// SPDX-License-Identifier: GPL-3.0-or-later

#pragma once

#include <aurora/aurora.h>

#include <cstdint>
#include <string>

namespace mkw::vr {

enum class OpenXRStartupResult {
    Disabled,
    Prepared,
    Unavailable,
};

// Performs the OpenXR instance/system and graphics-requirements work that must
// happen before Aurora selects an adapter. On success this may force the
// backend and populate AuroraConfig's XR interop fields.
OpenXRStartupResult OpenXRPrepareAurora(AuroraConfig& config);

// Completes the graphics binding and starts the asynchronous XR pacing thread.
// Call after aurora_initialize(), while Aurora's frame worker is idle.
bool OpenXRStartAfterAurora(AuroraBackend active_backend);

// Stops publishing stereo work, drains the pacing thread, and destroys the XR
// session before aurora_shutdown(). Safe to call after partial initialization.
void OpenXRShutdownBeforeAurora() noexcept;

// Services an XR-owned teardown request at the producer's safe frame boundary:
// after aurora_begin_frame() has granted the worker's prepare phase and before
// aurora_end_frame_tagged() seals the current frame. No-op unless the pacing
// thread has fallen back to desktop rendering.
void OpenXRServiceProducerFrameBoundary() noexcept;

bool OpenXRIsRunning() noexcept;

// Writes the controllers the pacing thread last published to the virtual
// gamepad. Call it from the thread that polls controllers, wherever the game
// is about to read them: the pacing thread deliberately leaves SDL alone, since
// SDL's joystick lock is held for the length of a device enumeration and an
// OpenXR frame may not wait that long. Cheap and safe to call when VR is off.
void OpenXRApplyControllerState() noexcept;
std::string OpenXRLastError();

// Recenters on where the player is sitting now: it moves the immersive race
// view's origin, and re-places the anchored menu screen upright in front of
// them. Position only for the race view: the forward direction and the horizon
// come from the OpenXR reference space and are never relatched from the
// headset, so recentering cannot tilt the game's horizon. Use the runtime's own
// recenter gesture to change forward. Callable from any thread; serviced once
// per frame on the XR pacing thread.
void OpenXRRequestRecenter() noexcept;

// Sets a fixed pitch of the game camera for a player sitting reclined, in
// degrees, clamped to RuntimeConfigFile::kVrLeanBackDegreesLimit. Positive
// tilts the camera back with the player, so an angle matching how far they are
// reclined puts the track back in front of them. 0 applies no pitch at all.
// Applies to the immersive race view only; callable from any thread and read
// once per published frame.
void OpenXRSetLeanBackDegrees(float degrees) noexcept;

// Shows the room through the headset's cameras around the menu screen and every
// other virtual screen, and around the immersive window, never during a fully
// immersive race. Only the standalone (Quest) backend offers it; elsewhere this
// changes nothing. Callable from any thread; applied on the XR pacing thread's
// next frame.
void OpenXRSetPassthrough(bool enabled) noexcept;

// The immersive window: an immersive race keeps its stereo view but is seen
// only through the screen its 2D layer sits on, with the room (or, without
// passthrough, black) around it. Callable from any thread; applied to the next
// published frame. Flat Screen mode, which keeps races off the immersive path
// altogether, makes it moot.
void OpenXRSetImmersiveWindow(bool enabled) noexcept;

// The headset's eye resolution, as a scale of the size the OpenXR runtime
// recommends (clamped to RuntimeConfigFile::kVrRenderScaleMin..Max). Callable
// from any thread. The pacing thread rebuilds the eye swapchains at it over the
// next two frames, never touching the one on display; a size the runtime
// cannot allocate keeps the eyes as they are.
void OpenXRSetRenderScale(float scale) noexcept;

// The left eye's image size: width x height is what the headset is shown now,
// scaled_width x scaled_height what `scale` gives on this headset. All zero
// while no OpenXR session runs.
struct OpenXREyeResolution {
    uint32_t width = 0;
    uint32_t height = 0;
    uint32_t scaled_width = 0;
    uint32_t scaled_height = 0;
};
OpenXREyeResolution OpenXRGetEyeResolution(float scale) noexcept;

// Live scene interpolation at the headset's own display deadlines.
// 0 = Off, 1 = Auto, otherwise 72/90/120 as a rendering-rate ceiling.
void OpenXRSetFrameInterpolationFps(uint32_t target) noexcept;
bool OpenXRFrameInterpolationAvailable() noexcept;

// This session started with XR_EXT_hand_tracking, so [vr] hand_tracking applies
// live (it is asked for when hand steering or tracked hands are on at launch).
bool OpenXRHandTrackingAvailable() noexcept;
struct OpenXRFrameTiming {
    float headset_hz = 0;
    float rendered_fps = 0; // Newly rendered pairs; excludes retained-layer repeats.
};
OpenXRFrameTiming OpenXRGetFrameTiming() noexcept;

} // namespace mkw::vr