You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: main.rs
    path of file: ./repos/darkfi/bin/fud/fud/src
    
    the code of the file until where you have to start completion: /* This file is part of DarkFi (https://dark.fi)
 *
 * Copyright (C) 2020-2024 Dyne.org foundation
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

use std::{
    collections::{HashMap, HashSet},
    sync::Arc,
};

use async_trait::async_trait;
use log::{debug, error, info, warn};
use smol::{
    channel,
    fs::File,
    lock::{Mutex, MutexGuard, RwLock},
    stream::StreamExt,
    Executor,
};
use structopt_toml::{structopt::StructOpt, StructOptToml};
use tinyjson::JsonValue;
use url::Url;

use darkfi::{
    async_daemonize, cli_desc,
    geode::Geode,
    net::{
        self, connector::Connector, protocol::ProtocolVersion, session::Session,
        settings::SettingsOpt, P2p, P2pPtr,
    },
    rpc::{
        jsonrpc::{ErrorCode, JsonError, JsonRequest, JsonResponse, JsonResult},
        server::{listen_and_serve, RequestHandler},
    },
    system::{StoppableTask, StoppableTaskPtr},
    util::path::expand_path,
    Error, Result,
};

/// P2P protocols
mod proto;
use proto::{
    FudChunkPut, FudChunkReply, FudChunkRequest, FudFilePut, FudFileReply, FudFileRequest,
    ProtocolFud,
};

const CONFIG_FILE: &str = "fud_config.toml";
const CONFIG_FILE_CONTENTS: &str = include_str!("../fud_config.toml");

#[derive(Clone, Debug, serde::Deserialize, StructOpt, StructOptToml)]
#[serde(default)]
#[structopt(name = "fud", about = cli_desc!())]
struct Args {
    #[structopt(short, parse(from_occurrences))]
    /// Increase verbosity (-vvv supported)
    verbose: u8,

    #[structopt(long, default_value = "tcp://127.0.0.1:13336")]
    /// JSON-RPC listen URL
    rpc_listen: Url,

    #[structopt(short, long)]
    /// Configuration file to use
    config: Option<String>,

    #[structopt(long)]
    /// Set log file path to output daemon logs into
    log: Option<String>,

    #[structopt(long, default_value = "~/.local/share/fud")]
    /// Base directory for filesystem storage
    base_dir: String,

    #[structopt(flatten)]
    /// Network settings
    net: SettingsOpt,
}

pub struct Fud {
    /// Routing table for file metadata
    metadata_router: Arc<RwLock<HashMap<blake3::Hash, HashSet<Url>>>>,
    /// Routing table for file chunks
    chunks_router: Arc<RwLock<HashMap<blake3::Hash, HashSet<Url>>>>,
    /// Pointer to the P2P network instance
    p2p: P2pPtr,
    /// The Geode instance
    geode: Geode,

    file_fetch_tx: channel::Sender<(blake3::Hash, Result<()>)>,
    file_fetch_rx: channel::Receiver<(blake3::Hash, Result<()>)>,
    chunk_fetch_tx: channel::Sender<(blake3::Hash, Result<()>)>,
    chunk_fetch_rx: channel::Receiver<(blake3::Hash, Result<()>)>,

    rpc_connections: Mutex<HashSet<StoppableTaskPtr>>,
}

#[async_trait]
impl RequestHandler for Fud {
    async fn handle_request(&self, req: JsonRequest) -> JsonResult {
        return match req.method.as_str() {
            "ping" => sel
    
async fn fetch_chunk_task(fud: Arc<Fud>, executor: Arc<Executor<'_>>) -> Result<()> {
    info!("Started background chunk fetch task");
    loop {
        let (chunk_hash, _) = fud.chunk_fetch_rx.recv().await.unwrap();
        info!("fetch_chunk_task: Received {}", chunk_hash);

        let mut chunk_router = fud.chunks_router.write().await;
        let peers = chunk_router.get_mut(&chunk_hash);

        if peers.is_none() {
            warn!("Chunk {} not in routing table, cannot fetch", chunk_hash);
            fud.chunk_fetch_tx
                .send((chunk_hash, Err(Error::GeodeChunkRouteNotFound)))
                .await
                .unwrap();
            continue
        }

        let mut found = false;
        let peers = peers.unwrap();
        let mut invalid_chunk_routes = vec![];

        for peer in peers.iter() {
            let session_out = fud.p2p.session_outbound();
            let session_weak = Arc::downgrade(&fud.p2p.session_outbound());

            info!("Connecting to {} to fetch {}", peer, chunk_hash);
            let connector = Connector::new(fud.p2p.settings(), session_weak);
            match connector.connect(peer).await {
                Ok((url, channel)) => {
                    let proto_ver = ProtocolVersion::new(
                        channel.clone(),
                        fud.p2p.settings().clone(),
                        fud.p2p.hosts().clone(),
                    )
                    .await;

                    let handshake_task = session_out.perform_handshake_protocols(
                        proto_ver,
                        channel.clone(),
                        executor.clone(),
                    );

                    channel.clone().start(executor.clone());

                    if let Err(e) = handshake_task.await {
                        error!("Handshake with {} failed: {}", url, e);
                        // Delete peer from router
                        invalid_chunk_routes.push(peer.clone());
                        continue
                    }

                    let msg_subscriber = channel.subscribe_msg::<FudChunkReply>().await.unwrap();
                    let request = FudChunkRequest { chunk_hash };

                    if let Err(e) = channel.send(&request).await {
                        error!("Failed sending FudChunkRequest({}) to {}: {}", chunk_hash, url, e);
                        continue
                    }

                    // TODO: With timeout!
                    let reply = match msg_subscriber.receive().await {
                        Ok(v) => v,
                        Err(e) => {
                            error!("Error receiving FudChunkReply from subscriber: {}", e);
                            continue
                        }
                    };

                    msg_subscriber.unsubscribe().await;
                    channel.stop().await;

                    match fud.geode.insert_chunk(&reply.chunk).await {
                        Ok(inserted_hash) => {
                            if inserted_hash != chunk_hash {
                                warn!("Received chunk does not match requested chunk");
                                invalid_chunk_routes.push(peer.clone());
                                continue
                            }
                        }
                        Err(e) => {
                            error!("Failed inserting chunk {} to Geode: {}", chunk_hash, e);
                            continue
                        }
                    }

                    found = true;
                    break
                }

                Err(e) => {
                    error!("Failed to connect to {}: {}", peer, e);
                    continue
                }
            }
        }

        for peer in invalid_chunk_routes {
            debug!("Removing peer {} from {} chunk router", peer, chunk_hash);
            peers.remove(&peer);
        }

        if !found {
            warn!("Did not manage to fetch {} chunk", chunk_hash);
            fud.chunk_fetch_tx
                .send((chunk_hash, Err(Error::GeodeChunkRouteNotFound)))
                .await
                .unwrap();
            continue
        }

        info!("Successfully fetched {} chunk", chunk_hash);
        fud.chunk_fetch_tx.send((chunk_hash, Ok(()))).await.unwrap();
    }
}