# Code to process XML-based tutorials. See $FG_ROOT/Docs/README.tutorials
# ---------------------------------------------------------------------------------------


var STEP_INTERVAL = 5;   # time between tutorial steps
var EXIT_INTERVAL = 1;   # time between fulfillment of a step and the start of the next step

var tutorial = nil;
var steps = [];
var loop_id = 0;
var current_step = nil;
var num_errors = nil;
var num_step_runs = nil;
var last_run_time = nil;
var audio_dir = nil;



var startTutorial = func {
	var name = getprop("/sim/tutorials/current-tutorial");
	if (name == nil) {
		screen.log.write("No tutorial selected");
		return;
	}

	tutorial = nil;
	foreach (var c; props.globals.getNode("/sim/tutorials").getChildren("tutorial")) {
		if (c.getNode("name").getValue() == name) {
			tutorial = c;
			break;
		}
	}

	if (tutorial == nil) {
		screen.log.write('Unable to find tutorial "' ~ name ~ '"');
		return;
	}

	stopTutorial();
	screen.log.write('Loading tutorial "' ~ name ~ '" ...');
	current_step = 0;
	num_step_runs = 0;
	num_errors = 0;
	last_run_time = time_elapsed.getValue();
	steps = tutorial.getChildren("step");
	view.point.save();
	init_nasal();

	STEP_INTERVAL = delay(tutorial, STEP_INTERVAL);
	run_nasal(tutorial);
	set_models(tutorial.getNode("models"));

	var dir = tutorial.getNode("audio-dir");
	if (dir != nil) {
		audio_dir = getprop("/sim/fg-root") ~ "/" ~ dir.getValue() ~ "/";
	} else {
		audio_dir = "";
	}

	var presets = tutorial.getChild("presets");
	if (presets != nil) {
		props.copy(presets, props.globals.getNode("/sim/presets"));
		fgcommand("presets-commit", props.Node.new());

		if (getprop("/sim/presets/on-ground")) {
			var eng = props.globals.getNode("/controls/engines");
			if (eng != nil) {
				foreach (var c; eng.getChildren("engine")) {
					c.getNode("magnetos", 1).setIntValue(3);
					c.getNode("throttle", 1).setDoubleValue(0.5);
				}
			}
		}
	}

	var timeofday = tutorial.getChild("timeofday");
	if (timeofday != nil) {
		fgcommand("timeofday", props.Node.new({ "timeofday" : timeofday.getValue() }));
	}

	var init = tutorial.getNode("init");
	set_properties(init);
	set_view(init);
	run_nasal(init);
	is_running(1);  # needs to be after "presets-commit"

	# Pick up any weather conditions/scenarios set
	setprop("/environment/rebuild-layers", getprop("/environment/rebuild-layers") + 1);
	settimer(func { step_tutorial(loop_id += 1) }, STEP_INTERVAL);
}



var stopTutorial = func {
	loop_id += 1;
	if (is_running()) {
		var end = tutorial.getNode("end");
		set_properties(end);
		run_nasal(end);
	}
	set_marker();
	is_running(0);
}

_setlistener("/sim/crashed", stopTutorial);



# - Gets the current step node from the tutorial
# - If this is the first time the step is entered, it displays the instruction message
# - Otherwise, it
#   - Checks if the exit conditions have been met. If so, it increments the step counter.
#   - Checks for any error conditions, in which case it displays a message to the screen and
#     increments an error counter
#   - Otherwise display the instructions for the step.
#
var step_tutorial = func(id) {
	id == loop_id or return;
	var continue_after = func(i) { settimer(func { step_tutorial(id) }, i) }

	if (current_step >= size(steps)) {
		# end of the tutorial
		var end = tutorial.getNode("end");
		say_message(end, "Tutorial finished.");
		say_message(nil, "Deviations: " ~ num_errors);
		set_view(end) or view.point.restore();
		stopTutorial();
		return;
	}

	var step = steps[current_step];
	set_marker(step);
	set_targets(tutorial.getNode("targets"));

	if (num_step_runs == 0) {
		# first time we've encountered this step
		say_message(step, "Tutorial step " ~ current_step);
		set_view(step);
		set_properties(step);
		run_nasal(step);

		num_step_runs += 1;
		return continue_after(delay(step, STEP_INTERVAL));
	}

	# check for error conditions in random order
	foreach (var error; shuffle(step.getChildren("error"))) {
		if (props.condition(error.getNode("condition"))) {
			num_errors += 1;
			run_nasal(error);
			say_message(error);
			return continue_after(delay(error, STEP_INTERVAL));
		}
	}

	# check for exit condition
	var exit = step.getNode("exit");
	if (exit != nil) {
		if (!props.condition(exit.getNode("condition"))) {
			return continue_after(delay(exit, STEP_INTERVAL));
		}
		run_nasal(exit);
		set_view(exit);
	}

	# success!
	current_step += 1;
	num_step_runs = 0;
	return continue_after(delay(tutorial, EXIT_INTERVAL));
}


var delay = func(node, default) {
	if (node != nil) {
		var d = node.getNode("interval");
		if (d != nil) {
			return num(d.getValue());
		}
	}
	return num(default);
}


# scan all <set> blocks and set their <property> to <value> or
# the value of a property that <property n="1"> points to
# <set>
#	 <property>/foo/bar</property>
#	 <value>woof</value>
# </set>
#
var set_properties = func(node) {
	node != nil or return;
	foreach (var c; node.getChildren("set")) {
		var dest = c.getChild("property", 0);
		var src = c.getChild("property", 1);
		var val = c.getChild("value");

		dest != nil or die("<set> without <property>");
		if (val != nil) {
			setprop(dest.getValue(), val.getValue());
		} elsif (src != nil) {
			src = getprop(src.getValue());
			src != nil or die("<property n=\"1\"> doesn't refer to defined property");
			setprop(dest.getValue(), src);
		} else {
			die("<set> without <value> or <property n=\"1\">");
		}
	}
}


var set_targets = func(node) {
	node != nil or return;

	var time = time_elapsed.getValue();
	var dest = props.globals.getNode("/sim/tutorials/targets", 1);
	var aircraft = geo.aircraft_position();
	var hdg = heading.getValue() + slip.getValue();

	foreach (var t; node.getChildren()) {
		var lon = t.getNode("longitude-deg");
		var lat = t.getNode("latitude-deg");
		if (lon == nil or lat == nil) {
			die("target coords undefined");
		}
		var target = geo.Coord.new().set_lonlat(lon.getValue(), lat.getValue());
		var dist = aircraft.distance_to(target);
		var course = aircraft.course_to(target);
		var angle = geo.normdeg(course - hdg);
		if (angle >= 180) {
			angle -= 360;
		}

		var d = dest.getChild(t.getName(), t.getIndex(), 1);
		d.getNode("heading-deg", 1).setDoubleValue(course);
		d.getNode("direction-deg", 1).setDoubleValue(angle);
		var distN = d.getNode("distance-m", 1);
		var lastdist = distN.getValue();
		distN.setDoubleValue(dist);
		if (lastdist != nil) {
			var speed = (lastdist - dist) / (time - last_run_time) + 0.00001;  # m/s
			d.getNode("eta-min", 1).setDoubleValue(dist / (speed * 60));
		}
	}
	last_run_time = time;
}


var models = [];
var set_models = func(node) {
	node != nil or return;

	var manager = props.globals.getNode("/models", 1);
	foreach (var src; node.getChildren("model")) {
		var i = 0;
		for (; 1; i += 1) {
			if (manager.getChild("model", i, 0) == nil) {
				break;
			}
		}
		var dest = manager.getChild("model", i, 1);
		props.copy(src, dest);
		dest.getNode("load", 1);  # makes the modelmgr load the model
		dest.removeChildren("load");
		append(models, dest);
	}
}


var remove_models = func {
	foreach (var m; models) {
		m.getParent().removeChild(m.getName(), m.getIndex());
	}
	models = [];
}


var set_view = func(node = nil) {
	node != nil or return;
	var v = node.getChild("view");
	if (v != nil) {
		view.point.move(v);
		return 1;
	}
	return 0;
}


var set_marker = func(node = nil) {
	if (node != nil) {
		var loc = node.getNode("marker");
		if (loc != nil) {
			var s = loc.getNode("scale");
			marker.setValues({
				"x/value": loc.getNode("x-m", 1).getValue(),
				"y/value": loc.getNode("y-m", 1).getValue(),
				"z/value": loc.getNode("z-m", 1).getValue(),
				"scale/value": s != nil ? s.getValue() : 1,
				"arrow-enabled": 1,
			});
			return;
		}
	}
	marker.getNode("arrow-enabled", 1).setBoolValue(0);
}


# Set and return running state. Disable/enable stop menu.
#
var is_running = func(which = nil) {
	var prop = "/sim/tutorials/running";
	if (which != nil) {
		setprop(prop, which);
		gui.menuEnable("tutorial-stop", which);
	}
	return getprop(prop);
}


# Output the message and optional sound recording.
#
var lastmsgcount = 0;
var say_message = func(node, default = nil) {
	var msg = default;
	var audio = nil;
	var is_error = 0;

	if (node != nil) {
		is_error = node.getName() == "error";

		var m = node.getChildren("message");
		if (size(m)) {
			msg = m[rand() * size(m)].getValue();
		}

		var a = node.getChildren("audio");
		if (size(a)) {
			audio = a[rand() * size(a)].getValue();
		}
	}

	if (msg != last_message.getValue() or (is_error and lastmsgcount == 1)) {
		# Error messages are only displayed every 10 seconds (2 iterations)
		# Other messages are only displayed if they change
		if (audio != nil) {
			var prop = { path : audio_dir, file : audio };
			fgcommand("play-audio-message", props.Node.new(prop));
			screen.log.write(msg, 1, 1, 1);
		} else {
			setprop("/sim/messages/copilot", msg);
		}

		last_message.setValue(msg);
		lastmsgcount = 0;
	} else {
		lastmsgcount += 1;
	}
}


var shuffle = func(vec) {
	var s = size(vec);
	forindex (var i; vec) {
		var j = rand() * s;
		if (i != j) {
			var swap = vec[j];
			vec[j] = vec[i];
			vec[i] = swap;
		}
	}
	return vec;
}


var run_nasal = func(node) {
	node != nil or return;
	foreach (var n; node.getChildren("nasal")) {
		if (n.getNode("module") == nil) {
			n.getNode("module", 1).setValue("__tutorial");
		}
		fgcommand("nasal", n);
	}
}


var say = func(what, who = "copilot", delay = 0) {
	settimer(func { setprop("/sim/messages/", who, what) }, delay);
}


# Set up namespace "__tutorial" for embedded Nasal.
#
var init_nasal = func {
	globals.__tutorial = {
		say : say,   # just exporting tutorial.say as __turorial.say
		next : func(n = 1) { current_step += n; num_step_runs = 0 },
		previous : func(n = 1) {
			current_step -= n;
			num_step_runs = 0;
			if (current_step < 0) {
				current_step = 0;
			}
		},
	};
}


var dialog = func {
	fgcommand("dialog-show", props.Node.new({ "dialog-name" : "marker-adjust" }));
}


var marker = nil;
var heading = nil;
var slip = nil;
var last_message = nil;
var time_elapsed = nil;

_setlistener("/sim/signals/nasal-dir-initialized", func {
	marker = props.globals.getNode("/sim/model/marker", 1);
	heading = props.globals.getNode("/orientation/heading-deg", 1);
	slip = props.globals.getNode("/orientation/side-slip-deg", 1);
	last_message = props.globals.getNode("/sim/tutorials/last-message", 1);
	time_elapsed = props.globals.getNode("/sim/time/elapsed-sec", 1);
});