use gstreamer::prelude::*;
use gstreamer::{self as gst, Element, Pipeline};
use tracing::{error, info, warn};

pub fn create_camera_pipeline(name: &str, rtsp_uri: &str) -> Option<(Pipeline, Element)> {
    let pipeline_name = format!("cam-{name}");
    let pipeline = Pipeline::with_name(&pipeline_name);

    let src = gst::ElementFactory::make("rtspsrc")
        .property("location", rtsp_uri)
        .property("latency", 300u32)
        .property_from_str("protocols", "tcp")
        .build()
        .map_err(|e| error!("[{pipeline_name}] rtspsrc: {e}"))
        .ok()?;

    let decode = gst::ElementFactory::make("decodebin")
        .build()
        .map_err(|e| error!("[{pipeline_name}] decodebin: {e}"))
        .ok()?;

    let convert = gst::ElementFactory::make("videoconvert")
        .build()
        .map_err(|e| error!("[{pipeline_name}] videoconvert: {e}"))
        .ok()?;

    let sink = gst::ElementFactory::make("gtk4paintablesink")
        .build()
        .map_err(|e| error!("[{pipeline_name}] gtk4paintablesink: {e}"))
        .ok()?;

    pipeline.add_many([&src, &decode, &convert, &sink]).ok()?;
    gst::Element::link_many([&convert, &sink])
        .map_err(|e| error!("[{pipeline_name}] link convert→sink failed: {e}"))
        .ok()?;

    // rtspsrc → decodebin (dynamic pads)
    let decode_weak = decode.downgrade();
    let pn = pipeline_name.clone();
    src.connect_pad_added(move |_src, pad| {
        info!("[{pn}] rtspsrc pad added: {}", pad.name());
        let Some(decode) = decode_weak.upgrade() else { return };
        let sink_pad = decode.static_pad("sink").unwrap();
        if !sink_pad.is_linked() {
            match pad.link(&sink_pad) {
                Ok(_) => info!("[{pn}] rtspsrc→decodebin linked"),
                Err(e) => error!("[{pn}] rtspsrc→decodebin link failed: {e:?}"),
            }
        }
    });

    // decodebin → convert (dynamic pads, video only)
    let convert_weak = convert.downgrade();
    let pn2 = pipeline_name.clone();
    decode.connect_pad_added(move |_decode, pad| {
        let caps = pad.current_caps().unwrap_or_else(|| pad.query_caps(None));
        let structure = caps.structure(0);
        let media = structure.map(|s| s.name().to_string()).unwrap_or_default();

        info!("[{pn2}] decodebin pad: {media}");

        if !media.starts_with("video/") {
            return;
        }

        let Some(convert) = convert_weak.upgrade() else { return };
        let sink_pad = convert.static_pad("sink").unwrap();
        if !sink_pad.is_linked() {
            match pad.link(&sink_pad) {
                Ok(_) => info!("[{pn2}] decodebin→convert linked"),
                Err(e) => error!("[{pn2}] decodebin→convert link failed: {e:?}"),
            }
        }
    });

    // Watch bus for errors
    let pn3 = pipeline_name.clone();
    let bus = pipeline.bus().unwrap();
    bus.add_watch_local(move |_bus, msg| {
        use gst::MessageView;
        match msg.view() {
            MessageView::Error(err) => {
                error!("[{pn3}] pipeline error: {} ({:?})", err.error(), err.debug());
            }
            MessageView::Warning(w) => {
                warn!("[{pn3}] pipeline warning: {} ({:?})", w.error(), w.debug());
            }
            MessageView::StateChanged(sc) => {
                if sc.src().map(|s| s.name().as_str() == pn3).unwrap_or(false) {
                    info!("[{pn3}] state: {:?} → {:?}", sc.old(), sc.current());
                }
            }
            _ => {}
        }
        gst::glib::ControlFlow::Continue
    })
    .ok()?;

    info!("[{pipeline_name}] pipeline created for {rtsp_uri}");
    Some((pipeline, sink))
}

pub fn play(pipeline: &Pipeline) {
    match pipeline.set_state(gst::State::Playing) {
        Ok(r) => info!("[{}] set_state(Playing) = {r:?}", pipeline.name()),
        Err(e) => error!("[{}] set_state(Playing) failed: {e:?}", pipeline.name()),
    }
}

pub fn stop(pipeline: &Pipeline) {
    let _ = pipeline.set_state(gst::State::Null);
}