/**
 * cg-tools -- Cooperative gamma-enabled tools
 * Copyright (C) 2016  Mattias Andrée (maandree@kth.se)
 * 
 * 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 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 "cg-base.h"

#include <libclut.h>

#if defined(_GNU_SOURCE)
# undef _GNU_SOURCE
#endif
#include <errno.h>
#include <sched.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>



/**
 * The default filter priority for the program
 */
const int64_t default_priority = ((int64_t)3) << 59;

/**
 * The default class for the program
 */
char default_class[] = PKGNAME "::cg-sleepmode::standard";



/**
 * -r: fade-out time for the red channel
 */
static char* rflag;

/**
 * -g: fade-out time for the green channel
 */
static char* gflag;

/**
 * -b: fade-out time for the blue channel
 */
static char* bflag;

/**
 * The duration, in seconds, of the red channel's fade out
 */
static double red_time = 3;

/**
 * The duration, in seconds, of the green channel's fade out
 */
static double green_time = 2;

/**
 * The duration, in seconds, of the blue channel's fade out
 */
static double blue_time = 1;

/**
 * The luminosity of red channel after the fade out
 */
static double red_target = 0.5;

/**
 * The luminosity of green channel after the fade out
 */
static double green_target = 0;

/**
 * The luminosity of blue channel after the fade out
 */
static double blue_target = 0;

/**
 * Time to fade in?
 */
static volatile sig_atomic_t received_int = 0;



/**
 * Print usage information and exit
 */
void usage(void)
{
  fprintf(stderr,
	  "Usage: %s [-M method] [-S site] [-c crtc]... [-R rule] [-p priority] "
	  "[-r red-fadeout-time] [-g green-fadeout-time] [-b blue-fadeout-time] "
	  "[red-luminosity [green-luminosity [blue-luminosity]]]\n",
	  argv0);
  exit(1);
}


/**
 * Called when a signal is received
 * that tells the program to terminate
 * 
 * @param  signo  The received signal
 */
static void sig_int(int signo)
{
  received_int = 1;
  (void) signo;
}


/**
 * Handle a command line option
 * 
 * @param   opt  The option, it is a NUL-terminate two-character
 *               string starting with either '-' or '+', if the
 *               argument is not recognised, call `usage`. This
 *               string will not be "-M", "-S", "-c", "-p", or "-R".
 * @param   arg  The argument associated with `opt`,
 *               `NULL` there is no next argument, if this
 *               parameter is `NULL` but needed, call `usage`
 * @return       0 if `arg` was not used,
 *               1 if `arg` was used,
 *               -1 on error
 */
int handle_opt(char* opt, char* arg)
{
  if (opt[0] == '-')
    switch (opt[1])
      {
      case 'r':
	if (rflag || !(rflag = arg))
	  usage();
	return 1;
      case 'g':
	if (gflag || !(gflag = arg))
	  usage();
	return 1;
      case 'b':
	if (bflag || !(bflag = arg))
	  usage();
	return 1;
      default:
	usage();
      }
  else
    usage();
  return 0;
}


/**
 * Parse a non-negative double encoded as a string
 * 
 * @param   out  Output parameter for the value
 * @param   str  The string
 * @retunr       Zero on success, -1 if the string is invalid
 */
static int parse_double(double* restrict out, const char* restrict str)
{
  char* end;
  errno = 0;
  *out = strtod(str, &end);
  if (errno || (*out < 0) || isinf(*out) || isnan(*out) || *end)
    return -1;
  if (!*str || !strchr("0123456789.", *str))
    return -1;
  return 0;
}


/**
 * This function is called after the last
 * call to `handle_opt`
 * 
 * @param   argc  The number of unparsed arguments
 * @param   argv  `NULL` terminated list of unparsed arguments
 * @param   prio  The argument associated with the "-p" option
 * @return        Zero on success, -1 on error
 */
int handle_args(int argc, char* argv[], char* prio)
{
  int q = (rflag || gflag || bflag || argc);
  if ((q > 1) || (argc > 3))
    usage();
  if (rflag != NULL)
    if (parse_double(&red_time, rflag) < 0)
      usage();
  if (gflag != NULL)
    if (parse_double(&green_time, gflag) < 0)
      usage();
  if (bflag != NULL)
    if (parse_double(&blue_time, bflag) < 0)
      usage();
  if (argc >= 1)
    if (parse_double(&red_target, argv[0]) < 0)
      usage();
  if (argc >= 2)
    if (parse_double(&green_target, argv[1]) < 0)
      usage();
  if (argc >= 3)
    if (parse_double(&blue_target, argv[2]) < 0)
      usage();
  if (red_target >= 1)
    red_time = 0;
  if (green_target >= 1)
    green_time = 0;
  if (blue_target >= 1)
    blue_time = 0;
  return 0;
  (void) prio;
}


/**
 * Fill a filter
 * 
 * @param  filter  The filter to fill
 * @param  red     The red brightness
 * @param  green   The green brightness
 * @param  blue    The blue brightness
 */
static void fill_filter(libcoopgamma_filter_t* restrict filter, double red, double green, double blue)
{
  switch (filter->depth)
    {
#define X(CONST, MEMBER, MAX, TYPE)\
    case CONST:\
      libclut_start_over(&(filter->ramps.MEMBER), MAX, TYPE, 1, 1, 1);\
      libclut_rgb_brightness(&(filter->ramps.MEMBER), MAX, TYPE, red, green, blue);\
      break;
LIST_DEPTHS
#undef X
    default:
      abort();
    }
}


/**
 * Get the current monotonic time as a double
 * 
 * @param   now  Output parameter for the current time (monotonic)
 * @return       Zero on success, -1 on error
 */
static int double_time(double* restrict now)
{
#ifndef CLOCK_MONOTONIC_RAW
# define CLOCK_MONOTONIC_RAW  CLOCK_MONOTONIC
#endif
  struct timespec ts;
  if (clock_gettime(CLOCK_MONOTONIC_RAW, &ts) < 0)
    return -1;
  *now  = (double)(ts.tv_nsec);
  *now /= 1000000000L;
  *now += (double)(ts.tv_sec);
  return 0;
}


/**
 * The main function for the program-specific code
 * 
 * @return  0: Success
 *          -1: Error, `errno` set
 *          -2: Error, `cg.error` set
 *          -3: Error, message already printed
 */
int start(void)
{
  int r, fade_red, fade_green, fade_blue;
  size_t i, j;
  double t, starttime, red, green, blue, redt, greent, bluet;
  
  redt   = (red_target   - 1) / red_time;
  greent = (green_target - 1) / green_time;
  bluet  = (blue_target  - 1) / blue_time;
  fade_red   = !isinf(redt)   && !isnan(redt);
  fade_green = !isinf(greent) && !isnan(greent);
  fade_blue  = !isinf(bluet)  && !isnan(bluet);
  
  for (i = 0; i < filters_n; i++)
    crtc_updates[i].filter.lifespan = LIBCOOPGAMMA_UNTIL_DEATH;
  
  if ((r = make_slaves()) < 0)
    return r;
  
  if ((r = double_time(&starttime)) < 0)
    return r;
  
  red   = red_target   < 0 ? 0 : red_target   > 1 ? 1 : red_target;
  green = green_target < 0 ? 0 : green_target > 1 ? 1 : green_target;
  blue  = blue_target  < 0 ? 0 : blue_target  > 1 ? 1 : blue_target;
  
  for (;;)
    {
      if ((r = double_time(&t)) < 0)
	return r;
      t -= starttime;
      if (fade_red)
	{if (red   = 1 + t * redt,   red   > 1)  red   = 1;  else if (red   < 0)  red   = 0;}
      if (fade_green)
	{if (green = 1 + t * greent, green > 1)  green = 1;  else if (green < 0)  green = 0;}
      if (fade_blue)
	{if (blue  = 1 + t * bluet,  blue  > 1)  blue  = 1;  else if (blue  < 0)  blue  = 0;}
      
      for (i = 0, r = 1; i < filters_n; i++)
	{
	  if (!(crtc_updates[i].master) || !(crtc_info[i].supported))
	    continue;
	  fill_filter(&(crtc_updates[i].filter), red, green, blue);
	  r = update_filter(i, 0);
	  if ((r == -2) || ((r == -1) && (errno != EAGAIN)))
	    return r;
	  if (crtc_updates[i].slaves != NULL)
	    for (j = 0; crtc_updates[i].slaves[j] != 0; j++)
	      {
		r = update_filter(crtc_updates[i].slaves[j], 0);
		if ((r == -2) || ((r == -1) && (errno != EAGAIN)))
		  return r;
	      }
	}
      
      while (r != 1)
	if ((r = synchronise(-1)) < 0)
	  return r;
      
      sched_yield();
      
      if ((t >= red_time) && (t >= green_time) && (t >= blue_time))
	break;
    }
  
  if ((signal(SIGINT,  sig_int) == SIG_ERR) ||
      (signal(SIGTERM, sig_int) == SIG_ERR) ||
      (signal(SIGHUP,  sig_int) == SIG_ERR))
    return -1;
  
  if (libcoopgamma_set_nonblocking(&cg, 0) < 0)
    return -1;
  for (;;)
    if (libcoopgamma_synchronise(&cg, NULL, 0, &j) < 0)
      {
	if (received_int)
	  goto fade_in;
	switch (errno)
	  {
	  case 0:
	    break;
	  case ENOTRECOVERABLE:
	    goto enotrecoverable;
	  default:
	    return 1;
	  }
      }
  
 fade_in:
  if (libcoopgamma_set_nonblocking(&cg, 1) < 0)
    return -1;
  
  t = red_time;
  t = t > green_time ? t : green_time;
  t = t > blue_time  ? t : blue_time;
  redt   = t - red_time;
  greent = t - green_time;
  bluet  = t - blue_time;
  t = red_time + green_time + blue_time;
  if (red_time > 0)
    t = t < red_time   ? t : red_time;
  if (green_time > 0)
    t = t < green_time ? t : green_time;
  if (blue_time > 0)
    t = t < blue_time  ? t : blue_time;
  red_time   = t + redt;
  green_time = t + greent;
  blue_time  = t + bluet;
  
  red = green = blue = 1;
  
  if ((r = double_time(&starttime)) < 0)
    return r;
  
  for (;;)
    {
      if ((r = double_time(&t)) < 0)
	return r;
      t -= starttime;
      redt   = t / red_time;
      greent = t / green_time;
      bluet  = t / blue_time;
      if (!isinf(redt) && !isnan(redt))
	{
	  red = red_target * (1 - redt) + redt;
	  if (red > 1)  red = 1;  else if (red < 0)  red = 0;
	}
      if (!isinf(greent) && !isnan(greent))
	{
	  green = green_target * (1 - greent) + greent;
	  if (green > 1)  green = 1;  else if (green < 0)  green = 0;
	}
      if (!isinf(bluet) && !isnan(bluet))
	{
	  blue = blue_target * (1 - bluet) + bluet;
	  if (blue > 1)  blue = 1;  else if (blue < 0)  blue = 0;
	}
      
      for (i = 0, r = 1; i < filters_n; i++)
	{
	  if (!(crtc_updates[i].master) || !(crtc_info[i].supported))
	    continue;
	  fill_filter(&(crtc_updates[i].filter), red, green, blue);
	  r = update_filter(i, 0);
	  if ((r == -2) || ((r == -1) && (errno != EAGAIN)))
	    return r;
	  if (crtc_updates[i].slaves != NULL)
	    for (j = 0; crtc_updates[i].slaves[j] != 0; j++)
	      {
		r = update_filter(crtc_updates[i].slaves[j], 0);
		if ((r == -2) || ((r == -1) && (errno != EAGAIN)))
		  return r;
	      }
	}
      
      while (r != 1)
	if ((r = synchronise(-1)) < 0)
	  return r;
      
      sched_yield();
      
      if ((t >= red_time) && (t >= green_time) && (t >= blue_time))
	break;
    }
  
  return 0;
 enotrecoverable:
  for (;;)
    if (pause() < 0)
      return -1;
}