// Copyright 2019 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.

#pragma once

#include <string>

namespace Common {

/**
 * Provides a platform-independent interface for loading a dynamic library and retrieving symbols.
 * The interface maintains an internal reference count to allow one handle to be shared between
 * multiple users.
 */
class DynamicLibrary final {
public:
    /// Default constructor, does not load a library.
    explicit DynamicLibrary();

    /// Automatically loads the specified library. Call IsOpen() to check validity before use.
    explicit DynamicLibrary(const char* filename);

    /// Moves the library.
    DynamicLibrary(DynamicLibrary&&) noexcept;
    DynamicLibrary& operator=(DynamicLibrary&&) noexcept;

    /// Delete copies, we can't copy a dynamic library.
    DynamicLibrary(const DynamicLibrary&) = delete;
    DynamicLibrary& operator=(const DynamicLibrary&) = delete;

    /// Closes the library.
    ~DynamicLibrary();

    /// Returns the specified library name with the platform-specific suffix added.
    static std::string GetUnprefixedFilename(const char* filename);

    /// Returns the specified library name in platform-specific format.
    /// Major/minor versions will not be included if set to -1.
    /// If libname already contains the "lib" prefix, it will not be added again.
    /// Windows: LIBNAME-MAJOR-MINOR.dll
    /// Linux: libLIBNAME.so.MAJOR.MINOR
    /// Mac: libLIBNAME.MAJOR.MINOR.dylib
    static std::string GetVersionedFilename(const char* libname, int major = -1, int minor = -1);

    /// Returns true if a module is loaded, otherwise false.
    bool IsOpen() const {
        return handle != nullptr;
    }

    /// Loads (or replaces) the handle with the specified library file name.
    /// Returns true if the library was loaded and can be used.
    bool Open(const char* filename);

    /// Unloads the library, any function pointers from this library are no longer valid.
    void Close();

    /// Returns the address of the specified symbol (function or variable) as an untyped pointer.
    /// If the specified symbol does not exist in this library, nullptr is returned.
    void* GetSymbolAddress(const char* name) const;

    /// Obtains the address of the specified symbol, automatically casting to the correct type.
    /// Returns true if the symbol was found and assigned, otherwise false.
    template <typename T>
    bool GetSymbol(const char* name, T* ptr) const {
        *ptr = reinterpret_cast<T>(GetSymbolAddress(name));
        return *ptr != nullptr;
    }

private:
    /// Platform-dependent data type representing a dynamic library handle.
    void* handle = nullptr;
};

} // namespace Common
