/* gamma-randr.c -- X RANDR gamma adjustment source
   This file is part of redshift-ng.

   redshift-ng 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.

   redshift-ng 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 redshift-ng.  If not, see <http://www.gnu.org/licenses/>.

   Copyright (c) 2010-2017  Jon Lund Steffensen <jonlst@gmail.com>
   Copyright (c) 2025       Mattias Andrée <m@maandree.se>
*/
#include "common.h"

#include <xcb/xcb.h>
#include <xcb/randr.h>
#if defined(__GNUC__)
# pragma GCC diagnostic ignored "-Waggregate-return"
#endif


#define RANDR_VERSION_MAJOR  1
#define RANDR_VERSION_MINOR  3


struct randr_crtc_state {
	xcb_randr_crtc_t crtc;
	unsigned int ramp_size;
	uint16_t *saved_ramps;
};

struct gamma_state {
	xcb_connection_t *conn;
	xcb_screen_t *screen;
	int preferred_screen;
	int screen_num;
	int crtc_num_count;
	int *crtc_num;
	unsigned int crtc_count;
	struct randr_crtc_state *crtcs;
};


static int
randr_init(struct gamma_state **state)
{
	xcb_randr_query_version_cookie_t ver_cookie;
	xcb_randr_query_version_reply_t *ver_reply;
	xcb_generic_error_t *error;
	struct gamma_state *s;
	int ec;

	/* Initialize state. */
	*state = emalloc(sizeof(**state));

	s = *state;
	s->screen_num = -1;
	s->crtc_num = NULL;

	s->crtc_num_count = 0;
	s->crtc_count = 0;
	s->crtcs = NULL;

	/* Open X server connection */
	s->conn = xcb_connect(NULL, &s->preferred_screen);

	/* Query RandR version */
	ver_cookie = xcb_randr_query_version(s->conn, RANDR_VERSION_MAJOR, RANDR_VERSION_MINOR);
	ver_reply = xcb_randr_query_version_reply(s->conn, ver_cookie, &error);

	/* TODO What does it mean when both error and ver_reply is NULL?
	   Apparently, we have to check both to avoid seg faults. */
	if (error || ver_reply == NULL) {
		ec = (error != 0) ? error->error_code : -1;
		weprintf(_("`%s' returned error %i\n"), "RANDR Query Version", ec);
		xcb_disconnect(s->conn);
		free(s);
		return -1;
	}

	if (ver_reply->major_version != RANDR_VERSION_MAJOR ||
	    ver_reply->minor_version < RANDR_VERSION_MINOR) {
		weprintf(_("Unsupported RANDR version (%u.%u)\n"),
		         ver_reply->major_version, ver_reply->minor_version);
		free(ver_reply);
		xcb_disconnect(s->conn);
		free(s);
		return -1;
	}

	free(ver_reply);

	return 0;
}

static int
randr_start(struct gamma_state *state, enum program_mode mode)
{
	xcb_generic_error_t *error;
	const xcb_setup_t *setup;
	xcb_screen_iterator_t iter;
	int i, screen_num;
	xcb_randr_get_screen_resources_current_cookie_t res_cookie;
	xcb_randr_get_screen_resources_current_reply_t *res_reply;
	xcb_randr_crtc_t *crtcs;

	(void) mode;

	screen_num = state->screen_num;
	if (screen_num < 0)
		screen_num = state->preferred_screen;

	/* Get screen */
	setup = xcb_get_setup(state->conn);
	iter = xcb_setup_roots_iterator(setup);
	state->screen = NULL;

	for (i = 0; iter.rem > 0; i++) {
		if (i == screen_num) {
			state->screen = iter.data;
			break;
		}
		xcb_screen_next(&iter);
	}

	if (!state->screen) {
		weprintf(_("Screen %i could not be found.\n"), screen_num);
		return -1;
	}

	/* Get list of CRTCs for the screen */
	res_cookie = xcb_randr_get_screen_resources_current(state->conn, state->screen->root);
	res_reply = xcb_randr_get_screen_resources_current_reply(state->conn, res_cookie, &error);

	if (error) {
		weprintf(_("`%s' returned error %i\n"), "RANDR Get Screen Resources Current", error->error_code);
		return -1;
	}

	state->crtc_count = res_reply->num_crtcs;
	state->crtcs = ecalloc(state->crtc_count, sizeof(struct randr_crtc_state));

	crtcs = xcb_randr_get_screen_resources_current_crtcs(res_reply);

	/* Save CRTC identifier in state */
	for (i = 0; i < state->crtc_count; i++)
		state->crtcs[i].crtc = crtcs[i];

	free(res_reply);

	/* Save size and gamma ramps of all CRTCs.
	   Current gamma ramps are saved so we can restore them
	   at program exit. */
	for (i = 0; i < state->crtc_count; i++) {
		xcb_randr_crtc_t crtc = state->crtcs[i].crtc;
		xcb_randr_get_crtc_gamma_size_cookie_t gamma_size_cookie;
		xcb_randr_get_crtc_gamma_size_reply_t *gamma_size_reply;
		xcb_randr_get_crtc_gamma_cookie_t gamma_get_cookie;
		xcb_randr_get_crtc_gamma_reply_t *gamma_get_reply;
		uint16_t *gamma_r, *gamma_g, *gamma_b;
		unsigned int ramp_size;

		/* Request size of gamma ramps */
		gamma_size_cookie = xcb_randr_get_crtc_gamma_size(state->conn, crtc);
		gamma_size_reply = xcb_randr_get_crtc_gamma_size_reply(state->conn, gamma_size_cookie, &error);

		if (error) {
			weprintf(_("`%s' returned error %i\n"), "RANDR Get CRTC Gamma Size", error->error_code);
			return -1;
		}

		ramp_size = gamma_size_reply->size;
		state->crtcs[i].ramp_size = ramp_size;

		free(gamma_size_reply);

		if (ramp_size == 0) {
			weprintf(_("Gamma ramp size too small: %i"), ramp_size);
			return -1;
		}

		/* Request current gamma ramps */
		gamma_get_cookie = xcb_randr_get_crtc_gamma(state->conn, crtc);
		gamma_get_reply = xcb_randr_get_crtc_gamma_reply(state->conn, gamma_get_cookie, &error);

		if (error) {
			weprintf(_("`%s' returned error %i\n"), "RANDR Get CRTC Gamma", error->error_code);
			return -1;
		}

		gamma_r = xcb_randr_get_crtc_gamma_red(gamma_get_reply);
		gamma_g = xcb_randr_get_crtc_gamma_green(gamma_get_reply);
		gamma_b = xcb_randr_get_crtc_gamma_blue(gamma_get_reply);

		/* Allocate space for saved gamma ramps */
		state->crtcs[i].saved_ramps = emalloc(3 * ramp_size * sizeof(uint16_t));

		/* Copy gamma ramps into CRTC state */
		memcpy(&state->crtcs[i].saved_ramps[0 * ramp_size], gamma_r, ramp_size * sizeof(uint16_t));
		memcpy(&state->crtcs[i].saved_ramps[1 * ramp_size], gamma_g, ramp_size * sizeof(uint16_t));
		memcpy(&state->crtcs[i].saved_ramps[2 * ramp_size], gamma_b, ramp_size * sizeof(uint16_t));

		free(gamma_get_reply);
	}

	return 0;
}

static void
randr_restore(struct gamma_state *state)
{
	xcb_generic_error_t *error;
	int i;

	/* Restore CRTC gamma ramps */
	for (i = 0; i < state->crtc_count; i++) {
		xcb_randr_crtc_t crtc = state->crtcs[i].crtc;

		unsigned int ramp_size = state->crtcs[i].ramp_size;
		uint16_t *gamma_r = &state->crtcs[i].saved_ramps[0*ramp_size];
		uint16_t *gamma_g = &state->crtcs[i].saved_ramps[1*ramp_size];
		uint16_t *gamma_b = &state->crtcs[i].saved_ramps[2*ramp_size];

		/* Set gamma ramps */
		xcb_void_cookie_t gamma_set_cookie =
			xcb_randr_set_crtc_gamma_checked(state->conn, crtc,
							 ramp_size, gamma_r,
							 gamma_g, gamma_b);
		error = xcb_request_check(state->conn, gamma_set_cookie);

		if (error) {
			weprintf(_("`%s' returned error %i\n"), "RANDR Set CRTC Gamma", error->error_code);
			weprintf(_("Unable to restore CRTC %i\n"), i);
		}
	}
}

static void
randr_free(struct gamma_state *state)
{
	int i;

	/* Free CRTC state */
	for (i = 0; i < state->crtc_count; i++)
		free(state->crtcs[i].saved_ramps);
	free(state->crtcs);
	free(state->crtc_num);

	/* Close connection */
	xcb_disconnect(state->conn);

	free(state);
}

static void
randr_print_help(FILE *f)
{
	fputs(_("Adjust gamma ramps with the X RANDR extension.\n"), f);
	fputs("\n", f);

	/* TRANSLATORS: RANDR help output
	   left column must not be translated */
	fputs(_("  screen=N\t\tX screen to apply adjustments to\n"
		"  crtc=N\tList of comma separated CRTCs to apply"
		" adjustments to\n"),
	      f);
	fputs("\n", f);
}

static int
randr_set_option(struct gamma_state *state, const char *key, const char *value)
{
	if (!strcasecmp(key, "screen")) {
		state->screen_num = atoi(value);
	} else if (!strcasecmp(key, "crtc")) {
		char *tail;
		int i, parsed;

		/* Check how many crtcs are configured */
		const char *local_value = value;
		for (;;) {
			errno = 0;
			parsed = strtol(local_value, &tail, 0);
			if (parsed == 0 && (errno != 0 || tail == local_value)) {
				weprintf(_("Unable to read screen number: `%s'.\n"), value);
				return -1;
			}
			state->crtc_num_count += 1;
			local_value = tail;

			if (*local_value == ',')
				local_value += 1;
			else if (!*local_value)
				break;
		}

		/* Configure all given crtcs */
		state->crtc_num = calloc(state->crtc_num_count, sizeof(int));
		local_value = value;
		for (i = 0; i < state->crtc_num_count; i++) {
			errno = 0;
			parsed = strtol(local_value, &tail, 0);
			if (parsed == 0 && (errno != 0 || tail == local_value))
				return -1;
			state->crtc_num[i] = parsed;
			local_value = tail;

			if (*local_value == ',')
				local_value += 1;
			else if (!*local_value)
				break;
		}
	} else if (strcasecmp(key, "preserve") == 0) {
		weprintf(_("Parameter `%s' is now always on; use the `%s' command-line option to disable."), key, "-P");
	} else {
		weprintf(_("Unknown method parameter: `%s'."), key);
		return -1;
	}

	return 0;
}

static int
randr_set_temperature_for_crtc(struct gamma_state *state, int crtc_num,
                               const struct color_setting *setting, int preserve)
{
	xcb_randr_crtc_t crtc;
	xcb_void_cookie_t gamma_set_cookie;
	xcb_generic_error_t *error;
	unsigned int i, ramp_size;
	uint16_t *gamma_ramps, *gamma_r, *gamma_g, *gamma_b, value;

	if (crtc_num >= state->crtc_count || crtc_num < 0) {
		fprintf(stderr, _("CRTC %i does not exist. "), crtc_num);
		if (state->crtc_count > 1)
			fprintf(stderr, _("Valid CRTCs are [0-%i].\n"), state->crtc_count-1);
		else
			fprintf(stderr, _("Only CRTC 0 exists.\n"));

		return -1;
	}

	crtc = state->crtcs[crtc_num].crtc;
	ramp_size = state->crtcs[crtc_num].ramp_size;

	/* Create new gamma ramps */
	gamma_ramps = emalloc(3 * ramp_size * sizeof(uint16_t));

	gamma_r = &gamma_ramps[0 * ramp_size];
	gamma_g = &gamma_ramps[1 * ramp_size];
	gamma_b = &gamma_ramps[2 * ramp_size];

	if (preserve) {
		/* Initialize gamma ramps from saved state */
		memcpy(gamma_ramps, state->crtcs[crtc_num].saved_ramps,
		       3 * ramp_size * sizeof(uint16_t));
	} else {
		/* Initialize gamma ramps to pure state */
		for (i = 0; i < ramp_size; i++) {
			value = (double)i / (ramp_size - 1) * UINT16_MAX;
			gamma_r[i] = value;
			gamma_g[i] = value;
			gamma_b[i] = value;
		}
	}

	colorramp_fill_u16(gamma_r, gamma_g, gamma_b, ramp_size,
			   ramp_size, ramp_size, setting);

	/* Set new gamma ramps */
	gamma_set_cookie = xcb_randr_set_crtc_gamma_checked(state->conn, crtc, ramp_size,
	                                                    gamma_r, gamma_g, gamma_b);
	error = xcb_request_check(state->conn, gamma_set_cookie);

	if (error) {
		weprintf(_("`%s' returned error %i\n"), "RANDR Set CRTC Gamma", error->error_code);
		free(gamma_ramps);
		return -1;
	}

	free(gamma_ramps);

	return 0;
}

static int
randr_set_temperature(struct gamma_state *state, const struct color_setting *setting, int preserve)
{
	int i, r;

	/* If no CRTC numbers have been specified, set temperature on all CRTCs. */
	if (!state->crtc_num_count) {
		for (i = 0; i < state->crtc_count; i++) {
			r = randr_set_temperature_for_crtc(state, i, setting, preserve);
			if (r < 0)
				return -1;
		}
	} else {
		for (i = 0; i < state->crtc_num_count; ++i) {
			r = randr_set_temperature_for_crtc(state, state->crtc_num[i], setting, preserve);
			if (r < 0)
				return -1;
		}
	}

	return 0;
}


const struct gamma_method randr_gamma_method = {
	"randr", 1,
	&randr_init,
	&randr_start,
	&randr_free,
	&randr_print_help,
	&randr_set_option,
	&randr_restore,
	&randr_set_temperature
};