#include <EGL/egl.h>
#include <EGL/eglext.h>
#include <gbm.h> // GBM_FORMAT_XRGB8888

#include "backend/egl.h"
#include "common/log.h"

static const char *egl_error(void) {
	switch (eglGetError()) {
	case EGL_SUCCESS:
		return "Success";
	case EGL_NOT_INITIALIZED:
		return "Not initialized";
	case EGL_BAD_ACCESS:
		return "Bad access";
	case EGL_BAD_ALLOC:
		return "Bad alloc";
	case EGL_BAD_ATTRIBUTE:
		return "Bad attribute";
	case EGL_BAD_CONTEXT:
		return "Bad Context";
	case EGL_BAD_CONFIG:
		return "Bad Config";
	case EGL_BAD_CURRENT_SURFACE:
		return "Bad current surface";
	case EGL_BAD_DISPLAY:
		return "Bad display";
	case EGL_BAD_SURFACE:
		return "Bad surface";
	case EGL_BAD_MATCH:
		return "Bad match";
	case EGL_BAD_PARAMETER:
		return "Bad parameter";
	case EGL_BAD_NATIVE_PIXMAP:
		return "Bad native pixmap";
	case EGL_BAD_NATIVE_WINDOW:
		return "Bad native window";
	case EGL_CONTEXT_LOST:
		return "Context lost";
	default:
		return "Unknown";
	}
}

// EGL extensions
PFNEGLGETPLATFORMDISPLAYEXTPROC get_platform_display;
PFNEGLCREATEPLATFORMWINDOWSURFACEEXTPROC create_platform_window_surface;

static bool egl_exts() {
	get_platform_display = (PFNEGLGETPLATFORMDISPLAYEXTPROC)
		eglGetProcAddress("eglGetPlatformDisplayEXT");

	if (!get_platform_display) {
		wlr_log(L_ERROR, "Failed to load EGL extension 'eglGetPlatformDisplayEXT'");
		return false;
	}

	create_platform_window_surface = (PFNEGLCREATEPLATFORMWINDOWSURFACEEXTPROC)
		eglGetProcAddress("eglCreatePlatformWindowSurfaceEXT");

	if (!get_platform_display) {
		wlr_log(L_ERROR,
			"Failed to load EGL extension 'eglCreatePlatformWindowSurfaceEXT'");
		return false;
	}

	return true;
}

static bool egl_get_config(EGLDisplay disp, EGLConfig *out) {
	EGLint count = 0, matched = 0, ret;

	ret = eglGetConfigs(disp, NULL, 0, &count);
	if (ret == EGL_FALSE || count == 0) {
		return false;
	}

	EGLConfig configs[count];

	ret = eglChooseConfig(disp, NULL, configs, count, &matched);
	if (ret == EGL_FALSE) {
		return false;
	}

	for (int i = 0; i < matched; ++i) {
		EGLint gbm_format;

		if (!eglGetConfigAttrib(disp,
					configs[i],
					EGL_NATIVE_VISUAL_ID,
					&gbm_format)) {
			continue;
		}

		// XXX: Is GBM_FORMAT_XRGB8888 what we want?
		// I don't know if this works for wl_displays.
		if (gbm_format == GBM_FORMAT_XRGB8888) {
			*out = configs[i];
			return true;
		}
	}

	return false;
}


bool wlr_egl_init(struct wlr_egl *egl, EGLenum platform, void *display) {
	if (!egl_exts()) {
		return false;
	}
	
	if (eglBindAPI(EGL_OPENGL_ES_API) == EGL_FALSE) {
		wlr_log(L_ERROR, "Failed to bind to the OpenGL ES API: %s", egl_error());
		goto error;
	}

	egl->display = get_platform_display(platform, display, NULL);
	if (egl->display == EGL_NO_DISPLAY) {
		wlr_log(L_ERROR, "Failed to create EGL display: %s", egl_error());
		goto error;
	}

	if (eglInitialize(egl->display, NULL, NULL) == EGL_FALSE) {
		wlr_log(L_ERROR, "Failed to initialize EGL: %s", egl_error());
		goto error;
	}

	if (!egl_get_config(egl->display, &egl->config)) {
		wlr_log(L_ERROR, "Failed to get EGL config");
		goto error;
	}

	static const EGLint attribs[] = {EGL_CONTEXT_CLIENT_VERSION, 3, EGL_NONE};

	egl->context = eglCreateContext(egl->display, egl->config,
		EGL_NO_CONTEXT, attribs);

	if (egl->context == EGL_NO_CONTEXT) {
		wlr_log(L_ERROR, "Failed to create EGL context: %s", egl_error());
		goto error;
	}

	return true;

error:
	eglTerminate(egl->display);
	eglReleaseThread();
	eglMakeCurrent(EGL_NO_DISPLAY, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);

	return false;
}

void wlr_egl_free(struct wlr_egl *egl) {
	eglDestroyContext(egl->display, egl->context);
	eglTerminate(egl->display);
	eglReleaseThread();
	eglMakeCurrent(EGL_NO_DISPLAY, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);	
}

EGLSurface wlr_egl_create_surface(struct wlr_egl *egl, void *window) {
	EGLSurface surf = create_platform_window_surface(egl->display, egl->config,
		window, NULL);
	if (surf == EGL_NO_SURFACE) {
		wlr_log(L_ERROR, "Failed to create EGL surface: %s", egl_error());
		return EGL_NO_SURFACE;
	}

	return surf;
}