qftf 0.2.0

use anyhow::Result;
use fltk::app::App;
use fltk::app::Receiver;
use fltk::enums::Color;
use fltk::frame::Frame;
use fltk::image::SvgImage;
use fltk::misc::Progress as ProgressBar;
use fltk::{app, prelude::*, window::Window};
use human_repr::{HumanCount, HumanDuration, HumanThroughput};
use iroh::Endpoint;
use iroh::EndpointAddr;
use qrcode::QrCode;
use qrcode::render::svg;
use rand::RngCore;
use serde::{Deserialize, Serialize};
use std::env;
use std::future::Future;
use std::io;
use std::mem::MaybeUninit;
use std::path::Path;
use std::time::{Duration, Instant};
use strum::Display;
use tokio::fs::File;
use tokio::io::{AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt};
use tracing::{info, warn};
use tracing_subscriber::{EnvFilter, fmt, prelude::*};

use qftf::*;

const URL_PREFIX_ENV: &str = "QFTF_URL_PREFIX";
const DEFAULT_URL_PREFIX: &str = "https://cibyr.github.io/qftf-web/";
const UPDATE_PERIOD: Duration = Duration::from_millis(500);

#[derive(Debug, Serialize, Deserialize)]
struct FileTransfer {
    /// Public key of sender
    addr: EndpointAddr,
    /// Name of the file to transfer
    name: String,
    /// File size in bytes
    size: u64,
    /// Random 8 bytes
    token: [u8; 8],
}

struct Progress {
    name: String,
    bytes_sent: u64,
    total_size: u64,
    finished: bool,
}

#[derive(Display)]
enum Direction {
    Sending,
    Receving,
}

/// Copy data from a reader to a writer with progress callbacks
///
/// Similar to `tokio::io::copy`, but calls the provided callback function
/// whenever a chunk of data is copied, providing the total bytes copied so far.
///
/// # Parameters
/// * `reader` - The source implementing AsyncRead
/// * `writer` - The destination implementing AsyncWrite
/// * `on_progress` - A callback function that takes the total bytes copied so far
///
/// # Returns
/// The total number of bytes copied
pub async fn copy_with_progress<R, W, F, Fut>(
    mut reader: R,
    mut writer: W,
    mut on_progress: F,
) -> io::Result<u64>
where
    R: AsyncRead + Unpin,
    W: AsyncWrite + Unpin,
    F: FnMut(u64) -> Fut,
    Fut: Future<Output = ()>,
{
    let buf_size = 8 * 1024; // 8KB buffer
    let mut buffer = vec![MaybeUninit::uninit(); buf_size];
    let mut total_bytes = 0;

    loop {
        let mut read_buf = tokio::io::ReadBuf::uninit(&mut buffer);
        reader.read_buf(&mut read_buf).await?;
        let filled = read_buf.filled();
        let bytes_read = filled.len();
        if bytes_read == 0 {
            break;
        }

        writer.write_all(filled).await?;
        total_bytes += bytes_read as u64;

        // Call the progress callback with the current total
        on_progress(total_bytes).await;
    }

    writer.flush().await?;
    Ok(total_bytes)
}

struct UI {
    app: App,
    window: Window,
    frame: Frame,
    progress_bar: ProgressBar,
}

impl UI {
    /// Create the UI (initially showing the URL code for the given URL)
    fn create(title: &str, url: &str) -> Self {
        let app = app::App::default();

        let code = QrCode::new(url).unwrap();
        let svg = code
            .render::<svg::Color>()
            .quiet_zone(true)
            .min_dimensions(400, 400)
            .build();
        let image = SvgImage::from_data(&svg).unwrap();
        let width = image.width();
        let height = image.height();

        let mut window = Window::default().with_size(width, height).with_label(title);

        let mut frame = Frame::default().with_size(width, height).center_of(&window);
        frame.set_image(Some(image));

        let mut progress_bar = ProgressBar::default().with_size(width, 20);
        progress_bar.set_selection_color(Color::Blue);
        progress_bar.hide();

        window.end();
        window.show();

        Self {
            app,
            window,
            frame,
            progress_bar,
        }
    }

    /// UI during transfer
    fn display_progress(&mut self, direction: Direction, progress_receiver: Receiver<Progress>) {
        let mut started = false;
        let mut start = Instant::now();
        let mut last_update = start - UPDATE_PERIOD;
        while self.app.wait() {
            if let Some(progress) = progress_receiver.recv() {
                if progress.finished {
                    app::quit();
                    break;
                }
                let now = Instant::now();
                if !started {
                    if matches!(direction, Direction::Receving) {
                        self.window
                            .set_label(&format!("QFTF - Receiving {}", progress.name));
                    }
                    self.progress_bar.set_minimum(0.0);
                    self.progress_bar.set_maximum(progress.total_size as f64);
                    self.progress_bar.show();
                    start = now;
                    started = true;
                    continue;
                }
                self.progress_bar.set_value(progress.bytes_sent as f64);
                if now - last_update < UPDATE_PERIOD {
                    continue;
                }

                let seconds_so_far = (now - start).as_secs_f64();
                let rate = progress.bytes_sent as f64 / seconds_so_far;
                let remaining_bytes = progress.total_size - progress.bytes_sent;
                let remaining_time = Duration::try_from_secs_f64(remaining_bytes as f64 / rate)
                    .map(|d| d.human_duration().to_string());
                self.frame.set_image::<SvgImage>(None);
                self.frame.set_label(&format!(
                    "{} {}\n
                    {} / {}\n
                    {} remaining ({})",
                    direction,
                    progress.name,
                    progress.bytes_sent.human_count_bytes(),
                    progress.total_size.human_count_bytes(),
                    remaining_time.as_deref().unwrap_or("forever"),
                    rate.human_throughput_bytes()
                ));
                last_update = now;
            }
        }
    }
}

// The plan:
// Parse arguments (filename to send, no args to receive)
// Sender:
//  * create endpoint, stat file -> fill out FileTransfer struct
//  * display QR code ("qftf-tx:<encoded struct>")
//  * listen on the endpoint, waiting for receiver to supply token
//  * stream the file over the connection
//    * display progress
//  * (maybe) append some kind of hash or CRC?
// Receiver:
//  * create endpoint
//  * display QR code ("qftf-rx:<EndpointAddr>")
//  * listen on the endpoint, waiting for app to supply FT struct
//  * connect to sender's endpoint, send token
//  * receive the file over the connection (stream to disk)
//    * display progress
//  * (maybe) check hash/CRC?
// Web App:
//  * Scan both QR codes
//  * (maybe) display metadata
//  * Connect to receiver, send FT struct

async fn send_file(path: &str) -> Result<()> {
    // Create an endpoint, it allows creating and accepting
    // connections in the iroh p2p world
    let endpoint = Endpoint::builder()
        .alpns(vec![ALPN.to_vec()])
        .bind()
        .await?;

    // Open the file, learn its length
    let path = Path::new(path);
    let file = File::open(path).await?;
    let file_name = path.file_name().expect("file has no name");
    let file_size = file.metadata().await?.len();

    // Generate a random 8-byte token
    let mut token = [0u8; 8];
    let mut rng = rand::rng();
    rng.fill_bytes(&mut token);

    // Wait for us to have a home relay
    endpoint.online().await;

    let transfer = FileTransfer {
        addr: endpoint.addr(),
        name: file_name.to_string_lossy().into_owned(),
        size: file_size,
        token,
    };

    info!("Sending {:?}", &transfer);
    let transfer_json = serde_json::to_string(&transfer)?;
    let env_url = env::var(URL_PREFIX_ENV);
    let url_prefix = env_url.as_deref().unwrap_or(DEFAULT_URL_PREFIX);
    let url = format!("{url_prefix}#{TX_PREFIX}{transfer_json}");
    println!("URL: {url}");

    let title = format!("QFTF - Sending {}", transfer.name);
    let mut ui = UI::create(&title, &url);

    let (progress_sender, progress_receiver) = app::channel::<Progress>();

    tokio::spawn(async move {
        loop {
            let Some(connecting) = endpoint.accept().await else {
                break;
            };
            let connection = match connecting.await {
                Ok(connection) => connection,
                Err(cause) => {
                    warn!("error accepting connection: {}", cause);
                    // if accept fails, we want to continue accepting connections
                    continue;
                }
            };
            let remote_id = &connection.remote_id();
            info!("got connection from {}", remote_id);
            let (mut s, mut r) = match connection.accept_bi().await {
                Ok(x) => x,
                Err(cause) => {
                    warn!("error accepting stream: {}", cause);
                    // if accept_bi fails, we want to continue accepting connections
                    continue;
                }
            };
            info!("accepted stream from {}", remote_id);
            // read the token and verify it
            let mut buf = [0u8; 8];
            r.read_exact(&mut buf).await?;
            anyhow::ensure!(buf == transfer.token, "invalid token");

            progress_sender.send(Progress {
                name: transfer.name.clone(),
                bytes_sent: 0,
                total_size: transfer.size,
                finished: false,
            });

            // Send the file
            let _bytes_sent = copy_with_progress(file, &mut s, |bytes_sent| {
                let name = transfer.name.clone();
                let size = transfer.size;
                async move {
                    progress_sender.send(Progress {
                        name,
                        bytes_sent,
                        total_size: size,
                        finished: false,
                    });
                }
            })
            .await?;
            s.finish()?;
            s.stopped().await?;
            info!("Transfer complete!");
            progress_sender.send(Progress {
                name: transfer.name,
                bytes_sent: transfer.size,
                total_size: transfer.size,
                finished: true,
            });

            break;
        }

        Ok(())
    });

    ui.display_progress(Direction::Sending, progress_receiver);

    println!("Done!");
    Ok(())
}

async fn receive_file() -> Result<()> {
    //  * create endpoint
    let endpoint = Endpoint::builder()
        .alpns(vec![ALPN.to_vec()])
        .bind()
        .await?;

    // Wait for us to have a home relay
    endpoint.online().await;

    //  * display QR code ("qftf-rx:<EndpointAddr>")
    let addr = endpoint.addr();
    let env_url = env::var(URL_PREFIX_ENV);
    let url_prefix = env_url.as_deref().unwrap_or(DEFAULT_URL_PREFIX);
    let url = format!(
        "{}#{}{}",
        url_prefix,
        RX_PREFIX,
        serde_json::to_string(&addr)?
    );

    println!("URL: {url}");

    let title = "QFTF - Waiting to receive...".to_string();
    let mut ui = UI::create(&title, &url);

    let (progress_sender, progress_receiver) = app::channel::<Progress>();

    tokio::spawn(async move {
        loop {
            //  * listen on the endpoint, waiting for app to supply FT struct
            let Some(connecting) = endpoint.accept().await else {
                break;
            };
            let connection = match connecting.await {
                Ok(connection) => connection,
                Err(cause) => {
                    warn!("error accepting connection: {}", cause);
                    // if accept fails, we want to continue accepting connections
                    continue;
                }
            };
            let remote_id = &connection.remote_id();
            info!("got connection from {}", remote_id);
            let mut rs = match connection.accept_uni().await {
                Ok(x) => x,
                Err(cause) => {
                    warn!("error accepting stream: {}", cause);
                    // if accept_uni fails, we want to continue accepting connections
                    continue;
                }
            };
            info!("accepted stream from {}", remote_id);
            // read tx json
            let tx_json = rs.read_to_end(MAX_QR_BYTES).await?;
            let tx_json = String::from_utf8(tx_json)?;
            let transfer: FileTransfer = serde_json::from_str(&tx_json)?;

            //  * connect to sender's endpoint, send token
            let connection = endpoint.connect(transfer.addr, ALPN).await?;
            info!("Connected!");
            let (mut s, r) = connection.open_bi().await?;
            s.write_all(&transfer.token).await?;

            //  * receive the file over the connection (stream to disk)
            let f = File::create_new(&transfer.name).await?;
            copy_with_progress(r, f, |bytes_sent| {
                let name = transfer.name.clone();
                let size = transfer.size;
                async move {
                    progress_sender.send(Progress {
                        name,
                        bytes_sent,
                        total_size: size,
                        finished: false,
                    });
                }
            })
            .await?;
            info!("Transfer complete!");
            progress_sender.send(Progress {
                name: transfer.name,
                bytes_sent: transfer.size,
                total_size: transfer.size,
                finished: true,
            });
            break;
        }

        Ok::<(), anyhow::Error>(())
    });

    ui.display_progress(Direction::Receving, progress_receiver);

    println!("Done!");
    Ok(())
}

fn usage() -> ! {
    eprintln!("usage: qftf [file]");
    std::process::exit(2)
}

#[tokio::main]
async fn main() -> Result<()> {
    tracing_subscriber::registry()
        .with(fmt::layer())
        .with(EnvFilter::from_default_env())
        .init();

    let args: Vec<String> = env::args().collect();
    match args.len() {
        1 => receive_file().await,
        2 => send_file(&args[1]).await,
        _ => usage(),
    }
}