// Minimal OpenXR bring-up for questshock's immersive Quest build. Keeps the
// game's own rendering untouched (see android/engine-patches/
// 11-android-openxr-present.patch) - this module only owns the OpenXR
// instance/session/swapchains and the final "submit quad layers instead of
// presenting to a window" step. No stereo rendering - the game composite is
// shown as a single flat quad floating in front of the viewer.
#ifndef QUESTSHOCK_XR_SESSION_H
#define QUESTSHOCK_XR_SESSION_H

#include <stdbool.h>

#ifdef __cplusplus
extern "C" {
#endif

// Call once, right after init_opengl() (OpenGL.cc) has created and made
// current the GL context SDL/gl4es already use - creates the OpenXR
// instance/session sharing that same EGL display/context, plus the game
// quad's own swapchain, sized to the game's logical resolution
// (game_width/height, i.e. grd_cap->w/h - see Shock.c's InitSDL()). The
// menu quad's own, independently-sized swapchain (see xr_menu.h) is created
// alongside it. Returns false if OpenXR bring-up failed (e.g. no runtime
// installed) - callers should fall back to the existing window-present path
// in that case.
bool xr_init(int game_width, int game_height);

// Pumps XR session-state events. Call once per frame, before
// xr_frame_begin(). Must still be called even when xr_init() returned
// false (no-op in that case).
void xr_poll_events(void);

// True once the session has reached a state where frames are expected
// (XR_SESSION_STATE_SYNCHRONIZED or later) - i.e. it's safe/required to
// start calling xr_frame_begin()/xr_frame_end() each frame.
bool xr_is_session_running(void);

// Begins the XR frame (xrWaitFrame/xrBeginFrame) and, if the runtime wants
// this frame rendered, acquires the game quad's next swapchain image and
// binds its framebuffer as the current render target - ready for the
// caller to draw into exactly as it would have drawn to the default
// framebuffer. Returns true if the caller should draw this frame;
// xr_frame_end() must be called unconditionally afterward either way (a
// begun XR frame must always be ended, rendered or not).
bool xr_frame_begin(void);

// Releases the game quad's swapchain image (if one was acquired this
// frame), acquires/renders/releases the menu quad's own swapchain image if
// it's currently visible (see xr_menu.h), submits whichever of the two
// quads actually rendered this frame as composition layers positioned in
// front of the local reference space's origin, then ends the XR frame.
void xr_frame_end(void);

void xr_shutdown(void);

// Local-space geometry of the single game quad xr_frame_end() submits
// (distance in front of the local space origin, half-width/half-height,
// all in meters) - shared with xr_input.c's ray/quad hit-testing so the
// laser pointer always matches whatever's actually visible.
void xr_get_game_quad_extent(float *distance_m, float *half_width_m, float *half_height_m);

#ifdef __cplusplus
}
#endif

#endif