btpeer 0.4.0

mod query;
mod response;

use bendy::decoding::FromBencode;
use cyphernet::addr::{HostName, PartialAddr, i2p::I2pAddr};
use std::{
    error::Error,
    net::{IpAddr, Ipv4Addr, Ipv6Addr},
    str::FromStr,
    time::Duration,
};

pub use query::Query;

pub struct Response {
    pub interval: u32,
    pub leechers: u32,
    pub seeders: u32,
    pub peers: Vec<PartialAddr<HostName, 0>>,
}

pub fn request(query: &Query, timeout: u64) -> Result<Response, Box<dyn Error>> {
    let client = reqwest::blocking::Client::builder()
        .timeout(Duration::from_secs(timeout))
        .build()?;

    let response = client.get(query.to_string()).send()?;

    if !response.status().is_success() {
        return Err(format!("Tracker returned status: {}", response.status()).into());
    }

    // Handle response...
    let result = response::Response::from_bencode(&response.bytes()?)?;

    let mut peers = Vec::with_capacity(100);

    if !result.peers.is_empty() {
        if query.url().host_str().is_some_and(|h| h.ends_with(".i2p")) {
            for chunk in result.peers.chunks_exact(32) {
                if let Ok(i2p) = I2pAddr::from_str(&data_encoding::BASE32_NOPAD.encode(chunk)) {
                    peers.push(PartialAddr {
                        host: HostName::I2p(i2p),
                        port: None,
                    })
                }
            }
        } else {
            for chunk in result.peers.chunks_exact(6) {
                let ip_bytes: [u8; 4] = chunk[0..4].try_into()?;
                peers.push(PartialAddr {
                    host: HostName::Ip(IpAddr::V4(Ipv4Addr::from(ip_bytes))),
                    port: Some(u16::from_be_bytes(chunk[4..6].try_into()?)),
                })
            }
        }
    }

    if !result.peers6.is_empty() {
        for chunk in result.peers6.chunks_exact(18) {
            let ip_bytes: [u8; 16] = chunk[0..16].try_into()?;
            peers.push(PartialAddr {
                host: HostName::Ip(IpAddr::V6(Ipv6Addr::from(ip_bytes))),
                port: Some(u16::from_be_bytes(chunk[16..18].try_into()?)),
            })
        }
    }

    // Done.
    Ok(Response {
        interval: result.interval,
        leechers: result.complete,
        seeders: result.incomplete,
        peers,
    })
}