/* See LICENSE file for copyright and license details. */
#include "cg-base.h"

#include <libclut.h>

#include <errno.h>
#include <math.h>
#include <sched.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)1 << 60;

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

/**
 * Class suffixes
 */
const char *const *class_suffixes = (const char *const[]){NULL};



/**
 * -s: rainbow-frequency in Hz
 */
static char *sflag = NULL;

/**
 * -l: base luminosity
 */
static char *lflag = NULL;

/**
 * The rainbow-frequency multiplied by 3
 */
double rainbows_per_third_second = 1;

/**
 * The base luminosity
 */
double luminosity = (double)1 / 3;



/**
 * Print usage information and exit
 */
void
usage(void)
{
	fprintf(stderr,
	       "usage: %s [-M method] [-S site] [-c crtc]... [-R rule] [-p priority]"
	       " [-l luminosity] [-s rainbowhz]\n",
	       argv0);
	exit(1);
}


/**
 * 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 'l':
			if (lflag || !(lflag = arg))
				usage();
			return 1;
		case 's':
			if (sflag || !(sflag = 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
 * @return       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 = (lflag || sflag);
	if (q > 1 || argc)
		usage();
	if (sflag) {
		if (parse_double(&rainbows_per_third_second, sflag) < 0)
			usage();
		rainbows_per_third_second *= 3;
	}
	if (lflag) {
		if (parse_double(&luminosity, lflag) < 0)
			usage();
	}
	return 0;
	(void) argv;
	(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;
	size_t i, j;
	double pal[3];
	double t, starttime;

	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;

	for (;;) {
		if ((r = double_time(&t)) < 0)
			return r;
		t -= starttime;
		t *= rainbows_per_third_second;
		pal[0] = pal[1] = pal[2] = luminosity;
		pal[((long)t) % 3] += 1 - fmod(t, 1);
		pal[((long)t + 1) % 3] += fmod(t, 1);
		if (pal[0] > 1)
			pal[0] = 1;
		if (pal[1] > 1)
			pal[1] = 1;
		if (pal[2] > 1)
			pal[2] = 1;

		for (i = 0, r = 1; i < filters_n; i++) {
			if (!crtc_updates[i].master || !crtc_info[crtc_updates[i].crtc].supported)
				continue;
			fill_filter(&crtc_updates[i].filter, pal[0], pal[1], pal[2]);
			r = update_filter(i, 0);
			if (r == -2 || (r == -1 && errno != EAGAIN))
				return r;
			if (crtc_updates[i].slaves) {
				for (j = 0; crtc_updates[i].slaves[j]; 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();
	}
}