mod common;

use std::time::{Duration, Instant};

use common::{late_reply, reply, sent, ts};
use irtt_client::{ClientEvent, PacketMeta};
use irtt_stats::{EventStatsUpdate, IpdvPairUpdate, SampleMode, StatsCollector, StatsConfig};

#[test]
fn running_only_samples_avoid_finite_retention() {
    let mut collector = StatsCollector::new(StatsConfig::continuous());
    collector.process(&reply(0, 10, 9));
    collector.process(&reply(1, 20, 19));

    let snapshot = collector.snapshot();
    assert_eq!(snapshot.rtt.primary.median_ns, None);
    assert_eq!(snapshot.rtt.raw.median_ns, None);
    assert_eq!(snapshot.rtt.adjusted.median_ns, None);
    assert_eq!(snapshot.ipdv.round_trip.median_ns, None);
    assert_eq!(snapshot.one_way_delay.send_delay.median_ns, None);
    assert_eq!(snapshot.one_way_delay.receive_delay.median_ns, None);
}

#[test]
fn continuous_mode_tracks_running_samples_without_exact_medians() {
    let mut collector = StatsCollector::new(StatsConfig::continuous());
    for seq in 0..4104 {
        collector.process(&reply(seq, 10, 10));
    }

    let snapshot = collector.snapshot();
    assert_eq!(snapshot.rtt.primary.count, 4104);
    assert_eq!(snapshot.ipdv.round_trip.count, 4103);
    assert_eq!(snapshot.rtt.primary.median_ns, None);
    assert_eq!(snapshot.ipdv.round_trip.median_ns, None);
}

#[test]
fn cumulative_rtt_uses_signed_effective_and_tracks_raw() {
    let mut collector = StatsCollector::new(StatsConfig::finite());
    collector.process(&reply(0, 1, -2));
    collector.process(&reply(1, 10, 8));

    let snapshot = collector.snapshot();
    assert_eq!(snapshot.rtt.primary.count, 2);
    assert_eq!(snapshot.rtt.primary.min_ns, Some(-2_000_000));
    assert_eq!(snapshot.rtt.primary.median_ns, Some(3_000_000.0));
    assert_eq!(snapshot.rtt.raw.total_ns, 11_000_000);
}

#[test]
fn late_unique_counts_and_duplicates_do_not_update_measurements() {
    let mut collector = StatsCollector::new(StatsConfig::finite());
    collector.process(&sent(0, ts(0)));
    collector.process(&sent(1, ts(10)));
    collector.process(&reply(1, 10, 9));
    collector.process(&late_reply(0, 20, 19));
    collector.process(&ClientEvent::DuplicateReply {
        seq: 0,
        remote: "127.0.0.1:2112".parse().unwrap(),
        received_at: ts(50),
        bytes: 64,
    });

    let snapshot = collector.snapshot();
    assert_eq!(snapshot.packets.packets_sent, 2);
    assert_eq!(snapshot.packets.packets_received, 3);
    assert_eq!(snapshot.packets.unique_replies, 2);
    assert_eq!(snapshot.packets.duplicates, 1);
    assert_eq!(snapshot.packets.late_packets, 1);
    assert_eq!(snapshot.rtt.primary.count, 2);
    assert_eq!(snapshot.loss.lost_packets, 0);
    assert_eq!(snapshot.loss.duplicate_percent, 100.0 / 3.0);
}

#[test]
fn final_loss_uses_sent_minus_unique_replies_not_echo_loss_events() {
    let mut collector = StatsCollector::new(StatsConfig::finite());
    collector.process(&sent(0, ts(0)));
    collector.process(&sent(1, ts(10)));
    collector.process(&ClientEvent::EchoLoss {
        seq: 0,
        sent_at: ts(0),
        timeout_at: Instant::now(),
    });
    collector.process(&late_reply(0, 10, 9));

    let snapshot = collector.snapshot();
    assert_eq!(snapshot.events.loss_events, 1);
    assert_eq!(snapshot.packets.unique_replies, 1);
    assert_eq!(snapshot.loss.lost_packets, 1);
    assert_eq!(snapshot.loss.packet_loss_percent, 50.0);
}

fn assert_no_ipdv_pairs(update: &EventStatsUpdate) {
    assert!(update.ipdv_pairs.is_empty(), "{update:?}");
}

fn assert_one_ipdv_pair(
    update: &EventStatsUpdate,
    previous_seq: u32,
    current_seq: u32,
    rtt_ipdv: Duration,
) -> &IpdvPairUpdate {
    assert_eq!(update.ipdv_pairs.len(), 1, "{update:?}");
    let pair = &update.ipdv_pairs[0];
    assert_eq!(pair.previous_seq, previous_seq);
    assert_eq!(pair.current_seq, current_seq);
    assert_eq!(pair.rtt_ipdv, rtt_ipdv);
    pair
}

#[test]
fn ipdv_is_sequence_adjacent_and_gap_preserving() {
    let mut collector = StatsCollector::new(StatsConfig::finite());
    let first = collector.process(&reply(0, 10, 10));
    let gap = collector.process(&reply(2, 15, 15));
    let adjacent = collector.process(&reply(3, 12, 12));

    let snapshot = collector.snapshot();
    assert!(first.contributed_sample);
    assert_no_ipdv_pairs(&first);

    assert!(gap.contributed_sample);
    assert_no_ipdv_pairs(&gap);

    assert!(adjacent.contributed_sample);
    assert_one_ipdv_pair(&adjacent, 2, 3, Duration::from_millis(3));
    assert_eq!(snapshot.ipdv.round_trip.count, 1);
    assert_eq!(snapshot.ipdv.round_trip.total_ns, 3_000_000);
}

#[test]
fn late_reply_can_complete_ipdv_pair() {
    let mut collector = StatsCollector::new(StatsConfig::finite());
    collector.process(&reply(1, 20, 20));
    let update = collector.process(&late_reply(0, 10, 10));

    let snapshot = collector.snapshot();

    assert!(update.contributed_sample);
    assert_one_ipdv_pair(&update, 0, 1, Duration::from_millis(10));

    assert_eq!(snapshot.ipdv.round_trip.count, 1);
    assert_eq!(snapshot.ipdv.round_trip.total_ns, 10_000_000);
}

#[test]
fn update_exposes_directional_ipdv_when_available() {
    let mut collector = StatsCollector::new(StatsConfig::finite());
    collector.process(&reply(0, 10, 10));
    let update = collector.process(&reply(1, 13, 13));

    assert!(update.contributed_sample);

    let pair = assert_one_ipdv_pair(&update, 0, 1, Duration::from_millis(3));
    assert!(pair.send_ipdv.is_some());
    assert!(pair.receive_ipdv.is_some());
}

#[test]
fn gap_fill_update_exposes_both_completed_ipdv_pairs() {
    let mut collector = StatsCollector::new(StatsConfig::finite());

    let first = collector.process(&reply(0, 10, 10));
    let gap = collector.process(&reply(2, 20, 20));
    let fill = collector.process(&reply(1, 13, 13));

    assert!(first.contributed_sample);
    assert!(first.ipdv_pairs.is_empty());

    assert!(gap.contributed_sample);
    assert!(gap.ipdv_pairs.is_empty());

    assert!(fill.contributed_sample);
    assert_eq!(fill.ipdv_pairs.len(), 2);

    assert_eq!(fill.ipdv_pairs[0].previous_seq, 0);
    assert_eq!(fill.ipdv_pairs[0].current_seq, 1);
    assert_eq!(fill.ipdv_pairs[0].rtt_ipdv, Duration::from_millis(3));

    assert_eq!(fill.ipdv_pairs[1].previous_seq, 1);
    assert_eq!(fill.ipdv_pairs[1].current_seq, 2);
    assert_eq!(fill.ipdv_pairs[1].rtt_ipdv, Duration::from_millis(7));

    let snapshot = collector.snapshot();
    assert_eq!(snapshot.ipdv.round_trip.count, 2);
    assert_eq!(snapshot.ipdv.round_trip.total_ns, 10_000_000);
}

#[test]
fn server_processing_and_one_way_require_available_samples() {
    let mut collector = StatsCollector::new(StatsConfig::finite());
    collector.process(&reply(0, 10, 9));
    collector.process(&ClientEvent::LateReply {
        seq: 9,
        highest_seen: 10,
        remote: "127.0.0.1:2112".parse().unwrap(),
        sent_at: None,
        received_at: ts(100),
        rtt: None,
        server_timing: None,
        one_way: None,
        received_stats: None,
        bytes: 64,
        packet_meta: PacketMeta::default(),
    });

    let snapshot = collector.snapshot();
    assert_eq!(snapshot.server_processing.processing.count, 1);
    assert_eq!(snapshot.one_way_delay.send_delay.count, 1);
    assert_eq!(snapshot.events.untracked_late_replies, 1);
}

#[test]
fn rolling_count_eviction_recomputes_from_bounded_events() {
    let mut collector = StatsCollector::new(StatsConfig {
        samples: SampleMode::RunningOnly,
        rolling_count: Some(2),
        rolling_time: None,
    });
    collector.process(&sent(0, ts(0)));
    collector.process(&reply(0, 10, 10));
    collector.process(&reply(1, 20, 20));

    let rolling = collector.rolling_count().unwrap();
    assert_eq!(rolling.packets.packets_sent, 0);
    assert_eq!(rolling.packets.unique_replies, 2);
    assert_eq!(rolling.rtt.primary.count, 2);
}

#[test]
fn rolling_time_eviction_uses_event_timestamps() {
    let mut collector = StatsCollector::new(StatsConfig {
        samples: SampleMode::RunningOnly,
        rolling_count: None,
        rolling_time: Some(Duration::from_millis(15)),
    });
    collector.process(&sent(0, ts(0)));
    collector.process(&sent(1, ts(10)));
    collector.process(&sent(2, ts(30)));

    let rolling = collector.rolling_time().unwrap();
    assert_eq!(rolling.packets.packets_sent, 1);
}

#[test]
fn empty_and_all_lost_edges_are_defined() {
    let empty = StatsCollector::new(StatsConfig::finite()).snapshot();
    assert_eq!(empty.loss.packet_loss_percent, 0.0);

    let mut collector = StatsCollector::new(StatsConfig::finite());
    collector.process(&sent(0, ts(0)));
    let all_lost = collector.snapshot();
    assert_eq!(all_lost.loss.lost_packets, 1);
    assert_eq!(all_lost.loss.packet_loss_percent, 100.0);
}

#[test]
fn directional_loss_uses_server_received_count_when_available() {
    let mut collector = StatsCollector::new(StatsConfig::finite());
    collector.process(&sent(0, ts(0)));
    collector.process(&sent(1, ts(10)));
    collector.process(&reply(0, 10, 10));

    let loss = collector.snapshot().loss;
    assert_eq!(loss.upstream_loss_packets, Some(1));
    assert_eq!(loss.downstream_loss_packets, Some(0));
    assert_eq!(loss.upstream_loss_percent, 50.0);
}