeline.set_state(Gst.State.PLAYING)

bg = cv2.createBackgroundSubtractorMOG2(
    history=200, varThreshold=25, detectShadows=True)
kernel = np.ones((3, 3), np.uint8)
writer = None
frame_idx = 0
motion_frames = 0

while True:
    sample = sink.emit("pull-sample")
    if sample is None:
        break
    buf = sample.get_buffer()
    caps = sample.get_caps().get_structure(0)
    width = caps.get_value("width")
    height = caps.get_value("height")

    ok, mapinfo = buf.map(Gst.MapFlags.READ)
    if not ok:
        continue
    frame = np.ndarray((height, width, 3), dtype=np.uint8,
                       buffer=mapinfo.data).copy()
    buf.unmap(mapinfo)
    frame_idx += 1

    fg = bg.apply(frame)
    fg = cv2.threshold(fg, 200, 255, cv2.THRESH_BINARY)[1]
    fg = cv2.morphologyEx(fg, cv2.MORPH_OPEN, kernel)
    contours, _ = cv2.findContours(
        fg, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
    regions = [c for c in contours if cv2.contourArea(c) >= MIN_AREA]
    if regions:
        motion_frames += 1
    for c in regions:
        x, y, w, h = cv2.boundingRect(c)
        cv2.rectangle(frame, (x, y), (x + w, y + h), (0, 0, 255), 2)
    status_text = "Motion Detected" if regions else "No Motion"
    status_color = (0, 0, 255) if regions else (0, 255, 0)
    cv2.putText(frame, status_text, (10, 30),
                cv2.FONT_HERSHEY_SIMPLEX, 0.9, status_color, 2)

    if writer is None:
        writer = cv2.VideoWriter(
            "output_dlstreamer.mp4", cv2.VideoWriter_fourcc(*"mp4v"),
            30.0, (width, height))
    writer.write(frame)
    print(f"Frame {frame_idx}: motion regions={len(regions)}", flush=True)

pipeline.set_state(Gst.State.NULL)
if writer:
    writer.release()
print(f"Motion detected in {motion_frames} frames", flush=True)