// Copyright (C) 2019, Cloudflare, Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright notice,
//       this list of conditions and the following disclaimer.
//
//     * Redistributions in binary form must reproduce the above copyright
//       notice, this list of conditions and the following disclaimer in the
//       documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
// IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
// THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#[macro_use]
extern crate log;

use std::net::ToSocketAddrs;

use ring::rand::*;

const MAX_DATAGRAM_SIZE: usize = 1350;

fn main() {
    let mut buf = [0; 65535];
    let mut out = [0; MAX_DATAGRAM_SIZE];

    let mut args = std::env::args();

    let cmd = &args.next().unwrap();

    if args.len() != 1 {
        println!("Usage: {} URL", cmd);
        println!("\nSee tools/apps/ for more complete implementations.");
        return;
    }

    let url = url::Url::parse(&args.next().unwrap()).unwrap();

    // Setup the event loop.
    let poll = mio::Poll::new().unwrap();
    let mut events = mio::Events::with_capacity(1024);

    // Resolve server address.
    let peer_addr = url.to_socket_addrs().unwrap().next().unwrap();

    // Bind to INADDR_ANY or IN6ADDR_ANY depending on the IP family of the
    // server address. This is needed on macOS and BSD variants that don't
    // support binding to IN6ADDR_ANY for both v4 and v6.
    let bind_addr = match peer_addr {
        std::net::SocketAddr::V4(_) => "0.0.0.0:0",
        std::net::SocketAddr::V6(_) => "[::]:0",
    };

    // Create the UDP socket backing the QUIC connection, and register it with
    // the event loop.
    let socket = std::net::UdpSocket::bind(bind_addr).unwrap();
    socket.connect(peer_addr).unwrap();

    let socket = mio::net::UdpSocket::from_socket(socket).unwrap();
    poll.register(
        &socket,
        mio::Token(0),
        mio::Ready::readable(),
        mio::PollOpt::edge(),
    )
    .unwrap();

    // Create the configuration for the QUIC connection.
    let mut config = quiche::Config::new(quiche::PROTOCOL_VERSION).unwrap();

    // *CAUTION*: this should not be set to `false` in production!!!
    config.verify_peer(false);

    config
        .set_application_protos(quiche::h3::APPLICATION_PROTOCOL)
        .unwrap();

    config.set_max_idle_timeout(5000);
    config.set_max_udp_payload_size(MAX_DATAGRAM_SIZE as u64);
    config.set_initial_max_data(10_000_000);
    config.set_initial_max_stream_data_bidi_local(1_000_000);
    config.set_initial_max_stream_data_bidi_remote(1_000_000);
    config.set_initial_max_stream_data_uni(1_000_000);
    config.set_initial_max_streams_bidi(100);
    config.set_initial_max_streams_uni(100);
    config.set_disable_active_migration(true);

    let mut http3_conn = None;

    // Generate a random source connection ID for the connection.
    let mut scid = [0; quiche::MAX_CONN_ID_LEN];
    SystemRandom::new().fill(&mut scid[..]).unwrap();

    // Create a QUIC connection and initiate handshake.
    let mut conn = quiche::connect(url.domain(), &scid, &mut config).unwrap();

    info!(
        "connecting to {:} from {:} with scid {}",
        peer_addr,
        socket.local_addr().unwrap(),
        hex_dump(&scid)
    );

    let write = conn.send(&mut out).expect("initial send failed");

    while let Err(e) = socket.send(&out[..write]) {
        if e.kind() == std::io::ErrorKind::WouldBlock {
            debug!("send() would block");
            continue;
        }

        panic!("send() failed: {:?}", e);
    }

    debug!("written {}", write);

    let h3_config = quiche::h3::Config::new().unwrap();

    // Prepare request.
    let mut path = String::from(url.path());

    if let Some(query) = url.query() {
        path.push('?');
        path.push_str(query);
    }

    let req = vec![
        quiche::h3::Header::new(":method", "GET"),
        quiche::h3::Header::new(":scheme", url.scheme()),
        quiche::h3::Header::new(":authority", url.host_str().unwrap()),
        quiche::h3::Header::new(":path", &path),
        quiche::h3::Header::new("user-agent", "quiche"),
    ];

    let req_start = std::time::Instant::now();

    let mut req_sent = false;

    loop {
        poll.poll(&mut events, conn.timeout()).unwrap();

        // Read incoming UDP packets from the socket and feed them to quiche,
        // until there are no more packets to read.
        'read: loop {
            // If the event loop reported no events, it means that the timeout
            // has expired, so handle it without attempting to read packets. We
            // will then proceed with the send loop.
            if events.is_empty() {
                debug!("timed out");

                conn.on_timeout();

                break 'read;
            }

            let len = match socket.recv(&mut buf) {
                Ok(v) => v,

                Err(e) => {
                    // There are no more UDP packets to read, so end the read
                    // loop.
                    if e.kind() == std::io::ErrorKind::WouldBlock {
                        debug!("recv() would block");
                        break 'read;
                    }

                    panic!("recv() failed: {:?}", e);
                },
            };

            debug!("got {} bytes", len);

            // Process potentially coalesced packets.
            let read = match conn.recv(&mut buf[..len]) {
                Ok(v) => v,

                Err(e) => {
                    error!("recv failed: {:?}", e);
                    continue 'read;
                },
            };

            debug!("processed {} bytes", read);
        }

        debug!("done reading");

        if conn.is_closed() {
            info!("connection closed, {:?}", conn.stats());
            break;
        }

        // Create a new HTTP/3 connection once the QUIC connection is established.
        if conn.is_established() && http3_conn.is_none() {
            http3_conn = Some(
                quiche::h3::Connection::with_transport(&mut conn, &h3_config)
                    .unwrap(),
            );
        }

        // Send HTTP requests once the QUIC connection is established, and until
        // all requests have been sent.
        if let Some(h3_conn) = &mut http3_conn {
            if !req_sent {
                info!("sending HTTP request {:?}", req);

                h3_conn.send_request(&mut conn, &req, true).unwrap();

                req_sent = true;
            }
        }

        if let Some(http3_conn) = &mut http3_conn {
            // Process HTTP/3 events.
            loop {
                match http3_conn.poll(&mut conn) {
                    Ok((stream_id, quiche::h3::Event::Headers { list, .. })) => {
                        info!(
                            "got response headers {:?} on stream id {}",
                            list, stream_id
                        );
                    },

                    Ok((stream_id, quiche::h3::Event::Data)) => {
                        if let Ok(read) =
                            http3_conn.recv_body(&mut conn, stream_id, &mut buf)
                        {
                            debug!(
                                "got {} bytes of response data on stream {}",
                                read, stream_id
                            );

                            print!("{}", unsafe {
                                std::str::from_utf8_unchecked(&buf[..read])
                            });
                        }
                    },

                    Ok((_stream_id, quiche::h3::Event::Finished)) => {
                        info!(
                            "response received in {:?}, closing...",
                            req_start.elapsed()
                        );

                        conn.close(true, 0x00, b"kthxbye").unwrap();
                    },

                    Ok((_flow_id, quiche::h3::Event::Datagram)) => (),

                    Ok((goaway_id, quiche::h3::Event::GoAway)) => {
                        info!("GOAWAY id={}", goaway_id);
                    },

                    Err(quiche::h3::Error::Done) => {
                        break;
                    },

                    Err(e) => {
                        error!("HTTP/3 processing failed: {:?}", e);

                        break;
                    },
                }
            }
        }

        // Generate outgoing QUIC packets and send them on the UDP socket, until
        // quiche reports that there are no more packets to be sent.
        loop {
            let write = match conn.send(&mut out) {
                Ok(v) => v,

                Err(quiche::Error::Done) => {
                    debug!("done writing");
                    break;
                },

                Err(e) => {
                    error!("send failed: {:?}", e);

                    conn.close(false, 0x1, b"fail").ok();
                    break;
                },
            };

            if let Err(e) = socket.send(&out[..write]) {
                if e.kind() == std::io::ErrorKind::WouldBlock {
                    debug!("send() would block");
                    break;
                }

                panic!("send() failed: {:?}", e);
            }

            debug!("written {}", write);
        }

        if conn.is_closed() {
            info!("connection closed, {:?}", conn.stats());
            break;
        }
    }
}

fn hex_dump(buf: &[u8]) -> String {
    let vec: Vec<String> = buf.iter().map(|b| format!("{:02x}", b)).collect();

    vec.join("")
}