rusteal-core 0.5.0

// Reify registry: manages Rust-side type info, function callbacks, and instance data
// for runtime-created UE classes.
//
// Three registries:
// 1. Type registry: maps type_id -> RustTypeInfo (constructor, destructor, name)
// 2. Function registry: maps callback_id -> Rust function closure
// 3. Instance data: maps UObject pointer -> the allocated Rust data of each
//    Rust class it is (a Rust class whose parent is a Rust class has both)

use std::collections::HashMap;
use std::sync::{Arc, Mutex, OnceLock, RwLock};

use crate::{lock_or_recover, read_or_recover, write_or_recover};

// ---------------------------------------------------------------------------
// Inventory-based auto-registration
// ---------------------------------------------------------------------------

/// Submitted by `#[uclass]` — holds register + finalize fn pointers.
pub struct ClassRegistration {
    /// The class's Rust type ID.
    pub type_id: u64,
    /// Create the UClass (type info, parent, class handle). `false` while its
    /// parent, a Rust class not created yet, is missing; on the last try the
    /// missing parent is logged and it returns `true`.
    pub create: fn(last_try: bool) -> bool,
    /// Add its properties and components, which may name other Rust classes
    /// (`SubclassOf<MyCharacter>`): every class exists by then.
    pub register: fn(),
    pub finalize: fn(),
    /// Once its class defaults are written: a config class loads its ini
    /// values over them.
    pub after_defaults: fn(),
}
inventory::collect!(ClassRegistration);

/// Submitted by `#[ustruct]`.
pub struct StructRegistration {
    /// Create the UScriptStruct (its handle).
    pub create: fn(),
    /// Add its properties, which may name Rust classes and structs: every
    /// class and struct exists by then.
    pub register: fn(),
    /// Link it, after the Rust structs it holds.
    pub finalize: fn(),
}
inventory::collect!(StructRegistration);

/// Submitted by `#[uclass_impl]` — holds register_functions fn pointer, and the
/// `#[class_defaults]` method's caller when the block has one.
pub struct ClassFunctionRegistration {
    /// The Rust type ID of the class the block implements.
    pub type_id: u64,
    pub register_functions: fn(),
    pub class_defaults: Option<fn()>,
}
inventory::collect!(ClassFunctionRegistration);

/// What a `#[class_defaults]` method may return: nothing, or a result whose
/// error is logged.
pub trait ClassDefaultsOutcome {
    fn report(self, class: &str);
}

impl ClassDefaultsOutcome for () {
    fn report(self, _class: &str) {}
}

impl ClassDefaultsOutcome for crate::error::RustealResult<()> {
    fn report(self, class: &str) {
        if let Err(e) = self {
            let msg = format!("[Rusteal] {class}: class defaults failed: {e}");
            let bytes = msg.as_bytes();
            unsafe {
                crate::ffi_dispatch::logging_log(1, bytes.as_ptr(), bytes.len() as u32);
            }
        }
    }
}

/// Registration in phases, parents before children: create every class →
/// create, fill and link every struct → add every class's properties and
/// components → register every function →
/// finalize each class and write its class defaults. A Rust class whose parent
/// is a Rust class is created after it and finalized after the parent's class
/// defaults, so its class default object starts from them.
pub fn register_all_from_inventory() {
    let mut pending: Vec<&ClassRegistration> = inventory::iter::<ClassRegistration>.into_iter().collect();
    let class_count = pending.len() as u32;
    let mut ordered: Vec<&ClassRegistration> = Vec::with_capacity(pending.len());
    loop {
        let before = pending.len();
        pending.retain(|reg| {
            if (reg.create)(false) {
                ordered.push(reg);
                false
            } else {
                true
            }
        });
        if pending.is_empty() || pending.len() == before {
            break;
        }
    }
    // Parents never created: log them.
    for reg in pending {
        (reg.create)(true);
    }

    // Structs, which classes' properties and functions may hold, and whose
    // properties may name classes.
    for sreg in inventory::iter::<StructRegistration> {
        (sreg.create)();
    }
    for sreg in inventory::iter::<StructRegistration> {
        (sreg.register)();
    }
    for sreg in inventory::iter::<StructRegistration> {
        (sreg.finalize)();
    }

    for reg in &ordered {
        (reg.register)();
    }
    let mut func_reg_count = 0u32;
    for freg in inventory::iter::<ClassFunctionRegistration> {
        (freg.register_functions)();
        func_reg_count += 1;
    }
    for reg in &ordered {
        (reg.finalize)();
        for freg in inventory::iter::<ClassFunctionRegistration> {
            if freg.type_id == reg.type_id
                && let Some(class_defaults) = freg.class_defaults
            {
                class_defaults();
            }
        }
        (reg.after_defaults)();
    }

    // Log registration summary (helps diagnose hot-reload issues).
    let total_funcs = read_or_recover(func_registry()).len();
    let msg = format!(
        "[Rusteal] register_all_from_inventory: {} classes, {} impl blocks, {} function callbacks",
        class_count, func_reg_count, total_funcs,
    );
    let bytes = msg.as_bytes();
    unsafe {
        crate::ffi_dispatch::logging_log(0, bytes.as_ptr(), bytes.len() as u32);
    }
}

use rusteal_ffi::UObjectHandle;

/// Information about a Rust type registered for reification.
pub struct RustTypeInfo {
    /// Human-readable type name (for debugging).
    pub name: &'static str,
    /// Allocate and return a default-initialized instance. The returned pointer
    /// must be freeable by `drop_fn`.
    pub construct_fn: fn() -> *mut u8,
    /// Drop and deallocate an instance previously created by `construct_fn`.
    pub drop_fn: unsafe fn(*mut u8),
}

use crate::ffi_dispatch::NativePtr;

// Type for reify function callbacks: (obj, rust_data, params)
// Uses Arc so we can clone the reference out of the registry and release
// the lock before invoking the callback (prevents deadlock if the callback
// makes FFI calls that re-enter Rust).
// `params` is an opaque FFI buffer pointer (`NativePtr` = `*mut u8`).
type ReifyFunctionCallback = Arc<dyn Fn(UObjectHandle, *mut u8, NativePtr) + Send + Sync>;

/// A registered function and the Rust type whose data it is called with.
struct FunctionEntry {
    callback: ReifyFunctionCallback,
    type_id: u64,
}

// ---------------------------------------------------------------------------
// Statics
// ---------------------------------------------------------------------------

static TYPE_REGISTRY: OnceLock<Mutex<HashMap<u64, RustTypeInfo>>> = OnceLock::new();
static FUNC_REGISTRY: OnceLock<RwLock<Vec<FunctionEntry>>> = OnceLock::new();
static INSTANCE_DATA: OnceLock<RwLock<HashMap<u64, Vec<InstanceEntry>>>> = OnceLock::new();

struct InstanceEntry {
    data: *mut u8,
    type_id: u64,
}

// SAFETY: The raw pointer in InstanceEntry is only accessed on the game thread.
unsafe impl Send for InstanceEntry {}
unsafe impl Sync for InstanceEntry {}

fn type_registry() -> &'static Mutex<HashMap<u64, RustTypeInfo>> {
    TYPE_REGISTRY.get_or_init(|| Mutex::new(HashMap::new()))
}

fn func_registry() -> &'static RwLock<Vec<FunctionEntry>> {
    FUNC_REGISTRY.get_or_init(|| RwLock::new(Vec::new()))
}

fn instance_data() -> &'static RwLock<HashMap<u64, Vec<InstanceEntry>>> {
    INSTANCE_DATA.get_or_init(|| RwLock::new(HashMap::new()))
}

// ---------------------------------------------------------------------------
// Type registry
// ---------------------------------------------------------------------------

/// Register a Rust type for reification. Must be called before `create_class`.
pub fn register_type(type_id: u64, info: RustTypeInfo) {
    lock_or_recover(type_registry())
        .insert(type_id, info);
}

// ---------------------------------------------------------------------------
// Function registry
// ---------------------------------------------------------------------------

/// Register a Rust function callback of the Rust type `type_id`, which it is
/// called with the data of, and return its unique callback ID.
pub fn register_function<F>(type_id: u64, f: F) -> u64
where
    F: Fn(UObjectHandle, *mut u8, NativePtr) + Send + Sync + 'static,
{
    let mut vec = write_or_recover(func_registry());
    let id = vec.len() as u64;
    vec.push(FunctionEntry { callback: Arc::new(f), type_id });
    id
}

// ---------------------------------------------------------------------------
// Instance lifecycle
// ---------------------------------------------------------------------------

/// Construct the Rust instance of the type `type_id` for a newly created
/// UObject, once per Rust class the object is. Called from the C++ class
/// constructor via `construct_rust_instance` callback.
pub fn construct_instance(obj: UObjectHandle, type_id: u64) {
    let types = lock_or_recover(type_registry());
    let Some(info) = types.get(&type_id) else {
        // Log warning — type not registered (might be a CDO before registration completes)
        if crate::api::is_api_initialized() {
            let msg = format!("[Rusteal] construct_instance: unknown type_id {type_id}");
            let bytes = msg.as_bytes();
            unsafe {
                crate::ffi_dispatch::logging_log(1, bytes.as_ptr(), bytes.len() as u32);
            }
        }
        return;
    };
    let data = (info.construct_fn)();
    drop(types); // Release lock before acquiring instance_data lock

    let key = obj.to_addr();
    let old = {
        let mut map = write_or_recover(instance_data());
        let entries = map.entry(key).or_default();
        match entries.iter_mut().find(|e| e.type_id == type_id) {
            Some(entry) => Some(std::mem::replace(&mut entry.data, data)),
            None => {
                entries.push(InstanceEntry { data, type_id });
                None
            }
        }
    };
    // A new object at the address of one whose deletion went unnoticed.
    if let Some(old) = old {
        drop_data(type_id, old);
    }
}

fn drop_data(type_id: u64, data: *mut u8) {
    let types = lock_or_recover(type_registry());
    if let Some(info) = types.get(&type_id) {
        unsafe {
            (info.drop_fn)(data);
        }
    }
}

/// Drop and remove the Rust instances of a destroyed UObject, every Rust
/// class's it is. Called from the C++ delete listener via
/// `drop_rust_instance` callback.
pub fn drop_instance(obj: UObjectHandle, _type_id: u64) {
    let key = obj.to_addr();
    let entries = write_or_recover(instance_data()).remove(&key);
    for entry in entries.into_iter().flatten() {
        drop_data(entry.type_id, entry.data);
    }
}

/// Invoke a registered Rust function callback.
/// Called from the C++ thunk via `invoke_rust_function` callback.
pub fn invoke_function(callback_id: u64, obj: UObjectHandle, params: NativePtr) {
    // Clone the callback Arc out of the registry and release the read lock
    // BEFORE invoking the callback. This prevents deadlocks if the callback
    // makes FFI calls that re-enter Rust.
    let func = {
        let vec = read_or_recover(func_registry());
        vec.get(callback_id as usize)
            .map(|entry| (entry.callback.clone(), entry.type_id))
    };

    if let Some((func, type_id)) = func {
        // The data of the Rust class the function belongs to.
        let rust_data = get_instance_data(obj, type_id);
        func(obj, rust_data, params);
    } else if crate::api::is_api_initialized() {
        let vec_len = read_or_recover(func_registry()).len();
        let msg = format!(
            "[Rusteal] invoke_function: callback_id {} not found (registry size = {})",
            callback_id, vec_len,
        );
        let bytes = msg.as_bytes();
        unsafe {
            crate::ffi_dispatch::logging_log(1, bytes.as_ptr(), bytes.len() as u32);
        }
    }
}

/// Clear all registries and drop all instance data.
/// Called during shutdown before DLL unload (enables hot reload).
pub fn clear_all() {
    // 1. Drop all instance data, using the type's drop_fn.
    if let Some(instances) = INSTANCE_DATA.get() {
        let mut map = write_or_recover(instances);
        let types = lock_or_recover(type_registry());
        for entry in map.drain().flat_map(|(_, entries)| entries) {
            if let Some(info) = types.get(&entry.type_id) {
                unsafe {
                    (info.drop_fn)(entry.data);
                }
            }
        }
        drop(types);
    }
    // 2. Clear function registry.
    if let Some(funcs) = FUNC_REGISTRY.get() {
        write_or_recover(funcs).clear();
    }
    // 3. Clear type registry.
    if let Some(types) = TYPE_REGISTRY.get() {
        lock_or_recover(types).clear();
    }
}

/// Get the Rust instance data pointer of the type `type_id` for a UObject.
/// Returns null if no instance data is registered.
pub fn get_instance_data(obj: UObjectHandle, type_id: u64) -> *mut u8 {
    let key = obj.to_addr();
    read_or_recover(instance_data())
        .get(&key)
        .and_then(|entries| entries.iter().find(|e| e.type_id == type_id))
        .map(|e| e.data)
        .unwrap_or(std::ptr::null_mut())
}