// client/src/output/audio.rs

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

pub struct AudioOut {
    src: gst_app::AppSrc,
}

impl AudioOut {
    pub fn new() -> anyhow::Result<Self> {
        gst::init()?;

        // Auto-audiosink picks PipeWire / Pulse etc.
        const PIPE: &str =
            "appsrc name=src is-live=true format=time do-timestamp=true block=false ! \
             queue leaky=downstream ! aacparse ! avdec_aac ! audioresample ! autoaudiosink";

        // `parse_launch()` returns `gst::Element`; down-cast manually and
        // map the error into anyhow ourselves (no `?` on the downcast).
        let pipeline: gst::Pipeline = gst::parse::launch(PIPE)?
            .downcast::<gst::Pipeline>()
            .expect("not a pipeline");

        let src: gst_app::AppSrc = pipeline
            .by_name("src")
            .expect("no src element")
            .downcast::<gst_app::AppSrc>()
            .expect("src not an AppSrc");
        
        src.set_caps(Some(&gst::Caps::builder("audio/mpeg")        // mpeg‑4 AAC
            .field("mpegversion", &4i32)
            .field("stream-format", &"adts")
            .build()));
        src.set_format(gst::Format::Time);

        {
            let bus = pipeline.bus().expect("bus");
            std::thread::spawn(move || {
                use gst::MessageView::*;
                for msg in bus.iter_timed(gst::ClockTime::NONE) {
                    if let Error(e) = msg.view() {
                        error!("💥 client‑audio: {} ({})",
                               e.error(), e.debug().unwrap_or_default());
                    }
                }
            });
        }

        pipeline.set_state(gst::State::Playing)?;

        Ok(Self { src })
    }

    pub fn push(&self, pkt: AudioPacket) {
        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 % 300 == 0 || n < 10 {
            debug!(bytes = pkt.data.len(), pts = pkt.pts, "⬇️  received audio 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);
    }
}