//! 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,
        player_stance: MovementStance::default(),
        player_inventory: vec![],
        entities,
        visible_tiles: vec![],
        nearby_interactions: vec![],
        current_monologue: None,
        pending_recognitions: vec![],
    }
}

#[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,
        PlayerAction::SetTickRate(TickRate::Half),
        PlayerAction::ToggleStanceUp,
        PlayerAction::ToggleStanceDown,
    ];

    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,
        player_stance: MovementStance::default(),
        player_inventory: vec![],
        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,
        pending_recognitions: vec![],
    };

    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, 7,
        "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,
            player_stance: MovementStance::default(),
            player_inventory: vec![],
            entities: vec![],
            visible_tiles: vec![],
            nearby_interactions: vec![],
            current_monologue: None,
            pending_recognitions: vec![],
        };
        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);
    }
}

/// v6 fields: all MovementStance variants round-trip (#449, D-053)
#[test]
fn all_movement_stance_variants_roundtrip() {
    let stances = [
        MovementStance::Sprint,
        MovementStance::Walk,
        MovementStance::Careful,
        MovementStance::Crouch,
    ];

    for stance in stances {
        let snapshot = test_snapshot(0, vec![]);
        let mut snapshot = snapshot;
        snapshot.player_stance = stance;
        let bytes = rmp_serde::to_vec_named(&snapshot).expect("serialize");
        let decoded: ObserverSnapshot = rmp_serde::from_slice(&bytes).expect("deserialize");
        assert_eq!(decoded.player_stance, stance);
    }
}

/// v6 fields: player_inventory with items round-trips (#449, D-065)
#[test]
fn snapshot_v6_inventory_roundtrip() {
    let mut snapshot = test_snapshot(0, vec![]);
    snapshot.player_stance = MovementStance::Careful;
    snapshot.player_inventory = vec![
        InventoryItem {
            item_id: 100,
            name: "Manifest Copy".into(),
            slot: 0,
        },
        InventoryItem {
            item_id: 101,
            name: "Access Token".into(),
            slot: 1,
        },
        InventoryItem {
            item_id: 102,
            name: "Comm Log".into(),
            slot: 2,
        },
    ];

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

    assert_eq!(decoded.player_stance, MovementStance::Careful);
    assert_eq!(decoded.player_inventory.len(), 3);
    assert_eq!(decoded.player_inventory[0].item_id, 100);
    assert_eq!(decoded.player_inventory[0].name, "Manifest Copy");
    assert_eq!(decoded.player_inventory[0].slot, 0);
    assert_eq!(decoded.player_inventory[2].name, "Comm Log");
    assert_eq!(decoded.player_inventory[2].slot, 2);
}

/// v6 fields: default stance is Walk, default inventory is empty (#449)
#[test]
fn snapshot_v6_defaults() {
    let snapshot = test_snapshot(0, vec![]);
    assert_eq!(snapshot.player_stance, MovementStance::Walk);
    assert!(snapshot.player_inventory.is_empty());
}

/// v5 payloads (without player_stance/player_inventory) must deserialize into
/// the v6 struct via #[serde(default)]. Guards backwards compat during migration.
#[test]
fn v5_payload_deserializes_into_v6_struct() {
    // Local v5 struct: ObserverSnapshot without player_stance and player_inventory
    #[derive(serde::Serialize)]
    struct ObserverSnapshotV5 {
        version: u8,
        tick: u64,
        game_time: GameTime,
        player_facing: FacingDirection,
        entities: Vec<VisibleEntity>,
        visible_tiles: Vec<VisibleTile>,
        nearby_interactions: Vec<NearbyInteraction>,
        current_monologue: Option<MonologueEvent>,
    }

    let v5 = ObserverSnapshotV5 {
        version: 5,
        tick: 42,
        game_time: GameTime {
            day: 0,
            time_of_day: 0,
            day_phase: DayPhase::Morning,
            tick_rate: TickRate::Full,
        },
        player_facing: FacingDirection::North,
        entities: vec![],
        visible_tiles: vec![],
        nearby_interactions: vec![],
        current_monologue: None,
    };

    let bytes = rmp_serde::to_vec_named(&v5).expect("serialize v5");
    let decoded: ObserverSnapshot = rmp_serde::from_slice(&bytes)
        .expect("v5 payload should deserialize into v6 struct via serde(default)");

    // New fields should get their defaults
    assert_eq!(decoded.version, 5, "version field preserved from v5");
    assert_eq!(decoded.tick, 42);
    assert_eq!(
        decoded.player_stance,
        MovementStance::Walk,
        "missing stance should default to Walk"
    );
    assert!(
        decoded.player_inventory.is_empty(),
        "missing inventory should default to empty"
    );
    assert!(
        decoded.current_monologue.is_none(),
        "missing monologue should default to None"
    );
    assert!(
        decoded.pending_recognitions.is_empty(),
        "missing pending_recognitions should default to empty"
    );
}

/// Full 9-slot inventory roundtrip (D-065: 3x3 grid = 9 slots universal)
#[test]
fn snapshot_v6_full_inventory_roundtrip() {
    let items: Vec<InventoryItem> = (0..9)
        .map(|i| InventoryItem {
            item_id: 100 + i as u64,
            name: format!("Item {}", i),
            slot: i,
        })
        .collect();

    let mut snapshot = test_snapshot(0, vec![]);
    snapshot.player_inventory = items;

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

    assert_eq!(decoded.player_inventory.len(), 9);
    for (i, item) in decoded.player_inventory.iter().enumerate() {
        assert_eq!(item.slot, i as u8, "slot {} should match index", i);
        assert_eq!(item.item_id, 100 + i as u64);
    }
    // Slot 8 is max valid (0-indexed, 3x3 grid)
    assert_eq!(decoded.player_inventory[8].slot, 8);
}

/// PendingRecognitionWire round-trips through MessagePack (#423, D-060).
/// Guards against cognitive delay wire data corruption during serialization.
#[test]
fn pending_recognition_wire_roundtrip() {
    let mut snapshot = test_snapshot(0, vec![]);
    snapshot.pending_recognitions = vec![
        PendingRecognitionWire {
            entity_id: 42,
            x: 10.5,
            y: 20.0,
            z: 0,
            remaining_ticks: 4,
            total_delay_ticks: 6,
        },
        PendingRecognitionWire {
            entity_id: 99,
            x: 15.0,
            y: 8.5,
            z: 1,
            remaining_ticks: 1,
            total_delay_ticks: 3,
        },
    ];

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

    assert_eq!(decoded.pending_recognitions.len(), 2);
    assert_eq!(decoded.pending_recognitions[0].entity_id, 42);
    assert_eq!(decoded.pending_recognitions[0].remaining_ticks, 4);
    assert_eq!(decoded.pending_recognitions[0].total_delay_ticks, 6);
    assert!((decoded.pending_recognitions[0].x - 10.5).abs() < f32::EPSILON);
    assert_eq!(decoded.pending_recognitions[1].entity_id, 99);
    assert_eq!(decoded.pending_recognitions[1].z, 1);
    assert_eq!(decoded.pending_recognitions[1].total_delay_ticks, 3);
}

/// All VerbKind variants must survive MessagePack round-trip (#421, D-057).
/// Guards against serde mapping breakage when new verbs are added.
#[test]
fn all_verb_kind_variants_roundtrip() {
    let all_verbs = [
        (VerbKind::ExamineNpc, "Observe"),
        (VerbKind::Talk, "Talk"),
        (VerbKind::Observe, "Observe"),
        (VerbKind::Read, "Read"),
        (VerbKind::Open, "Open"),
        (VerbKind::Close, "Close"),
        (VerbKind::Search, "Search"),
        (VerbKind::Use, "Use"),
        (VerbKind::Take, "Take"),
        (VerbKind::Sit, "Sit"),
        (VerbKind::Confront, "Confront"),
        (VerbKind::ExamineObject, "Examine"),
    ];

    for (kind, label) in all_verbs {
        let mut snapshot = test_snapshot(0, vec![]);
        snapshot.nearby_interactions = vec![NearbyInteraction {
            entity_id: 1,
            entity_type: EntityKind::Object,
            distance: 1,
            verbs: vec![VerbOption {
                kind,
                label: label.into(),
                priority: 1,
                available: true,
            }],
            object_type: None,
            contradicted: false,
        }];

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

        assert_eq!(decoded.nearby_interactions.len(), 1);
        assert_eq!(
            decoded.nearby_interactions[0].verbs[0].kind, kind,
            "VerbKind::{:?} did not roundtrip",
            kind
        );
    }
}

/// ObjectType enum round-trips through MessagePack (#421).
/// While not on the wire in ObserverSnapshot, ObjectType has Serialize/Deserialize
/// for future save/load and must round-trip cleanly.
#[test]
fn all_object_type_variants_roundtrip() {
    use settled_reach_server::simulation::interaction::ObjectType;

    let types = [
        ObjectType::Readable,
        ObjectType::Container,
        ObjectType::Terminal,
        ObjectType::Door,
        ObjectType::Pickup,
        ObjectType::Furniture,
    ];

    for obj_type in types {
        let bytes = rmp_serde::to_vec_named(&obj_type).expect("serialize");
        let decoded: ObjectType = rmp_serde::from_slice(&bytes).expect("deserialize");
        assert_eq!(
            decoded, obj_type,
            "ObjectType::{:?} roundtrip failed",
            obj_type
        );
    }
}

/// VerbKind::Confront (Phase 2, #422) must survive MessagePack round-trip.
/// Guards against Confront being omitted from serde mapping.
#[test]
fn verb_kind_confront_roundtrip() {
    let mut snapshot = test_snapshot(0, vec![]);
    snapshot.nearby_interactions = vec![NearbyInteraction {
        entity_id: 1,
        entity_type: EntityKind::Npc,
        distance: 1,
        verbs: vec![VerbOption {
            kind: VerbKind::Confront,
            label: "Confront".into(),
            priority: 3,
            available: true,
        }],
        object_type: None,
        contradicted: false,
    }];

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

    assert_eq!(decoded.nearby_interactions.len(), 1);
    assert_eq!(
        decoded.nearby_interactions[0].verbs[0].kind,
        VerbKind::Confront
    );
    assert_eq!(decoded.nearby_interactions[0].verbs[0].label, "Confront");
}

/// CharacterArchetype enum round-trips through MessagePack (#422).
/// Used in Phase 2 label relabeling — must survive the wire.
#[test]
fn all_character_archetype_variants_roundtrip() {
    let archetypes = [CharacterArchetype::Smuggler, CharacterArchetype::Detective];

    for archetype in archetypes {
        let bytes = rmp_serde::to_vec_named(&archetype).expect("serialize");
        let decoded: CharacterArchetype = rmp_serde::from_slice(&bytes).expect("deserialize");
        assert_eq!(
            decoded, archetype,
            "CharacterArchetype::{:?} roundtrip failed",
            archetype
        );
    }
}

/// NearbyInteraction.contradicted=true round-trips through MessagePack (#422).
/// Guards the contradiction flag survives serialization.
#[test]
fn nearby_interaction_contradicted_roundtrip() {
    let mut snapshot = test_snapshot(0, vec![]);
    snapshot.nearby_interactions = vec![NearbyInteraction {
        entity_id: 1,
        entity_type: EntityKind::Npc,
        distance: 1,
        verbs: vec![VerbOption {
            kind: VerbKind::Talk,
            label: "Talk".into(),
            priority: 1,
            available: true,
        }],
        object_type: None,
        contradicted: true,
    }];

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

    assert!(
        decoded.nearby_interactions[0].contradicted,
        "contradicted flag should survive roundtrip"
    );
}

/// NearbyInteraction.object_type round-trips through MessagePack (#422).
/// Verifies object_type=Some(Container) survives the wire.
#[test]
fn nearby_interaction_object_type_roundtrip() {
    let mut snapshot = test_snapshot(0, vec![]);
    snapshot.nearby_interactions = vec![NearbyInteraction {
        entity_id: 1,
        entity_type: EntityKind::Object,
        distance: 1,
        verbs: vec![VerbOption {
            kind: VerbKind::Open,
            label: "Open".into(),
            priority: 1,
            available: true,
        }],
        object_type: Some(ObjectType::Container),
        contradicted: false,
    }];

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

    assert_eq!(
        decoded.nearby_interactions[0].object_type,
        Some(ObjectType::Container)
    );
}