prism/engine/platform/include/platform.hpp

#pragma once

#include <functional>
#include <string>
#include <string_view>

#include "common.hpp"
#include "gfx_context.hpp"

/// Requestable window flags, which may or may not be respected by the platform.
enum class WindowFlags {
    None = 0,
    Resizable = 2,
    Borderless = 4,
    Hidden = 8
};

inline WindowFlags operator|(const WindowFlags a, const WindowFlags b) {
    return static_cast<WindowFlags>(static_cast<int>(a) | static_cast<int>(b));
}

inline bool operator&(const WindowFlags a, const WindowFlags b) {
    return static_cast<int>(a) & static_cast<int>(b);
}

/// Represents a button. This includes keyboard, gamepad and mouse buttons.
enum class InputButton {
    Invalid,
    C,
    V,
    X,
    Y,
    Z,
    Backspace,
    Enter,
    W,
    A,
    S,
    D,
    Q,
    Shift,
    Alt,
    Super,
    Escape,
    Tab,
    Ctrl,
    Space,
    LeftArrow,
    RightArrow,

    // gamepad inputs
    ButtonA,
    ButtonB,
    ButtonX,
    ButtonY,

    DPadUp,
    DPadDown,
    DPadLeft,
    DPadRight,

    // mouse inputs
    MouseLeft,
    MouseRight
};

enum class PlatformFeature {
    Windowing
};

/// On platforms that has a GUI with a seperate light/dark mode.
enum class PlatformTheme {
    Light,
    Dark
};

// note: a platform may be built with support for a specific context (e.g. ENABLE_VULKAN, ENABLE_DIRECTX, etc)
// this only determines it at build-time, not at runtime.
#ifdef ENABLE_VULKAN
    #include <vector>
    #include <vulkan/vulkan.h>

struct vulkan_information {
    std::vector<const char*> surface_extensions;
};

struct vulkan_surface_creation_info {
    VkInstance instance;
};

struct vulkan_surface {
    VkSurfaceKHR surface;
};
#endif

#ifdef ENABLE_DIRECTX
struct directx_surface_creation_info {
    // TODO: stub
};
#endif

#ifdef ENABLE_METAL
    #include <Metal/Metal.hpp>
    #include <QuartzCore/CAMetalDrawable.hpp>

struct metal_surface_creation_info {
    MTL::Device* device;
};

struct metal_surface {
    MTL::PixelFormat format;
};

using metal_next_image = CA::MetalDrawable*;
#endif

namespace platform {
    using window_ptr = void*;

    /// Returns a human readable platform name, e.g. Linux.
    const char* get_name();

    /// Returns the current platform theme.
    PlatformTheme get_theme();

    /// Queries whether or not the platform supports a certain feature.
    bool supports_feature(PlatformFeature feature);

    /*
     * This queries whether the context is supported by the platform at build-time. This does not mean the
     * context can be used properly at runtime, this is handled by GFX::is_supported().
     */
    bool supports_context(GFXContext context);

    /**
     * This initializes before window creation, for a specific gfx context type. This is designed to be called within
     * helper classes such as gfx_chooser, but may also be called within a platform implementation as well.
     * @param context
     */
    void initialize_context(GFXContext context);

    /*
     * This is used in specific cases where the gfx backend may need to know important information before window
     * creation. A good example is the surface extension required by a specific window backend, but this is between
     * initialize_context and create_surface calls.
     *
     * the returned structs are in a naming scheme of X_information.
     */
    void* get_context_information();

    /** Opens a new window.
     @param title The title of the window.
     @param rect The requested size and position of the window.
     @param flags The requested window flags.
     @note Depending on the platform, some of these parameters might be unused. The best practice is to always assume
     that none of them may be used.
     @note On platforms that do not support the Windowing feature, calling open_window more than once is not supported.
     In this case, the same identifier is returned.
     @return A valid window identifier.
     */
    window_ptr open_window(std::string_view title, prism::Rectangle rect, WindowFlags flags);

    bool is_main_window(window_ptr index);

    /*
     * This creates a new surface, with the gfx context type already set ahead of time (see initialize_context)
     * The parameter 'surface_creation_info' must be a type of the gfx context you want to use, and support must be
     * built at build-time (ENABLE_VULKAN, gfx context is Vulkan, and the struct would be vulkan_surface_creation_info.)
     *
     * The return type is usually {Your GFX Context}_surface, such as vulkan_surface. See each gfx context's struct for
     * more information.
     */
    void* create_surface(window_ptr window, void* surface_creation_info);

    /*
     * This needs to be implemented under certain gfx contexts (such as metal) which calls [layer nextDrawable]
     * underneath can be no-op for contexts such as vulkan which can happen within it's own API.
     *
     * the return type is named as X_next_image. may be null.
     */
    void* get_next_image(window_ptr window);

    /** Closes a window.
     @param index The window to close.
     */
    void close_window(window_ptr window);

    /// Forces the platform to quit the application. This is not related to Engine::quit().
    void force_quit();

    /// Gets the content scale for the monitor. 1.0 would be 1x scale, 2.0 would be 2x scale, etc.
    float get_monitor_dpi();

    /// Get the monitor resolution.
    prism::Rectangle get_monitor_resolution();

    /// Get the monitor work area. For example on macOS this may exclude the areas of the menu bar and dock.
    prism::Rectangle get_monitor_work_area();

    /// Get the window position.
    prism::Offset get_window_position(window_ptr window);

    /// Get the window size, note that in hidpi scenarios this is the non-scaled resolution.
    prism::Extent get_window_size(window_ptr window);

    /// Get the window's drawable size. Always use this instead of manually multiplying the window size by the content
    /// scale.
    prism::Extent get_window_drawable_size(window_ptr window);

    /// Query whether or not the window is focused.
    bool is_window_focused(window_ptr window);

    /// If possible, try to manually focus the window.
    void set_window_focused(window_ptr window);

    /// Sets the window position to the offset provided.
    void set_window_position(window_ptr window, prism::Offset offset);

    /// Sets the window to the specified size. The platform will handle the subsequent resize events.
    void set_window_size(window_ptr window, prism::Extent extent);

    /// Sets the window title.
    void set_window_title(window_ptr window, std::string_view title);

    /// Show window
    void show_window(window_ptr window);

    /// Queries whether or not the button is currently pressed.
    bool get_key_down(InputButton key);

    /// If available for the InputButton, returns the platform-specific keycode.
    int get_keycode(InputButton key);

    /// Returns the current moue cursor position, relative to the window.
    prism::Offset get_cursor_position();

    /// Returns the current moue cursor position, relative to the monitor.
    prism::Offset get_screen_cursor_position();

    /// Queries whether or not the mouse button requested is pressed or not.
    bool get_mouse_button_down(int button);

    /// Returns the current mouse wheel delta on both axes.
    std::tuple<float, float> get_wheel_delta();

    /// Returns the current right stick axes values from 0->1
    std::tuple<float, float> get_right_stick_position();

    /// Returns the current left stick axes values  from 0->1
    std::tuple<float, float> get_left_stick_position();

    /// On platforms that support moue capture, this will lock the mouse cursor to the window and hide it.
    void capture_mouse(bool capture);

    // TODO: right now the OS intercepting and saying "We dont want text input anymore" ala software keyboards is NOT
    // supported yet
    void begin_text_input();

    void end_text_input();
} // namespace platform