// client/src/input/camera.rs
use anyhow::Context;
use gst::prelude::*;
use gstreamer as gst;
use gstreamer_app as gst_app;
use lesavka_common::lesavka::VideoPacket;

fn env_u32(name: &str, default: u32) -> u32 {
    std::env::var(name)
        .ok()
        .and_then(|v| v.parse::<u32>().ok())
        .unwrap_or(default)
}

#[derive(Clone, Copy, Debug)]
pub enum CameraCodec {
    H264,
    Mjpeg,
}

#[derive(Clone, Copy, Debug)]
pub struct CameraConfig {
    pub codec: CameraCodec,
    pub width: u32,
    pub height: u32,
    pub fps: u32,
}

pub struct CameraCapture {
    #[allow(dead_code)] // kept alive to hold PLAYING state
    pipeline: gst::Pipeline,
    sink: gst_app::AppSink,
}

impl CameraCapture {
    pub fn new(device_fragment: Option<&str>, cfg: Option<CameraConfig>) -> anyhow::Result<Self> {
        gst::init().ok();

        // Select source: V4L2 device or test pattern
        let (src_desc, dev_label, allow_mjpg_source) = match device_fragment {
            Some(fragment)
                if fragment.eq_ignore_ascii_case("test")
                    || fragment.eq_ignore_ascii_case("videotestsrc") =>
            {
                let pattern =
                    std::env::var("LESAVKA_CAM_TEST_PATTERN").unwrap_or_else(|_| "smpte".into());
                (
                    format!("videotestsrc is-live=true pattern={pattern}"),
                    format!("videotestsrc:{pattern}"),
                    false,
                )
            }
            Some(path) if path.starts_with("/dev/") => (
                format!("v4l2src device={path} do-timestamp=true"),
                path.to_string(),
                true,
            ),
            Some(fragment) => {
                let dev = Self::find_device(fragment).unwrap_or_else(|| "/dev/video0".into());
                (format!("v4l2src device={dev} do-timestamp=true"), dev, true)
            }
            None => {
                let dev = "/dev/video0".to_string();
                (format!("v4l2src device={dev} do-timestamp=true"), dev, true)
            }
        };

        let use_mjpg_source = allow_mjpg_source
            && (std::env::var("LESAVKA_CAM_MJPG").is_ok()
                || std::env::var("LESAVKA_CAM_FORMAT")
                    .ok()
                    .map(|v| matches!(v.to_ascii_lowercase().as_str(), "mjpg" | "mjpeg" | "jpeg"))
                    .unwrap_or(false));
        let output_mjpeg = cfg
            .map(|cfg| matches!(cfg.codec, CameraCodec::Mjpeg))
            .unwrap_or_else(|| {
                std::env::var("LESAVKA_CAM_CODEC")
                    .ok()
                    .map(|v| matches!(v.to_ascii_lowercase().as_str(), "mjpeg" | "mjpg" | "jpeg"))
                    .unwrap_or(false)
            });
        let jpeg_quality = env_u32("LESAVKA_CAM_JPEG_QUALITY", 85).clamp(1, 100);
        let width = cfg
            .map(|cfg| cfg.width)
            .unwrap_or_else(|| env_u32("LESAVKA_CAM_WIDTH", 1280));
        let height = cfg
            .map(|cfg| cfg.height)
            .unwrap_or_else(|| env_u32("LESAVKA_CAM_HEIGHT", 720));
        let fps = cfg
            .map(|cfg| cfg.fps)
            .unwrap_or_else(|| env_u32("LESAVKA_CAM_FPS", 25))
            .max(1);
        let keyframe_interval = env_u32("LESAVKA_CAM_KEYFRAME_INTERVAL", fps.min(5)).clamp(1, fps);
        let (enc, kf_prop) = if use_mjpg_source && !output_mjpeg {
            ("x264enc", Some("key-int-max"))
        } else {
            Self::choose_encoder()
        };
        if use_mjpg_source && !output_mjpeg {
            tracing::info!("📸 using MJPG source with software encode");
        }
        let _enc_opts = if enc == "x264enc" {
            let bitrate_kbit = env_u32("LESAVKA_CAM_H264_KBIT", 4500);
            let keyframe_opt = kf_prop
                .map(|property| format!(" {property}={keyframe_interval}"))
                .unwrap_or_default();
            format!(
                "{enc} tune=zerolatency speed-preset=faster bitrate={bitrate_kbit}{keyframe_opt}"
            )
        } else if let Some(property) = kf_prop {
            format!("{enc} {property}={keyframe_interval}")
        } else {
            enc.to_string()
        };
        if output_mjpeg {
            tracing::info!("📸 outputting MJPEG frames for UVC (quality={jpeg_quality})");
        } else {
            tracing::info!("📸 using encoder element: {enc}");
        }
        #[cfg(not(coverage))]
        let have_nvvidconv = gst::ElementFactory::find("nvvidconv").is_some();
        let (src_caps, preenc) = match enc {
            // ───────────────────────────────────────────────────────────────────
            // Jetson (has nvvidconv)      Desktop (falls back to videoconvert)
            // ───────────────────────────────────────────────────────────────────
            #[cfg(not(coverage))]
            "nvh264enc" if have_nvvidconv =>
                (format!(
                    "video/x-raw(memory:NVMM),format=NV12,width={width},height={height},framerate={fps}/1"
                ), "nvvidconv !"),
            #[cfg(not(coverage))]
            "nvh264enc" /* else */ =>
                (format!(
                    "video/x-raw,format=NV12,width={width},height={height},framerate={fps}/1"
                ), "videoconvert !"),
            #[cfg(not(coverage))]
            "vaapih264enc" =>
                (format!(
                    "video/x-raw,format=NV12,width={width},height={height},framerate={fps}/1"
                ), "videoconvert !"),
            _ =>
                (format!(
                    "video/x-raw,width={width},height={height},framerate={fps}/1"
                ), "videoconvert !"),
        };

        // let desc = format!(
        //     "v4l2src device={dev} do-timestamp=true ! {raw_caps},width=1280,height=720 ! \
        //     videoconvert ! {enc} key-int-max=30 ! \
        //     h264parse config-interval=-1 ! \
        //     appsink name=asink emit-signals=true max-buffers=60 drop=true"
        // );
        // tracing::debug!(%desc, "📸 pipeline-desc");
        // Build a pipeline that works for any of the three encoders.
        //  * nvh264enc needs NVMM memory caps;
        //  * vaapih264enc wants system-memory caps;
        //  * x264enc needs the usual raw caps.
        let desc = if output_mjpeg {
            if use_mjpg_source {
                format!(
                    "{src_desc} ! \
                     image/jpeg,width={width},height={height},framerate={fps}/1 ! \
                     queue max-size-buffers=30 leaky=downstream ! \
                     appsink name=asink emit-signals=true max-buffers=60 drop=true"
                )
            } else {
                format!(
                    "{src_desc} ! \
                     video/x-raw,width={width},height={height},framerate={fps}/1 ! \
                     videoconvert ! jpegenc quality={jpeg_quality} ! \
                     queue max-size-buffers=30 leaky=downstream ! \
                     appsink name=asink emit-signals=true max-buffers=60 drop=true"
                )
            }
        } else if use_mjpg_source {
            format!(
                "{src_desc} ! \
                 image/jpeg,width={width},height={height} ! \
                 jpegdec ! videorate ! video/x-raw,framerate={fps}/1 ! \
                 videoconvert ! {_enc_opts} ! \
                 h264parse config-interval=-1 ! video/x-h264,stream-format=byte-stream,alignment=au ! \
                 queue max-size-buffers=30 leaky=downstream ! \
                 appsink name=asink emit-signals=true max-buffers=60 drop=true"
            )
        } else {
            format!(
                "{src_desc} ! {src_caps} ! \
                 {preenc} {_enc_opts} ! \
                 h264parse config-interval=-1 ! video/x-h264,stream-format=byte-stream,alignment=au ! \
                 queue max-size-buffers=30 leaky=downstream ! \
                 appsink name=asink emit-signals=true max-buffers=60 drop=true"
            )
        };
        tracing::info!(%enc, width, height, fps, ?desc, "📸 using encoder element");

        let pipeline: gst::Pipeline = gst::parse::launch(&desc)
            .context("gst parse_launch(cam)")?
            .downcast::<gst::Pipeline>()
            .expect("not a pipeline");

        tracing::debug!("📸 pipeline built OK – setting PLAYING…");
        let sink: gst_app::AppSink = pipeline
            .by_name("asink")
            .expect("appsink element not found")
            .downcast::<gst_app::AppSink>()
            .expect("appsink down‑cast");

        pipeline.set_state(gst::State::Playing)?;
        tracing::info!("📸 webcam pipeline ▶️ device={dev_label}");

        Ok(Self { pipeline, sink })
    }

    pub fn pull(&self) -> Option<VideoPacket> {
        let sample = self.sink.pull_sample().ok()?;
        let buf = sample.buffer()?;
        let map = buf.map_readable().ok()?;
        let pts = buf.pts().unwrap_or(gst::ClockTime::ZERO).nseconds() / 1_000;
        Some(VideoPacket {
            id: 2,
            pts,
            data: map.as_slice().to_vec(),
            ..Default::default()
        })
    }

    /// Fuzzy‑match devices under `/dev/v4l/by-id`, preferring capture nodes
    #[cfg(not(coverage))]
    fn find_device(substr: &str) -> Option<String> {
        let wanted = substr.to_ascii_lowercase();
        let mut matches: Vec<_> = std::fs::read_dir("/dev/v4l/by-id")
            .ok()?
            .flatten()
            .filter_map(|e| {
                let p = e.path();
                let name = p.file_name()?.to_string_lossy().to_ascii_lowercase();
                if name.contains(&wanted) {
                    Some(p)
                } else {
                    None
                }
            })
            .collect();

        // deterministic order
        matches.sort();

        for p in matches {
            if let Ok(target) = std::fs::read_link(&p) {
                let dev = format!("/dev/{}", target.file_name()?.to_string_lossy());
                if Self::is_capture(&dev) {
                    return Some(dev);
                }
            }
        }
        None
    }

    #[cfg(coverage)]
    fn find_device(substr: &str) -> Option<String> {
        let wanted = substr.to_ascii_lowercase();
        let by_id_dir =
            std::env::var("LESAVKA_CAM_BY_ID_DIR").unwrap_or_else(|_| "/dev/v4l/by-id".to_string());
        let dev_root = std::env::var("LESAVKA_CAM_DEV_ROOT").unwrap_or_else(|_| "/dev".to_string());
        let mut matches: Vec<_> = std::fs::read_dir(by_id_dir)
            .ok()?
            .flatten()
            .filter_map(|e| {
                let p = e.path();
                let name = p.file_name()?.to_string_lossy().to_ascii_lowercase();
                if name.contains(&wanted) {
                    Some(p)
                } else {
                    None
                }
            })
            .collect();
        matches.sort();
        for p in matches {
            if let Ok(target) = std::fs::read_link(&p) {
                let dev = format!("{}/{}", dev_root, target.file_name()?.to_string_lossy());
                if Self::is_capture(&dev) {
                    return Some(dev);
                }
            }
        }
        None
    }

    #[cfg(not(coverage))]
    fn is_capture(dev: &str) -> bool {
        const V4L2_CAP_VIDEO_CAPTURE: u32 = 0x0000_0001;
        const V4L2_CAP_VIDEO_CAPTURE_MPLANE: u32 = 0x0000_1000;

        v4l::Device::with_path(dev)
            .ok()
            .and_then(|d| d.query_caps().ok())
            .map(|caps| {
                let bits = caps.capabilities.bits();
                (bits & V4L2_CAP_VIDEO_CAPTURE != 0) || (bits & V4L2_CAP_VIDEO_CAPTURE_MPLANE != 0)
            })
            .unwrap_or(false)
    }

    #[cfg(coverage)]
    fn is_capture(dev: &str) -> bool {
        dev.starts_with("/dev/video")
    }

    /// Cheap stub used when the web‑cam is disabled
    pub fn new_stub() -> Self {
        let pipeline = gst::Pipeline::new();
        let sink: gst_app::AppSink = gst::ElementFactory::make("appsink")
            .build()
            .expect("appsink")
            .downcast::<gst_app::AppSink>()
            .unwrap();
        Self { pipeline, sink }
    }

    #[allow(dead_code)] // helper kept for future heuristics
    #[cfg(not(coverage))]
    fn pick_encoder() -> (&'static str, &'static str) {
        let encoders = &[
            ("nvh264enc", "video/x-raw(memory:NVMM),format=NV12"),
            ("vaapih264enc", "video/x-raw,format=NV12"),
            ("v4l2h264enc", "video/x-raw"), // RPi, Jetson, etc.
            ("x264enc", "video/x-raw"),     // software
        ];
        for (name, caps) in encoders {
            if gst::ElementFactory::find(name).is_some() {
                return (name, caps);
            }
        }
        // last resort – software
        ("x264enc", "video/x-raw")
    }

    #[cfg(coverage)]
    fn pick_encoder() -> (&'static str, &'static str) {
        ("x264enc", "video/x-raw")
    }

    #[cfg(not(coverage))]
    fn choose_encoder() -> (&'static str, Option<&'static str>) {
        if buildable_encoder("nvh264enc") {
            return (
                "nvh264enc",
                supported_encoder_property(
                    "nvh264enc",
                    &["iframeinterval", "idrinterval", "gop-size"],
                ),
            );
        }
        if buildable_encoder("vaapih264enc") {
            return (
                "vaapih264enc",
                supported_encoder_property("vaapih264enc", &["keyframe-period"]),
            );
        }
        if buildable_encoder("v4l2h264enc") {
            return (
                "v4l2h264enc",
                supported_encoder_property("v4l2h264enc", &["idrcount"]),
            );
        }
        ("x264enc", Some("key-int-max"))
    }

    #[cfg(coverage)]
    fn choose_encoder() -> (&'static str, Option<&'static str>) {
        match std::env::var("LESAVKA_CAM_TEST_ENCODER")
            .ok()
            .as_deref()
            .map(str::trim)
        {
            Some("nvh264enc") => ("nvh264enc", None),
            Some("vaapih264enc") => ("vaapih264enc", Some("keyframe-period")),
            Some("v4l2h264enc") => ("v4l2h264enc", Some("idrcount")),
            _ => ("x264enc", Some("key-int-max")),
        }
    }
}

#[cfg(not(coverage))]
fn buildable_encoder(encoder: &'static str) -> bool {
    gst::ElementFactory::find(encoder).is_some()
        && gst::ElementFactory::make(encoder).build().is_ok()
}

#[cfg(not(coverage))]
fn supported_encoder_property(
    encoder: &'static str,
    properties: &[&'static str],
) -> Option<&'static str> {
    let element = gst::ElementFactory::make(encoder).build().ok()?;
    properties
        .iter()
        .copied()
        .find(|property| element.find_property(property).is_some())
}

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