pub use solana_tpu_client::tpu_connection_cache::{
    DEFAULT_TPU_CONNECTION_POOL_SIZE, DEFAULT_TPU_ENABLE_UDP, DEFAULT_TPU_USE_QUIC,
};
use {
    crate::{
        nonblocking::tpu_connection::NonblockingConnection, tpu_connection::BlockingConnection,
    },
    indexmap::map::{Entry, IndexMap},
    quinn::Endpoint,
    rand::{thread_rng, Rng},
    solana_measure::measure::Measure,
    solana_quic_client::nonblocking::quic_client::{
        QuicClient, QuicClientCertificate, QuicLazyInitializedEndpoint,
    },
    solana_sdk::{
        pubkey::Pubkey, quic::QUIC_PORT_OFFSET, signature::Keypair, timing::AtomicInterval,
    },
    solana_streamer::{
        nonblocking::quic::{compute_max_allowed_uni_streams, ConnectionPeerType},
        streamer::StakedNodes,
        tls_certificates::new_self_signed_tls_certificate,
    },
    solana_tpu_client::{
        connection_cache_stats::{ConnectionCacheStats, CONNECTION_STAT_SUBMISSION_INTERVAL},
        tpu_connection_cache::MAX_CONNECTIONS,
    },
    std::{
        error::Error,
        net::{IpAddr, Ipv4Addr, SocketAddr, UdpSocket},
        sync::{atomic::Ordering, Arc, RwLock},
    },
};

pub struct ConnectionCache {
    map: RwLock<IndexMap<SocketAddr, ConnectionPool>>,
    stats: Arc<ConnectionCacheStats>,
    last_stats: AtomicInterval,
    connection_pool_size: usize,
    tpu_udp_socket: Arc<UdpSocket>,
    client_certificate: Arc<QuicClientCertificate>,
    use_quic: bool,
    maybe_staked_nodes: Option<Arc<RwLock<StakedNodes>>>,
    maybe_client_pubkey: Option<Pubkey>,

    // The optional specified endpoint for the quic based client connections
    // If not specified, the connection cache we create as needed.
    client_endpoint: Option<Endpoint>,
}

/// Models the pool of connections
struct ConnectionPool {
    /// The connections in the pool
    connections: Vec<Arc<BaseTpuConnection>>,

    /// Connections in this pool share the same endpoint
    endpoint: Option<Arc<QuicLazyInitializedEndpoint>>,
}

impl ConnectionPool {
    /// Get a connection from the pool. It must have at least one connection in the pool.
    /// This randomly picks a connection in the pool.
    fn borrow_connection(&self) -> Arc<BaseTpuConnection> {
        let mut rng = thread_rng();
        let n = rng.gen_range(0, self.connections.len());
        self.connections[n].clone()
    }

    /// Check if we need to create a new connection. If the count of the connections
    /// is smaller than the pool size.
    fn need_new_connection(&self, required_pool_size: usize) -> bool {
        self.connections.len() < required_pool_size
    }
}

impl ConnectionCache {
    pub fn new(connection_pool_size: usize) -> Self {
        Self::_new_with_endpoint(connection_pool_size, None)
    }

    /// Create a connection cache with a specific quic client endpoint.
    pub fn new_with_endpoint(connection_pool_size: usize, client_endpoint: Endpoint) -> Self {
        Self::_new_with_endpoint(connection_pool_size, Some(client_endpoint))
    }

    fn _new_with_endpoint(connection_pool_size: usize, client_endpoint: Option<Endpoint>) -> Self {
        // The minimum pool size is 1.
        let connection_pool_size = 1.max(connection_pool_size);
        Self {
            use_quic: true,
            connection_pool_size,
            client_endpoint,
            ..Self::default()
        }
    }

    pub fn update_client_certificate(
        &mut self,
        keypair: &Keypair,
        ipaddr: IpAddr,
    ) -> Result<(), Box<dyn Error>> {
        let (cert, priv_key) = new_self_signed_tls_certificate(keypair, ipaddr)?;
        self.client_certificate = Arc::new(QuicClientCertificate {
            certificate: cert,
            key: priv_key,
        });
        Ok(())
    }

    pub fn set_staked_nodes(
        &mut self,
        staked_nodes: &Arc<RwLock<StakedNodes>>,
        client_pubkey: &Pubkey,
    ) {
        self.maybe_staked_nodes = Some(staked_nodes.clone());
        self.maybe_client_pubkey = Some(*client_pubkey);
    }

    pub fn with_udp(connection_pool_size: usize) -> Self {
        // The minimum pool size is 1.
        let connection_pool_size = 1.max(connection_pool_size);
        Self {
            use_quic: false,
            connection_pool_size,
            ..Self::default()
        }
    }

    pub fn use_quic(&self) -> bool {
        self.use_quic
    }

    fn create_endpoint(&self, force_use_udp: bool) -> Option<Arc<QuicLazyInitializedEndpoint>> {
        if self.use_quic() && !force_use_udp {
            Some(Arc::new(QuicLazyInitializedEndpoint::new(
                self.client_certificate.clone(),
                self.client_endpoint.as_ref().cloned(),
            )))
        } else {
            None
        }
    }

    fn compute_max_parallel_streams(&self) -> usize {
        let (client_type, stake, total_stake) =
            self.maybe_client_pubkey
                .map_or((ConnectionPeerType::Unstaked, 0, 0), |pubkey| {
                    self.maybe_staked_nodes.as_ref().map_or(
                        (ConnectionPeerType::Unstaked, 0, 0),
                        |stakes| {
                            let rstakes = stakes.read().unwrap();
                            rstakes.pubkey_stake_map.get(&pubkey).map_or(
                                (ConnectionPeerType::Unstaked, 0, rstakes.total_stake),
                                |stake| (ConnectionPeerType::Staked, *stake, rstakes.total_stake),
                            )
                        },
                    )
                });
        compute_max_allowed_uni_streams(client_type, stake, total_stake)
    }

    /// Create a lazy connection object under the exclusive lock of the cache map if there is not
    /// enough used connections in the connection pool for the specified address.
    /// Returns CreateConnectionResult.
    fn create_connection(
        &self,
        lock_timing_ms: &mut u64,
        addr: &SocketAddr,
        force_use_udp: bool,
    ) -> CreateConnectionResult {
        let mut get_connection_map_lock_measure = Measure::start("get_connection_map_lock_measure");
        let mut map = self.map.write().unwrap();
        get_connection_map_lock_measure.stop();
        *lock_timing_ms = lock_timing_ms.saturating_add(get_connection_map_lock_measure.as_ms());
        // Read again, as it is possible that between read lock dropped and the write lock acquired
        // another thread could have setup the connection.

        let (to_create_connection, endpoint) =
            map.get(addr)
                .map_or((true, self.create_endpoint(force_use_udp)), |pool| {
                    (
                        pool.need_new_connection(self.connection_pool_size),
                        pool.endpoint.clone(),
                    )
                });

        let (cache_hit, num_evictions, eviction_timing_ms) = if to_create_connection {
            let connection = if !self.use_quic() || force_use_udp {
                BaseTpuConnection::Udp(self.tpu_udp_socket.clone())
            } else {
                BaseTpuConnection::Quic(Arc::new(QuicClient::new(
                    endpoint.as_ref().unwrap().clone(),
                    *addr,
                    self.compute_max_parallel_streams(),
                )))
            };

            let connection = Arc::new(connection);

            // evict a connection if the cache is reaching upper bounds
            let mut num_evictions = 0;
            let mut get_connection_cache_eviction_measure =
                Measure::start("get_connection_cache_eviction_measure");
            while map.len() >= MAX_CONNECTIONS {
                let mut rng = thread_rng();
                let n = rng.gen_range(0, MAX_CONNECTIONS);
                map.swap_remove_index(n);
                num_evictions += 1;
            }
            get_connection_cache_eviction_measure.stop();

            match map.entry(*addr) {
                Entry::Occupied(mut entry) => {
                    let pool = entry.get_mut();
                    pool.connections.push(connection);
                }
                Entry::Vacant(entry) => {
                    entry.insert(ConnectionPool {
                        connections: vec![connection],
                        endpoint,
                    });
                }
            }
            (
                false,
                num_evictions,
                get_connection_cache_eviction_measure.as_ms(),
            )
        } else {
            (true, 0, 0)
        };

        let pool = map.get(addr).unwrap();
        let connection = pool.borrow_connection();

        CreateConnectionResult {
            connection,
            cache_hit,
            connection_cache_stats: self.stats.clone(),
            num_evictions,
            eviction_timing_ms,
        }
    }

    fn get_or_add_connection(&self, addr: &SocketAddr) -> GetConnectionResult {
        let mut get_connection_map_lock_measure = Measure::start("get_connection_map_lock_measure");
        let map = self.map.read().unwrap();
        get_connection_map_lock_measure.stop();

        let port_offset = if self.use_quic() { QUIC_PORT_OFFSET } else { 0 };

        let port = addr
            .port()
            .checked_add(port_offset)
            .unwrap_or_else(|| addr.port());
        let force_use_udp = port == addr.port();
        let addr = SocketAddr::new(addr.ip(), port);

        let mut lock_timing_ms = get_connection_map_lock_measure.as_ms();

        let report_stats = self
            .last_stats
            .should_update(CONNECTION_STAT_SUBMISSION_INTERVAL);

        let mut get_connection_map_measure = Measure::start("get_connection_hit_measure");
        let CreateConnectionResult {
            connection,
            cache_hit,
            connection_cache_stats,
            num_evictions,
            eviction_timing_ms,
        } = match map.get(&addr) {
            Some(pool) => {
                if pool.need_new_connection(self.connection_pool_size) {
                    // create more connection and put it in the pool
                    drop(map);
                    self.create_connection(&mut lock_timing_ms, &addr, force_use_udp)
                } else {
                    let connection = pool.borrow_connection();
                    CreateConnectionResult {
                        connection,
                        cache_hit: true,
                        connection_cache_stats: self.stats.clone(),
                        num_evictions: 0,
                        eviction_timing_ms: 0,
                    }
                }
            }
            None => {
                // Upgrade to write access by dropping read lock and acquire write lock
                drop(map);
                self.create_connection(&mut lock_timing_ms, &addr, force_use_udp)
            }
        };
        get_connection_map_measure.stop();

        GetConnectionResult {
            connection,
            cache_hit,
            report_stats,
            map_timing_ms: get_connection_map_measure.as_ms(),
            lock_timing_ms,
            connection_cache_stats,
            num_evictions,
            eviction_timing_ms,
        }
    }

    fn get_connection_and_log_stats(
        &self,
        addr: &SocketAddr,
    ) -> (Arc<BaseTpuConnection>, Arc<ConnectionCacheStats>) {
        let mut get_connection_measure = Measure::start("get_connection_measure");
        let GetConnectionResult {
            connection,
            cache_hit,
            report_stats,
            map_timing_ms,
            lock_timing_ms,
            connection_cache_stats,
            num_evictions,
            eviction_timing_ms,
        } = self.get_or_add_connection(addr);

        if report_stats {
            connection_cache_stats.report();
        }

        if cache_hit {
            connection_cache_stats
                .cache_hits
                .fetch_add(1, Ordering::Relaxed);
            connection_cache_stats
                .get_connection_hit_ms
                .fetch_add(map_timing_ms, Ordering::Relaxed);
        } else {
            connection_cache_stats
                .cache_misses
                .fetch_add(1, Ordering::Relaxed);
            connection_cache_stats
                .get_connection_miss_ms
                .fetch_add(map_timing_ms, Ordering::Relaxed);
            connection_cache_stats
                .cache_evictions
                .fetch_add(num_evictions, Ordering::Relaxed);
            connection_cache_stats
                .eviction_time_ms
                .fetch_add(eviction_timing_ms, Ordering::Relaxed);
        }

        get_connection_measure.stop();
        connection_cache_stats
            .get_connection_lock_ms
            .fetch_add(lock_timing_ms, Ordering::Relaxed);
        connection_cache_stats
            .get_connection_ms
            .fetch_add(get_connection_measure.as_ms(), Ordering::Relaxed);

        (connection, connection_cache_stats)
    }

    pub fn get_connection(&self, addr: &SocketAddr) -> BlockingConnection {
        let (connection, connection_cache_stats) = self.get_connection_and_log_stats(addr);
        connection.new_blocking_connection(*addr, connection_cache_stats)
    }

    pub fn get_nonblocking_connection(&self, addr: &SocketAddr) -> NonblockingConnection {
        let (connection, connection_cache_stats) = self.get_connection_and_log_stats(addr);
        connection.new_nonblocking_connection(*addr, connection_cache_stats)
    }
}

impl Default for ConnectionCache {
    fn default() -> Self {
        let (cert, priv_key) =
            new_self_signed_tls_certificate(&Keypair::new(), IpAddr::V4(Ipv4Addr::new(0, 0, 0, 0)))
                .expect("Failed to initialize QUIC client certificates");
        Self {
            map: RwLock::new(IndexMap::with_capacity(MAX_CONNECTIONS)),
            stats: Arc::new(ConnectionCacheStats::default()),
            last_stats: AtomicInterval::default(),
            connection_pool_size: DEFAULT_TPU_CONNECTION_POOL_SIZE,
            tpu_udp_socket: Arc::new(
                solana_net_utils::bind_with_any_port(IpAddr::V4(Ipv4Addr::new(0, 0, 0, 0)))
                    .expect("Unable to bind to UDP socket"),
            ),
            client_certificate: Arc::new(QuicClientCertificate {
                certificate: cert,
                key: priv_key,
            }),
            use_quic: DEFAULT_TPU_USE_QUIC,
            maybe_staked_nodes: None,
            maybe_client_pubkey: None,
            client_endpoint: None,
        }
    }
}

enum BaseTpuConnection {
    Udp(Arc<UdpSocket>),
    Quic(Arc<QuicClient>),
}
impl BaseTpuConnection {
    fn new_blocking_connection(
        &self,
        addr: SocketAddr,
        stats: Arc<ConnectionCacheStats>,
    ) -> BlockingConnection {
        use crate::{quic_client::QuicTpuConnection, udp_client::UdpTpuConnection};
        match self {
            BaseTpuConnection::Udp(udp_socket) => {
                UdpTpuConnection::new_from_addr(udp_socket.clone(), addr).into()
            }
            BaseTpuConnection::Quic(quic_client) => {
                QuicTpuConnection::new_with_client(quic_client.clone(), stats).into()
            }
        }
    }

    fn new_nonblocking_connection(
        &self,
        addr: SocketAddr,
        stats: Arc<ConnectionCacheStats>,
    ) -> NonblockingConnection {
        use crate::nonblocking::{quic_client::QuicTpuConnection, udp_client::UdpTpuConnection};
        match self {
            BaseTpuConnection::Udp(udp_socket) => {
                UdpTpuConnection::new_from_addr(udp_socket.try_clone().unwrap(), addr).into()
            }
            BaseTpuConnection::Quic(quic_client) => {
                QuicTpuConnection::new_with_client(quic_client.clone(), stats).into()
            }
        }
    }
}

struct GetConnectionResult {
    connection: Arc<BaseTpuConnection>,
    cache_hit: bool,
    report_stats: bool,
    map_timing_ms: u64,
    lock_timing_ms: u64,
    connection_cache_stats: Arc<ConnectionCacheStats>,
    num_evictions: u64,
    eviction_timing_ms: u64,
}

struct CreateConnectionResult {
    connection: Arc<BaseTpuConnection>,
    cache_hit: bool,
    connection_cache_stats: Arc<ConnectionCacheStats>,
    num_evictions: u64,
    eviction_timing_ms: u64,
}

#[cfg(test)]
mod tests {
    use {
        crate::{
            connection_cache::{ConnectionCache, MAX_CONNECTIONS},
            tpu_connection::TpuConnection,
        },
        crossbeam_channel::unbounded,
        rand::{Rng, SeedableRng},
        rand_chacha::ChaChaRng,
        solana_sdk::{
            pubkey::Pubkey,
            quic::{
                QUIC_MAX_UNSTAKED_CONCURRENT_STREAMS, QUIC_MIN_STAKED_CONCURRENT_STREAMS,
                QUIC_PORT_OFFSET, QUIC_TOTAL_STAKED_CONCURRENT_STREAMS,
            },
            signature::Keypair,
        },
        solana_streamer::{
            nonblocking::quic::DEFAULT_WAIT_FOR_CHUNK_TIMEOUT_MS, quic::StreamStats,
            streamer::StakedNodes,
        },
        std::{
            net::{IpAddr, Ipv4Addr, SocketAddr, UdpSocket},
            sync::{
                atomic::{AtomicBool, Ordering},
                Arc, RwLock,
            },
        },
    };

    fn server_args() -> (
        UdpSocket,
        Arc<AtomicBool>,
        Keypair,
        IpAddr,
        Arc<StreamStats>,
    ) {
        (
            UdpSocket::bind("127.0.0.1:0").unwrap(),
            Arc::new(AtomicBool::new(false)),
            Keypair::new(),
            "127.0.0.1".parse().unwrap(),
            Arc::new(StreamStats::default()),
        )
    }

    fn get_addr(rng: &mut ChaChaRng) -> SocketAddr {
        let a = rng.gen_range(1, 255);
        let b = rng.gen_range(1, 255);
        let c = rng.gen_range(1, 255);
        let d = rng.gen_range(1, 255);

        let addr_str = format!("{a}.{b}.{c}.{d}:80");

        addr_str.parse().expect("Invalid address")
    }

    #[test]
    fn test_connection_cache() {
        solana_logger::setup();
        // Allow the test to run deterministically
        // with the same pseudorandom sequence between runs
        // and on different platforms - the cryptographic security
        // property isn't important here but ChaChaRng provides a way
        // to get the same pseudorandom sequence on different platforms
        let mut rng = ChaChaRng::seed_from_u64(42);

        // Generate a bunch of random addresses and create TPUConnections to them
        // Since TPUConnection::new is infallible, it should't matter whether or not
        // we can actually connect to those addresses - TPUConnection implementations should either
        // be lazy and not connect until first use or handle connection errors somehow
        // (without crashing, as would be required in a real practical validator)
        let connection_cache = ConnectionCache::default();
        let port_offset = if connection_cache.use_quic() {
            QUIC_PORT_OFFSET
        } else {
            0
        };
        let addrs = (0..MAX_CONNECTIONS)
            .map(|_| {
                let addr = get_addr(&mut rng);
                connection_cache.get_connection(&addr);
                addr
            })
            .collect::<Vec<_>>();
        {
            let map = connection_cache.map.read().unwrap();
            assert!(map.len() == MAX_CONNECTIONS);
            addrs.iter().for_each(|a| {
                let port = a
                    .port()
                    .checked_add(port_offset)
                    .unwrap_or_else(|| a.port());
                let addr = &SocketAddr::new(a.ip(), port);

                let conn = &map.get(addr).expect("Address not found").connections[0];
                let conn = conn.new_blocking_connection(*addr, connection_cache.stats.clone());
                assert!(addr.ip() == conn.tpu_addr().ip());
            });
        }

        let addr = &get_addr(&mut rng);
        connection_cache.get_connection(addr);

        let port = addr
            .port()
            .checked_add(port_offset)
            .unwrap_or_else(|| addr.port());
        let addr_with_quic_port = SocketAddr::new(addr.ip(), port);
        let map = connection_cache.map.read().unwrap();
        assert!(map.len() == MAX_CONNECTIONS);
        let _conn = map.get(&addr_with_quic_port).expect("Address not found");
    }

    #[test]
    fn test_connection_cache_max_parallel_chunks() {
        solana_logger::setup();
        let mut connection_cache = ConnectionCache::default();
        assert_eq!(
            connection_cache.compute_max_parallel_streams(),
            QUIC_MAX_UNSTAKED_CONCURRENT_STREAMS
        );

        let staked_nodes = Arc::new(RwLock::new(StakedNodes::default()));
        let pubkey = Pubkey::new_unique();
        connection_cache.set_staked_nodes(&staked_nodes, &pubkey);
        assert_eq!(
            connection_cache.compute_max_parallel_streams(),
            QUIC_MAX_UNSTAKED_CONCURRENT_STREAMS
        );

        staked_nodes.write().unwrap().total_stake = 10000;
        assert_eq!(
            connection_cache.compute_max_parallel_streams(),
            QUIC_MAX_UNSTAKED_CONCURRENT_STREAMS
        );

        staked_nodes
            .write()
            .unwrap()
            .pubkey_stake_map
            .insert(pubkey, 1);

        let delta =
            (QUIC_TOTAL_STAKED_CONCURRENT_STREAMS - QUIC_MIN_STAKED_CONCURRENT_STREAMS) as f64;

        assert_eq!(
            connection_cache.compute_max_parallel_streams(),
            (QUIC_MIN_STAKED_CONCURRENT_STREAMS as f64 + (1f64 / 10000f64) * delta) as usize
        );

        staked_nodes
            .write()
            .unwrap()
            .pubkey_stake_map
            .remove(&pubkey);
        staked_nodes
            .write()
            .unwrap()
            .pubkey_stake_map
            .insert(pubkey, 1000);
        assert_ne!(
            connection_cache.compute_max_parallel_streams(),
            QUIC_MIN_STAKED_CONCURRENT_STREAMS
        );
    }

    // Test that we can get_connection with a connection cache configured for quic
    // on an address with a port that, if QUIC_PORT_OFFSET were added to it, it would overflow to
    // an invalid port.
    #[test]
    fn test_overflow_address() {
        let port = u16::MAX - QUIC_PORT_OFFSET + 1;
        assert!(port.checked_add(QUIC_PORT_OFFSET).is_none());
        let addr = SocketAddr::new(IpAddr::V4(Ipv4Addr::new(127, 0, 0, 1)), port);
        let connection_cache = ConnectionCache::new(1);

        let conn = connection_cache.get_connection(&addr);
        // We (intentionally) don't have an interface that allows us to distinguish between
        // UDP and Quic connections, so check instead that the port is valid (non-zero)
        // and is the same as the input port (falling back on UDP)
        assert!(conn.tpu_addr().port() != 0);
        assert!(conn.tpu_addr().port() == port);
    }

    #[test]
    fn test_connection_with_specified_client_endpoint() {
        let port = u16::MAX - QUIC_PORT_OFFSET + 1;
        assert!(port.checked_add(QUIC_PORT_OFFSET).is_none());

        // Start a response receiver:
        let (
            response_recv_socket,
            response_recv_exit,
            keypair2,
            response_recv_ip,
            response_recv_stats,
        ) = server_args();
        let (sender2, _receiver2) = unbounded();

        let staked_nodes = Arc::new(RwLock::new(StakedNodes::default()));

        let (response_recv_endpoint, response_recv_thread) = solana_streamer::quic::spawn_server(
            response_recv_socket,
            &keypair2,
            response_recv_ip,
            sender2,
            response_recv_exit.clone(),
            1,
            staked_nodes,
            10,
            10,
            response_recv_stats,
            DEFAULT_WAIT_FOR_CHUNK_TIMEOUT_MS,
        )
        .unwrap();

        let connection_cache = ConnectionCache::new_with_endpoint(1, response_recv_endpoint);

        // server port 1:
        let port1 = 9001;
        let addr = SocketAddr::new(IpAddr::V4(Ipv4Addr::new(127, 0, 0, 1)), port1);
        let conn = connection_cache.get_connection(&addr);
        assert_eq!(conn.tpu_addr().port(), port1 + QUIC_PORT_OFFSET);

        // server port 2:
        let port2 = 9002;
        let addr = SocketAddr::new(IpAddr::V4(Ipv4Addr::new(127, 0, 0, 1)), port2);
        let conn = connection_cache.get_connection(&addr);
        assert_eq!(conn.tpu_addr().port(), port2 + QUIC_PORT_OFFSET);

        response_recv_exit.store(true, Ordering::Relaxed);
        response_recv_thread.join().unwrap();
    }
}
