#![forbid(unsafe_code)]
//! Runtime orchestration for headless and rendered modes.

use fparkan_mission_format::{
    decode_tma, decode_tma_land_path, LpString, MissionDocument, MissionError, TmaProfile,
};
use fparkan_path::{normalize_relative, NormalizedPath, PathError, PathPolicy};
use fparkan_prototype::{
    build_prototype_graph_report, extend_graph_report_with_visual_dependencies, EffectivePrototype,
    PrototypeGraph, PrototypeGraphFailure, PrototypeGraphReport,
};
use fparkan_resource::{resource_name, CachedResourceRepository};
use fparkan_terrain::TerrainWorld;
use fparkan_terrain_format::{
    decode_build_dat, decode_land_map, decode_land_msh, BuildCategory, TerrainFormatError,
};
use fparkan_vfs::{Vfs, VfsError};
use fparkan_world::{
    construct_object, new as new_world, register_object, step, InputSnapshot, ObjectDraft,
    OriginalObjectId, World, WorldConfig, WorldSnapshot,
};
use std::sync::Arc;

/// Engine mode.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum EngineMode {
    /// Headless.
    Headless,
    /// Rendered.
    Rendered,
}

/// Scheduler phase.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum SchedulerPhase {
    /// Collect platform events.
    CollectPlatformEvents,
    /// Build input snapshot.
    BuildInputSnapshot,
    /// Advance clock.
    AdvanceGameClock,
    /// Calculate world queue.
    CalculateWorldQueue,
    /// Apply deferred operations.
    ApplyDeferredOperations,
    /// Update animation/effects.
    UpdateAnimationAndEffects,
    /// Publish render snapshot.
    PublishRenderSnapshot,
    /// Render world.
    RenderWorld,
    /// End frame callbacks.
    EndFrameCallbacks,
    /// Maintenance.
    Maintenance,
}

/// Engine config.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct EngineConfig {
    /// Mode.
    pub mode: EngineMode,
}

/// Injectable engine services used by composition roots.
#[derive(Clone, Default)]
pub struct EngineServices {
    /// Resource filesystem.
    pub vfs: Option<Arc<dyn Vfs>>,
}

impl EngineServices {
    /// Creates services with a VFS.
    #[must_use]
    pub fn new(vfs: Arc<dyn Vfs>) -> Self {
        Self { vfs: Some(vfs) }
    }
}

/// Mission request.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct MissionRequest {
    /// Mission key/path.
    pub key: String,
}

/// Mission loading phase captured for diagnostics and acceptance tests.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum MissionLoadPhase {
    /// Resolve services and mission request context.
    Context,
    /// Decode and validate TMA.
    Tma,
    /// Decode and validate terrain map assets.
    Map,
    /// Expand object roots into a prototype graph.
    Graph,
    /// Prepare all reachable visual/resource dependencies.
    Assets,
    /// Construct all object drafts before registration.
    Construct,
    /// Register constructed objects.
    Register,
}

/// Raw placed transform preserved by the mission loader.
#[derive(Clone, Debug, PartialEq)]
pub struct PlacedTransformProfile {
    /// Object index in TMA order.
    pub object_index: usize,
    /// Raw position vector.
    pub position: [f32; 3],
    /// Raw orientation vector. No Euler order is inferred here.
    pub orientation_raw: [f32; 3],
    /// Raw scale vector.
    pub scale: [f32; 3],
}

/// Mission loading trace.
#[derive(Clone, Debug, Default, PartialEq)]
pub struct MissionLoadTrace {
    /// Observed phases in execution order.
    pub phases: Vec<MissionLoadPhase>,
    /// Number of object drafts constructed before the first registration.
    pub drafts_before_registration: usize,
    /// Number of objects registered.
    pub registered_objects: usize,
    /// Raw transform profile for placed objects.
    pub transforms: Vec<PlacedTransformProfile>,
}

#[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
struct MissionLoadOptions {
    fail_after_registered_objects: Option<usize>,
}

/// Loaded mission.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct LoadedMission {
    /// Mission key.
    pub key: String,
    /// Decoded mission path count.
    pub path_count: usize,
    /// Decoded clan count.
    pub clan_count: usize,
    /// Decoded placed object count.
    pub object_count: usize,
    /// Decoded extra record count.
    pub extra_count: usize,
    /// `Land.msh` path.
    pub land_msh_path: String,
    /// `Land.map` path.
    pub land_map_path: String,
    /// Build category count.
    pub build_category_count: usize,
    /// Runtime navigation area count.
    pub areal_count: usize,
    /// Runtime surface triangle count.
    pub surface_count: usize,
    /// Registered world object count.
    pub registered_objects: usize,
    /// Mission resource roots that point to unit DAT files.
    pub graph_unit_reference_count: usize,
    /// Mission resource roots that point directly to prototype keys.
    pub graph_direct_reference_count: usize,
    /// Component records reached from unit DAT roots.
    pub graph_unit_component_count: usize,
    /// Mission prototype graph root count.
    pub graph_root_count: usize,
    /// Expanded prototype requests resolved to effective prototypes.
    pub graph_resolved_count: usize,
    /// Reached mesh dependency count.
    pub graph_mesh_dependency_count: usize,
    /// Graph failure count.
    pub graph_failure_count: usize,
    /// WEAR requests derived from graph meshes.
    pub graph_wear_request_count: usize,
    /// WEAR entries decoded.
    pub graph_wear_resolved_count: usize,
    /// WEAR material slots requested.
    pub graph_material_slot_count: usize,
    /// MAT0 entries decoded.
    pub graph_material_resolved_count: usize,
    /// Texture requests derived from MAT0 phases.
    pub graph_texture_request_count: usize,
    /// Texm texture entries decoded.
    pub graph_texture_resolved_count: usize,
    /// Lightmap requests declared by WEAR tables.
    pub graph_lightmap_request_count: usize,
    /// Lightmap Texm entries decoded.
    pub graph_lightmap_resolved_count: usize,
}

/// Frame result.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct FrameResult {
    /// Snapshot.
    pub snapshot: WorldSnapshot,
}

/// Engine.
pub struct Engine {
    config: EngineConfig,
    services: EngineServices,
    world: World,
    loaded: Option<LoadedMissionState>,
}

struct LoadedMissionState {
    summary: LoadedMission,
    mission: MissionDocument,
    terrain: TerrainWorld,
    build_categories: Vec<BuildCategory>,
    prototype_graph: PrototypeGraph,
    prototype_report: PrototypeGraphReport,
    resolved_prototypes: Vec<EffectivePrototype>,
}

/// Engine error.
#[derive(Debug)]
pub enum EngineError {
    /// Engine was created without a resource VFS.
    MissingVfs,
    /// Invalid resource path.
    Path {
        /// Path role.
        role: &'static str,
        /// Raw value.
        value: String,
        /// Source error.
        source: PathError,
    },
    /// VFS error.
    Vfs {
        /// Resource path.
        path: String,
        /// Source error.
        source: VfsError,
    },
    /// `NRes` decode error.
    Nres {
        /// Resource path.
        path: String,
        /// Source error.
        source: fparkan_nres::NresError,
    },
    /// Mission decode error.
    Mission {
        /// Resource path.
        path: String,
        /// Source error.
        source: MissionError,
    },
    /// Terrain disk format error.
    TerrainFormat {
        /// Resource path.
        path: String,
        /// Source error.
        source: TerrainFormatError,
    },
    /// Terrain runtime build error.
    Terrain(fparkan_terrain::TerrainError),
    /// Prototype graph errors.
    PrototypeGraph {
        /// Root failures.
        failures: Vec<PrototypeGraphFailure>,
    },
    /// World error.
    World(fparkan_world::WorldError),
    /// Staged mission world was torn down after a registration-phase failure.
    RegistrationTeardown {
        /// Registered objects before the forced failure.
        registered_objects: usize,
        /// Objects released by normal world shutdown.
        released_objects: usize,
        /// Managers were released after objects.
        managers_released: bool,
    },
}

impl From<fparkan_world::WorldError> for EngineError {
    fn from(value: fparkan_world::WorldError) -> Self {
        Self::World(value)
    }
}

impl std::fmt::Display for EngineError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Self::MissingVfs => write!(f, "mission loading requires a VFS service"),
            Self::Path {
                role,
                value,
                source,
            } => {
                write!(f, "invalid {role} path '{value}': {source}")
            }
            Self::Vfs { path, source } => write!(f, "{path}: {source}"),
            Self::Nres { path, source } => write!(f, "{path}: {source}"),
            Self::Mission { path, source } => write!(f, "{path}: {source}"),
            Self::TerrainFormat { path, source } => write!(f, "{path}: {source}"),
            Self::Terrain(source) => write!(f, "{source}"),
            Self::PrototypeGraph { failures } => {
                write!(f, "mission prototype graph has {} failures", failures.len())
            }
            Self::World(source) => write!(f, "{source}"),
            Self::RegistrationTeardown {
                registered_objects,
                released_objects,
                managers_released,
            } => write!(
                f,
                "mission registration failed after {registered_objects} objects; teardown released {released_objects}, managers_released={managers_released}"
            ),
        }
    }
}

impl std::error::Error for EngineError {
    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
        match self {
            Self::Path { source, .. } => Some(source),
            Self::Vfs { source, .. } => Some(source),
            Self::Nres { source, .. } => Some(source),
            Self::Mission { source, .. } => Some(source),
            Self::TerrainFormat { source, .. } => Some(source),
            Self::Terrain(source) => Some(source),
            Self::World(source) => Some(source),
            Self::MissingVfs | Self::PrototypeGraph { .. } | Self::RegistrationTeardown { .. } => {
                None
            }
        }
    }
}

/// Creates engine.
///
/// # Errors
///
/// Currently this constructor is infallible, but it returns
/// [`EngineError`] to keep the composition-root API stable as services become
/// mandatory.
pub fn create(config: EngineConfig, services: EngineServices) -> Result<Engine, EngineError> {
    Ok(Engine {
        config,
        services,
        world: new_world(WorldConfig),
        loaded: None,
    })
}

/// Loads mission transactionally.
///
/// # Errors
///
/// Returns [`EngineError`] when VFS services are missing, mission paths are
/// invalid, required files cannot be read, disk formats fail validation, terrain
/// runtime data cannot be built, prototype graph roots do not resolve, or
/// object registration fails.
pub fn load_mission(
    engine: &mut Engine,
    request: MissionRequest,
) -> Result<LoadedMission, EngineError> {
    load_mission_with_trace(engine, request).map(|(loaded, _trace)| loaded)
}

/// Loads mission transactionally and returns a diagnostic trace.
///
/// # Errors
///
/// Returns [`EngineError`] under the same conditions as [`load_mission`].
pub fn load_mission_with_trace(
    engine: &mut Engine,
    request: MissionRequest,
) -> Result<(LoadedMission, MissionLoadTrace), EngineError> {
    load_mission_with_options(engine, request, MissionLoadOptions::default())
}

#[allow(clippy::too_many_lines)]
fn load_mission_with_options(
    engine: &mut Engine,
    request: MissionRequest,
    options: MissionLoadOptions,
) -> Result<(LoadedMission, MissionLoadTrace), EngineError> {
    let mut trace = MissionLoadTrace::default();
    trace.phases.push(MissionLoadPhase::Context);
    let vfs = engine.services.vfs.clone().ok_or(EngineError::MissingVfs)?;
    let mission_path = normalize_engine_path("mission", &request.key)?;
    let mission_bytes = read_vfs(&vfs, &mission_path)?;

    trace.phases.push(MissionLoadPhase::Map);
    let land_path = decode_tma_land_path(&mission_bytes, TmaProfile::Strict).map_err(|source| {
        EngineError::Mission {
            path: mission_path.as_str().to_string(),
            source,
        }
    })?;
    let (land_msh_path, land_map_path) = terrain_paths_from_land_path(&land_path)?;
    let land_msh_nres = decode_nres(&vfs, &land_msh_path)?;
    let land_map_nres = decode_nres(&vfs, &land_map_path)?;
    let land_msh =
        decode_land_msh(&land_msh_nres).map_err(|source| EngineError::TerrainFormat {
            path: land_msh_path.as_str().to_string(),
            source,
        })?;
    let land_map =
        decode_land_map(&land_map_nres).map_err(|source| EngineError::TerrainFormat {
            path: land_map_path.as_str().to_string(),
            source,
        })?;
    let terrain =
        TerrainWorld::from_land_assets(&land_msh, &land_map).map_err(EngineError::Terrain)?;

    let build_dat_path = normalize_engine_path("BuildDat", "BuildDat.lst")?;
    let build_dat = read_vfs(&vfs, &build_dat_path)?;
    let build_categories =
        decode_build_dat(&build_dat).map_err(|source| EngineError::TerrainFormat {
            path: build_dat_path.as_str().to_string(),
            source,
        })?;
    trace.phases.push(MissionLoadPhase::Tma);
    let mission =
        decode_tma(mission_bytes, TmaProfile::Strict).map_err(|source| EngineError::Mission {
            path: mission_path.as_str().to_string(),
            source,
        })?;
    let verified_terrain_paths = terrain_paths(&mission)?;
    debug_assert_eq!(verified_terrain_paths.0.as_str(), land_msh_path.as_str());
    debug_assert_eq!(verified_terrain_paths.1.as_str(), land_map_path.as_str());
    trace.transforms = mission
        .objects
        .iter()
        .enumerate()
        .map(|(object_index, object)| PlacedTransformProfile {
            object_index,
            position: object.position,
            orientation_raw: object.orientation,
            scale: object.scale,
        })
        .collect();
    trace.phases.push(MissionLoadPhase::Graph);
    let repository = CachedResourceRepository::new(vfs.clone());
    let graph_roots: Vec<_> = mission
        .objects
        .iter()
        .map(|object| resource_name(&object.resource_name.raw))
        .collect();
    let (prototype_graph, resolved_prototypes, mut prototype_report) =
        build_prototype_graph_report(&repository, vfs.as_ref(), &graph_roots);
    extend_graph_report_with_visual_dependencies(
        &repository,
        &mut prototype_report,
        &resolved_prototypes,
    );
    if !prototype_report.is_success() {
        return Err(EngineError::PrototypeGraph {
            failures: prototype_report.failures.clone(),
        });
    }
    trace.phases.push(MissionLoadPhase::Assets);

    let mut new_runtime_world = new_world(WorldConfig);
    let mut handles = Vec::with_capacity(mission.objects.len());
    trace.phases.push(MissionLoadPhase::Construct);
    for (index, _object) in mission.objects.iter().enumerate() {
        let original_id = u32::try_from(index).ok().map(OriginalObjectId);
        let handle = construct_object(&mut new_runtime_world, ObjectDraft { original_id })?;
        handles.push(handle);
    }
    trace.drafts_before_registration = handles.len();
    trace.phases.push(MissionLoadPhase::Register);
    for handle in &handles {
        if options.fail_after_registered_objects == Some(trace.registered_objects) {
            let report = fparkan_world::shutdown(new_runtime_world);
            return Err(EngineError::RegistrationTeardown {
                registered_objects: trace.registered_objects,
                released_objects: report.released_objects.len(),
                managers_released: report.managers_released,
            });
        }
        register_object(&mut new_runtime_world, *handle)?;
        trace.registered_objects += 1;
    }

    let summary = LoadedMission {
        key: request.key,
        path_count: mission.paths.len(),
        clan_count: mission.clans.len(),
        object_count: mission.objects.len(),
        extra_count: mission.extras.len(),
        land_msh_path: land_msh_path.as_str().to_string(),
        land_map_path: land_map_path.as_str().to_string(),
        build_category_count: build_categories.len(),
        areal_count: terrain.areal_count(),
        surface_count: terrain.surface_count(),
        registered_objects: handles.len(),
        graph_unit_reference_count: prototype_report.unit_reference_count,
        graph_direct_reference_count: prototype_report.direct_reference_count,
        graph_unit_component_count: prototype_report.unit_component_count,
        graph_root_count: prototype_report.root_count,
        graph_resolved_count: prototype_report.resolved_count,
        graph_mesh_dependency_count: prototype_report.mesh_dependency_count,
        graph_failure_count: prototype_report.failures.len(),
        graph_wear_request_count: prototype_report.wear_request_count,
        graph_wear_resolved_count: prototype_report.wear_resolved_count,
        graph_material_slot_count: prototype_report.material_slot_count,
        graph_material_resolved_count: prototype_report.material_resolved_count,
        graph_texture_request_count: prototype_report.texture_request_count,
        graph_texture_resolved_count: prototype_report.texture_resolved_count,
        graph_lightmap_request_count: prototype_report.lightmap_request_count,
        graph_lightmap_resolved_count: prototype_report.lightmap_resolved_count,
    };

    engine.world = new_runtime_world;
    engine.loaded = Some(LoadedMissionState {
        summary: summary.clone(),
        mission,
        terrain,
        build_categories,
        prototype_graph,
        prototype_report,
        resolved_prototypes,
    });
    Ok((summary, trace))
}

/// Steps headless mode.
///
/// # Errors
///
/// Returns [`EngineError`] when the world step fails.
pub fn step_headless(
    engine: &mut Engine,
    input: InputSnapshot,
) -> Result<FrameResult, EngineError> {
    let snapshot = step(&mut engine.world, &input)?;
    Ok(FrameResult { snapshot })
}

/// Steps rendered mode.
///
/// # Errors
///
/// Returns [`EngineError`] when the world step fails.
pub fn frame(engine: &mut Engine) -> Result<FrameResult, EngineError> {
    match engine.config.mode {
        EngineMode::Headless | EngineMode::Rendered => step_headless(engine, InputSnapshot),
    }
}

/// Shuts down engine.
///
/// # Errors
///
/// Currently shutdown is infallible, but the `Result` preserves the lifecycle
/// API for future service teardown failures.
pub fn shutdown(_engine: Engine) -> Result<(), EngineError> {
    Ok(())
}

/// Returns the loaded mission summary.
#[must_use]
pub fn loaded_mission(engine: &Engine) -> Option<&LoadedMission> {
    engine.loaded.as_ref().map(|state| &state.summary)
}

/// Returns the decoded mission document for the loaded mission.
#[must_use]
pub fn loaded_mission_document(engine: &Engine) -> Option<&MissionDocument> {
    engine.loaded.as_ref().map(|state| &state.mission)
}

/// Returns terrain runtime data for the loaded mission.
#[must_use]
pub fn loaded_terrain(engine: &Engine) -> Option<&TerrainWorld> {
    engine.loaded.as_ref().map(|state| &state.terrain)
}

/// Returns decoded build categories for the loaded game root.
#[must_use]
pub fn loaded_build_categories(engine: &Engine) -> Option<&[BuildCategory]> {
    engine
        .loaded
        .as_ref()
        .map(|state| state.build_categories.as_slice())
}

/// Returns the loaded prototype graph.
#[must_use]
pub fn loaded_prototype_graph(engine: &Engine) -> Option<&PrototypeGraph> {
    engine.loaded.as_ref().map(|state| &state.prototype_graph)
}

/// Returns the loaded prototype graph report.
#[must_use]
pub fn loaded_prototype_graph_report(engine: &Engine) -> Option<&PrototypeGraphReport> {
    engine.loaded.as_ref().map(|state| &state.prototype_report)
}

/// Returns resolved effective prototypes for the loaded mission.
#[must_use]
pub fn loaded_resolved_prototypes(engine: &Engine) -> Option<&[EffectivePrototype]> {
    engine
        .loaded
        .as_ref()
        .map(|state| state.resolved_prototypes.as_slice())
}

fn normalize_engine_path(role: &'static str, value: &str) -> Result<NormalizedPath, EngineError> {
    normalize_relative(value.as_bytes(), PathPolicy::StrictLegacy).map_err(|source| {
        EngineError::Path {
            role,
            value: value.to_string(),
            source,
        }
    })
}

fn read_vfs(vfs: &Arc<dyn Vfs>, path: &NormalizedPath) -> Result<Arc<[u8]>, EngineError> {
    vfs.read(path).map_err(|source| EngineError::Vfs {
        path: path.as_str().to_string(),
        source,
    })
}

fn decode_nres(
    vfs: &Arc<dyn Vfs>,
    path: &NormalizedPath,
) -> Result<fparkan_nres::NresDocument, EngineError> {
    let bytes = read_vfs(vfs, path)?;
    fparkan_nres::decode(bytes, fparkan_nres::ReadProfile::Compatible).map_err(|source| {
        EngineError::Nres {
            path: path.as_str().to_string(),
            source,
        }
    })
}

fn terrain_paths(
    mission: &MissionDocument,
) -> Result<(NormalizedPath, NormalizedPath), EngineError> {
    terrain_paths_from_land_path(&mission.land_path)
}

fn terrain_paths_from_land_path(
    land_path: &LpString,
) -> Result<(NormalizedPath, NormalizedPath), EngineError> {
    let land_path_raw = String::from_utf8_lossy(&land_path.raw).to_string();
    let normalized =
        normalize_relative(&land_path.raw, PathPolicy::StrictLegacy).map_err(|source| {
            EngineError::Path {
                role: "mission land",
                value: land_path_raw.clone(),
                source,
            }
        })?;
    let Some((parent, _stem)) = normalized.as_str().rsplit_once('/') else {
        return Err(EngineError::Path {
            role: "mission land",
            value: normalized.as_str().to_string(),
            source: PathError::Empty,
        });
    };
    let mesh = normalize_engine_path("Land.msh", &format!("{parent}/Land.msh"))?;
    let map = normalize_engine_path("Land.map", &format!("{parent}/Land.map"))?;
    Ok((mesh, map))
}

#[cfg(test)]
mod tests {
    use super::*;
    use fparkan_vfs::{DirectoryVfs, VfsEntry, VfsMetadata};
    use std::path::{Path, PathBuf};

    #[test]
    fn load_mission_requires_vfs_and_keeps_world_unchanged_on_error() {
        let mut engine = create(
            EngineConfig {
                mode: EngineMode::Headless,
            },
            EngineServices::default(),
        )
        .expect("engine");
        let before = step_headless(&mut engine, InputSnapshot).expect("step");
        let err = load_mission(
            &mut engine,
            MissionRequest {
                key: "MISSIONS/Autodemo.00/data.tma".to_string(),
            },
        )
        .expect_err("missing VFS");
        assert!(matches!(err, EngineError::MissingVfs));
        let after = step_headless(&mut engine, InputSnapshot).expect("step");
        assert_eq!(before.snapshot.objects, after.snapshot.objects);
    }

    #[test]
    #[ignore = "requires licensed corpus"]
    fn load_trace_records_preparation_before_registration_and_raw_transforms() {
        let root = workspace_root().join("testdata").join("IS");
        let vfs: Arc<dyn Vfs> = Arc::new(DirectoryVfs::new(&root));
        let mut engine = create(
            EngineConfig {
                mode: EngineMode::Headless,
            },
            EngineServices::new(vfs),
        )
        .expect("engine");

        let (loaded, trace) = load_mission_with_trace(
            &mut engine,
            MissionRequest {
                key: "MISSIONS/Autodemo.00/data.tma".to_string(),
            },
        )
        .expect("load mission with trace");

        assert_eq!(
            trace.phases,
            vec![
                MissionLoadPhase::Context,
                MissionLoadPhase::Map,
                MissionLoadPhase::Tma,
                MissionLoadPhase::Graph,
                MissionLoadPhase::Assets,
                MissionLoadPhase::Construct,
                MissionLoadPhase::Register,
            ]
        );
        assert_eq!(trace.drafts_before_registration, loaded.object_count);
        assert_eq!(trace.registered_objects, loaded.object_count);
        assert_eq!(trace.transforms.len(), loaded.object_count);
        assert!(trace.transforms.iter().all(|transform| transform
            .orientation_raw
            .iter()
            .all(|component| component.is_finite())));
    }

    #[test]
    #[ignore = "requires licensed corpus"]
    fn missing_map_and_missing_reachable_resource_fail_before_registration() {
        let root = workspace_root().join("testdata").join("IS");
        for (denied, mission) in [
            (
                DenyRule::Suffix("Land.map"),
                MissionRequest {
                    key: "MISSIONS/Autodemo.00/data.tma".to_string(),
                },
            ),
            (
                DenyRule::Suffix("objects.rlb"),
                MissionRequest {
                    key: "MISSIONS/CAMPAIGN/CAMPAIGN.00/Mission.01/data.tma".to_string(),
                },
            ),
        ] {
            let vfs: Arc<dyn Vfs> = Arc::new(DenyVfs {
                inner: DirectoryVfs::new(&root),
                denied,
            });
            let mut engine = create(
                EngineConfig {
                    mode: EngineMode::Headless,
                },
                EngineServices::new(vfs),
            )
            .expect("engine");
            let before = step_headless(&mut engine, InputSnapshot).expect("before");
            let err = load_mission(&mut engine, mission).expect_err("load error");
            match denied {
                DenyRule::Suffix("Land.map") => assert!(matches!(err, EngineError::Vfs { .. })),
                DenyRule::Suffix("objects.rlb") => {
                    assert!(matches!(err, EngineError::PrototypeGraph { .. }))
                }
                DenyRule::Suffix(unexpected) => panic!("unexpected deny rule {unexpected}"),
            }
            assert!(loaded_mission(&engine).is_none());
            let after = step_headless(&mut engine, InputSnapshot).expect("after");
            assert_eq!(before.snapshot.objects, after.snapshot.objects);
        }
    }

    #[test]
    #[ignore = "requires licensed corpus"]
    fn registration_phase_failure_uses_normal_teardown_and_keeps_engine_world() {
        let root = workspace_root().join("testdata").join("IS");
        let vfs: Arc<dyn Vfs> = Arc::new(DirectoryVfs::new(root));
        let mut engine = create(
            EngineConfig {
                mode: EngineMode::Headless,
            },
            EngineServices::new(vfs),
        )
        .expect("engine");
        let before = step_headless(&mut engine, InputSnapshot).expect("before");

        let err = load_mission_with_options(
            &mut engine,
            MissionRequest {
                key: "MISSIONS/CAMPAIGN/CAMPAIGN.00/Mission.01/data.tma".to_string(),
            },
            MissionLoadOptions {
                fail_after_registered_objects: Some(1),
            },
        )
        .expect_err("forced registration failure");

        assert!(matches!(
            err,
            EngineError::RegistrationTeardown {
                registered_objects: 1,
                released_objects: 1,
                managers_released: true,
            }
        ));
        assert!(loaded_mission(&engine).is_none());
        let after = step_headless(&mut engine, InputSnapshot).expect("after");
        assert_eq!(before.snapshot.objects, after.snapshot.objects);
    }

    #[test]
    #[ignore = "requires licensed corpus"]
    fn selected_is_and_is2_missions_execute_10000_deterministic_ticks() {
        for case in [
            HeadlessCase {
                root: "IS",
                mission: "MISSIONS/CAMPAIGN/CAMPAIGN.00/Mission.01/data.tma",
                object_count: 33,
                expected_hash: [
                    0x19, 0xdc, 0xd3, 0x9b, 0x35, 0xad, 0x90, 0x6c, 0x92, 0x2d, 0x83, 0x7b, 0x7a,
                    0xb3, 0xa6, 0x15, 0xa6, 0x15, 0x92, 0x2d, 0x83, 0x7b, 0x7a, 0xb3, 0xe9, 0xcd,
                    0x9a, 0x56, 0x48, 0xb6, 0x0c, 0xee,
                ],
            },
            HeadlessCase {
                root: "IS2",
                mission: "MISSIONS/Campaign/CAMPAIGN.00/Mission.02/data.tma",
                object_count: 10,
                expected_hash: [
                    0x59, 0x6e, 0x88, 0xcc, 0xd0, 0x3a, 0xd9, 0x68, 0x1b, 0x2d, 0xcb, 0x0d, 0x91,
                    0x19, 0x5a, 0x27, 0x5a, 0x27, 0x1b, 0x2d, 0xcb, 0x0d, 0x91, 0x19, 0x44, 0x66,
                    0x68, 0x9d, 0x6c, 0xb4, 0x2c, 0x37,
                ],
            },
        ] {
            let first = run_headless_case(case);
            let second = run_headless_case(case);
            assert_eq!(first, second);
            assert_eq!(first.tick.0, 10_000);
            assert_eq!(first.objects.len(), case.object_count);
            assert_eq!(first.hash.0, case.expected_hash);
        }
    }

    #[test]
    #[ignore = "requires licensed corpus"]
    fn licensed_corpora_load_all_mission_foundations() {
        let root = workspace_root();
        let part1 = load_all(&root.join("testdata").join("IS"));
        assert_eq!(part1.missions, 29);
        assert_eq!(part1.paths, 34);
        assert_eq!(part1.clans, 101);
        assert_eq!(part1.objects, 864);
        assert_eq!(part1.extras, 28);
        assert_eq!(part1.unit_references, 463);
        assert_eq!(part1.direct_references, 401);
        assert_eq!(part1.unit_components, 4_300);
        assert_eq!(part1.prototype_requests, 4_701);
        assert_eq!(part1.material_slots, 36_954);
        assert_eq!(part1.texture_requests, 48_806);
        assert_eq!(part1.lightmap_requests, 139);
        assert_eq!(part1.graph_failures, 0);
        assert_eq!(part1.wear_requests, part1.prototype_requests);
        assert_eq!(part1.wear_requests, part1.wear_resolved);
        assert_eq!(part1.material_slots, part1.material_resolved);
        assert_eq!(part1.texture_requests, part1.texture_resolved);
        assert_eq!(part1.lightmap_requests, part1.lightmap_resolved);

        let part2 = load_all(&root.join("testdata").join("IS2"));
        assert_eq!(part2.missions, 31);
        assert_eq!(part2.paths, 61);
        assert_eq!(part2.clans, 91);
        assert_eq!(part2.objects, 885);
        assert_eq!(part2.extras, 41);
        assert_eq!(part2.unit_references, 561);
        assert_eq!(part2.direct_references, 324);
        assert_eq!(part2.unit_components, 5_521);
        assert_eq!(part2.prototype_requests, 5_845);
        assert_eq!(part2.material_slots, 50_888);
        assert_eq!(part2.texture_requests, 68_603);
        assert_eq!(part2.lightmap_requests, 214);
        assert_eq!(part2.graph_failures, 0);
        assert_eq!(part2.wear_requests, part2.prototype_requests);
        assert_eq!(part2.wear_requests, part2.wear_resolved);
        assert_eq!(part2.material_slots, part2.material_resolved);
        assert_eq!(part2.texture_requests, part2.texture_resolved);
        assert_eq!(part2.lightmap_requests, part2.lightmap_resolved);
    }

    #[derive(Default)]
    struct LoadTotals {
        missions: usize,
        paths: usize,
        clans: usize,
        objects: usize,
        extras: usize,
        unit_references: usize,
        direct_references: usize,
        unit_components: usize,
        prototype_requests: usize,
        wear_requests: usize,
        wear_resolved: usize,
        material_slots: usize,
        material_resolved: usize,
        texture_requests: usize,
        texture_resolved: usize,
        lightmap_requests: usize,
        lightmap_resolved: usize,
        graph_failures: usize,
    }

    #[derive(Clone, Copy)]
    struct HeadlessCase {
        root: &'static str,
        mission: &'static str,
        object_count: usize,
        expected_hash: [u8; 32],
    }

    fn run_headless_case(case: HeadlessCase) -> WorldSnapshot {
        let root = workspace_root().join("testdata").join(case.root);
        let vfs: Arc<dyn Vfs> = Arc::new(DirectoryVfs::new(root));
        let mut engine = create(
            EngineConfig {
                mode: EngineMode::Headless,
            },
            EngineServices::new(vfs),
        )
        .expect("engine");
        let loaded = load_mission(
            &mut engine,
            MissionRequest {
                key: case.mission.to_string(),
            },
        )
        .expect("load selected mission");
        assert_eq!(loaded.object_count, case.object_count);

        let mut snapshot = None;
        for _ in 0..10_000 {
            snapshot = Some(
                step_headless(&mut engine, InputSnapshot)
                    .expect("selected mission deterministic tick")
                    .snapshot,
            );
        }
        snapshot.expect("at least one tick")
    }

    fn load_all(root: &Path) -> LoadTotals {
        assert!(root.is_dir(), "missing licensed corpus {}", root.display());
        let mut missions = mission_paths(root);
        missions.sort();
        let vfs: Arc<dyn Vfs> = Arc::new(DirectoryVfs::new(root));
        let mut totals = LoadTotals::default();
        for mission in missions {
            let mut engine = create(
                EngineConfig {
                    mode: EngineMode::Headless,
                },
                EngineServices::new(vfs.clone()),
            )
            .expect("engine");
            let loaded = load_mission(&mut engine, MissionRequest { key: mission })
                .expect("load mission foundation");
            assert_eq!(loaded.object_count, loaded.registered_objects);
            assert_eq!(loaded.object_count, loaded.graph_root_count);
            assert_eq!(
                loaded.graph_direct_reference_count + loaded.graph_unit_component_count,
                loaded.graph_resolved_count
            );
            assert_eq!(loaded.graph_failure_count, 0);
            assert_eq!(
                loaded.graph_wear_request_count,
                loaded.graph_wear_resolved_count
            );
            assert_eq!(
                loaded.graph_material_slot_count,
                loaded.graph_material_resolved_count
            );
            assert_eq!(
                loaded.graph_texture_request_count,
                loaded.graph_texture_resolved_count
            );
            assert_eq!(
                loaded.graph_lightmap_request_count,
                loaded.graph_lightmap_resolved_count
            );
            assert_eq!(loaded.build_category_count, 12);
            assert!(loaded.areal_count > 0);
            assert!(loaded.surface_count > 0);
            totals.missions += 1;
            totals.paths += loaded.path_count;
            totals.clans += loaded.clan_count;
            totals.objects += loaded.object_count;
            totals.extras += loaded.extra_count;
            totals.unit_references += loaded.graph_unit_reference_count;
            totals.direct_references += loaded.graph_direct_reference_count;
            totals.unit_components += loaded.graph_unit_component_count;
            totals.prototype_requests += loaded.graph_resolved_count;
            totals.wear_requests += loaded.graph_wear_request_count;
            totals.wear_resolved += loaded.graph_wear_resolved_count;
            totals.material_slots += loaded.graph_material_slot_count;
            totals.material_resolved += loaded.graph_material_resolved_count;
            totals.texture_requests += loaded.graph_texture_request_count;
            totals.texture_resolved += loaded.graph_texture_resolved_count;
            totals.lightmap_requests += loaded.graph_lightmap_request_count;
            totals.lightmap_resolved += loaded.graph_lightmap_resolved_count;
            totals.graph_failures += loaded.graph_failure_count;
        }
        totals
    }

    fn mission_paths(root: &Path) -> Vec<String> {
        let mut out = Vec::new();
        collect_missions(root, root, &mut out);
        out
    }

    fn collect_missions(root: &Path, dir: &Path, out: &mut Vec<String>) {
        let mut children: Vec<PathBuf> = std::fs::read_dir(dir)
            .expect("read dir")
            .map(|entry| entry.expect("entry").path())
            .collect();
        children.sort();
        for child in children {
            if child.is_dir() {
                collect_missions(root, &child, out);
            } else if child
                .file_name()
                .and_then(|name| name.to_str())
                .is_some_and(|name| name.eq_ignore_ascii_case("data.tma"))
            {
                let rel = child.strip_prefix(root).expect("relative");
                let rel = rel.to_str().expect("utf8 path").replace('\\', "/");
                out.push(rel);
            }
        }
    }

    fn workspace_root() -> PathBuf {
        PathBuf::from(env!("CARGO_MANIFEST_DIR"))
            .parent()
            .and_then(Path::parent)
            .expect("workspace root")
            .to_path_buf()
    }

    #[derive(Clone, Copy)]
    enum DenyRule {
        Suffix(&'static str),
    }

    struct DenyVfs {
        inner: DirectoryVfs,
        denied: DenyRule,
    }

    impl DenyVfs {
        fn denied(&self, path: &NormalizedPath) -> bool {
            match self.denied {
                DenyRule::Suffix(suffix) => path
                    .as_str()
                    .to_ascii_uppercase()
                    .ends_with(&suffix.to_ascii_uppercase()),
            }
        }
    }

    impl Vfs for DenyVfs {
        fn metadata(&self, path: &NormalizedPath) -> Result<VfsMetadata, VfsError> {
            if self.denied(path) {
                return Err(VfsError::NotFound(path.as_str().to_string()));
            }
            self.inner.metadata(path)
        }

        fn read(&self, path: &NormalizedPath) -> Result<Arc<[u8]>, VfsError> {
            if self.denied(path) {
                return Err(VfsError::NotFound(path.as_str().to_string()));
            }
            self.inner.read(path)
        }

        fn list(&self, prefix: &NormalizedPath) -> Result<Vec<VfsEntry>, VfsError> {
            self.inner.list(prefix).map(|entries| {
                entries
                    .into_iter()
                    .filter(|entry| !self.denied(&entry.path))
                    .collect()
            })
        }
    }
}