// client/src/output/video.rs

use std::process::Command;
use std::time::Duration;
use std::thread;
use anyhow::Context;
use gstreamer as gst;
use gstreamer_app as gst_app;
use gstreamer_video::{prelude::*, VideoOverlay};
use gst::prelude::*;
use lesavka_common::lesavka::VideoPacket;
use tracing::{error, info, warn, debug};
use gstreamer_video as gst_video;
use gstreamer_video::glib::Type;

use crate::output::{display, layout};

/* ---------- 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");

        /* -------- placement maths -------------------------------------- */
        let monitors    = display::enumerate_monitors();
        let stream_defs = &[("eye-0", 1920, 1080), ("eye-1", 1920, 1080)];
        let rects       = layout::assign_rectangles(&monitors, stream_defs);

        // --- 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);

        /* -------- move/resize overlay ---------------------------------- */
        if let Some(sink_elem) = pipeline.by_name("sink") {
            if let Ok(overlay) = sink_elem.dynamic_cast::<VideoOverlay>() {
                if let Some(r) = rects.get(id as usize) {
                    // 1. Tell glimagesink how to crop the texture in its own window
                    overlay.set_render_rectangle(r.x, r.y, r.w, r.h);
                    debug!(
                        "🔲 eye-{id} → render_rectangle({}, {}, {}, {})",
                        r.x, r.y, r.w, r.h
                    );
        
                    // 2. **Compositor-level** placement (Wayland only)
                    if std::env::var_os("WAYLAND_DISPLAY").is_some() {
                        use std::process::{Command, ExitStatus};
                        use std::sync::Arc;
                        use std::thread;
                        use std::time::Duration;
        
                        // A small helper struct so the two branches return the same type
                        struct Placer {
                            name: &'static str,
                            run:  Arc<dyn Fn(&str) -> std::io::Result<ExitStatus> + Send + Sync>,
                        }
        
                        let placer = if Command::new("swaymsg").arg("-t").arg("get_tree")
                            .output().is_ok()
                        {
                            Placer {
                                name: "swaymsg",
                                run: Arc::new(|cmd| Command::new("swaymsg").arg(cmd).status()),
                            }
                        } else if Command::new("hyprctl").arg("version").output().is_ok() {
                            Placer {
                                name: "hyprctl",
                                run: Arc::new(|cmd| {
                                    Command::new("hyprctl")
                                        .args(["dispatch", "exec", cmd])
                                        .status()
                                }),
                            }
                        } else {
                            Placer {
                                name: "noop",
                                run: Arc::new(|_| {
                                    Err(std::io::Error::new(
                                        std::io::ErrorKind::Other,
                                        "no swaymsg/hyprctl found",
                                    ))
                                }),
                            }
                        };
        
                        if placer.name != "noop" {
                            // Criteria string that works for i3-/sway-compatible IPC
                            let criteria = format!(
                                r#"[title="^Lesavka-eye-{id}$"] \
                                   resize set {w} {h}; \
                                   move absolute position {x} {y}"#,
                                w = r.w,
                                h = r.h,
                                x = r.x,
                                y = r.y,
                            );
        
                            // Retry in a detached thread - avoids blocking GStreamer
                            let placename = placer.name;
                            let runner    = placer.run.clone();
                            thread::spawn(move || {
                                for attempt in 1..=10 {
                                    thread::sleep(Duration::from_millis(300));
                                    match runner(&criteria) {
                                        Ok(st) if st.success() => {
                                            tracing::info!(
                                                "✅ {placename}: placed eye-{id} (attempt {attempt})"
                                            );
                                            break;
                                        }
                                        _ => tracing::debug!(
                                            "⌛ {placename}: eye-{id} not mapped yet (attempt {attempt})"
                                        ),
                                    }
                                }
                            });
                        }
                    }
                }
            }
        }
        

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

        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
    }
}