// Copyright (C) 2021 Scott Lamb <slamb@slamb.org>
// SPDX-License-Identifier: MIT OR Apache-2.0

//! Tests client performance against a mock server.

use std::{io::ErrorKind, net::SocketAddr, num::NonZeroU32};

use bytes::Bytes;
use criterion::{criterion_group, criterion_main, Criterion, Throughput};
use futures::StreamExt;
use retina::{
    client::{PlayOptions, SetupOptions},
    codec::CodecItem,
};
use std::convert::TryFrom;
use tokio::io::AsyncWriteExt;
use url::Url;

/// Mock server. Serves `data` on every connection.
async fn serve(data: Bytes) -> SocketAddr {
    let listener = tokio::net::TcpListener::bind("127.0.0.1:0").await.unwrap();
    let addr = listener.local_addr().unwrap();
    tokio::task::spawn(async move {
        loop {
            let conn = match listener.accept().await {
                Err(_) => return,
                Ok((conn, _addr)) => conn,
            };
            tokio::task::spawn(serve_connection(conn, data.clone()));
        }
    });
    addr
}

/// Mock server connection handler.
///
/// Tries to send the canned data. Doesn't even try to read any data from the
/// client until the end. This assumes the total data written from client fits
/// within the socket buffer; it might cause deadlock otherwise.
async fn serve_connection(mut stream: tokio::net::TcpStream, data: Bytes) {
    // Send.
    if stream.write_all(&data[..]).await.is_err() {
        return;
    }

    // Wait until the client has read it all and closes the connection.
    // This reads and discards whatever the client sent earlier.
    if stream.shutdown().await.is_err() {
        return;
    }
    loop {
        if stream.readable().await.is_err() {
            return;
        }
        let mut buf = [0u8; 1024];
        match stream.try_read(&mut buf) {
            Err(e) if e.kind() == ErrorKind::WouldBlock => {}
            Err(_) | Ok(0) => return,
            Ok(_) => {}
        }
    }
}

fn make_test_data(max_payload_size: u16) -> Bytes {
    let mut data = Vec::new();
    data.extend_from_slice(include_bytes!(
        "../src/client/testdata/hikvision_describe.txt"
    ));
    data.extend_from_slice(include_bytes!("../src/client/testdata/hikvision_setup.txt"));
    data.extend_from_slice(include_bytes!("../src/client/testdata/hikvision_play.txt"));

    // These are the actual sizes of the slice NALs in one (two-second, 60-frame) Group of Pictures
    // from a Dahua IP camera. This is about 3.5 Mbps.
    let frame_sizes: [u32; 60] = [
        667339, 7960, 2296, 3153, 3687, 3246, 3621, 2300, 2603, 2956, 2888, 3187, 3439, 3299, 3252,
        3372, 3052, 2988, 2921, 2859, 2806, 3400, 2811, 3143, 2972, 4097, 2906, 3307, 3628, 3750,
        3575, 3144, 3431, 3317, 3154, 3387, 3630, 3232, 3574, 3254, 4198, 4235, 4898, 4890, 4854,
        4854, 4863, 4652, 4227, 4101, 3867, 3870, 3716, 3074, 3253, 3267, 3192, 3995, 3904, 3781,
    ];
    let mut dummy_frame = vec![0; 1048576];
    dummy_frame[4] = h264_reader::nal::UnitType::SliceLayerWithoutPartitioningIdr.id();
    let mut p =
        retina::codec::h264::Packetizer::new(max_payload_size, 0, 24104, 96, 0x4cacc3d1).unwrap();
    let mut timestamp = retina::Timestamp::new(0, NonZeroU32::new(90_000).unwrap(), 0).unwrap();
    for _ in 0..30 {
        for &f in &frame_sizes {
            dummy_frame[0..4].copy_from_slice(&f.to_be_bytes()[..]);
            let frame = Bytes::copy_from_slice(&dummy_frame[..(usize::try_from(f).unwrap() + 4)]);
            p.push(timestamp, frame).unwrap();
            while let Some(pkt) = p.pull().unwrap() {
                let pkt = pkt.raw();
                data.push(b'$'); // interleaved data
                data.push(0); // channel 0
                data.extend_from_slice(&u16::try_from(pkt.len()).unwrap().to_be_bytes()[..]);
                data.extend_from_slice(pkt);
            }
            timestamp = timestamp.try_add(3000).unwrap();
        }
    }
    Bytes::from(data)
}

async fn read_to_eof(addr: SocketAddr) {
    let url = Url::parse(&format!("rtsp://{}/", &addr)).unwrap();
    let mut session =
        retina::client::Session::describe(url, retina::client::SessionOptions::default())
            .await
            .unwrap();
    session.setup(0, SetupOptions::default()).await.unwrap();
    let session = session
        .play(PlayOptions::default())
        .await
        .unwrap()
        .demuxed()
        .unwrap();
    tokio::pin!(session);
    let mut i = 0;
    while let Some(item) = session.next().await {
        match item {
            Ok(CodecItem::VideoFrame(_)) => i += 1,
            o => panic!("bad item: {o:#?}"),
        }
    }
    assert_eq!(i, 30 * 60);
}

fn criterion_benchmark(c: &mut Criterion) {
    let mut g = c.benchmark_group("client");
    let rt = tokio::runtime::Runtime::new().unwrap();
    let data = make_test_data(1440);
    g.throughput(Throughput::Bytes(u64::try_from(data.len()).unwrap()));
    let addr = rt.block_on(serve(data));
    g.bench_function("h264", |b| b.to_async(&rt).iter(|| read_to_eof(addr)));
}

criterion_group!(benches, criterion_benchmark);
criterion_main!(benches);