////////////////////////////////////////////////////////////
//
// SFML - Simple and Fast Multimedia Library
// Copyright (C) 2007-2024 Laurent Gomila (laurent@sfml-dev.org)
//
// This software is provided 'as-is', without any express or implied warranty.
// In no event will the authors be held liable for any damages arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it freely,
// subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented;
//    you must not claim that you wrote the original software.
//    If you use this software in a product, an acknowledgment
//    in the product documentation would be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such,
//    and must not be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source distribution.
//
////////////////////////////////////////////////////////////

#pragma once

////////////////////////////////////////////////////////////
// Headers
////////////////////////////////////////////////////////////
#include <SFML/Config.hpp>

#include <SFML/Window/Context.hpp>
#include <SFML/Window/ContextSettings.hpp>

#include <SFML/System/Vector2.hpp>

#include <memory>

#include <cstdint>


namespace sf::priv
{
class WindowImpl;

////////////////////////////////////////////////////////////
/// \brief Abstract class representing an OpenGL context
///
////////////////////////////////////////////////////////////
class GlContext
{
public:
    ////////////////////////////////////////////////////////////
    /// \brief Get a shared_ptr to the shared context
    ///
    /// \return shared_ptr to the shared context
    ///
    ////////////////////////////////////////////////////////////
    static std::shared_ptr<void> getSharedContext();

    ////////////////////////////////////////////////////////////
    /// \brief Register an OpenGL object to be destroyed when its containing context is destroyed
    ///
    /// This is used for internal purposes in order to properly
    /// clean up OpenGL resources that cannot be shared bwteen
    /// contexts.
    ///
    /// \param object Object to be destroyed when its containing context is destroyed
    ///
    ////////////////////////////////////////////////////////////
    static void registerUnsharedGlObject(std::shared_ptr<void> object);

    ////////////////////////////////////////////////////////////
    /// \brief Unregister an OpenGL object from its containing context
    ///
    /// \param object Object to be unregister
    ///
    ////////////////////////////////////////////////////////////
    static void unregisterUnsharedGlObject(std::shared_ptr<void> object);

    ////////////////////////////////////////////////////////////
    /// \brief Acquires a context for short-term use on the current thread
    ///
    ////////////////////////////////////////////////////////////
    static void acquireTransientContext();

    ////////////////////////////////////////////////////////////
    /// \brief Releases a context after short-term use on the current thread
    ///
    ////////////////////////////////////////////////////////////
    static void releaseTransientContext();

    ////////////////////////////////////////////////////////////
    /// \brief Create a new context, not associated to a window
    ///
    /// This function automatically chooses the specialized class
    /// to use according to the OS.
    ///
    /// \return Pointer to the created context
    ///
    ////////////////////////////////////////////////////////////
    static std::unique_ptr<GlContext> create();

    ////////////////////////////////////////////////////////////
    /// \brief Create a new context attached to a window
    ///
    /// This function automatically chooses the specialized class
    /// to use according to the OS.
    ///
    /// \param settings     Creation parameters
    /// \param owner        Pointer to the owner window
    /// \param bitsPerPixel Pixel depth (in bits per pixel)
    ///
    /// \return Pointer to the created context
    ///
    ////////////////////////////////////////////////////////////
    static std::unique_ptr<GlContext> create(const ContextSettings& settings, const WindowImpl& owner, unsigned int bitsPerPixel);

    ////////////////////////////////////////////////////////////
    /// \brief Create a new context that embeds its own rendering target
    ///
    /// This function automatically chooses the specialized class
    /// to use according to the OS.
    ///
    /// \param settings Creation parameters
    /// \param size     Back buffer width and height
    ///
    /// \return Pointer to the created context
    ///
    ////////////////////////////////////////////////////////////
    static std::unique_ptr<GlContext> create(const ContextSettings& settings, Vector2u size);

    ////////////////////////////////////////////////////////////
    /// \brief Check whether a given OpenGL extension is available
    ///
    /// \param name Name of the extension to check for
    ///
    /// \return True if available, false if unavailable
    ///
    ////////////////////////////////////////////////////////////
    static bool isExtensionAvailable(std::string_view name);

    ////////////////////////////////////////////////////////////
    /// \brief Get the address of an OpenGL function
    ///
    /// \param name Name of the function to get the address of
    ///
    /// \return Address of the OpenGL function, 0 on failure
    ///
    ////////////////////////////////////////////////////////////
    static GlFunctionPointer getFunction(const char* name);

    ////////////////////////////////////////////////////////////
    /// \brief Get the currently active context
    ///
    /// \return The currently active context or a null pointer if none is active
    ///
    ////////////////////////////////////////////////////////////
    static const GlContext* getActiveContext();

    ////////////////////////////////////////////////////////////
    /// \brief Get the currently active context's ID
    ///
    /// The context ID is used to identify contexts when
    /// managing unshareable OpenGL resources.
    ///
    /// \return The active context's ID or 0 if no context is currently active
    ///
    ////////////////////////////////////////////////////////////
    static std::uint64_t getActiveContextId();

    ////////////////////////////////////////////////////////////
    /// \brief Destructor
    ///
    ////////////////////////////////////////////////////////////
    virtual ~GlContext();

    ////////////////////////////////////////////////////////////
    /// \brief Deleted copy constructor
    ///
    ////////////////////////////////////////////////////////////
    GlContext(const GlContext&) = delete;

    ////////////////////////////////////////////////////////////
    /// \brief Deleted copy assignment
    ///
    ////////////////////////////////////////////////////////////
    GlContext& operator=(const GlContext&) = delete;

    ////////////////////////////////////////////////////////////
    /// \brief Get the settings of the context
    ///
    /// Note that these settings may be different than the ones
    /// passed to the constructor; they are indeed adjusted if the
    /// original settings are not directly supported by the system.
    ///
    /// \return Structure containing the settings
    ///
    ////////////////////////////////////////////////////////////
    [[nodiscard]] const ContextSettings& getSettings() const;

    ////////////////////////////////////////////////////////////
    /// \brief Activate or deactivate the context as the current target for rendering
    ///
    /// A context is active only on the current thread, if you want to
    /// make it active on another thread you have to deactivate it
    /// on the previous thread first if it was active.
    /// Only one context can be active on a thread at a time, thus
    /// the context previously active (if any) automatically gets deactivated.
    ///
    /// \param active True to activate, false to deactivate
    ///
    /// \return True if operation was successful, false otherwise
    ///
    ////////////////////////////////////////////////////////////
    bool setActive(bool active);

    ////////////////////////////////////////////////////////////
    /// \brief Display what has been rendered to the context so far
    ///
    ////////////////////////////////////////////////////////////
    virtual void display() = 0;

    ////////////////////////////////////////////////////////////
    /// \brief Enable or disable vertical synchronization
    ///
    /// Activating vertical synchronization will limit the number
    /// of frames displayed to the refresh rate of the monitor.
    /// This can avoid some visual artifacts, and limit the framerate
    /// to a good value (but not constant across different computers).
    ///
    /// \param enabled True to enable v-sync, false to deactivate
    ///
    ////////////////////////////////////////////////////////////
    virtual void setVerticalSyncEnabled(bool enabled) = 0;

protected:
    ////////////////////////////////////////////////////////////
    /// \brief Default constructor
    ///
    /// This constructor is meant for derived classes only.
    ///
    ////////////////////////////////////////////////////////////
    GlContext();

    ////////////////////////////////////////////////////////////
    /// \brief Activate the context as the current target
    ///        for rendering
    ///
    /// \param current Whether to make the context current or no longer current
    ///
    /// \return True on success, false if any error happened
    ///
    ////////////////////////////////////////////////////////////
    virtual bool makeCurrent(bool current) = 0;

    ////////////////////////////////////////////////////////////
    /// \brief Notify unshared GlResources of context destruction
    ///
    ////////////////////////////////////////////////////////////
    void cleanupUnsharedResources();

    ////////////////////////////////////////////////////////////
    /// \brief Evaluate a pixel format configuration
    ///
    /// This functions can be used by implementations that have
    /// several valid formats and want to get the best one.
    /// A score is returned for the given configuration: the
    /// lower the score is, the better the configuration is.
    ///
    /// \param bitsPerPixel Requested pixel depth (bits per pixel)
    /// \param settings     Requested additional settings
    /// \param colorBits    Color bits of the configuration to evaluate
    /// \param depthBits    Depth bits of the configuration to evaluate
    /// \param stencilBits  Stencil bits of the configuration to evaluate
    /// \param antiAliasing Anti-aliasing level of the configuration to evaluate
    /// \param accelerated  Whether the pixel format is hardware accelerated
    /// \param sRgb         Whether the pixel format is sRGB capable
    ///
    /// \return Score of the configuration
    ///
    ////////////////////////////////////////////////////////////
    static int evaluateFormat(unsigned int           bitsPerPixel,
                              const ContextSettings& settings,
                              int                    colorBits,
                              int                    depthBits,
                              int                    stencilBits,
                              int                    antiAliasing,
                              bool                   accelerated,
                              bool                   sRgb);

    ////////////////////////////////////////////////////////////
    // Member data
    ////////////////////////////////////////////////////////////
    ContextSettings m_settings; //!< Creation settings of the context

private:
    struct TransientContext;
    struct SharedContext;
    struct Impl;

    ////////////////////////////////////////////////////////////
    /// \brief Perform various initializations after the context construction
    /// \param requestedSettings Requested settings during context creation
    ///
    ////////////////////////////////////////////////////////////
    void initialize(const ContextSettings& requestedSettings);

    ////////////////////////////////////////////////////////////
    /// \brief Check whether the context is compatible with the requested settings
    /// \param requestedSettings Requested settings during context creation
    ///
    ////////////////////////////////////////////////////////////
    void checkSettings(const ContextSettings& requestedSettings) const;

    ////////////////////////////////////////////////////////////
    // Member data
    ////////////////////////////////////////////////////////////
    const std::unique_ptr<Impl> m_impl; //!< Implementation details
};

} // namespace sf::priv
