/*
 * This file is part of mpv.
 *
 * mpv is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * mpv is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with mpv.  If not, see <http://www.gnu.org/licenses/>.
 *
 * You can alternatively redistribute this file and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 */

#include <X11/Xlib.h>
#include <EGL/egl.h>
#include <EGL/eglext.h>

#include "common/common.h"
#include "x11_common.h"
#include "gl_common.h"

struct priv {
    EGLDisplay egl_display;
    EGLContext egl_context;
    EGLSurface egl_surface;
};

static EGLConfig select_fb_config_egl(struct MPGLContext *ctx)
{
    struct priv *p = ctx->priv;

    EGLint attributes[] = {
        EGL_SURFACE_TYPE, EGL_WINDOW_BIT,
        EGL_RED_SIZE, 8,
        EGL_GREEN_SIZE, 8,
        EGL_BLUE_SIZE, 8,
        EGL_DEPTH_SIZE, 0,
        EGL_RENDERABLE_TYPE, EGL_OPENGL_BIT,
        EGL_NONE
    };

    EGLint config_count;
    EGLConfig config;

    eglChooseConfig(p->egl_display, attributes, &config, 1, &config_count);

    if (!config_count) {
        MP_FATAL(ctx->vo, "Could find EGL configuration!\n");
        return NULL;
    }

    return config;
}

static bool create_context_egl(MPGLContext *ctx, EGLConfig config,
                                EGLNativeWindowType window)
{
    struct priv *p = ctx->priv;

    EGLint context_attributes[] = {
        EGL_CONTEXT_MAJOR_VERSION_KHR,
        MPGL_VER_GET_MAJOR(ctx->requested_gl_version),
        EGL_NONE
    };

    p->egl_surface = eglCreateWindowSurface(p->egl_display, config, window, NULL);

    if (p->egl_surface == EGL_NO_SURFACE) {
        MP_FATAL(ctx->vo, "Could not create EGL surface!\n");
        return false;
    }

    p->egl_context = eglCreateContext(p->egl_display, config,
                                      EGL_NO_CONTEXT, context_attributes);

    if (p->egl_context == EGL_NO_CONTEXT) {
        MP_FATAL(ctx->vo, "Could not create EGL context!\n");
        return false;
    }

    eglMakeCurrent(p->egl_display, p->egl_surface, p->egl_surface,
                   p->egl_context);

    return true;
}

static bool config_window_x11_egl(struct MPGLContext *ctx, int flags)
{
    struct priv *p = ctx->priv;
    struct vo *vo = ctx->vo;

    if (p->egl_context) {
        vo_x11_config_vo_window(vo, NULL, flags, "gl");
        return true;
    }

    eglBindAPI(EGL_OPENGL_API);

    p->egl_display = eglGetDisplay(vo->x11->display);
    eglInitialize(p->egl_display, NULL, NULL);

    EGLConfig config = select_fb_config_egl(ctx);
    if (!config)
        return false;

    int vID, n;
    eglGetConfigAttrib(p->egl_display, config, EGL_NATIVE_VISUAL_ID, &vID);
    XVisualInfo template = {.visualid = vID};
    XVisualInfo *vi = XGetVisualInfo(vo->x11->display, VisualIDMask, &template, &n);

    if (!vi) {
        MP_FATAL(ctx->vo, "Getting X visual failed!\n");
        return false;
    }

    vo_x11_config_vo_window(vo, vi, flags, "gl");

    XFree(vi);

    if (!create_context_egl(ctx, config, (EGLNativeWindowType)vo->x11->window))
    {
        vo_x11_uninit(ctx->vo);
        return false;
    }

    void *(*gpa)(const GLubyte*) = (void *(*)(const GLubyte*))eglGetProcAddress;
    mpgl_load_functions(ctx->gl, gpa, NULL, vo->log);

    return true;
}

static void releaseGlContext_egl(MPGLContext *ctx)
{
    struct priv *p = ctx->priv;
    if (p->egl_context) {
        eglMakeCurrent(p->egl_display, EGL_NO_SURFACE, EGL_NO_SURFACE,
                       EGL_NO_CONTEXT);
        eglDestroyContext(p->egl_display, p->egl_context);
    }
    p->egl_context = EGL_NO_CONTEXT;
}

static void swapGlBuffers_egl(MPGLContext *ctx)
{
    struct priv *p = ctx->priv;
    eglSwapBuffers(p->egl_display, p->egl_surface);
}

void mpgl_set_backend_x11egl(MPGLContext *ctx)
{
    ctx->priv = talloc_zero(ctx, struct priv);
    ctx->config_window = config_window_x11_egl;
    ctx->releaseGlContext = releaseGlContext_egl;
    ctx->swapGlBuffers = swapGlBuffers_egl;
    ctx->vo_init = vo_x11_init;
    ctx->vo_uninit = vo_x11_uninit;
    ctx->vo_control = vo_x11_control;
}
