//! Crds Gossip
//! This module ties together Crds and the push and pull gossip overlays.  The interface is
//! designed to run with a simulator or over a UDP network connection with messages up to a
//! packet::PACKET_DATA_SIZE size.

use crate::{
    cluster_info::Ping,
    contact_info::ContactInfo,
    crds::Crds,
    crds_gossip_error::CrdsGossipError,
    crds_gossip_pull::{CrdsFilter, CrdsGossipPull, ProcessPullStats},
    crds_gossip_push::{CrdsGossipPush, CRDS_GOSSIP_NUM_ACTIVE},
    crds_value::{CrdsData, CrdsValue},
    duplicate_shred::{self, DuplicateShredIndex, LeaderScheduleFn, MAX_DUPLICATE_SHREDS},
    ping_pong::PingCache,
};
use itertools::Itertools;
use rayon::ThreadPool;
use panoptis_ledger::shred::Shred;
use solana_sdk::{
    hash::Hash,
    pubkey::Pubkey,
    signature::{Keypair, Signer},
    timing::timestamp,
};
use std::{
    collections::{HashMap, HashSet},
    net::SocketAddr,
    sync::Mutex,
    time::Duration,
};

pub struct CrdsGossip {
    pub crds: Crds,
    pub id: Pubkey,
    pub shred_version: u16,
    pub push: CrdsGossipPush,
    pub pull: CrdsGossipPull,
}

impl Default for CrdsGossip {
    fn default() -> Self {
        CrdsGossip {
            crds: Crds::default(),
            id: Pubkey::default(),
            shred_version: 0,
            push: CrdsGossipPush::default(),
            pull: CrdsGossipPull::default(),
        }
    }
}

impl CrdsGossip {
    pub fn set_self(&mut self, id: &Pubkey) {
        self.id = *id;
    }
    pub fn set_shred_version(&mut self, shred_version: u16) {
        self.shred_version = shred_version;
    }

    /// process a push message to the network
    /// Returns origins' pubkeys of upserted values.
    pub fn process_push_message(
        &mut self,
        from: &Pubkey,
        values: Vec<CrdsValue>,
        now: u64,
    ) -> Vec<Pubkey> {
        values
            .into_iter()
            .flat_map(|val| {
                let origin = val.pubkey();
                self.push
                    .process_push_message(&mut self.crds, from, val, now)
                    .ok()?;
                Some(origin)
            })
            .collect()
    }

    /// remove redundant paths in the network
    pub fn prune_received_cache<I>(
        &mut self,
        origins: I, // Unique pubkeys of crds values' owners.
        stakes: &HashMap<Pubkey, u64>,
    ) -> HashMap</*gossip peer:*/ Pubkey, /*origins:*/ Vec<Pubkey>>
    where
        I: IntoIterator<Item = Pubkey>,
    {
        let self_pubkey = self.id;
        origins
            .into_iter()
            .flat_map(|origin| {
                self.push
                    .prune_received_cache(&self_pubkey, &origin, stakes)
                    .into_iter()
                    .zip(std::iter::repeat(origin))
            })
            .into_group_map()
    }

    pub fn new_push_messages(
        &mut self,
        pending_push_messages: Vec<CrdsValue>,
        now: u64,
    ) -> HashMap<Pubkey, Vec<CrdsValue>> {
        let self_pubkey = self.id;
        self.process_push_message(&self_pubkey, pending_push_messages, now);
        self.push.new_push_messages(&self.crds, now)
    }

    pub(crate) fn push_duplicate_shred(
        &mut self,
        keypair: &Keypair,
        shred: &Shred,
        other_payload: &[u8],
        leader_schedule: Option<impl LeaderScheduleFn>,
        // Maximum serialized size of each DuplicateShred chunk payload.
        max_payload_size: usize,
    ) -> Result<(), duplicate_shred::Error> {
        let pubkey = keypair.pubkey();
        // Skip if there are already records of duplicate shreds for this slot.
        let shred_slot = shred.slot();
        if self
            .crds
            .get_records(&pubkey)
            .any(|value| match &value.value.data {
                CrdsData::DuplicateShred(_, value) => value.slot == shred_slot,
                _ => false,
            })
        {
            return Ok(());
        }
        let chunks = duplicate_shred::from_shred(
            shred.clone(),
            pubkey,
            Vec::from(other_payload),
            leader_schedule,
            timestamp(),
            max_payload_size,
        )?;
        // Find the index of oldest duplicate shred.
        let mut num_dup_shreds = 0;
        let offset = self
            .crds
            .get_records(&pubkey)
            .filter_map(|value| match &value.value.data {
                CrdsData::DuplicateShred(ix, value) => {
                    num_dup_shreds += 1;
                    Some((value.wallclock, *ix))
                }
                _ => None,
            })
            .min() // Override the oldest records.
            .map(|(_ /*wallclock*/, ix)| ix)
            .unwrap_or(0);
        let offset = if num_dup_shreds < MAX_DUPLICATE_SHREDS {
            num_dup_shreds
        } else {
            offset
        };
        let entries = chunks
            .enumerate()
            .map(|(k, chunk)| {
                let index = (offset + k as DuplicateShredIndex) % MAX_DUPLICATE_SHREDS;
                let data = CrdsData::DuplicateShred(index, chunk);
                CrdsValue::new_signed(data, keypair)
            })
            .collect();
        self.process_push_message(&pubkey, entries, timestamp());
        Ok(())
    }

    /// add the `from` to the peer's filter of nodes
    pub fn process_prune_msg(
        &self,
        peer: &Pubkey,
        destination: &Pubkey,
        origin: &[Pubkey],
        wallclock: u64,
        now: u64,
    ) -> Result<(), CrdsGossipError> {
        let expired = now > wallclock + self.push.prune_timeout;
        if expired {
            return Err(CrdsGossipError::PruneMessageTimeout);
        }
        if self.id == *destination {
            self.push.process_prune_msg(&self.id, peer, origin);
            Ok(())
        } else {
            Err(CrdsGossipError::BadPruneDestination)
        }
    }

    /// refresh the push active set
    /// * ratio - number of actives to rotate
    pub fn refresh_push_active_set(
        &mut self,
        stakes: &HashMap<Pubkey, u64>,
        gossip_validators: Option<&HashSet<Pubkey>>,
    ) {
        self.push.refresh_push_active_set(
            &self.crds,
            stakes,
            gossip_validators,
            &self.id,
            self.shred_version,
            self.crds.num_nodes(),
            CRDS_GOSSIP_NUM_ACTIVE,
        )
    }

    /// generate a random request
    pub fn new_pull_request(
        &self,
        thread_pool: &ThreadPool,
        self_keypair: &Keypair,
        now: u64,
        gossip_validators: Option<&HashSet<Pubkey>>,
        stakes: &HashMap<Pubkey, u64>,
        bloom_size: usize,
        ping_cache: &Mutex<PingCache>,
        pings: &mut Vec<(SocketAddr, Ping)>,
    ) -> Result<(ContactInfo, Vec<CrdsFilter>), CrdsGossipError> {
        self.pull.new_pull_request(
            thread_pool,
            &self.crds,
            self_keypair,
            self.shred_version,
            now,
            gossip_validators,
            stakes,
            bloom_size,
            ping_cache,
            pings,
        )
    }

    /// time when a request to `from` was initiated
    /// This is used for weighted random selection during `new_pull_request`
    /// It's important to use the local nodes request creation time as the weight
    /// instead of the response received time otherwise failed nodes will increase their weight.
    pub fn mark_pull_request_creation_time(&mut self, from: Pubkey, now: u64) {
        self.pull.mark_pull_request_creation_time(from, now)
    }
    /// process a pull request and create a response
    pub fn process_pull_requests<I>(&mut self, callers: I, now: u64)
    where
        I: IntoIterator<Item = CrdsValue>,
    {
        self.pull
            .process_pull_requests(&mut self.crds, callers, now);
    }

    pub fn generate_pull_responses(
        &self,
        filters: &[(CrdsValue, CrdsFilter)],
        output_size_limit: usize, // Limit number of crds values returned.
        now: u64,
    ) -> Vec<Vec<CrdsValue>> {
        self.pull
            .generate_pull_responses(&self.crds, filters, output_size_limit, now)
    }

    pub fn filter_pull_responses(
        &self,
        timeouts: &HashMap<Pubkey, u64>,
        response: Vec<CrdsValue>,
        now: u64,
        process_pull_stats: &mut ProcessPullStats,
    ) -> (
        Vec<CrdsValue>, // valid responses.
        Vec<CrdsValue>, // responses with expired timestamps.
        Vec<Hash>,      // hash of outdated values.
    ) {
        self.pull
            .filter_pull_responses(&self.crds, timeouts, response, now, process_pull_stats)
    }

    /// process a pull response
    pub fn process_pull_responses(
        &mut self,
        from: &Pubkey,
        responses: Vec<CrdsValue>,
        responses_expired_timeout: Vec<CrdsValue>,
        failed_inserts: Vec<Hash>,
        now: u64,
        process_pull_stats: &mut ProcessPullStats,
    ) {
        self.pull.process_pull_responses(
            &mut self.crds,
            from,
            responses,
            responses_expired_timeout,
            failed_inserts,
            now,
            process_pull_stats,
        );
    }

    pub fn make_timeouts(
        &self,
        stakes: &HashMap<Pubkey, u64>,
        epoch_duration: Duration,
    ) -> HashMap<Pubkey, u64> {
        self.pull.make_timeouts(self.id, stakes, epoch_duration)
    }

    pub fn purge(
        &mut self,
        thread_pool: &ThreadPool,
        now: u64,
        timeouts: &HashMap<Pubkey, u64>,
    ) -> usize {
        let mut rv = 0;
        if now > 5 * self.push.msg_timeout {
            let min = now - 5 * self.push.msg_timeout;
            self.push.purge_old_received_cache(min);
        }
        if now > self.pull.crds_timeout {
            //sanity check
            assert_eq!(timeouts[&self.id], std::u64::MAX);
            assert!(timeouts.contains_key(&Pubkey::default()));
            rv = self
                .pull
                .purge_active(thread_pool, &mut self.crds, now, &timeouts);
        }
        self.crds
            .trim_purged(now.saturating_sub(5 * self.pull.crds_timeout));
        self.pull.purge_failed_inserts(now);
        rv
    }

    // Only for tests and simulations.
    pub(crate) fn mock_clone(&self) -> Self {
        Self {
            crds: self.crds.clone(),
            push: self.push.mock_clone(),
            pull: self.pull.mock_clone(),
            ..*self
        }
    }
}

/// Computes a normalized(log of actual stake) stake
pub fn get_stake<S: std::hash::BuildHasher>(id: &Pubkey, stakes: &HashMap<Pubkey, u64, S>) -> f32 {
    // cap the max balance to u32 max (it should be plenty)
    let bal = f64::from(u32::max_value()).min(*stakes.get(id).unwrap_or(&0) as f64);
    1_f32.max((bal as f32).ln())
}

/// Computes bounded weight given some max, a time since last selected, and a stake value
/// The minimum stake is 1 and not 0 to allow 'time since last' picked to factor in.
pub fn get_weight(max_weight: f32, time_since_last_selected: u32, stake: f32) -> f32 {
    let mut weight = time_since_last_selected as f32 * stake;
    if weight.is_infinite() {
        weight = max_weight;
    }
    1.0_f32.max(weight.min(max_weight))
}

#[cfg(test)]
mod test {
    use super::*;
    use crate::contact_info::ContactInfo;
    use crate::crds_value::CrdsData;
    use solana_sdk::hash::hash;
    use solana_sdk::timing::timestamp;

    #[test]
    fn test_prune_errors() {
        let mut crds_gossip = CrdsGossip {
            id: Pubkey::new(&[0; 32]),
            ..CrdsGossip::default()
        };
        let id = crds_gossip.id;
        let ci = ContactInfo::new_localhost(&Pubkey::new(&[1; 32]), 0);
        let prune_pubkey = Pubkey::new(&[2; 32]);
        crds_gossip
            .crds
            .insert(
                CrdsValue::new_unsigned(CrdsData::ContactInfo(ci.clone())),
                0,
            )
            .unwrap();
        crds_gossip.refresh_push_active_set(&HashMap::new(), None);
        let now = timestamp();
        //incorrect dest
        let mut res = crds_gossip.process_prune_msg(
            &ci.id,
            &Pubkey::new(hash(&[1; 32]).as_ref()),
            &[prune_pubkey],
            now,
            now,
        );
        assert_eq!(res.err(), Some(CrdsGossipError::BadPruneDestination));
        //correct dest
        res = crds_gossip.process_prune_msg(&ci.id, &id, &[prune_pubkey], now, now);
        res.unwrap();
        //test timeout
        let timeout = now + crds_gossip.push.prune_timeout * 2;
        res = crds_gossip.process_prune_msg(&ci.id, &id, &[prune_pubkey], now, timeout);
        assert_eq!(res.err(), Some(CrdsGossipError::PruneMessageTimeout));
    }
}
