#![forbid(unsafe_code)]

use std::{path::PathBuf, time::Duration};

use anyhow::{Context, Result, bail};
use gstreamer as gst;
use gstreamer::prelude::*;
use gstreamer_app as gst_app;
use lesavka_common::lesavka::{
    AudioEncoding, AudioPacket, UpstreamMediaBundle, VideoPacket, relay_client::RelayClient,
};
use tokio::sync::mpsc;
use tokio_stream::wrappers::ReceiverStream;
use tonic::Request;

const DEFAULT_SERVER: &str = "http://127.0.0.1:50051";
const DEFAULT_SAMPLE_RATE: u32 = 48_000;
const DEFAULT_CHANNELS: u32 = 2;
const DEFAULT_JPEG_QUALITY: i32 = 90;
const MARKER_BITS: usize = 32;
const MARKER_COLUMNS: usize = 16;

#[derive(Clone, Debug)]
struct Args {
    server: String,
    width: usize,
    height: usize,
    fps: u32,
    duration: Duration,
    jpeg_quality: i32,
    session_id: u64,
    artifact_dir: Option<PathBuf>,
    print_every: u64,
}

impl Args {
    fn parse() -> Result<Self> {
        let mut args = Self {
            server: DEFAULT_SERVER.to_string(),
            width: 1280,
            height: 720,
            fps: 30,
            duration: Duration::from_secs(300),
            jpeg_quality: DEFAULT_JPEG_QUALITY,
            session_id: unix_millis(),
            artifact_dir: None,
            print_every: 150,
        };
        let mut it = std::env::args().skip(1);
        while let Some(flag) = it.next() {
            match flag.as_str() {
                "--server" => args.server = next_value(&mut it, &flag)?,
                "--width" => args.width = parse_next(&mut it, &flag)?,
                "--height" => args.height = parse_next(&mut it, &flag)?,
                "--fps" => args.fps = parse_next(&mut it, &flag)?,
                "--duration" => {
                    let seconds: f64 = parse_next(&mut it, &flag)?;
                    args.duration = Duration::from_secs_f64(seconds.max(0.0));
                }
                "--jpeg-quality" => args.jpeg_quality = parse_next(&mut it, &flag)?,
                "--session-id" => args.session_id = parse_next(&mut it, &flag)?,
                "--artifact-dir" => {
                    args.artifact_dir = Some(PathBuf::from(next_value(&mut it, &flag)?))
                }
                "--print-every" => args.print_every = parse_next(&mut it, &flag)?,
                "--mode" => {
                    let value = next_value(&mut it, &flag)?;
                    let (width, height, fps) = parse_mode(&value)?;
                    args.width = width;
                    args.height = height;
                    args.fps = fps;
                }
                "--help" | "-h" => {
                    print_help();
                    std::process::exit(0);
                }
                other => bail!("unknown argument {other:?}; pass --help for usage"),
            }
        }
        if args.width == 0 || args.height == 0 || args.fps == 0 {
            bail!("width, height, and fps must be positive");
        }
        args.jpeg_quality = args.jpeg_quality.clamp(1, 100);
        Ok(args)
    }

    fn frame_step_us(&self) -> u64 {
        (1_000_000_u64 / u64::from(self.fps)).max(1)
    }

    fn total_frames(&self) -> u64 {
        let frames = self.duration.as_secs_f64() * f64::from(self.fps);
        frames.ceil().max(1.0) as u64
    }
}

struct MjpegEncoder {
    src: gst_app::AppSrc,
    sink: gst_app::AppSink,
    pipeline: gst::Pipeline,
    width: usize,
    height: usize,
    frame_step_us: u64,
}

impl MjpegEncoder {
    fn new(args: &Args) -> Result<Self> {
        gst::init().context("gst init")?;
        let width = args.width as i32;
        let height = args.height as i32;
        let fps = args.fps as i32;
        let raw_caps = gst::Caps::builder("video/x-raw")
            .field("format", "RGB")
            .field("width", width)
            .field("height", height)
            .field("framerate", gst::Fraction::new(fps, 1))
            .build();
        let jpeg_caps = gst::Caps::builder("image/jpeg")
            .field("parsed", true)
            .field("width", width)
            .field("height", height)
            .field("framerate", gst::Fraction::new(fps, 1))
            .build();
        let pipeline = gst::Pipeline::new();
        let src = gst::ElementFactory::make("appsrc")
            .name("lesavka_synthetic_uplink_src")
            .build()?
            .downcast::<gst_app::AppSrc>()
            .expect("appsrc");
        src.set_is_live(false);
        src.set_format(gst::Format::Time);
        src.set_property("do-timestamp", false);
        src.set_caps(Some(&raw_caps));
        let convert = gst::ElementFactory::make("videoconvert").build()?;
        let encoder = gst::ElementFactory::make("jpegenc")
            .property("quality", args.jpeg_quality)
            .build()?;
        let capsfilter = gst::ElementFactory::make("capsfilter")
            .property("caps", &jpeg_caps)
            .build()?;
        let sink = gst::ElementFactory::make("appsink")
            .name("lesavka_synthetic_uplink_sink")
            .property("sync", false)
            .property("emit-signals", false)
            .property("max-buffers", 8u32)
            .build()?
            .downcast::<gst_app::AppSink>()
            .expect("appsink");
        pipeline.add_many([
            src.upcast_ref(),
            &convert,
            &encoder,
            &capsfilter,
            sink.upcast_ref(),
        ])?;
        gst::Element::link_many([
            src.upcast_ref(),
            &convert,
            &encoder,
            &capsfilter,
            sink.upcast_ref(),
        ])?;
        pipeline
            .set_state(gst::State::Playing)
            .context("starting synthetic MJPEG encoder")?;
        Ok(Self {
            src,
            sink,
            pipeline,
            width: args.width,
            height: args.height,
            frame_step_us: args.frame_step_us(),
        })
    }

    fn encode(&mut self, sequence: u64) -> Result<Vec<u8>> {
        let pts_us = sequence.saturating_mul(self.frame_step_us);
        let mut buffer =
            gst::Buffer::from_slice(synthetic_rgb_frame(self.width, self.height, sequence));
        if let Some(meta) = buffer.get_mut() {
            let pts = gst::ClockTime::from_useconds(pts_us);
            meta.set_pts(Some(pts));
            meta.set_dts(Some(pts));
            meta.set_duration(Some(gst::ClockTime::from_useconds(self.frame_step_us)));
        }
        self.src
            .push_buffer(buffer)
            .context("encoding synthetic frame")?;
        let sample = self
            .sink
            .pull_sample()
            .context("pulling encoded synthetic frame")?;
        let buffer = sample
            .buffer()
            .context("encoded synthetic frame had no buffer")?;
        let map = buffer
            .map_readable()
            .context("mapping encoded synthetic frame")?;
        Ok(map.as_slice().to_vec())
    }
}

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

#[tokio::main(flavor = "current_thread")]
async fn main() -> Result<()> {
    let args = Args::parse()?;
    if let Some(dir) = &args.artifact_dir {
        std::fs::create_dir_all(dir).with_context(|| format!("creating {}", dir.display()))?;
        std::fs::write(
            dir.join("command.txt"),
            std::env::args().collect::<Vec<_>>().join(" ") + "\n",
        )?;
        std::fs::write(dir.join("summary.json"), args_summary_json(&args) + "\n")?;
    }

    let channel = tonic::transport::Channel::from_shared(args.server.clone())?
        .tcp_nodelay(true)
        .connect()
        .await
        .with_context(|| format!("connecting to {}", args.server))?;
    let mut client = RelayClient::new(channel);
    let (tx, rx) = mpsc::channel::<UpstreamMediaBundle>(8);
    let response_task = tokio::spawn(async move {
        let response = client
            .stream_webcam_media(Request::new(ReceiverStream::new(rx)))
            .await
            .context("opening StreamWebcamMedia")?;
        let mut inbound = response.into_inner();
        while inbound
            .message()
            .await
            .context("reading StreamWebcamMedia response")?
            .is_some()
        {}
        Ok::<(), anyhow::Error>(())
    });

    let mut encoder = MjpegEncoder::new(&args)?;
    let frame_step = Duration::from_micros(args.frame_step_us());
    let started = tokio::time::Instant::now() + Duration::from_millis(250);
    let total_frames = args.total_frames();
    eprintln!(
        "lesavka synthetic uplink: mode={}x{}@{} frames={} server={} session={}",
        args.width, args.height, args.fps, total_frames, args.server, args.session_id
    );
    for sequence in 0..total_frames {
        tokio::time::sleep_until(started + duration_mul(frame_step, sequence)).await;
        let pts_us = sequence.saturating_mul(args.frame_step_us());
        let encoded = encoder.encode(sequence)?;
        let bundle = synthetic_bundle(&args, sequence, pts_us, encoded);
        tx.send(bundle).await.context("sending synthetic bundle")?;
        if args.print_every > 0 && sequence > 0 && sequence % args.print_every == 0 {
            eprintln!("sent synthetic frame {sequence}/{total_frames}");
        }
    }
    drop(tx);
    response_task
        .await
        .context("joining StreamWebcamMedia task")??;
    eprintln!("lesavka synthetic uplink complete: frames={total_frames}");
    Ok(())
}

fn synthetic_bundle(args: &Args, sequence: u64, pts_us: u64, data: Vec<u8>) -> UpstreamMediaBundle {
    let video = VideoPacket {
        id: 0,
        pts: pts_us,
        data,
        seq: sequence,
        effective_fps: args.fps,
        client_capture_pts_us: pts_us,
        client_send_pts_us: pts_us,
        ..Default::default()
    };
    let audio = AudioPacket {
        id: 0,
        pts: pts_us,
        data: silence_pcm(args.frame_step_us()),
        seq: sequence,
        client_capture_pts_us: pts_us,
        client_send_pts_us: pts_us,
        encoding: AudioEncoding::PcmS16le as i32,
        sample_rate: DEFAULT_SAMPLE_RATE,
        channels: DEFAULT_CHANNELS,
        frame_duration_us: args.frame_step_us().min(u64::from(u32::MAX)) as u32,
        ..Default::default()
    };
    UpstreamMediaBundle {
        session_id: args.session_id,
        seq: sequence,
        capture_start_us: pts_us,
        capture_end_us: pts_us,
        video: Some(video),
        audio: vec![audio],
        audio_sample_rate: DEFAULT_SAMPLE_RATE,
        audio_channels: DEFAULT_CHANNELS,
        video_width: args.width as u32,
        video_height: args.height as u32,
        video_fps: args.fps,
        audio_encoding: AudioEncoding::PcmS16le as i32,
    }
}

fn silence_pcm(duration_us: u64) -> Vec<u8> {
    let samples = (u64::from(DEFAULT_SAMPLE_RATE).saturating_mul(duration_us) / 1_000_000).max(1);
    let bytes = samples
        .saturating_mul(u64::from(DEFAULT_CHANNELS))
        .saturating_mul(std::mem::size_of::<i16>() as u64)
        .min(usize::MAX as u64) as usize;
    vec![0; bytes]
}

fn synthetic_rgb_frame(width: usize, height: usize, sequence: u64) -> Vec<u8> {
    let mut frame = vec![0u8; width.saturating_mul(height).saturating_mul(3)];
    let moving_period = (width / 3).max(64);
    let moving_width = (width / 18).max(12);
    let moving_offset = (sequence as usize).wrapping_mul(17) % moving_period;
    for y in 0..height {
        for x in 0..width {
            let mut value = synthetic_luma(
                width,
                height,
                x,
                y,
                sequence,
                moving_period,
                moving_width,
                moving_offset,
            );
            if y >= height / 2 && (((x / 32) + (y / 24) + sequence as usize) & 1) == 0 {
                value /= 3;
            }
            let offset = (y * width + x) * 3;
            frame[offset] = value;
            frame[offset + 1] = value;
            frame[offset + 2] = value;
        }
    }
    draw_sequence_marker(&mut frame, width, height, sequence);
    frame
}

fn synthetic_luma(
    width: usize,
    height: usize,
    x: usize,
    y: usize,
    sequence: u64,
    moving_period: usize,
    moving_width: usize,
    moving_offset: usize,
) -> u8 {
    let mut value = ((x as u64 * 3 + y as u64 * 5 + sequence.saturating_mul(11)) & 0xff) as u8;
    let moving = (x + moving_offset) % moving_period;
    if moving < moving_width {
        value = value.saturating_add(70);
    }
    let center_x = width / 2;
    let center_y = height / 2;
    if x.abs_diff(center_x) < width / 9 && y.abs_diff(center_y) < height / 12 {
        value = 255u8.saturating_sub(value / 2);
    }
    value
}

fn marker_cell(width: usize, height: usize) -> usize {
    (width.min(height) / 80).clamp(6, 16)
}

fn draw_sequence_marker(frame: &mut [u8], width: usize, height: usize, sequence: u64) {
    let cell = marker_cell(width, height);
    let rows = MARKER_BITS.div_ceil(MARKER_COLUMNS);
    if width < (MARKER_COLUMNS + 4) * cell || height < (rows + 4) * cell {
        return;
    }
    let x0 = 2 * cell;
    let y0 = 2 * cell;
    fill_rect(
        frame,
        width,
        cell,
        cell,
        (MARKER_COLUMNS + 2) * cell,
        (rows + 2) * cell,
        32,
    );
    fill_rect(frame, width, x0 - cell, y0 - cell, cell, cell, 255);
    fill_rect(
        frame,
        width,
        x0 + MARKER_COLUMNS * cell,
        y0 - cell,
        cell,
        cell,
        0,
    );
    for bit in 0..MARKER_BITS {
        let col = bit % MARKER_COLUMNS;
        let row = bit / MARKER_COLUMNS;
        let value = if ((sequence >> bit) & 1) != 0 { 255 } else { 0 };
        fill_rect(
            frame,
            width,
            x0 + col * cell,
            y0 + row * cell,
            cell,
            cell,
            value,
        );
    }
}

fn fill_rect(frame: &mut [u8], width: usize, x0: usize, y0: usize, w: usize, h: usize, value: u8) {
    let pixels = frame.len() / 3;
    let height = pixels / width.max(1);
    let x1 = (x0 + w).min(width);
    let y1 = (y0 + h).min(height);
    for y in y0..y1 {
        for x in x0..x1 {
            let offset = (y * width + x) * 3;
            if let Some(pixel) = frame.get_mut(offset..offset + 3) {
                pixel[0] = value;
                pixel[1] = value;
                pixel[2] = value;
            }
        }
    }
}

fn parse_mode(value: &str) -> Result<(usize, usize, u32)> {
    let (size, fps) = value
        .split_once('@')
        .with_context(|| format!("mode must look like WIDTHxHEIGHT@FPS, got {value:?}"))?;
    let (width, height) = size
        .split_once('x')
        .with_context(|| format!("mode must look like WIDTHxHEIGHT@FPS, got {value:?}"))?;
    Ok((width.parse()?, height.parse()?, fps.parse()?))
}

fn next_value(it: &mut impl Iterator<Item = String>, flag: &str) -> Result<String> {
    it.next()
        .with_context(|| format!("{flag} requires a value"))
}

fn parse_next<T>(it: &mut impl Iterator<Item = String>, flag: &str) -> Result<T>
where
    T: std::str::FromStr,
    T::Err: std::error::Error + Send + Sync + 'static,
{
    Ok(next_value(it, flag)?.parse()?)
}

fn duration_mul(duration: Duration, count: u64) -> Duration {
    Duration::from_nanos(
        duration
            .as_nanos()
            .saturating_mul(u128::from(count))
            .min(u128::from(u64::MAX)) as u64,
    )
}

fn unix_millis() -> u64 {
    std::time::SystemTime::now()
        .duration_since(std::time::UNIX_EPOCH)
        .unwrap_or_default()
        .as_millis()
        .min(u128::from(u64::MAX)) as u64
}

fn args_summary_json(args: &Args) -> String {
    format!(
        "{{\"schema\":\"lesavka.synthetic-uplink.v1\",\"server\":{server:?},\"width\":{width},\"height\":{height},\"fps\":{fps},\"duration_s\":{duration:.3},\"session_id\":{session}}}",
        server = args.server,
        width = args.width,
        height = args.height,
        fps = args.fps,
        duration = args.duration.as_secs_f64(),
        session = args.session_id,
    )
}

fn print_help() {
    println!(
        "lesavka-synthetic-uplink\n\n\
         Sends sequence-coded synthetic MJPEG plus silent PCM through StreamWebcamMedia.\n\n\
         Options:\n\
           --server URL             gRPC endpoint, default {DEFAULT_SERVER}\n\
           --mode WIDTHxHEIGHT@FPS  shorthand for width/height/fps\n\
           --width N --height N --fps N\n\
           --duration SECONDS       default 300\n\
           --jpeg-quality N         default {DEFAULT_JPEG_QUALITY}\n\
           --artifact-dir PATH      write command/summary metadata\n\
           --print-every N          progress interval in frames"
    );
}