ReshadePluginsCore/libs/Unity/MonoLoader.hpp

#pragma once
#include <spdlog/spdlog.h>
#include <spdlog/sinks/basic_file_sink.h>

// Forward declarations Mono
struct MonoDomain;
struct MonoAssembly;
struct MonoImage;
struct MonoClass;
struct MonoMethod;
struct MonoMethodSignature;
struct MonoClassField;
struct MonoObject;
struct MonoThread;

// Typedefs pour les exports Mono
using mono_assembly_foreach_t = void(*)(void(*)(MonoAssembly*, void*), void*);
using mono_assembly_get_name_t = const void* (*)(MonoAssembly*);
using mono_assembly_name_get_name_t = const char* (*)(const void*);
using mono_class_get_methods_t = MonoMethod * (*)(MonoClass*, void**);
using mono_method_get_name_t = const char* (*)(MonoMethod*);
using mono_method_signature_t = MonoMethodSignature * (*)(MonoMethod*);
using mono_signature_get_param_count_t = uint32_t(*)(MonoMethodSignature*);
using mono_class_get_field_from_name_t = MonoClassField * (*)(MonoClass*, const char*);
using mono_runtime_invoke_t = MonoObject * (*)(MonoMethod*, void*, void**, MonoObject**);
using mono_field_get_offset_t = int (*)(MonoClassField*);
using mono_field_set_value_t = void (*)(MonoObject*, MonoClassField*, void*);
using mono_field_get_value_t = void (*)(MonoObject*, MonoClassField*, void*);

class MonoLoader {
public:
    MonoLoader() = default;
    ~MonoLoader() = default;


    bool Initialize(std::shared_ptr<spdlog::logger> log = nullptr, const char* monoName = "mono-2.0-bdwgc.dll");
    MonoDomain* GetDomain() const { return g_monoDomain; }

    /**
     * @brief Finds a Mono assembly by its name.
     * This function iterates over all loaded assemblies in the Mono domain and
     * returns a pointer to the assembly matching the given name.
     * @param name Name of the assembly to search for.
     * @return MonoAssembly* Pointer to the found assembly, or nullptr if not found.
     */
    MonoAssembly* FindAssembly(const std::string& name);

    /**
     * @brief Finds a class in a loaded assembly by namespace and name.
     * @param assemblyName Name of the assembly (ex: "UnityEngine.CoreModule").
     * @param namespaceName Namespace of the class (ex: "UnityEngine").
     * @param className Name of the class (ex: "Screen").
     * @return Pointer to the MonoClass, or nullptr if not found.
     */
    MonoClass* FindClass(const std::string& assemblyName, const std::string& namespaceName, const std::string& className);

    /**
     * @brief Finds a method in a MonoClass and compiles it.
     * @param monoClass The MonoClass to search in.
     * @param methodName The method name (ex: "get_width").
     * @param paramCount Number of parameters.
     * @return Compiled method address (uint8_t*), or nullptr if not found.
     */
    uint8_t* GetCompiledMethod(MonoClass* monoClass, const std::string& methodName, int paramCount);

    /**
     * @brief Attach the current thread to the Mono domain (required before invoking methods).
     * @return MonoThread* pointer to the attached thread.
     */
    MonoThread* AttachCurrentThread();

    /**
     * @brief Detach the current thread from the Mono runtime.
     * Should be called if AttachCurrentThread() was used on a manually created thread.
     * For the main thread, Mono typically handles detachment automatically.
     * @param thread Pointer to the MonoThread previously returned by AttachCurrentThread().
     */
    void DetachCurrentThread(MonoThread* thread);

    /**
     * @brief Retrieve a method from a Mono class by name and parameter count.
     * @param monoClass The MonoClass to search in.
     * @param methodName The name of the method.
     * @param paramCount Number of parameters (use -1 for any).
     * @return MonoMethod* pointer, or nullptr if not found.
     */
    MonoMethod* GetMethod(MonoClass* monoClass, const std::string& methodName, int paramCount);

    /**
     * @brief Invoke a Mono method safely.
     * @param method MonoMethod* to invoke.
     * @param obj MonoObject* instance, or nullptr for static methods.
     * @param params Array of pointers to arguments, or nullptr if none.
     * @param exception Optional pointer to MonoObject* to catch exceptions.
     * @return MonoObject* result of the method call, or nullptr.
     */
    MonoObject* InvokeMethod(MonoMethod* method, MonoObject* obj, void** params = nullptr, MonoObject** exception = nullptr);

    /**
     * @brief Dump all methods of a MonoClass to the log.
     * Iterates over all methods defined in the given MonoClass and logs their
     * names and signatures. Useful for debugging or exploring Mono assemblies.
     * @param monoClass Pointer to the MonoClass whose methods will be dumped.
     * @param log Optional logger to output the method information. If nullptr,
     *            no logging is performed.
     */
    void DumpMethods(MonoClass* monoClass, std::shared_ptr<spdlog::logger> log = nullptr);

    // Exports
    mono_assembly_foreach_t mono_assembly_foreach = nullptr;
    mono_assembly_get_name_t mono_assembly_get_name = nullptr;
    mono_assembly_name_get_name_t mono_assembly_name_get_name = nullptr;
    MonoDomain* (*mono_get_root_domain)() = nullptr;
    MonoThread* (*mono_thread_attach)(MonoDomain*) = nullptr;
    void* (*mono_thread_detach)(MonoThread*) = nullptr;
    MonoAssembly* (*mono_domain_assembly_open)(MonoDomain*, const char*) = nullptr;
    MonoImage* (*mono_assembly_get_image)(MonoAssembly*) = nullptr;
    MonoClass* (*mono_class_from_name)(MonoImage*, const char*, const char*) = nullptr;
    MonoMethod* (*mono_class_get_method_from_name)(MonoClass*, const char*, int) = nullptr;
    void* (*mono_compile_method)(MonoMethod*) = nullptr;
    mono_class_get_methods_t mono_class_get_methods = nullptr;
    mono_method_get_name_t mono_method_get_name = nullptr;
    mono_method_signature_t mono_method_signature = nullptr;
    mono_signature_get_param_count_t mono_signature_get_param_count = nullptr;
    mono_class_get_field_from_name_t mono_class_get_field_from_name = nullptr;
    mono_runtime_invoke_t mono_runtime_invoke = nullptr;
    mono_field_get_offset_t mono_field_get_offset = nullptr;
    mono_field_set_value_t mono_field_set_value = nullptr;
    mono_field_get_value_t mono_field_get_value = nullptr;

private:
    MonoDomain* g_monoDomain = nullptr;
    std::shared_ptr<spdlog::logger> logger;

    /**
     * @brief Waits for the Mono module to be loaded in the process and returns its handle.
     * This function loops every 200 ms until the "mono-2.0-bdwgc.dll" module
     * is present in the current process. Useful to ensure that Mono is initialized
     * before resolving its exports.
     * @return HMODULE Handle of the Mono module, or nullptr if not found (practically never).
     */
    HMODULE WaitForMono(const char* monoName);

    /**
     * @brief Callback used during Mono assembly enumeration.
     * This function is passed to `mono_assembly_foreach` and checks each loaded assembly
     * to find the one matching a specific name (provided via userData).
     * Can be used to initialize pointers to target assemblies.
     * @param assembly Pointer to the current assembly.
     * @param userData User data passed to `mono_assembly_foreach`, typically a structure
     *                 containing the target name and a location to store the result.
     */
    static void FindAssemblyCallback(MonoAssembly* assembly, void* userData);
};