/**
 * Looking Glass
 * Copyright © 2017-2021 The Looking Glass Authors
 * https://looking-glass.io
 *
 * This program 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.
 *
 * This program 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 this program; if not, write to the Free Software Foundation, Inc., 59
 * Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include "texture_util.h"

#include <EGL/egl.h>
#include <GLES3/gl3.h>
#include <GLES2/gl2ext.h>

#include "egldebug.h"

/**
 * the following comes from drm_fourcc.h and is included here to avoid the
 * external dependency for the few simple defines we need
 */
#define fourcc_code(a, b, c, d) ((uint32_t)(a) | ((uint32_t)(b) << 8) | \
         ((uint32_t)(c) << 16) | ((uint32_t)(d) << 24))
#define DRM_FORMAT_ARGB8888      fourcc_code('A', 'R', '2', '4')
#define DRM_FORMAT_ABGR8888      fourcc_code('A', 'B', '2', '4')
#define DRM_FORMAT_BGRA1010102   fourcc_code('B', 'A', '3', '0')
#define DRM_FORMAT_ABGR16161616F fourcc_code('A', 'B', '4', 'H')

bool egl_texUtilGetFormat(const EGL_TexSetup * setup, EGL_TexFormat * fmt)
{
  switch(setup->pixFmt)
  {
    case EGL_PF_BGRA:
      fmt->bpp        = 4;
      fmt->format     = GL_BGRA_EXT;
      fmt->intFormat  = GL_BGRA_EXT;
      fmt->dataType   = GL_UNSIGNED_BYTE;
      fmt->fourcc     = DRM_FORMAT_ARGB8888;
      break;

    case EGL_PF_RGBA:
      fmt->bpp        = 4;
      fmt->format     = GL_RGBA;
      fmt->intFormat  = GL_RGBA;
      fmt->dataType   = GL_UNSIGNED_BYTE;
      fmt->fourcc     = DRM_FORMAT_ABGR8888;
      break;

    case EGL_PF_RGBA10:
      fmt->bpp        = 4;
      fmt->format     = GL_RGBA;
      fmt->intFormat  = GL_RGB10_A2;
      fmt->dataType   = GL_UNSIGNED_INT_2_10_10_10_REV;
      fmt->fourcc     = DRM_FORMAT_BGRA1010102;
      break;

    case EGL_PF_RGBA16F:
      fmt->bpp        = 8;
      fmt->format     = GL_RGBA;
      fmt->intFormat  = GL_RGBA16F;
      fmt->dataType   = GL_HALF_FLOAT;
      fmt->fourcc     = DRM_FORMAT_ABGR16161616F;
      break;

    default:
      DEBUG_ERROR("Unsupported pixel format");
      return false;
  }

  fmt->width      = setup->width;
  fmt->height     = setup->height;
  fmt->stride     = setup->stride;
  fmt->pitch      = setup->stride / fmt->bpp;
  fmt->bufferSize = setup->height * setup->stride;

  return true;
}

bool egl_texUtilGenBuffers(const EGL_TexFormat * fmt, EGL_TexBuffer * buffers,
    int count)
{
  for(int i = 0; i < count; ++i)
  {
    EGL_TexBuffer *buffer = &buffers[i];

    buffer->size = fmt->bufferSize;
    glGenBuffers(1, &buffer->pbo);
    glBindBuffer(GL_PIXEL_UNPACK_BUFFER, buffer->pbo);
    glBufferStorageEXT(
      GL_PIXEL_UNPACK_BUFFER,
      fmt->bufferSize,
      NULL,
      GL_MAP_WRITE_BIT          |
      GL_MAP_PERSISTENT_BIT_EXT |
      GL_MAP_COHERENT_BIT_EXT
    );

    if (!egl_texUtilMapBuffer(buffer))
      return false;
  }

  return true;
}

void egl_texUtilFreeBuffers(EGL_TexBuffer * buffers, int count)
{
  for(int i = 0; i < count; ++i)
  {
    EGL_TexBuffer *buffer = &buffers[i];

    if (!buffer->pbo)
      continue;

    egl_texUtilUnmapBuffer(buffer);
    glDeleteBuffers(1, &buffer->pbo);
    buffer->pbo = 0;
  }
}

bool egl_texUtilMapBuffer(EGL_TexBuffer * buffer)
{
  glBindBuffer(GL_PIXEL_UNPACK_BUFFER, buffer->pbo);
  buffer->map = glMapBufferRange(
      GL_PIXEL_UNPACK_BUFFER,
      0,
      buffer->size,
      GL_MAP_WRITE_BIT             |
      GL_MAP_UNSYNCHRONIZED_BIT    |
      GL_MAP_INVALIDATE_BUFFER_BIT |
      GL_MAP_PERSISTENT_BIT_EXT    |
      GL_MAP_COHERENT_BIT_EXT);

  if (!buffer->map)
    DEBUG_GL_ERROR("glMapBufferRange failed of %lu bytes", buffer->size);

  glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
  return buffer->map;
}

void egl_texUtilUnmapBuffer(EGL_TexBuffer * buffer)
{
  if (!buffer->map)
    return;

  glBindBuffer(GL_PIXEL_UNPACK_BUFFER, buffer->pbo);
  glUnmapBuffer(GL_PIXEL_UNPACK_BUFFER);
  glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
  buffer->map = NULL;
}