import gi
gi.require_version('Gst', '1.0')
from gi.repository import Gst, GLib
import threading

class GstRelay:
    def __init__(self):
        Gst.init(None)

        # Pipeline 1: Generate video frames
        self.pipeline1 = Gst.parse_launch(
            "videotestsrc is-live=true ! video/x-raw,format=RGB,width=640,height=480 ! videoconvert ! appsink name=sink"
        )
        self.appsink = self.pipeline1.get_by_name("sink")
        self.appsink.set_property("emit-signals", True)
        self.appsink.connect("new-sample", self.on_new_sample)

        # Pipeline 2: Receive video frames
        self.pipeline2 = Gst.parse_launch(
            "appsrc name=src is-live=true format=time ! videoconvert ! autovideosink"
        )
        self.appsrc = self.pipeline2.get_by_name("src")
        self.appsrc.set_property("caps", Gst.Caps.from_string("video/x-raw,format=RGB,width=640,height=480"))

    def on_new_sample(self, sink):
        """Callback when new frame arrives at appsink (Pipeline 1)."""
        sample = sink.emit("pull-sample")
        if not sample:
            return Gst.FlowReturn.ERROR

        buffer = sample.get_buffer()
        success, map_info = buffer.map(Gst.MapFlags.READ)
        if not success:
            return Gst.FlowReturn.ERROR

        # Create a new Gst.Buffer for appsrc
        new_buffer = Gst.Buffer.new_allocate(None, len(map_info.data), None)
        new_buffer.fill(0, map_info.data)
        new_buffer.pts = buffer.pts
        new_buffer.dts = buffer.dts
        new_buffer.duration = buffer.duration

        buffer.unmap(map_info)

        # Push buffer to appsrc (Pipeline 2)
        self.appsrc.emit("push-buffer", new_buffer)

        return Gst.FlowReturn.OK

    def start(self):
        """Start both pipelines."""
        self.pipeline1.set_state(Gst.State.PLAYING)
        self.pipeline2.set_state(Gst.State.PLAYING)

    def stop(self):
        """Stop both pipelines."""
        self.pipeline1.set_state(Gst.State.NULL)
        self.pipeline2.set_state(Gst.State.NULL)

def main():
    gst_relay = GstRelay()
    gst_relay.start()

    loop = GLib.MainLoop()
    try:
        loop.run()
    except KeyboardInterrupt:
        print("Stopping pipelines...")
        gst_relay.stop()

if __name__ == "__main__":
    main()