path: root/crates/fparkan-assets/src/lib.rs

#![forbid(unsafe_code)]
//! Asset manager ports and transactional preparation models.

use fparkan_material::{decode_wear, resolve_material, WEAR_KIND};
use fparkan_msh::{decode_msh, validate_msh};
use fparkan_nres::{decode as decode_nres, ReadProfile};
use fparkan_path::{normalize_relative, NormalizedPath, PathPolicy, ResourceName};
use fparkan_prototype::{EffectivePrototype, PrototypeGeometry, PrototypeGraph};
use fparkan_resource::{ResourceKey, ResourceRepository};
use fparkan_texm::decode_texm;
use std::collections::BTreeSet;
use std::fmt;
use std::hash::{Hash, Hasher};
use std::marker::PhantomData;
use std::sync::Arc;

const TEXTURES_ARCHIVE: &str = "textures.lib";
const LIGHTMAP_ARCHIVE: &str = "lightmap.lib";

/// Stable typed identifier for a prepared asset.
#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
pub struct AssetId<T> {
    raw: u64,
    marker: PhantomData<T>,
}

impl<T> AssetId<T> {
    /// Creates an asset id from a stable raw value.
    #[must_use]
    pub const fn new(raw: u64) -> Self {
        Self {
            raw,
            marker: PhantomData,
        }
    }

    /// Returns the stable raw id.
    #[must_use]
    pub const fn raw(self) -> u64 {
        self.raw
    }
}

/// CPU-side data needed before a visual can be handed to a renderer.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct PreparedVisual {
    /// Stable id derived from the prototype geometry key.
    pub id: AssetId<PreparedVisual>,
    /// Optional mesh resource backing the visual.
    pub mesh: Option<ResourceKey>,
    /// Number of validated model nodes.
    pub model_nodes: usize,
    /// Number of validated material slots on the model.
    pub model_slots: usize,
    /// Number of validated render batches.
    pub model_batches: usize,
    /// Number of WEAR material slots resolved through MAT0.
    pub material_count: usize,
    /// Number of texture phase requests decoded as TEXM.
    pub texture_count: usize,
    /// Number of lightmap requests decoded as TEXM.
    pub lightmap_count: usize,
}

/// A transactional mission asset preparation plan.
#[derive(Clone, Debug, Default, Eq, PartialEq)]
pub struct MissionAssetPlan {
    /// Number of visual prototypes in the plan.
    pub visual_count: usize,
    /// Number of mesh-backed visuals.
    pub model_count: usize,
    /// Number of material slot requests.
    pub material_count: usize,
    /// Number of texture phase requests.
    pub texture_count: usize,
    /// Number of lightmap requests.
    pub lightmap_count: usize,
}

/// Coarse CPU-side asset budgets.
#[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
pub struct AssetBudgets {
    /// Bytes parsed from source resource payloads.
    pub parsed_bytes: u64,
}

/// Errors raised while preparing CPU-side assets.
#[derive(Clone, Debug, Eq, PartialEq)]
pub enum AssetError {
    /// A required cross-resource dependency was not found.
    MissingDependency(String),
    /// A prototype did not describe a usable visual.
    InvalidPrototype(String),
    /// A repository operation failed.
    Resource(String),
    /// MSH parsing or validation failed.
    Msh(String),
    /// WEAR/MAT0 parsing or resolution failed.
    Material(String),
    /// TEXM parsing failed.
    Texture(String),
}

impl fmt::Display for AssetError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::MissingDependency(value) => write!(f, "missing dependency: {value}"),
            Self::InvalidPrototype(value) => write!(f, "invalid prototype: {value}"),
            Self::Resource(value) => write!(f, "resource error: {value}"),
            Self::Msh(value) => write!(f, "msh error: {value}"),
            Self::Material(value) => write!(f, "material error: {value}"),
            Self::Texture(value) => write!(f, "texture error: {value}"),
        }
    }
}

impl std::error::Error for AssetError {}

/// Port implemented by typed asset loaders.
pub trait AssetLoader<T> {
    /// Loads an asset for the given resource key.
    ///
    /// # Errors
    ///
    /// Returns [`AssetError`] when the resource cannot be resolved or decoded.
    fn load(&self, key: &ResourceKey) -> Result<Arc<T>, AssetError>;
}

/// Minimal asset manager façade over an immutable resource repository.
#[derive(Debug)]
pub struct AssetManager<R> {
    repository: R,
}

impl<R> AssetManager<R> {
    /// Creates a manager backed by the given repository.
    #[must_use]
    pub const fn new(repository: R) -> Self {
        Self { repository }
    }

    /// Returns the backing repository.
    #[must_use]
    pub const fn repository(&self) -> &R {
        &self.repository
    }
}

impl<R: ResourceRepository> AssetManager<R> {
    /// Prepares one prototype visual using the manager repository.
    ///
    /// # Errors
    ///
    /// Returns [`AssetError`] if any model, material, texture, or lightmap
    /// dependency is missing or malformed.
    pub fn prepare_visual(&self, proto: &EffectivePrototype) -> Result<PreparedVisual, AssetError> {
        prepare_visual_with_repository(&self.repository, proto)
    }

    /// Builds a mission plan by preparing each resolved prototype.
    ///
    /// # Errors
    ///
    /// Returns [`AssetError`] if any visual dependency is missing or malformed.
    pub fn build_mission_asset_plan<'a>(
        &self,
        prototypes: impl IntoIterator<Item = &'a EffectivePrototype>,
    ) -> Result<MissionAssetPlan, AssetError> {
        build_mission_asset_plan_with_repository(&self.repository, prototypes)
    }
}

/// Produces a count-only plan from a prototype graph.
#[must_use]
pub fn build_mission_asset_plan(graph: &PrototypeGraph) -> MissionAssetPlan {
    MissionAssetPlan {
        visual_count: graph.prototype_requests.len(),
        ..MissionAssetPlan::default()
    }
}

/// Builds a fully validated CPU-side mission asset plan.
///
/// # Errors
///
/// Returns [`AssetError`] if any reachable visual dependency is missing or
/// malformed.
pub fn build_mission_asset_plan_with_repository<'a, R: ResourceRepository>(
    repository: &R,
    prototypes: impl IntoIterator<Item = &'a EffectivePrototype>,
) -> Result<MissionAssetPlan, AssetError> {
    let mut plan = MissionAssetPlan::default();
    let mut prepared_visuals = BTreeSet::new();

    for proto in prototypes {
        let visual_id = stable_visual_id(proto);
        if !prepared_visuals.insert(visual_id) {
            continue;
        }
        let visual = prepare_visual_with_repository(repository, proto)?;
        plan.visual_count += 1;
        if visual.mesh.is_some() {
            plan.model_count += 1;
        }
        plan.material_count += visual.material_count;
        plan.texture_count += visual.texture_count;
        plan.lightmap_count += visual.lightmap_count;
    }

    Ok(plan)
}

/// Validates a prototype visual without resolving cross-resource dependencies.
///
/// This is useful for tests and API callers that only need a stable visual id.
///
/// # Errors
///
/// Returns [`AssetError`] when the prototype geometry is malformed.
pub fn prepare_visual(proto: &EffectivePrototype) -> Result<PreparedVisual, AssetError> {
    let id = stable_visual_id(proto);
    let mesh = match &proto.geometry {
        PrototypeGeometry::Mesh(key) => Some(key.clone()),
        PrototypeGeometry::NonGeometric => None,
    };

    Ok(PreparedVisual {
        id: AssetId::new(id),
        mesh,
        model_nodes: 0,
        model_slots: 0,
        model_batches: 0,
        material_count: 0,
        texture_count: 0,
        lightmap_count: 0,
    })
}

/// Prepares one visual and validates all CPU-side resource dependencies.
///
/// # Errors
///
/// Returns [`AssetError`] if the model, WEAR table, MAT0 materials, texture
/// phases, or lightmaps cannot be resolved and decoded.
pub fn prepare_visual_with_repository<R: ResourceRepository>(
    repository: &R,
    proto: &EffectivePrototype,
) -> Result<PreparedVisual, AssetError> {
    let PrototypeGeometry::Mesh(mesh_key) = &proto.geometry else {
        return prepare_visual(proto);
    };

    let nres = decode_nres(
        read_key(repository, mesh_key, Some("mesh"))?,
        ReadProfile::Compatible,
    )
    .map_err(|err| AssetError::Msh(err.to_string()))?;
    let msh_document = decode_msh(&nres).map_err(|err| AssetError::Msh(err.to_string()))?;
    let model = validate_msh(&msh_document).map_err(|err| AssetError::Msh(err.to_string()))?;

    let wear_name = sibling_name(mesh_key, "wea")?;
    let wear_key = ResourceKey {
        archive: mesh_key.archive.clone(),
        name: wear_name,
        type_id: Some(WEAR_KIND),
    };
    let wear = decode_wear(&read_key(repository, &wear_key, Some("wear"))?)
        .map_err(|err| AssetError::Material(err.to_string()))?;

    let mut material_count = 0;
    let mut texture_count = 0;
    let mut lightmap_count = 0;
    for material_index in 0..wear.entries.len() {
        let material_index = u16::try_from(material_index).map_err(|_| {
            AssetError::Material("material index does not fit archive format".to_string())
        })?;
        let material = resolve_material(repository, &wear, material_index)
            .map_err(|err| AssetError::Material(err.to_string()))?;
        material_count += 1;

        for texture in material.document.texture_requests() {
            resolve_texm(repository, &texture, &[TEXTURES_ARCHIVE, LIGHTMAP_ARCHIVE])?;
            texture_count += 1;
        }
    }

    for lightmap in &wear.lightmaps {
        resolve_texm(
            repository,
            &lightmap.lightmap,
            &[LIGHTMAP_ARCHIVE, TEXTURES_ARCHIVE],
        )?;
        lightmap_count += 1;
    }

    Ok(PreparedVisual {
        id: AssetId::new(stable_visual_id(proto)),
        mesh: Some(mesh_key.clone()),
        model_nodes: model.node_count,
        model_slots: model.slots.len(),
        model_batches: model.batches.len(),
        material_count,
        texture_count,
        lightmap_count,
    })
}

fn read_key<R: ResourceRepository>(
    repository: &R,
    key: &ResourceKey,
    label: Option<&str>,
) -> Result<Arc<[u8]>, AssetError> {
    let handle = repository
        .open_archive(&key.archive)
        .map_err(|err| AssetError::Resource(format!("{label:?} {key:?}: {err}")))
        .and_then(|archive| {
            repository
                .find(archive, &key.name)
                .map_err(|err| AssetError::Resource(format!("{label:?} {key:?}: {err}")))
        })?
        .ok_or_else(|| AssetError::MissingDependency(format!("{label:?} {key:?}")))?;
    let bytes = repository
        .read(handle)
        .map_err(|err| AssetError::Resource(format!("{label:?} {key:?}: {err}")))?;
    Ok(Arc::from(bytes.into_owned()))
}

fn resolve_texm<R: ResourceRepository>(
    repository: &R,
    name: &ResourceName,
    archives: &[&str],
) -> Result<(), AssetError> {
    for archive in archives {
        let key = ResourceKey {
            archive: parse_path(archive)?,
            name: name.clone(),
            type_id: None,
        };
        match read_key(repository, &key, Some("texm")) {
            Ok(bytes) => {
                decode_texm(bytes).map_err(|err| AssetError::Texture(err.to_string()))?;
                return Ok(());
            }
            Err(AssetError::MissingDependency(_) | AssetError::Resource(_)) => {}
            Err(err) => return Err(err),
        }
    }

    Err(AssetError::MissingDependency(format!("{name:?}")))
}

fn sibling_name(key: &ResourceKey, extension: &str) -> Result<ResourceName, AssetError> {
    let dot = key
        .name
        .0
        .iter()
        .rposition(|byte| *byte == b'.')
        .ok_or_else(|| {
            AssetError::InvalidPrototype(format!("resource name has no extension: {:?}", key.name))
        })?;
    let mut name = key.name.0[..dot].to_vec();
    name.push(b'.');
    name.extend_from_slice(extension.as_bytes());
    Ok(ResourceName(name))
}

fn stable_visual_id(proto: &EffectivePrototype) -> u64 {
    let mut hasher = StableHasher::default();
    match &proto.geometry {
        PrototypeGeometry::Mesh(key) => {
            1_u8.hash(&mut hasher);
            key.archive.as_str().hash(&mut hasher);
            key.name.0.hash(&mut hasher);
            key.type_id.hash(&mut hasher);
        }
        PrototypeGeometry::NonGeometric => {
            0_u8.hash(&mut hasher);
        }
    }
    hasher.finish()
}

fn parse_path(value: &str) -> Result<NormalizedPath, AssetError> {
    normalize_relative(value.as_bytes(), PathPolicy::HostCompatible)
        .map_err(|err| AssetError::InvalidPrototype(format!("{err}")))
}

#[derive(Default)]
struct StableHasher(u64);

impl Hasher for StableHasher {
    fn finish(&self) -> u64 {
        self.0
    }

    fn write(&mut self, bytes: &[u8]) {
        let mut value = if self.0 == 0 {
            0xcbf2_9ce4_8422_2325
        } else {
            self.0
        };
        for byte in bytes {
            value ^= u64::from(*byte);
            value = value.wrapping_mul(0x0000_0100_0000_01b3);
        }
        self.0 = value;
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use fparkan_prototype::build_prototype_graph;
    use fparkan_resource::{resource_name, CachedResourceRepository};
    use fparkan_vfs::{DirectoryVfs, Vfs};
    use std::path::PathBuf;

    #[test]
    fn count_only_plan_uses_graph_requests() {
        let graph = PrototypeGraph::default();

        let plan = build_mission_asset_plan(&graph);

        assert_eq!(plan.visual_count, 0);
        assert_eq!(plan.model_count, 0);
    }

    #[test]
    fn prepares_real_unit_asset_plan() {
        let root = fixture_root("IS");
        let vfs: Arc<dyn Vfs> = Arc::new(DirectoryVfs::new(&root));
        let repository = CachedResourceRepository::new(Arc::clone(&vfs));
        let roots = [resource_name(b"UNITS/AUTO/swlklas.dat")];

        let (graph, prototypes) =
            build_prototype_graph(&repository, vfs.as_ref(), &roots).expect("prototype graph");
        let count_only = build_mission_asset_plan(&graph);
        let plan = build_mission_asset_plan_with_repository(&repository, &prototypes)
            .expect("asset preparation");

        assert_eq!(count_only.visual_count, 12);
        assert_eq!(prototypes.len(), 12);
        assert_eq!(plan.visual_count, 11);
        assert_eq!(plan.model_count, 11);
        assert_eq!(plan.material_count, 62);
        assert_eq!(plan.texture_count, 77);
        assert_eq!(plan.lightmap_count, 0);
    }

    #[test]
    fn repository_plan_deduplicates_duplicate_visuals_but_graph_preserves_requests() {
        let root = fixture_root("IS");
        let vfs: Arc<dyn Vfs> = Arc::new(DirectoryVfs::new(&root));
        let repository = CachedResourceRepository::new(Arc::clone(&vfs));
        let roots = [
            resource_name(b"UNITS/AUTO/swlklas.dat"),
            resource_name(b"UNITS/AUTO/swlklas.dat"),
        ];

        let (graph, prototypes) =
            build_prototype_graph(&repository, vfs.as_ref(), &roots).expect("prototype graph");
        let count_only = build_mission_asset_plan(&graph);
        let plan = build_mission_asset_plan_with_repository(&repository, &prototypes)
            .expect("asset preparation");

        assert_eq!(graph.roots.len(), 2);
        assert_eq!(count_only.visual_count, 24);
        assert_eq!(prototypes.len(), 24);
        assert_eq!(plan.visual_count, 11);
        assert_eq!(plan.model_count, 11);
        assert_eq!(plan.material_count, 62);
        assert_eq!(plan.texture_count, 77);
    }

    fn fixture_root(part: &str) -> PathBuf {
        PathBuf::from(env!("CARGO_MANIFEST_DIR"))
            .join("../..")
            .join("testdata")
            .join(part)
    }
}