//! AZ-677 integration tests — snapshot on subscribe, diff stream while
//! connected, fresh snapshot on reconnect (no diff replay).

use std::net::TcpListener;
use std::sync::atomic::{AtomicUsize, Ordering};
use std::sync::Arc;
use std::time::Duration;

use chrono::Utc;
use tokio::time::timeout;
use tokio_stream::StreamExt;
use tonic::transport::{Channel, Endpoint};
use tonic::Request;
use uuid::Uuid;

use shared::models::mapobject::{
    BundleFreshness, DiffKind, IgnoredItem, IgnoredItemSource, MapObject, MapObjectObservation,
    MapObjectSource, MapObjectsBundle, RetentionScope,
};
use shared::models::mission::Coordinate;

use telemetry_stream::internal::mapobjects::MapObjectsDiff;
use telemetry_stream::{
    MapObjectsSnapshotSource, MapObjectsTopicMessage, SubscribeRequest, TelemetryStream,
    TelemetryStreamClient, TelemetryTopic,
};

fn bind_ephemeral() -> (TcpListener, u16) {
    let l = TcpListener::bind("127.0.0.1:0").expect("bind ephemeral");
    let port = l.local_addr().unwrap().port();
    (l, port)
}

async fn connect(port: u16) -> TelemetryStreamClient<Channel> {
    let url = format!("http://127.0.0.1:{port}");
    let endpoint = Endpoint::from_shared(url)
        .unwrap()
        .connect_timeout(Duration::from_secs(2));
    for _ in 0..50 {
        if let Ok(c) = TelemetryStreamClient::connect(endpoint.clone()).await {
            return c;
        }
        tokio::time::sleep(Duration::from_millis(20)).await;
    }
    panic!("gRPC client failed to connect");
}

fn coord(lat: f64, lon: f64) -> Coordinate {
    Coordinate {
        latitude: lat,
        longitude: lon,
        altitude_m: 0.0,
    }
}

fn make_mapobject(class: &str) -> MapObject {
    let now = Utc::now();
    MapObject {
        h3_cell: 0,
        mgrs_key: "33UWP00".to_string(),
        class: class.to_string(),
        class_group: "vehicle".to_string(),
        gps_lat: 0.0,
        gps_lon: 0.0,
        size_width_m: 2.0,
        size_length_m: 4.0,
        confidence: 0.8,
        first_seen: now,
        last_seen: now,
        mission_id: "m1".to_string(),
        source: MapObjectSource::LocalObserved,
        pending_upload: true,
    }
}

fn make_ignored() -> IgnoredItem {
    IgnoredItem {
        id: Uuid::new_v4(),
        mgrs: "33UWP01".to_string(),
        h3_cell: 0,
        class_group: "vehicle".to_string(),
        decline_time: Utc::now(),
        operator_id: None,
        mission_id: "m1".to_string(),
        retention_scope: RetentionScope::Mission,
        expires_at: None,
        source: IgnoredItemSource::LocalAppended,
        pending_upload: true,
    }
}

fn make_observation(class: &str) -> MapObjectObservation {
    MapObjectObservation {
        id: Uuid::new_v4(),
        h3_cell: 0,
        class: class.to_string(),
        class_group: "vehicle".to_string(),
        mission_id: "m1".to_string(),
        uav_id: "uav_1".to_string(),
        observed_at_monotonic_ns: 1,
        observed_at_wallclock: Utc::now(),
        gps_lat: 0.0,
        gps_lon: 0.0,
        mgrs: "33UWP02".to_string(),
        size_width_m: 2.0,
        size_length_m: 4.0,
        confidence: 0.7,
        diff_kind: DiffKind::New,
        photo_ref: None,
        raw_evidence: None,
    }
}

/// Snapshot source whose `snapshot()` content can be mutated between
/// subscribes. Tracks how many times it has been called so the
/// reconnect test can verify the source was re-queried (rather than a
/// cached snapshot).
struct MutableSource {
    bundle: parking_lot::Mutex<MapObjectsBundle>,
    snapshots_emitted: AtomicUsize,
}

impl MutableSource {
    fn new(initial: MapObjectsBundle) -> Self {
        Self {
            bundle: parking_lot::Mutex::new(initial),
            snapshots_emitted: AtomicUsize::new(0),
        }
    }

    fn set(&self, b: MapObjectsBundle) {
        *self.bundle.lock() = b;
    }
}

impl MapObjectsSnapshotSource for MutableSource {
    fn snapshot(&self) -> MapObjectsBundle {
        self.snapshots_emitted.fetch_add(1, Ordering::Relaxed);
        self.bundle.lock().clone()
    }
}

fn empty_bundle() -> MapObjectsBundle {
    MapObjectsBundle {
        schema_version: "1.0".to_string(),
        mission_id: "m1".to_string(),
        bbox: [coord(0.0, 0.0), coord(1.0, 1.0)],
        map_objects: Vec::new(),
        observations: Vec::new(),
        ignored_items: Vec::new(),
        as_of: Utc::now(),
        freshness: Some(BundleFreshness::Fresh),
    }
}

/// AC-1 — A fresh subscriber to MapObjectsBundle receives exactly one
/// snapshot, populated from the configured source.
#[tokio::test]
async fn ac1_first_subscribe_receives_snapshot() {
    // Arrange
    let (listener, port) = bind_ephemeral();
    let server = TelemetryStream::new(64);
    let handle = server.handle();
    let initial = MapObjectsBundle {
        map_objects: (0..50).map(|_| make_mapobject("tank")).collect(),
        ignored_items: (0..10).map(|_| make_ignored()).collect(),
        ..empty_bundle()
    };
    let src = Arc::new(MutableSource::new(initial));
    server.set_mapobjects_snapshot_source(src.clone());
    let (_join, _guard) = server.spawn_grpc_server_on(listener).unwrap();

    let mut client = connect(port).await;
    let mut stream = client
        .subscribe(Request::new(SubscribeRequest {
            client_id: "op_a".to_string(),
            topics: vec![TelemetryTopic::MapObjectsBundle as i32],
        }))
        .await
        .unwrap()
        .into_inner();

    // Act — pull the first message off the stream.
    let msg = timeout(Duration::from_secs(2), stream.next())
        .await
        .unwrap()
        .unwrap()
        .unwrap();
    let payload: MapObjectsTopicMessage = serde_json::from_slice(&msg.payload_json).unwrap();

    // Assert
    let snap = match payload {
        MapObjectsTopicMessage::Snapshot(s) => s,
        MapObjectsTopicMessage::Diff(_) => panic!("expected Snapshot first; got Diff"),
    };
    assert_eq!(snap.bundle.map_objects.len(), 50);
    assert_eq!(snap.bundle.ignored_items.len(), 10);
    assert_eq!(src.snapshots_emitted.load(Ordering::Relaxed), 1);
    // Drop client + handle scope (cleanup).
    drop(stream);
    drop(client);
    drop(handle);
}

/// AC-2 — While connected, diffs appended by the composition root are
/// received by the client.
#[tokio::test]
async fn ac2_inflight_changes_emit_diffs() {
    // Arrange
    let (listener, port) = bind_ephemeral();
    let server = TelemetryStream::new(64);
    let handle = server.handle();
    let src = Arc::new(MutableSource::new(empty_bundle()));
    server.set_mapobjects_snapshot_source(src);
    let (_join, _guard) = server.spawn_grpc_server_on(listener).unwrap();

    let mut client = connect(port).await;
    let mut stream = client
        .subscribe(Request::new(SubscribeRequest {
            client_id: "op_b".to_string(),
            topics: vec![TelemetryTopic::MapObjectsBundle as i32],
        }))
        .await
        .unwrap()
        .into_inner();

    // Drain the snapshot first.
    let snap_msg = timeout(Duration::from_secs(2), stream.next())
        .await
        .unwrap()
        .unwrap()
        .unwrap();
    let snap_payload: MapObjectsTopicMessage =
        serde_json::from_slice(&snap_msg.payload_json).unwrap();
    assert!(matches!(snap_payload, MapObjectsTopicMessage::Snapshot(_)));

    // Wait for the client to register before publishing diffs.
    for _ in 0..50 {
        if handle.snapshot().subscribed_clients == 1 {
            break;
        }
        tokio::time::sleep(Duration::from_millis(10)).await;
    }

    // Act — push one diff with 3 added observations + 1 ignored item.
    let diff = MapObjectsDiff {
        added: vec![
            make_observation("tank"),
            make_observation("apc"),
            make_observation("truck"),
        ],
        moved: vec![],
        removed_candidates: vec![],
        ignored: vec![make_ignored()],
    };
    handle.push_mapobjects_diff(diff).unwrap();

    // Pull the next message — must be a Diff carrying our content.
    let diff_msg = timeout(Duration::from_secs(2), stream.next())
        .await
        .unwrap()
        .unwrap()
        .unwrap();
    let diff_payload: MapObjectsTopicMessage =
        serde_json::from_slice(&diff_msg.payload_json).unwrap();
    let received_diff = match diff_payload {
        MapObjectsTopicMessage::Diff(d) => d,
        MapObjectsTopicMessage::Snapshot(_) => panic!("expected Diff; got Snapshot"),
    };

    // Assert
    assert_eq!(received_diff.added.len(), 3);
    assert_eq!(received_diff.ignored.len(), 1);
    assert!(received_diff.moved.is_empty());
    assert!(received_diff.removed_candidates.is_empty());
}

/// AC-3 — Reconnect after disconnect emits a fresh snapshot reflecting
/// current state; diffs that flew during the gap are NOT replayed.
#[tokio::test]
async fn ac3_reconnect_resnaps_without_replay() {
    // Arrange
    let (listener, port) = bind_ephemeral();
    let server = TelemetryStream::new(64);
    let handle = server.handle();
    let src = Arc::new(MutableSource::new(empty_bundle()));
    server.set_mapobjects_snapshot_source(src.clone());
    let (_join, _guard) = server.spawn_grpc_server_on(listener).unwrap();

    // Subscribe once, drain snapshot, drop.
    let mut client = connect(port).await;
    let mut stream = client
        .subscribe(Request::new(SubscribeRequest {
            client_id: "op_c".to_string(),
            topics: vec![TelemetryTopic::MapObjectsBundle as i32],
        }))
        .await
        .unwrap()
        .into_inner();
    let first_snap = timeout(Duration::from_secs(2), stream.next())
        .await
        .unwrap()
        .unwrap()
        .unwrap();
    let first: MapObjectsTopicMessage = serde_json::from_slice(&first_snap.payload_json).unwrap();
    let first_snap = match first {
        MapObjectsTopicMessage::Snapshot(s) => s,
        MapObjectsTopicMessage::Diff(_) => panic!("first must be Snapshot"),
    };
    assert!(first_snap.bundle.map_objects.is_empty());

    // Disconnect.
    drop(stream);
    drop(client);
    for _ in 0..50 {
        if handle.snapshot().subscribed_clients == 0 {
            break;
        }
        tokio::time::sleep(Duration::from_millis(20)).await;
    }

    // Act — store grew by 5 while client was disconnected. Also push
    // a couple of diffs that the reconnecting client must NOT see.
    src.set(MapObjectsBundle {
        map_objects: (0..5).map(|_| make_mapobject("tank")).collect(),
        ..empty_bundle()
    });
    handle
        .push_mapobjects_diff(MapObjectsDiff {
            added: vec![make_observation("ghost_during_gap")],
            ..MapObjectsDiff::default()
        })
        .unwrap();

    // Reconnect with the same client_id.
    let mut client2 = connect(port).await;
    let mut stream2 = client2
        .subscribe(Request::new(SubscribeRequest {
            client_id: "op_c".to_string(),
            topics: vec![TelemetryTopic::MapObjectsBundle as i32],
        }))
        .await
        .unwrap()
        .into_inner();
    let resnap_msg = timeout(Duration::from_secs(2), stream2.next())
        .await
        .unwrap()
        .unwrap()
        .unwrap();
    let resnap_payload: MapObjectsTopicMessage =
        serde_json::from_slice(&resnap_msg.payload_json).unwrap();

    // Assert — first message after reconnect is a snapshot reflecting
    // the new bundle. The skipped-during-gap diff is NOT in the
    // stream (we read with a short timeout to prove no replay).
    let resnap = match resnap_payload {
        MapObjectsTopicMessage::Snapshot(s) => s,
        MapObjectsTopicMessage::Diff(_) => {
            panic!("first message after reconnect MUST be Snapshot, not Diff");
        }
    };
    assert_eq!(
        resnap.bundle.map_objects.len(),
        5,
        "snapshot must reflect post-gap store"
    );
    assert!(
        src.snapshots_emitted.load(Ordering::Relaxed) >= 2,
        "snapshot source must have been re-queried on reconnect"
    );

    // The reconnected stream should NOT immediately deliver another
    // message — the gap diff was broadcast before reconnect and a
    // late subscriber MUST not see it.
    let maybe_extra = timeout(Duration::from_millis(300), stream2.next()).await;
    assert!(
        maybe_extra.is_err(),
        "reconnect MUST NOT replay gap diff (got unexpected message)"
    );
}