// Copyright 2021 Protocol Labs.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// DEALINGS IN THE SOFTWARE.

#![doc = include_str!("../README.md")]

mod network;

use async_std::task::spawn;
use clap::Parser;

use futures::prelude::*;
use futures::StreamExt;
use libp2p::{core::Multiaddr, multiaddr::Protocol, PeerId};
use std::error::Error;
use std::io::Write;
use std::path::PathBuf;

#[async_std::main]
async fn main() -> Result<(), Box<dyn Error>> {
    env_logger::init();

    let opt = Opt::parse();

    let (mut network_client, mut network_events, network_event_loop) =
        network::new(opt.secret_key_seed).await?;

    // Spawn the network task for it to run in the background.
    spawn(network_event_loop.run());

    // In case a listen address was provided use it, otherwise listen on any
    // address.
    match opt.listen_address {
        Some(addr) => network_client
            .start_listening(addr)
            .await
            .expect("Listening not to fail."),
        None => network_client
            .start_listening("/ip4/0.0.0.0/tcp/0".parse()?)
            .await
            .expect("Listening not to fail."),
    };

    // In case the user provided an address of a peer on the CLI, dial it.
    if let Some(addr) = opt.peer {
        let peer_id = match addr.iter().last() {
            Some(Protocol::P2p(hash)) => PeerId::from_multihash(hash).expect("Valid hash."),
            _ => return Err("Expect peer multiaddr to contain peer ID.".into()),
        };
        network_client
            .dial(peer_id, addr)
            .await
            .expect("Dial to succeed");
    }

    match opt.argument {
        // Providing a file.
        CliArgument::Provide { path, name } => {
            // Advertise oneself as a provider of the file on the DHT.
            network_client.start_providing(name.clone()).await;

            loop {
                match network_events.next().await {
                    // Reply with the content of the file on incoming requests.
                    Some(network::Event::InboundRequest { request, channel }) => {
                        if request == name {
                            network_client
                                .respond_file(std::fs::read(&path)?, channel)
                                .await;
                        }
                    }
                    e => todo!("{:?}", e),
                }
            }
        }
        // Locating and getting a file.
        CliArgument::Get { name } => {
            // Locate all nodes providing the file.
            let providers = network_client.get_providers(name.clone()).await;
            if providers.is_empty() {
                return Err(format!("Could not find provider for file {name}.").into());
            }

            // Request the content of the file from each node.
            let requests = providers.into_iter().map(|p| {
                let mut network_client = network_client.clone();
                let name = name.clone();
                async move { network_client.request_file(p, name).await }.boxed()
            });

            // Await the requests, ignore the remaining once a single one succeeds.
            let file_content = futures::future::select_ok(requests)
                .await
                .map_err(|_| "None of the providers returned file.")?
                .0;

            std::io::stdout().write_all(&file_content)?;
        }
    }

    Ok(())
}

#[derive(Parser, Debug)]
#[clap(name = "libp2p file sharing example")]
struct Opt {
    /// Fixed value to generate deterministic peer ID.
    #[clap(long)]
    secret_key_seed: Option<u8>,

    #[clap(long)]
    peer: Option<Multiaddr>,

    #[clap(long)]
    listen_address: Option<Multiaddr>,

    #[clap(subcommand)]
    argument: CliArgument,
}

#[derive(Debug, Parser)]
enum CliArgument {
    Provide {
        #[clap(long)]
        path: PathBuf,
        #[clap(long)]
        name: String,
    },
    Get {
        #[clap(long)]
        name: String,
    },
}