/**
 * Copyright © 2014  Mattias Andrée (maandree@member.fsf.org)
 * 
 * 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 3 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 Affero General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include <alloca.h>

#ifndef O_CLOEXEC
  #define O_CLOEXEC  02000000
#endif

/* Requires video group */
#include <xf86drm.h>
#include <xf86drmMode.h>



/**
 * File descriptor for the DRM connection
 */
static int drm_fd;

/**
 * DRM mode resources
 */
static drmModeRes* drm_res = NULL;

/**
 * Connector information
 */
static drmModeConnector* connector = NULL;



/**
 * Get the number of cards present on the system
 * 
 * @return  The number of cards present on the system
 */
int blueshift_drm_card_count()
{
  long maxlen = strlen(DRM_DIR_NAME) + strlen(DRM_DEV_NAME) + 10;
  char* pathname = alloca(maxlen * sizeof(char));
  int count = 0;
  struct stat attr;
  
  for (;;)
    {
      sprintf(pathname, DRM_DEV_NAME, DRM_DIR_NAME, count);
      if (stat(pathname, &attr))
	break;
      count++;
    }
  
  return count;
}


/**
 * Open connection to a graphics card
 * 
 * @param   card  The index of the graphics card
 * @return        Zero on success
 */
int blueshift_drm_open(int card)
{
  long maxlen = strlen(DRM_DIR_NAME) + strlen(DRM_DEV_NAME) + 10;
  char* pathname = alloca(maxlen * sizeof(char));
  
  sprintf(pathname, DRM_DEV_NAME, DRM_DIR_NAME, card);
  
  drm_fd = open(pathname, O_RDWR | O_CLOEXEC);
  if (drm_fd < 0)
    {
      perror("open");
      return 1;
    }
  
  return 0;
}


/**
 * Close connection to the graphics card
 */
void blueshift_drm_close()
{
  drmModeFreeResources(drm_res);
  close(drm_fd);
}


/**
 * Update the resource, required after `blueshift_drm_open`
 */
void blueshift_drm_update()
{
  if (drm_res)
    drmModeFreeResources(drm_res);
  
  drm_res = drmModeGetResources(drm_fd);
}


/**
 * Return the number of CRTC:s on the opened card
 * 
 * @return  The number of CRTC:s on the opened card
 */
int blueshift_drm_crtc_count()
{
  return drm_res->count_crtcs;
}


/**
 * Return the number of connectors on the opened card
 * 
 * @return  The number of connectors on the opened card
 */
int blueshift_drm_connector_count()
{
  return drm_res->count_connectors;
}


/**
 * Return the size of the gamma ramps on a CRTC
 * 
 * @param   crtc_index  The index of the CRTC
 * @return              The size of the gamma ramps on a CRTC
 */
int blueshift_drm_gamma_size(int crtc_index)
{
  drmModeCrtc* crtc = drmModeGetCrtc(drm_fd, *(drm_res->crtcs + crtc_index));
  int gamma_size;
  
  gamma_size = crtc->gamma_size;
  drmModeFreeCrtc(crtc);
  
  return gamma_size;
}


/**
 * Acquire information about a connector
 * 
 * @param  connector_index  The index of the connector
 */
void blueshift_drm_open_connector(int connector_index)
{
  connector = drmModeGetConnector(drm_fd, *(drm_res->connectors + connector_index));
}


/**
 * Release information about the connector
 */
void blueshift_drm_close_connector()
{
  drmModeFreeConnector(connector);
}


/* Accurate dimension on area not covered by the edges */

/**
 * Get the physical width the monitor connected to the connector
 * 
 * @return  The physical width of the monitor in millimetres, 0 if unknown or not connected
 */
int blueshift_drm_get_width()
{
  return connector->mmWidth;
}


/**
 * Get the physical height the monitor connected to the connector
 * 
 * @return  The physical height of the monitor in millimetres, 0 if unknown or not connected
 */
int blueshift_drm_get_height()
{
  return connector->mmHeight;
}


/**
 * Get whether a monitor is connected to a connector
 * 
 * @return  1 if there is a connection, 0 otherwise, -1 if unknown
 */
int blueshift_drm_is_connected()
{
  switch (connector->connection)
    {
    case DRM_MODE_CONNECTED:
      return 1;
    case DRM_MODE_DISCONNECTED:
      return 0;
    case DRM_MODE_UNKNOWNCONNECTION:
    default:
      return -1;
    }
}


/**
 * Get the index of the CRTC of the monitor connected to the connector
 * 
 * @return  The index of the CRTC
 */
int blueshift_drm_get_crtc()
{
  drmModeEncoder* encoder = drmModeGetEncoder(drm_fd, connector->encoder_id);
  uint32_t crtc_id = encoder->crtc_id;
  int crtc;
  
  drmModeFreeEncoder(encoder);
  
  for (crtc = 0; crtc < drm_res->count_crtcs; crtc++)
    if (*(drm_res->crtcs + crtc) == crtc_id)
      return crtc;
  
  return -1;
}


/**
 * Get the index of the type of the connector
 * 
 * @return  The connector type by index, 0 for unknown
 */
int blueshift_drm_get_connector_type_index()
{
  return connector->connector_type;
}


/**
 * Get the name of the type of the connector
 * 
 * @return  The connector type by name, "Unknown" if not identifiable,
 *          "Unrecognised" if Blueshift does not recognise it.
 */
const char* blueshift_drm_get_connector_type_name()
{
  static const char* TYPE_NAMES[] = {
    "Unknown", "VGA", "DVII", "DVID", "DVIA", "Composite", "SVIDEO", "LVDS", "Component",
    "9PinDIN", "DisplayPort", "HDMIA", "HDMIB", "TV", "eDP", "VIRTUAL", "DSI"};
  
  int type = connector->connector_type;
  return (size_t)type < sizeof(TYPE_NAMES) / sizeof(char*) ? TYPE_NAMES[type] : "Unrecognised";
}



int main(int argc, char** argv)
{
  (void) argc;
  (void) argv;
  
  
  printf("Card count: %i\n", blueshift_drm_card_count());
  
  blueshift_drm_open(0);
  blueshift_drm_update();
  blueshift_drm_open_connector(3);
  
  printf("CRTC count: %i\n", blueshift_drm_crtc_count());
  printf("Connector count: %i\n", blueshift_drm_connector_count());
  printf("Gamma size: %i\n", blueshift_drm_gamma_size(0));
  printf("Physical size: %i mm by %i mm\n", blueshift_drm_get_width(), blueshift_drm_get_height());
  printf("Connected: %i\n", blueshift_drm_is_connected());
  if (blueshift_drm_is_connected() == 1)
    {;
      int crtc = blueshift_drm_get_crtc();
      if (crtc >= 0)
	{
	  int gamma_size = blueshift_drm_gamma_size(crtc);
	  uint16_t* red = alloca(gamma_size * sizeof(uint16_t));
	  uint16_t* green = alloca(gamma_size * sizeof(uint16_t));
	  uint16_t* blue = alloca(gamma_size * sizeof(uint16_t));
	  int j;
	  
	  printf("CRTC: %i\n", crtc);
	  
	  /* We need to initialise it to avoid valgrind warnings */
	  for (j = 0; j < gamma_size; j++)
	    *(red + j) = *(green + j) = *(blue + j) = 0;
	  
	  if (!drmModeCrtcGetGamma(drm_fd, *(drm_res->crtcs + crtc), gamma_size, red, green, blue))
	    {
	      printf("Red:");
	      for (j = 0; j < gamma_size; j++)
		printf(" %u", *(red + j));
	      printf("\nGreen:");
	      for (j = 0; j < gamma_size; j++)
		printf(" %u", *(green + j));
	      printf("\nBlue:");
	      for (j = 0; j < gamma_size; j++)
		printf(" %u", *(blue + j));
	      printf("\n");
	      
	      for (j = 0; j < gamma_size; j++)
		*(red + j) /= 2;
	      for (j = 0; j < gamma_size; j++)
		*(green + j) /= 2;
	      for (j = 0; j < gamma_size; j++)
		*(blue + j) /= 2;
	      
	      drmModeCrtcSetGamma(drm_fd, *(drm_res->crtcs + crtc), gamma_size, red, green, blue);
	      /* TODO what more is required to set gamma ramps? */
	    }
	}
      
      int i;
      for (i = 0; i < connector->count_props; i++)
	{
	  drmModePropertyRes* prop;
	  prop = drmModeGetProperty(drm_fd, connector->props[i]);
	  if (!strcmp("EDID", prop->name))
	    {
	      drmModePropertyBlobRes* blob = drmModeGetPropertyBlob(drm_fd, connector->prop_values[i]);
	      char* value = alloca((blob->length * 2 + 1) * sizeof(char));
	      uint32_t j;
	      for (j = 0; j < blob->length; j++)
		{
		  *(value + j * 2 + 0) = "0123456789abcdef"[(*((char*)(blob->data) + j) >> 4) & 15];
		  *(value + j * 2 + 1) = "0123456789abcdef"[(*((char*)(blob->data) + j) >> 0) & 15];
		}
	      *(value + blob->length * 2) = 0;
	      printf("%s: %s\n", prop->name, value);
	      drmModeFreePropertyBlob(blob);
	    }
	  drmModeFreeProperty(prop);
	}
    }
  printf("Connector type: %s (%i)\n",
	 blueshift_drm_get_connector_type_name(),
	 blueshift_drm_get_connector_type_index());
  
  blueshift_drm_close_connector();
  blueshift_drm_close();
  
  return 0;
}