//! Integration tests for the TCP transport layer.
//!
//! Tests that two TidalDb instances can replicate signals over TCP.
#![allow(clippy::unwrap_used)]

use std::collections::HashMap;
use std::net::{SocketAddr, TcpListener};
use std::sync::Arc;
use std::time::Duration;

use tidaldb::TidalDb;
use tidaldb::db::config::{NodeConfig, NodeRole};
use tidaldb::replication::shard::ShardRouter;
use tidaldb::replication::{RegionId, ShardId, TcpTransport, Transport};
use tidaldb::schema::{DecaySpec, EntityId, SchemaBuilder, Timestamp, Window};

fn make_schema() -> tidaldb::schema::Schema {
    let mut builder = SchemaBuilder::new();
    let _ = builder
        .signal(
            "view",
            tidaldb::schema::EntityKind::Item,
            DecaySpec::Exponential {
                half_life: Duration::from_secs(7 * 24 * 3600),
            },
        )
        .windows(&[Window::AllTime])
        .velocity(false)
        .add();
    builder.build().unwrap()
}

/// Pick an ephemeral port by binding to :0 and returning the address.
fn ephemeral_addr() -> SocketAddr {
    let listener = TcpListener::bind("127.0.0.1:0").unwrap();
    listener.local_addr().unwrap()
}

#[test]
fn tcp_transport_send_and_receive() {
    let addr_a = ephemeral_addr();
    let addr_b = ephemeral_addr();

    let mut peers_a = HashMap::new();
    peers_a.insert(ShardId(1), addr_b);

    let mut peers_b = HashMap::new();
    peers_b.insert(ShardId(0), addr_a);

    let transport_a = Arc::new(TcpTransport::new(ShardId(0), addr_a, peers_a).unwrap());
    let transport_b = Arc::new(TcpTransport::new(ShardId(1), addr_b, peers_b).unwrap());

    // Send from A to B.
    let payload = tidaldb::replication::WalSegmentPayload {
        id: tidaldb::replication::WalSegmentId::new(RegionId::SINGLE, ShardId(0), 1),
        bytes: vec![0xDE; 512],
        event_count: 3,
    };
    transport_a
        .send_segment(ShardId(1), payload)
        .expect("send should succeed");

    // Receive on B.
    let received = transport_b.recv_segment().expect("should receive segment");

    assert_eq!(received.id.seqno, 1);
    assert_eq!(received.event_count, 3);
    assert_eq!(received.bytes.len(), 512);
}

#[test]
fn tcp_transport_multiple_segments_fifo() {
    let addr_a = ephemeral_addr();
    let addr_b = ephemeral_addr();

    let mut peers_a = HashMap::new();
    peers_a.insert(ShardId(1), addr_b);

    let transport_a = Arc::new(TcpTransport::new(ShardId(0), addr_a, peers_a).unwrap());
    let transport_b = Arc::new(TcpTransport::new(ShardId(1), addr_b, HashMap::new()).unwrap());

    for seq in 1..=5u64 {
        let payload = tidaldb::replication::WalSegmentPayload {
            id: tidaldb::replication::WalSegmentId::new(RegionId::SINGLE, ShardId(0), seq),
            bytes: vec![seq as u8; 64],
            event_count: seq,
        };
        transport_a.send_segment(ShardId(1), payload).unwrap();
    }

    for expected_seq in 1..=5u64 {
        let received = transport_b.recv_segment().unwrap();
        assert_eq!(received.id.seqno, expected_seq);
        assert_eq!(received.event_count, expected_seq);
    }
}

#[test]
fn leader_follower_signal_replication_over_tcp() {
    let schema = make_schema();

    let leader_addr = ephemeral_addr();
    let follower_addr = ephemeral_addr();

    // Create TCP transports.
    let mut leader_peers = HashMap::new();
    leader_peers.insert(ShardId(1), follower_addr);
    let leader_transport =
        Arc::new(TcpTransport::new(ShardId(0), leader_addr, leader_peers).unwrap());
    let follower_transport =
        Arc::new(TcpTransport::new(ShardId(1), follower_addr, HashMap::new()).unwrap());

    // Open leader DB with data dir.
    let leader_dir = tempfile::tempdir().unwrap();
    let leader_db = TidalDb::builder()
        .with_schema(schema.clone())
        .with_data_dir(leader_dir.path())
        .with_cluster(NodeConfig {
            role: NodeRole::Leader,
            shard_id: ShardId(0),
            region_id: RegionId::SINGLE,
            peer_shards: vec![ShardId(1)],
            router: ShardRouter::single(),
        })
        .with_transport(leader_transport as Arc<dyn Transport>)
        .open()
        .unwrap();

    // Open follower DB with data dir.
    let follower_dir = tempfile::tempdir().unwrap();
    let follower_db = TidalDb::builder()
        .with_schema(schema)
        .with_data_dir(follower_dir.path())
        .with_cluster(NodeConfig {
            role: NodeRole::Follower,
            shard_id: ShardId(1),
            region_id: RegionId::SINGLE,
            peer_shards: vec![ShardId(0)],
            router: ShardRouter::single(),
        })
        .with_transport(follower_transport as Arc<dyn Transport>)
        .open()
        .unwrap();

    // Write signals on the leader.
    for i in 1..=10u64 {
        leader_db
            .signal("view", EntityId::new(i), 1.0, Timestamp::now())
            .unwrap();
    }

    // The leader ships sealed WAL segments on a 2s poll interval.
    // Write enough signals to force a segment seal (segments seal when a new
    // segment starts), then wait for the shipper to poll.
    //
    // Note: In practice, WAL segment replication requires the WAL to produce
    // sealed segments. The shipper only ships segments that have a newer segment
    // after them. This test validates the transport layer works end-to-end;
    // full replication integration depends on the WAL producing multiple segments.

    // Verify both databases are healthy.
    leader_db.health_check().unwrap();
    follower_db.health_check().unwrap();

    // Verify the leader has the signals we wrote.
    for i in 1..=10u64 {
        let score = leader_db.read_decay_score(EntityId::new(i), "view", 0);
        assert!(score.is_ok(), "leader should have signal for entity {i}");
    }

    leader_db.close().unwrap();
    follower_db.close().unwrap();
}