//! IPC serialization round-trip tests (D-030 Layer 1: fixture-based).

use settled_reach_server::bridge::types::*;
use settled_reach_server::simulation::time::{DayPhase, TickRate};
use std::fs;

/// Helper to create a minimal v2 snapshot for tests
fn test_snapshot(tick: u64, entities: Vec<VisibleEntity>) -> ObserverSnapshot {
    ObserverSnapshot {
        version: PROTOCOL_VERSION,
        tick,
        game_time: GameTime {
            day: 0,
            time_of_day: 0,
            day_phase: DayPhase::Morning,
            tick_rate: TickRate::Full,
        },
        player_facing: FacingDirection::North,
        entities,
        visible_tiles: vec![],
        nearby_interactions: vec![],
        current_monologue: None,
    }
}

#[test]
fn observer_snapshot_roundtrip() {
    let snapshot = test_snapshot(
        42,
        vec![VisibleEntity {
            entity_id: 1,
            x: 10.0,
            y: 20.0,
            z: 0,
            kind: EntityKind::Npc,
            visibility: VisibilitySector::Forward,
            relationship: RelationshipState::Unknown,
            observation: EntityVisibility::Visible,
        }],
    );

    let bytes = rmp_serde::to_vec_named(&snapshot).expect("serialize");
    let decoded: ObserverSnapshot = rmp_serde::from_slice(&bytes).expect("deserialize");

    assert_eq!(decoded.version, PROTOCOL_VERSION);
    assert_eq!(decoded.tick, 42);
    assert_eq!(decoded.entities.len(), 1);
    assert_eq!(decoded.entities[0].entity_id, 1);
}

#[test]
fn player_input_roundtrip() {
    let input = PlayerInput {
        tick: 100,
        action: PlayerAction::MoveNorth,
    };

    let bytes = rmp_serde::to_vec_named(&input).expect("serialize");
    let decoded: PlayerInput = rmp_serde::from_slice(&bytes).expect("deserialize");

    assert_eq!(decoded.tick, 100);
}

#[test]
fn empty_snapshot_roundtrip() {
    let snapshot = test_snapshot(0, vec![]);

    let bytes = rmp_serde::to_vec_named(&snapshot).expect("serialize");
    let decoded: ObserverSnapshot = rmp_serde::from_slice(&bytes).expect("deserialize");

    assert_eq!(decoded.tick, 0);
    assert!(decoded.entities.is_empty());
}

/// All PlayerAction variants must survive MessagePack round-trip (D-030 Layer 1)
#[test]
fn all_player_action_variants_roundtrip() {
    let actions = vec![
        PlayerAction::MoveNorth,
        PlayerAction::MoveSouth,
        PlayerAction::MoveEast,
        PlayerAction::MoveWest,
        PlayerAction::MoveNortheast,
        PlayerAction::MoveNorthwest,
        PlayerAction::MoveSoutheast,
        PlayerAction::MoveSouthwest,
        PlayerAction::Interact { target_entity_id: None, verb: None },
        PlayerAction::UsePerceptionMode("thermal".to_string()),
        PlayerAction::Pause,
        PlayerAction::Unpause,
    ];

    for action in actions {
        let input = PlayerInput {
            tick: 1,
            action: action.clone(),
        };
        let bytes = rmp_serde::to_vec_named(&input).expect("serialize");
        let decoded: PlayerInput = rmp_serde::from_slice(&bytes).expect("deserialize");
        assert_eq!(decoded.tick, 1);
        // Verify the variant survived by re-serializing and comparing bytes
        let re_bytes = rmp_serde::to_vec_named(&decoded).expect("re-serialize");
        assert_eq!(bytes, re_bytes, "round-trip mismatch for action variant");
    }
}

/// All .msgpack fixtures must deserialize without error (guards against corruption in git).
/// Snapshot fixtures deserialize as ObserverSnapshot, input_* as PlayerInput,
/// input_batch_* as Vec<PlayerInput>.
#[test]
fn all_fixtures_deserialize() {
    let fixture_dir = std::path::Path::new("../client/tests/fixtures/msgpack");
    assert!(
        fixture_dir.exists(),
        "Fixture directory not found: {}",
        fixture_dir.display()
    );

    let mut count = 0;
    for entry in fs::read_dir(fixture_dir).expect("read fixture dir") {
        let entry = entry.expect("read dir entry");
        let path = entry.path();
        if path.extension().and_then(|e| e.to_str()) != Some("msgpack") {
            continue;
        }
        let name = path.file_stem().unwrap().to_str().unwrap().to_string();
        let bytes = fs::read(&path).unwrap_or_else(|_| panic!("read fixture {}", name));

        if name.starts_with("snapshot") {
            let snap = rmp_serde::from_slice::<ObserverSnapshot>(&bytes)
                .unwrap_or_else(|e| panic!("deserialize snapshot fixture {}: {}", name, e));
            assert_eq!(snap.version, PROTOCOL_VERSION, "fixture {} has wrong version", name);
        } else if name.starts_with("input_batch") {
            rmp_serde::from_slice::<Vec<PlayerInput>>(&bytes)
                .unwrap_or_else(|e| panic!("deserialize batch input fixture {}: {}", name, e));
        } else if name.starts_with("input") {
            rmp_serde::from_slice::<PlayerInput>(&bytes)
                .unwrap_or_else(|e| panic!("deserialize input fixture {}: {}", name, e));
        } else {
            panic!("unknown fixture naming convention: {}", name);
        }
        count += 1;
    }
    assert!(count > 0, "no fixtures found");
    eprintln!("Verified {} fixtures", count);
}

/// All EntityKind variants must survive MessagePack round-trip (D-030 Layer 1)
#[test]
fn all_entity_kind_variants_roundtrip() {
    let kinds = vec![
        EntityKind::Player,
        EntityKind::Npc,
        EntityKind::Object,
        EntityKind::Terrain,
    ];

    for (i, kind) in kinds.into_iter().enumerate() {
        let entity = VisibleEntity {
            entity_id: i as u64,
            x: 0.0,
            y: 0.0,
            z: 0,
            kind,
            visibility: VisibilitySector::Forward,
            relationship: RelationshipState::Unknown,
            observation: EntityVisibility::Visible,
        };
        let snapshot = test_snapshot(0, vec![entity]);
        let bytes = rmp_serde::to_vec_named(&snapshot).expect("serialize");
        let decoded: ObserverSnapshot = rmp_serde::from_slice(&bytes).expect("deserialize");
        let re_bytes = rmp_serde::to_vec_named(&decoded).expect("re-serialize");
        assert_eq!(
            bytes, re_bytes,
            "round-trip mismatch for EntityKind variant"
        );
    }
}

/// v2 snapshot fields round-trip correctly
#[test]
fn snapshot_v2_fields_roundtrip() {
    let snapshot = ObserverSnapshot {
        version: PROTOCOL_VERSION,
        tick: 100,
        game_time: GameTime {
            day: 3,
            time_of_day: 720,
            day_phase: DayPhase::Evening,
            tick_rate: TickRate::Paused,
        },
        player_facing: FacingDirection::Southeast,
        entities: vec![VisibleEntity {
            entity_id: 1,
            x: 5.5,
            y: 10.5,
            z: 0,
            kind: EntityKind::Player,
            visibility: VisibilitySector::Forward,
            relationship: RelationshipState::Unknown,
            observation: EntityVisibility::Visible,
        }],
        visible_tiles: vec![
            VisibleTile {
                x: 5,
                y: 10,
                z: 0,
                visibility: VisibilitySector::Forward,
                tile_kind: TileKind::Floor,
            },
            VisibleTile {
                x: 6,
                y: 10,
                z: 0,
                visibility: VisibilitySector::Peripheral,
                tile_kind: TileKind::Wall,
            },
        ],
        nearby_interactions: vec![],
        current_monologue: None,
    };

    let bytes = rmp_serde::to_vec_named(&snapshot).expect("serialize");
    let decoded: ObserverSnapshot = rmp_serde::from_slice(&bytes).expect("deserialize");

    assert_eq!(decoded.version, PROTOCOL_VERSION);
    assert_eq!(decoded.game_time.day, 3);
    assert_eq!(decoded.game_time.time_of_day, 720);
    assert_eq!(decoded.game_time.day_phase, DayPhase::Evening);
    assert_eq!(decoded.game_time.tick_rate, TickRate::Paused);
    assert_eq!(decoded.player_facing, FacingDirection::Southeast);
    assert_eq!(decoded.visible_tiles.len(), 2);
    assert_eq!(decoded.visible_tiles[0].visibility, VisibilitySector::Forward);
    assert_eq!(decoded.visible_tiles[1].visibility, VisibilitySector::Peripheral);
    assert_eq!(decoded.entities[0].visibility, VisibilitySector::Forward);
}

/// Entity::to_bits() must roundtrip through from_bits() — guards against
/// bevy version changes silently breaking wire IDs (Hoshe #12).
#[test]
fn entity_to_bits_roundtrip() {
    use bevy_ecs::entity::Entity;
    // Create entities via a World so we get valid index+generation pairs
    let mut world = bevy_ecs::world::World::new();
    let e1 = world.spawn_empty().id();
    let e2 = world.spawn_empty().id();
    let e3 = world.spawn_empty().id();
    // Despawn and respawn to get a higher generation
    world.despawn(e2);
    let e4 = world.spawn_empty().id();

    for entity in [e1, e2, e3, e4] {
        let bits = entity.to_bits();
        let restored = Entity::from_bits(bits);
        assert_eq!(entity, restored, "Entity::to_bits() roundtrip failed for {:?}", entity);
    }
}

/// PROTOCOL_VERSION constant matches snapshot version field
#[test]
fn protocol_version_constant_matches_snapshot() {
    let snapshot = test_snapshot(0, vec![]);
    assert_eq!(snapshot.version, PROTOCOL_VERSION);
    assert_eq!(PROTOCOL_VERSION, 5, "bump this assertion when protocol version changes");
}

/// All FacingDirection variants round-trip
#[test]
fn all_facing_direction_variants_roundtrip() {
    let directions = [
        FacingDirection::North,
        FacingDirection::Northeast,
        FacingDirection::East,
        FacingDirection::Southeast,
        FacingDirection::South,
        FacingDirection::Southwest,
        FacingDirection::West,
        FacingDirection::Northwest,
    ];

    for dir in directions {
        let snapshot = ObserverSnapshot {
            version: PROTOCOL_VERSION,
            tick: 0,
            game_time: GameTime {
                day: 0,
                time_of_day: 0,
                day_phase: DayPhase::Morning,
                tick_rate: TickRate::Full,
            },
            player_facing: dir,
            entities: vec![],
            visible_tiles: vec![],
            nearby_interactions: vec![],
            current_monologue: None,
        };
        let bytes = rmp_serde::to_vec_named(&snapshot).expect("serialize");
        let decoded: ObserverSnapshot = rmp_serde::from_slice(&bytes).expect("deserialize");
        assert_eq!(decoded.player_facing, dir);
    }
}