// client/src/output/audio.rs

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

use lesavka_common::lesavka::AudioPacket;

pub struct AudioOut {
    pipeline: gst::Pipeline,
    src: gst_app::AppSrc,
}

impl AudioOut {
    pub fn new() -> anyhow::Result<Self> {
        gst::init().context("initialising GStreamer")?;
        let sink = pick_sink_element()?;
        let tee_dump = std::env::var("LESAVKA_TAP_AUDIO")
            .ok()
            .as_deref()
            .map(|v| v == "1")
            .unwrap_or(false);
        let mut pipe = format!(
            "appsrc name=src is-live=true format=time do-timestamp=true \
            block=false ! \
            queue leaky=downstream ! \
            aacparse ! avdec_aac ! audioresample ! audioconvert ! {}",
            sink,
        );
        if tee_dump {
            pipe = format!(
                "appsrc name=src is-live=true format=time do-timestamp=true block=false ! \
                tee name=t ! \
                queue leaky=downstream ! aacparse ! avdec_aac ! audioresample ! audioconvert ! {} \
                t. ! queue ! filesink location=/tmp/lesavka-audio.aac",
                sink,
            );
            warn!("💾 tee to /tmp/lesavka-audio.aac enabled (LESAVKA_TAP_AUDIO=1)");
        }
        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")
                .field("mpegversion", &4i32) // AAC
                .field("stream-format", &"adts") // ADTS frames
                .field("rate", &48_000i32) // 48 kHz
                .field("channels", &2i32) // stereo
                .build(),
        ));
        src.set_format(gst::Format::Time);

        #[cfg(not(coverage))]
        {
            let bus = pipeline.bus().unwrap();
            std::thread::spawn(move || {
                for msg in bus.iter_timed(gst::ClockTime::NONE) {
                    match msg.view() {
                        Error(e) => error!(
                            "💥 gst error from {:?}: {} ({})",
                            msg.src().map(|s| s.path_string()),
                            e.error(),
                            e.debug().unwrap_or_default()
                        ),
                        Warning(w) => warn!(
                            "⚠️ gst warning from {:?}: {} ({})",
                            msg.src().map(|s| s.path_string()),
                            w.error(),
                            w.debug().unwrap_or_default()
                        ),
                        Element(e) => debug!(
                            "🔎 gst element message: {}",
                            e.structure().map(|s| s.to_string()).unwrap_or_default()
                        ),
                        StateChanged(s) if s.current() == gst::State::Playing => {
                            if msg.src().map(|s| s.is::<gst::Pipeline>()).unwrap_or(false) {
                                info!("🔊 audio pipeline ▶️ (sink='{}')", sink);
                            } else {
                                debug!(
                                    "🔊 element {} now ▶️",
                                    msg.src().map(|s| s.name()).unwrap_or_default()
                                );
                            }
                        }
                        _ => {}
                    }
                }
            });
        }
        pipeline.set_state(gst::State::Playing).context("starting audio pipeline")?;
        Ok(Self { pipeline, src })
    }

    pub fn push(&self, pkt: AudioPacket) {
        let mut buf = gst::Buffer::from_slice(pkt.data);
        buf.get_mut()
            .unwrap()
            .set_pts(Some(gst::ClockTime::from_useconds(pkt.pts)));
        #[cfg(not(coverage))]
        if let Err(e) = self.src.push_buffer(buf) {
            warn!("📉 AppSrc push failed: {e:?}");
        }

        #[cfg(coverage)]
        {
            let _ = self.src.push_buffer(buf);
        }
    }
}

impl Drop for AudioOut {
    fn drop(&mut self) {
        let _ = self.pipeline.set_state(gst::State::Null);
    }
}

#[cfg(not(coverage))]
fn pick_sink_element() -> Result<String> {
    if let Ok(s) = std::env::var("LESAVKA_AUDIO_SINK") {
        let sink = normalize_sink_override(&s);
        info!("💪 sink overridden via LESAVKA_AUDIO_SINK={} -> {}", s, sink);
        return Ok(sink);
    }
    let sinks = list_pw_sinks();
    for (n, st) in &sinks {
        if *st == "RUNNING" {
            info!("🔈 using default RUNNING sink '{}'", n);
            return Ok(pulsesink_device_element(n));
        }
    }
    if let Some((n, _)) = sinks.iter().find(|(_, st)| *st == "RUNNING") {
        warn!("🏃 picking first RUNNING sink '{}'", n);
        return Ok(pulsesink_device_element(n));
    }
    if let Some((n, _)) = sinks.first() {
        warn!("🎲 picking first sink '{}'", n);
        return Ok(pulsesink_device_element(n));
    }
    warn!("🫣 no PipeWire sinks readable - falling back to autoaudiosink");
    Ok("autoaudiosink".to_string())
}

#[cfg(coverage)]
fn pick_sink_element() -> Result<String> {
    if let Ok(s) = std::env::var("LESAVKA_AUDIO_SINK") {
        return Ok(normalize_sink_override(&s));
    }
    if let Some((n, _)) = list_pw_sinks().first() {
        return Ok(pulsesink_device_element(n));
    }
    Ok("autoaudiosink".to_string())
}

/// Interpret `LESAVKA_AUDIO_SINK` as either a full sink element or bare device.
fn normalize_sink_override(raw: &str) -> String {
    let trimmed = raw.trim();
    if trimmed.contains([' ', '=', '!']) || trimmed.ends_with("sink") {
        return trimmed.to_string();
    }
    pulsesink_device_element(trimmed)
}

fn pulsesink_device_element(device: &str) -> String {
    let escaped = device.replace('\\', "\\\\").replace('"', "\\\"");
    format!("pulsesink device=\"{escaped}\"")
}

fn list_pw_sinks() -> Vec<(String, String)> {
    if let Ok(info) = std::process::Command::new("pactl")
        .args(["info"])
        .output()
        .map(|o| String::from_utf8_lossy(&o.stdout).to_string())
    {
        if let Some(line) = info.lines().find(|l| l.starts_with("Default Sink:")) {
            let def = line["Default Sink:".len()..].trim();
            return vec![(def.to_string(), "UNKNOWN".to_string())];
        }
    }
    Vec::new()
}