#!/usr/bin/env nickle

autoimport Process;
autoload ParseArgs;

/* Parsed TILE property contents */
typedef struct {
	int	group_id;
	int	flags;
	int 	number_h;
	int	number_v;
	int	hpos;
	int	vpos;
} tile_t;

/* Configuration for one output */
typedef struct {
	string name;
	string mode;
	int mode_id;
	bool connected;
	bool primary;
	int width, height;
	int x, y;
	bool is_tile;
	tile_t tile;
} output_t;

/* Configuration for one monitor (collection of outputs) */
typedef struct {
	string		name;
	int		group_id;
	bool		primary;
	int		leader;
	int		width;
	int		height;
	int		x;
	int		y;
	(*output_t)[...]	outputs;
} monitor_t;

/* Overall screen configuration */
typedef struct {
	int		width;
	int		height;
} screen_t;

/* List the existing manually configured monitors
 */
string[]
get_existing_monitors() {
	file	input = popen(popen_direction.read, false,
			      "xrandr", "xrandr", "--listmonitors");
	string[...] names = {};
	while (!File::end(input)) {
		string		line = File::fgets(input);
		string[]	words = String::wordsplit(line, " \t");

		if (words[0] != "Monitors:" && dim(words) >= 2) {
			string	name = words[1];

			if (name[0] != '+') {
				if (name[0] == '*')
					name = String::substr(name, 1, String::length(name) - 1);
				names[dim(names)] = name;
			}
		}
	}
	return names;
}

const int priority_any = 0;
const int priority_preferred = 1;
const int priority_current = 2;

typedef enum { start, start_output, output, skip_output,
	       mode_get, mode_skip, done } state_t;

/* Parse xrandr results to compute the set of available monitors and
 * current screen size
 */
output_t[]
get_outputs(*screen_t screen) {
	file	input = popen(popen_direction.read, false,
			      "xrandr", "xrandr", "--verbose", "--prop");
	output_t[...] outputs = {};
	output_t output;
	int mode_priority;
	state_t state = state_t.start;
	string line;
	string[] words;

	void add_output() {
		switch (state) {
		case state_t.skip_output:
		case state_t.output:
		case state_t.mode_skip:
		case state_t.mode_get:
#			printf ("add output %s\n", output.name);
			outputs[dim(outputs)] = output;
		}
	}

	void getline() {
		if (File::end(input))
			line = "DONE";
		else
			line = File::fgets(input);

		words = String::wordsplit(line, " \t");
	}

	bool check_output() {
		if (dim(words) >= 2) {
			switch (words[1]) {
			case "connected":
			case "disconnected":
				add_output();
				state = state_t.start_output;
				return true;
			}
		}
		return false;
	}

	getline();

	while (state != state_t.done) {
#		printf("\tstate %v words: %v\n", state, words);
		if (words[0] == "DONE") {
			add_output();
			state = state_t.done;
			continue;
		}
		switch (state) {
		case state_t.start:
			if (dim(words) >= 10) {
				screen->width = string_to_integer(words[7]);
				screen->height = string_to_integer(words[9]);
				state = state_t.start_output;
			}
			getline();
			break;
		case state_t.start_output:
			/* Look for an output */
			if (dim(words) >= 2) {
				switch (words[1]) {
				case "connected":
					bool primary = false;
					if (dim(words) >= 3 && words[2] == "primary")
						primary = true;
					output = (output_t) {
						.name = words[0],
						.mode = "",
						.connected = true,
						.primary = primary,
						.width = 0,
						.height = 0,
						.is_tile = false,
					};
					state = state_t.output;
					mode_priority = -1;
					break;
				case "disconnected":
					output = (output_t) {
						.name = words[0],
						.mode = "",
						.connected = false,
						.primary = false,
						.width = 0,
						.height = 0,
						.is_tile = false,
					};
					state = state_t.skip_output;
					break;
				}
			}
			getline();
			break;
		case state_t.skip_output:
			if (check_output())
				break;
			getline();
			break;
		case state_t.output:
			if (check_output())
				break;

			/* Look for a mode */
			if (String::index(line, "MHz") >= 0) {
				int this_priority = priority_any;
				if (String::index(line, "current") >= 0) {
					this_priority = priority_current;
				} else if (String::index(line, "preferred") >= 0) {
					this_priority = priority_preferred;
				}
				if (this_priority > mode_priority) {
					output.mode = words[0];
					File::sscanf(words[1], "(0x%x)", &output.mode_id);
					state = state_t.mode_get;
					mode_priority = this_priority;
				} else {
					state = state_t.mode_skip;
				}
			} else if (words[0] == "TILE:" && dim(words) >= 7) {
				int[6] vals = { [i] = string_to_integer(words[i+1]) };
				output.is_tile = true;
				output.tile = (tile_t) {
					.group_id = vals[0],
					.flags = vals[1],
					.number_h = vals[2],
					.number_v = vals[3],
					.hpos = vals[4],
					.vpos = vals[5],
				};
			}
			getline();
			break;
		case state_t.mode_get:
		case state_t.mode_skip:
			if (words[0] == "h:") {
				if (state == state_t.mode_get) {
					for (int h = 0; h < dim(words) - 1; h++) {
						if (words[h] == "width") {
							output.width = string_to_integer(words[h+1]);
							break;
						}
					}
				}
			} else if (words[0] == "v:") {
				if (state == state_t.mode_get) {
					for (int v = 0; v < dim(words) - 1; v++) {
						if (words[v] == "height") {
							output.height = string_to_integer(words[v+1]);
							break;
						}
					}
				}
			} else {
				state = state_t.output;
				break;
			}
			getline();
			break;
		}
	}
	return outputs;
}

/*
 * Construct the set of monitors from the output information, building
 * composite monitors from outputs with the TILE property
 */
monitor_t[] get_monitors(&output_t[] outputs) {
	monitor_t[...]	monitors = {};

	for (int i = 0; i < dim(outputs); i++) {
		*output_t	output = &outputs[i];

		if (!output->connected)
			continue;

		if (output->is_tile) {
			int	m;

			for (m = 0; m < dim(monitors); m++) {
				if (monitors[m].group_id == output->tile.group_id)
					break;
			}
			if (m == dim(monitors)) {
				(*output_t)[...] outputs;
				outputs[0] = output;
				monitors[m] = (monitor_t) {
					.name = sprintf("DP-GROUP-%d", output->tile.group_id),
					.group_id = output->tile.group_id,
					.outputs = outputs,
					.primary = false,
					.leader = 0,
					.width = output->tile.number_h * output->width,
					.height = output->tile.number_v * output->height,
					.x = -1,
					.y = -1,
				};
			} else {
				&output_t	leader = monitors[m].outputs[monitors[m].leader];

				if (output->tile.vpos < leader.tile.vpos ||
				    output->tile.vpos == leader.tile.vpos &&
				    output->tile.hpos < leader.tile.hpos)

					monitors[m].leader = dim(monitors[m].outputs);

				monitors[m].outputs[dim(monitors[m].outputs)] = output;
			}
		} else {
			monitors[dim(monitors)] = (monitor_t) {
				.name = output->name,
				.group_id = -1,
				.outputs = ((*output_t)[1]) { output },
				.leader = 0,
				.primary = false,
				.width = output->width,
				.height = output->height,
				.x = -1,
				.y = -1,
			};
		}
	}

	return monitors;
}

bool
is_internal_output(&output_t output) {
	if (String::index(output.name, "eDP") >= 0)
		return true;
	if (String::index(output.name, "LVDS") >= 0)
		return true;
	return false;
}

bool
is_internal_monitor(&monitor_t monitor) {
	for (int o = 0; o < dim(monitor.outputs); o++)
		if (is_internal_output(monitor.outputs[o]))
			return true;
	return false;
}

/* Return the current primary monitor */
*monitor_t
get_primary(&monitor_t[] monitors)
{
	for (int m = 0; m < dim(monitors); m++) {
		&monitor_t	monitor = &monitors[m];
		if (monitor.primary)
			return &monitor;
	}

	monitors[0].primary = true;
	return &monitors[0];
}

/* Return the first internal monitor (LVDS or eDP) */
*monitor_t
get_internal(&monitor_t[] monitors)
{
	for (int m = 0; m < dim(monitors); m++) {
		&monitor_t	monitor = &monitors[m];
		if (is_internal_monitor(&monitor))
			return &monitor;
	}
	return &monitors[0];
}

/* Set output positions and primary status */
void
set_output(&monitor_t[] monitors)
{
	/* Set output positions and primary value */
	for (int m = 0; m < dim(monitors); m++) {
		*monitor_t	monitor = &monitors[m];

		if (monitor->primary)
			monitor->outputs[monitor->leader]->primary = true;

		if (monitor->group_id >= 0) {
			int	tile_width = monitor->outputs[0]->width;
			int	tile_height = monitor->outputs[0]->height;

			for (int o = 0; o < dim(monitor->outputs); o++) {
				monitor->outputs[o]->x = monitor->x + monitor->outputs[o]->tile.hpos * tile_width;
				monitor->outputs[o]->y = monitor->y + monitor->outputs[o]->tile.vpos * tile_height;
			}
		} else {
			monitor->outputs[0]->x = monitor->x;
			monitor->outputs[0]->y = monitor->y;
		}
	}
}

/* Set overall screen size */
void
set_screen(&output_t[] outputs, *screen_t screen)
{
	int	width = 0;
	int	height = 0;

	for (int o = 0; o < dim(outputs); o++) {
		if (outputs[o].connected) {
			int	w = outputs[o].x + outputs[o].width;
			int	h = outputs[o].y + outputs[o].height;

			if (w > width)
				width = w;
			if (h > height)
				height = h;
		}
	}
	screen->width = width;
	screen->height = height;
}

/*
 * Policy -- select the primary monitor
 *
 * Pick the largest external monitor if it's bigger than 1080p,
 * otherwise pick the internal monitor
 */
void
set_primary(&monitor_t[] monitors)
{
	*monitor_t	primary = &monitors[0];

	for (int m = 1; m < dim(monitors); m++) {
		*monitor_t	monitor = &monitors[m];

		if (is_internal_monitor(primary)) {
			if (!is_internal_monitor(monitor)) {
				if (monitor->height > 1080)
					primary = monitor;
			}
		} else {
			if (is_internal_monitor(monitor)) {
				if (primary->height <= 1080)
					primary = monitor;
			} else {
				if (monitor->height > primary->height)
					primary = monitor;
			}
		}
	}
	primary->primary = true;
}

/*
 * Policy -- position the monitors
 *
 * Place the primary monitor at the upper left corner of the
 * screen.
 *
 * If the internal monitor is not primary, place it just below the
 * primary monitor.
 *
 * Place all other monitors to the right of the primary monitor
 */

void
set_monitor_pos(&monitor_t[] monitors)
{
	int	nset = 0;

	/* Primary monitor goes upper left */
	*monitor_t	primary = get_primary(&monitors);

	primary->x = 0;
	primary->y = 0;

	/* Set panel position, if not primary */
	*monitor_t	internal = get_internal(&monitors);
	if (is_internal_monitor(internal) && !internal->primary) {
		internal->x = 0;
		internal->y = primary->height;
	}

	int	x = primary->width;

	/* Set remaining positions, right of primary */
	for (int m = 0; m < dim(monitors); m++) {
		*monitor_t	monitor = &monitors[m];

		if (monitor->x < 0) {
			monitor->x = x;
			monitor->y = 0;
			x += monitor->width;
		}
	}

}

string
tabs(int tab) {
	static string[]	t = { "", "\t", "\t\t", "\t\t\t", "t\t\t\t" };

	return t[tab];
}

void
print_output(*output_t output, int tab) {
	printf ("%soutput %s\n", tabs(tab), output->name);
	printf ("%sconnected %v\n", tabs(tab+1), output->connected);
	if (output->connected) {
		printf ("%smode %s (0x%x)\n", tabs(tab+1), output->mode, output->mode_id);
		printf ("%sprimary %v\n", tabs(tab+1), output->primary);
		printf ("%swidth, height %d,%d\n", tabs(tab+1), output->width, output->height);
		printf ("%sx, y %d, %d\n", tabs(tab+1), output->x, output->y);
	}
}

void
print_monitor(*monitor_t monitor, int tab) {

	printf ("%smonitor %s\n", tabs(tab), monitor->name);
	printf ("%sgroup_id %d\n", tabs(tab+1), monitor->group_id);
	printf ("%sprimary %v\n", tabs(tab+1), monitor->primary);
	printf ("%sleader %d\n", tabs(tab+1), monitor->leader);
	printf ("%swidth, height %d,%d\n", tabs(tab+1), monitor->width, monitor->height);
	printf ("%sx, y %d, %d\n", tabs(tab+1), monitor->x, monitor->y);
	printf ("%sgroup_id %d\n", tabs(tab+1), monitor->group_id);
	printf ("%soutputs", tabs(tab+1));
	for (int o = 0; o < dim(monitor->outputs); o++)
		printf(" %s", monitor->outputs[o]->name);
	printf ("\n");
}

string[]
output_config(*output_t output) {
	string[...] config;

	if (!output->connected) {
		config = (string[...]) {
			"--output",
			output->name,
			"--off"
		};
	} else {
		config = (string[...]) {
			"--output",
			output->name,
			"--mode",
			sprintf ("0x%x", output->mode_id),
			"--pos",
			sprintf("%dx%d", output->x, output->y)
		};
		if (output->primary)
			config[dim(config)] = "--primary";
	}
	return config;
}

string
output_names(&(*output_t)[] outputs) {
	string	name = outputs[0]->name;

	for (int o = 1; o < dim(outputs); o++)
		name = name + "," + outputs[o]->name;
	return name;
}

string[]
monitor_config(*monitor_t monitor) {
	if (monitor->group_id < 0)
		return (string[0]) {};

	string[...] config = {
		"--setmonitor",
		monitor->name,
		"auto",
		output_names(&monitor->outputs),
	};

	return config;
}

string[]
screen_config(*screen_t screen) {
	return (string[...]) {
		"--fb",
		sprintf("%dx%d", screen->width, screen->height),
		"--dpi", "115"
	};
}

string[]
cat_args(string[][] args) {
	string[...] ret = {};

	for (int a = 0; a < dim(args); a++) {
		for (int s = 0; s < dim(args[a]); s++)
			ret[dim(ret)] = args[a][s];
	}
	return ret;
}

bool	verbose = false;
bool	dry_run = false;

ParseArgs::argdesc argd = {
	.args = {
		{ .var = { .arg_flag = &verbose },
		  .abbr = 'v',
		  .name = "verbose",
		  .desc = "verbose mode"
		},
		{ .var = { .arg_flag = &dry_run },
		  .abbr = 'n',
		  .name = "dry-run",
		  .desc = "don't execute, just print"
		},
	},
	.unknown = &(int user_argind),
};

void
xrandr_auto()
{
	ParseArgs::parseargs(&argd, &argv);

	screen_t orig_screen;
	output_t[] outputs = get_outputs(&orig_screen);
	monitor_t[] monitors = get_monitors(&outputs);
	string[...][...] args = { {"xrandr"} };
	string[...] existing = get_existing_monitors();
	screen_t screen;
	screen_t temp_screen;

	/* Implement our policy */
	set_primary(&monitors);
	set_monitor_pos(&monitors);

	/* Using the specific configuration, place outputs
	 * and set the overall screen size
	 */
	set_output(&monitors);
	set_screen(&outputs, &screen);

	temp_screen.width = max(orig_screen.width, screen.width);
	temp_screen.height = max(orig_screen.height, screen.height);

	if (temp_screen.width != orig_screen.width || temp_screen.height != orig_screen.height)
		args[dim(args)] = screen_config(&temp_screen);

	for (int e = 0; e < dim(existing); e++)
		args[dim(args)] = (string[...]) {
			"--delmonitor",
			existing[e]
		};

	for (int m = 0; m < dim(monitors); m++) {
		args[dim(args)] = monitor_config(&monitors[m]);
	}

	for (int o = 0; o < dim(outputs); o++) {
		args[dim(args)] = output_config(&outputs[o]);
	}

	if (temp_screen.height != screen.height || temp_screen.width != screen.width)
		args[dim(args)] = screen_config(&screen);

	if (verbose) {
		for (int m = 0; m < dim(monitors); m++)
			print_monitor(&monitors[m], 0);
		for (int o = 0; o < dim(outputs); o++)
			print_output(&outputs[o], 0);
	}

	string[] xrandr_args = cat_args(args);

	if (dry_run || verbose) {
		for (int a = 0; a < dim(xrandr_args); a++)
			printf("%s ", xrandr_args[a]);
		printf ("\n");
	}
	if (!dry_run) {
		system("xrandr", xrandr_args ...);
	}
}

xrandr_auto();