// client/src/output/video.rs

use anyhow::Context;
use gstreamer as gst;
use gstreamer_app as gst_app;
use gst::prelude::*;
use lesavka_common::lesavka::VideoPacket;
use tracing::{error, info, warn, debug};

/* ---------- pipeline ----------------------------------------------------
* ┌────────────┐  H.264/AU  ┌─────────┐   Decoded  ┌─────────────┐
* │  AppSrc    │────────────► decodebin ├──────────► glimagesink │
* └────────────┘             (autoplug)               (overlay)  |
* ----------------------------------------------------------------------*/
const PIPELINE_DESC: &str = concat!(
    "appsrc name=src is-live=true format=time do-timestamp=true block=false ! ",
    "queue leaky=downstream ! ",
    "capsfilter caps=video/x-h264,stream-format=byte-stream,alignment=au ! ",
    "h264parse disable-passthrough=true ! decodebin ! videoconvert ! ",
    "glimagesink name=sink sync=false"
);

pub struct MonitorWindow {
    _pipeline: gst::Pipeline,
    src:     gst_app::AppSrc,
}

impl MonitorWindow {
    pub fn new(_id: u32) -> anyhow::Result<Self> {
        gst::init().context("initialising GStreamer")?;

        // --- Build pipeline ------------------------------------------------
        let pipeline: gst::Pipeline = gst::parse::launch(PIPELINE_DESC)?
            .downcast::<gst::Pipeline>()
            .expect("not a pipeline");

        // Optional: turn the sink full‑screen when LESAVKA_FULLSCREEN=1
        let fullscreen = std::env::var("LESAVKA_FULLSCREEN").is_ok();
        if let Some(sink) = pipeline.by_name("sink") {
            // glimagesink: title / fullscreen / force‑aspect‑ratio
            let title = format!("Lesavka‑eye‑{_id}");
            let _ = sink.set_property("title", &title);           // only if supported
            if fullscreen {
                let _ = sink.set_property("fullscreen", &true);   // ditto
            }
            let _ = sink.set_property("force-aspect-ratio", &true);
        }

        /* ---------- AppSrc ------------------------------------------------- */
        let src: gst_app::AppSrc = pipeline
            .by_name("src")
            .unwrap()
            .downcast::<gst_app::AppSrc>()
            .unwrap();

        src.set_caps(Some(&gst::Caps::builder("video/x-h264")
            .field("stream-format", &"byte-stream")
            .field("alignment",      &"au")
            .build()));
        src.set_format(gst::Format::Time);
        pipeline.set_state(gst::State::Playing)?;
        if let Some(sink) = pipeline.by_name("sink") {
            let title = format!("Lesavka‑eye‑{_id}");
            sink.set_property_from_str("window-title", &title);
            sink.set_property("force-aspect-ratio", &true);
        }

        Ok(Self { _pipeline: pipeline, src })
    }

    /// Feed one access-unit to the decoder.
    pub fn push_packet(&self, pkt: VideoPacket) {
        static CNT : std::sync::atomic::AtomicU64 =
            std::sync::atomic::AtomicU64::new(0);
        let n = CNT.fetch_add(1, std::sync::atomic::Ordering::Relaxed);
        if n % 150 == 0 || n < 10 {
            debug!(eye = pkt.id, bytes = pkt.data.len(), pts = pkt.pts, "⬇️  received video AU");
        }
        let mut buf = gst::Buffer::from_slice(pkt.data);
        buf.get_mut()
            .unwrap()
            .set_pts(Some(gst::ClockTime::from_useconds(pkt.pts)));
        let _ = self.src.push_buffer(buf); // ignore Eos/flushing
    }
}