mtorrent-core 0.5.1

use core::fmt;
use serde::{Serialize, Serializer};
use std::collections::{HashMap, HashSet};
use std::net::SocketAddr;
use tokio::time::Instant;

/// Indicates how the peer was discovered.
#[derive(Default, Clone, Copy, Debug, Hash, PartialEq, Eq, Serialize)]
pub enum PeerOrigin {
    Tracker,
    Listener,
    Pex,
    Dht,
    #[default]
    Other,
}

#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq, Serialize)]
pub enum TransportProto {
    Tcp,
    Utp,
}

/// The current state of the download of data from a remote peer.
#[derive(Clone, PartialEq, Eq, Debug, Serialize)]
#[serde(rename_all = "camelCase")]
pub struct DownloadState {
    pub am_interested: bool,
    pub peer_choking: bool,
    pub bytes_received: usize,
    pub last_bitrate_bps: usize,
}

impl Default for DownloadState {
    fn default() -> Self {
        Self {
            am_interested: false,
            peer_choking: true,
            bytes_received: 0,
            last_bitrate_bps: 0,
        }
    }
}

impl fmt::Display for DownloadState {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(
            f,
            "am_interested={:<5} peer_choking={:<5} rx_bps={:<8} bytes_recv={:<12}",
            self.am_interested, self.peer_choking, self.last_bitrate_bps, self.bytes_received
        )?;
        Ok(())
    }
}

/// The current state of the update of data to a remote peer.
#[derive(Clone, PartialEq, Eq, Debug, Serialize)]
#[serde(rename_all = "camelCase")]
pub struct UploadState {
    pub am_choking: bool,
    pub peer_interested: bool,
    pub bytes_sent: usize,
    pub last_bitrate_bps: usize,
}

impl Default for UploadState {
    fn default() -> Self {
        Self {
            am_choking: true,
            peer_interested: false,
            bytes_sent: 0,
            last_bitrate_bps: 0,
        }
    }
}

impl fmt::Display for UploadState {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(
            f,
            "peer_interested={:<5} am_choking={:<5} tx_bps={:<8} bytes_sent={:<12}",
            self.peer_interested, self.am_choking, self.last_bitrate_bps, self.bytes_sent
        )?;
        Ok(())
    }
}

/// The current state of a connected peer.
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct PeerState {
    pub download: DownloadState,
    pub upload: UploadState,
    pub extensions: Option<Box<super::ExtendedHandshake>>,
    pub origin: PeerOrigin,
    pub transport: Option<TransportProto>,
    pub encryption: bool,
    pub last_download_time: Instant,
    pub last_upload_time: Instant,
}

impl Default for PeerState {
    fn default() -> Self {
        Self {
            download: Default::default(),
            upload: Default::default(),
            extensions: None,
            encryption: false,
            origin: Default::default(),
            transport: None,
            last_download_time: Instant::now(),
            last_upload_time: Instant::now(),
        }
    }
}

impl Serialize for PeerState {
    /// [`PeerState`] is serialized in the following format:
    /// ```json
    /// {
    ///   "download": {
    ///     "amInterested": false,
    ///     "peerChoking": true,
    ///     "bytesReceived": 0,
    ///     "lastBitrateBps": 0
    ///   },
    ///   "upload": {
    ///     "peerInterested": false,
    ///     "amChoking": true,
    ///     "bytesSent": 0,
    ///     "lastBitrateBps": 0
    ///   },
    ///   "client": "n/a",
    ///   "reqq": null,
    ///   "origin": "Tracker",
    ///   "proto": null,
    ///   "encrypted": false
    /// }
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
        S: Serializer,
    {
        #[derive(Serialize)]
        struct Data<'a> {
            download: &'a DownloadState,
            upload: &'a UploadState,
            client: &'a str,
            reqq: Option<usize>,
            origin: PeerOrigin,
            proto: Option<TransportProto>,
            encrypted: bool,
        }
        let data = Data {
            download: &self.download,
            upload: &self.upload,
            client: self
                .extensions
                .as_ref()
                .and_then(|ext| ext.client_type.as_deref())
                .unwrap_or("n/a"),
            reqq: self.extensions.as_ref().and_then(|ext| ext.request_limit),
            origin: self.origin,
            proto: self.transport,
            encrypted: self.encryption,
        };
        data.serialize(serializer)
    }
}

/// Collections of states of the connected peers.
#[derive(Default, Debug)]
pub struct PeerStates {
    peers: HashMap<SocketAddr, PeerState>,
    seeders: HashSet<SocketAddr>,
    leeches: HashSet<SocketAddr>,
    previously_uploaded_bytes: usize,
}

impl PeerStates {
    /// Update the download state of the peer at `remote_ip`.
    pub fn update_download(&mut self, remote_ip: &SocketAddr, new_state: &DownloadState) {
        let state = self.peers.entry(*remote_ip).or_default();
        if new_state.bytes_received > state.download.bytes_received {
            state.last_download_time = Instant::now();
        }
        state.download = new_state.clone();
        if state.download.am_interested && !state.download.peer_choking {
            self.seeders.insert(*remote_ip);
        } else {
            self.seeders.remove(remote_ip);
        }
    }

    /// Update the upload state of the peer at `remote_ip`.
    pub fn update_upload(&mut self, remote_ip: &SocketAddr, new_state: &UploadState) {
        let state = self.peers.entry(*remote_ip).or_default();
        if new_state.bytes_sent > state.upload.bytes_sent {
            state.last_upload_time = Instant::now();
        }
        state.upload = new_state.clone();
        if state.upload.peer_interested && !state.upload.am_choking {
            self.leeches.insert(*remote_ip);
        } else {
            self.leeches.remove(remote_ip);
        }
    }

    /// Update the extended handshake received from the peer at `remote_ip`.
    pub fn set_extended_handshake(
        &mut self,
        remote_ip: &SocketAddr,
        extended_handshake: Box<super::ExtendedHandshake>,
    ) {
        let state = self.peers.entry(*remote_ip).or_default();
        if state.extensions.is_none() {
            state.extensions = Some(extended_handshake);
        }
    }

    /// Update how the peer at `remote_ip` was discovered.
    pub fn set_info(
        &mut self,
        remote_ip: &SocketAddr,
        origin: PeerOrigin,
        transport: TransportProto,
        encryption: bool,
    ) {
        let state = self.peers.entry(*remote_ip).or_default();
        state.origin = origin;
        state.transport = Some(transport);
        state.encryption = encryption;
    }

    /// Erase peer.
    pub fn remove_peer(&mut self, remote_ip: &SocketAddr) {
        if let Some(state) = self.peers.get(remote_ip) {
            self.previously_uploaded_bytes += state.upload.bytes_sent;
            self.peers.remove(remote_ip);
            self.seeders.remove(remote_ip);
            self.leeches.remove(remote_ip);
        }
    }

    /// Get peer state for a given remote socket addr.
    pub fn get(&self, peer_ip: &SocketAddr) -> Option<&PeerState> {
        self.peers.get(peer_ip)
    }

    /// Total number of seeding peers.
    pub fn seeders_count(&self) -> usize {
        self.seeders.len()
    }

    /// Total number of leeching peers.
    pub fn leeches_count(&self) -> usize {
        self.leeches.len()
    }

    /// Addresses of all leeching peers.
    pub fn leeches(&self) -> &HashSet<SocketAddr> {
        &self.leeches
    }

    /// States of all connected peers.
    pub fn iter(&self) -> impl ExactSizeIterator<Item = (&SocketAddr, &PeerState)> {
        self.peers.iter()
    }

    /// Total number of bytes uploaded to all peers during the entire lifetime (including peers that
    /// have been erased).
    pub fn uploaded_bytes(&self) -> usize {
        self.previously_uploaded_bytes
            + self.peers.values().map(|state| state.upload.bytes_sent).sum::<usize>()
    }
}