var kln94 = nil;

var KLN94 = {
	
	Page: {
		new : func(owner, s, idx)
		{
			m = { 
				parents:[KLN94.Page],
				section: s,
				index: idx
			};
			return m;
		},
		
		# encode various behavioural flags as predicates
		# real Pages can over-ride these defaults as needed
		hasActiveIdent: func { return 0; },    
		numberOfCyanLines: func { return 0; },
		showsCDI: func { return 0; },
		isMulti: func { return 0; },
		
		# cursor stuff
		
		display: func(gps)
		{
			
		},
		
		refresh: func(gps)
		{
			
		},
		
	},
	
	pageNames : ['APT', 'VOR', 'NDB', 'INT', 'USR', 'ACT', 'NAV', 'FPL', 'SET', 'AUX'],
	
	PAGE_APT: 0,
	PAGE_VOR: 1,
	PAGE_NDB: 2,
	PAGE_INT: 3,
	PAGE_USR: 4,
	PAGE_ACT: 5,
	PAGE_NAV: 6,
	PAGE_FPL: 7,
	PAGE_SET: 8,
	PAGE_AUX: 9,
	
	
	PAGE_BAR_HEIGHT: 20,
	NAV_DATA_WIDTH: 128,
	
	canvas_settings: {
		"name": "KLN94",
		"size": [512, 256],
		"view": [480, 160],
		"mipmapping": 1,
	},
	
	new : func(prop1, placement)
	{
		m = { parents : [KLN94]};
		
		m.rootNode = props.globals.initNode(prop1);   
		m._setupCanvas(placement);
		m._page = nil;
		
		m._messageScreenActive = 0;
		m._messages = [];
		
		m._cursorActive = 0;
		m._cursorField = 0;
		m._enterAction = nil;
		
		
		m._setupProps();
		
		return m;
	},
	
	_setupCanvas: func(placement)
	{
		me._canvas = canvas.new(KLN94.canvas_settings);        
		var text_style = {
			'font': "LiberationFonts/LiberationMono-Bold.ttf",
			'character-size': 34,
			'character-aspect-ratio': 1.2
		};
		
		me.rootNode.initNode('brightness-norm', 0.5, 'DOUBLE');
		
		me._canvas.setColorBackground(1.0, 0.0, 0.0);
		me._canvas.addPlacement(placement);
		
		me._navDataArea = me._canvas.createGroup();
		me._navDataArea.setTranslation(0, 0);
		me._navDataLines = [];
		
		var navAreaH = (KLN94.canvas_settings.view[1] - KLN94.PAGE_BAR_HEIGHT) / 2;
		var r1 = me._navDataArea.rect(0, 0, KLN94.NAV_DATA_WIDTH, navAreaH);
		var r2 = me._navDataArea.rect(0, navAreaH, KLN94.NAV_DATA_WIDTH, navAreaH);
		r1.setColor(0,1,1); # cyan
		r2.setColor(0,1,1);
		
		var lineH = (KLN94.canvas_settings.view[1] - KLN94.PAGE_BAR_HEIGHT) / 5;
		
		for (var i=0; i<4; i +=1) {
			var t = me._navDataArea.createChild("text");
			t.setColor(1, 1, 1);
			t._node.setValues(text_style);
			t.setAlignment("left-center");
			t.setTranslation(0.0, (i + 0.5) * lineH);        
			append(me._navDataLines, t);
		}
		
		me._pageBarArea = me._canvas.createGroup();
		me._pageBarArea.setTranslation(0, KLN94.canvas_settings.view[1] - KLN94.PAGE_BAR_HEIGHT);
		
		var ln = me._pageBarArea.createChild('path');
		ln.setColor(0,1,1); # cyan
		
		me._pageBarText = me._pageBarArea.createChild("text");
		me._pageBarText._node.setValues(text_style);
		me._pageBarText.setAlignment("left-center");
		me._pageBarText.setColor(0, 0, 1);
		
		me._pageBarInverseText = me._pageBarArea.createChild("text");
		me._pageBarInverseText._node.setValues(text_style);
		me._pageBarInverseText.setAlignment("left-center");
		me._pageBarInverseText.setColor(1, 1, 1);
		me._pageBarInverseText.setColorFill(0, 0, 1);
		
		me._pageArea = me._canvas.createGroup();
		me._pageBarArea.setTranslation(100, 0);
		
		me._pageAreaLines = [];
		for (var i=0; i<5; i +=1) {
			var t = me._pageArea.createChild("text");
			t.setColor(0, 1, 0);
			t._node.setValues(text_style);
			t.setAlignment("left-center");
			t.setTranslation(0.0, (i + 0.5) * lineH);        
			append(me._pageAreaLines, t);
		}
		
		# inverted text block
		me._pageAreaInverted = me._pageArea.createChild("text");
		me._pageAreaInverted.setColor(0, 0, 0);
		me._pageAreaInverted.setColorFill(0, 1, 0);
		me._pageAreaInverted._node.setValues(text_style);
		me._pageAreaInverted.setAlignment("left-center");
		
		me._cdiGroup = me._pageArea.createChild("group");
		canvas.parsesvg(me._cdiGroup, resolvepath('Aircraft/Instruments-3d/kln94/cdi.svg'));
		me._cdiGroup.setTranslation(0, lineH);
	},
	
	_setupProps: func
	{
		var p = me.rootNode;
		me.props = {
			distanceToActiveNm: p.getNode(),
			groundspeedKt: p.getNode(),
			activeIdent: p.getNode(),
			previousIdent: p.getNode(),
			obsBearing: p.getNode(),
			legTrack: p.getNode(),
			groundTrack: p.getNode(),
			cdiDeviationNm: p.getNode(),
		};
	},
	
	_setActivePage: func(pg)
	{
		me._page = pg;
		if (pg == nil) return;
		
		# update line colors
		for (var l=0; l<4; l+=1) {
			me._pageAreaLines[l].setColor(0, 1, l < pg.numberOfCyanLines() ? 1 : 0);
		}
		
		# hide or show the CDI area as appropriate
		me._cdiGroup.setVisible(pg.showsCDI());
	},
	
	_updateNavData : func
	{
		me._navDataLines[0].setText(sprintf('%4dnm', me._props.distanceToActiveNm.getValue()));
		if (me._page.hasActiveIdent()) {
			me._navDataLines[1].setText(sprintf('%4dkt', me._props.groundspeedKt.getValue()));
		} else {
			me._navDataLines[1].setText(me._props.activeIdent.getValue());
		}
		if (me._obsMode) {
			me._navDataLines[2].setText(sprintf('OBS%03d*', me._props.obsBearing.getValue()));      
		} else {
			me._navDataLines[2].setText(sprintf('DTK%03d*', me._props.legTrack.getValue()));
		}
		me._navDataLines[3].setText(sprintf(' TK%03d*', me._props.groundTrack.getValue()));
	},
	
	_updateAnnunciationArea : func
	{
		if (size(me._messages) > 0) {
			# show 'M' symbol
		}
		
		if (me._enterAction != nil) {
			# show 'ENT' symbol
		}
		
	},
	
	_updatePageBar : func
	{
		# hide in NAV-4 mode
		if (me.inNav4Mode()) {
			me._pageBarGroup.setVisible(0);
			return;
		}
		
		if (me._cursorActive) {
			me._pageBarText.setText('');
			var t = '    * CRSR *  ' ~ me.pageNames[activePage] ~ ' * CRSR *';
			me._pageBarInverseText.setText(t);
			return;
		}
		
		# assemble the string
		var barString = '';
		var inverseBarString = '';
		var activePage = me.pageIndex[0];
		
		for (var i=0; i < 10; i += 1) {
			if (activePage == i) {
				var sep = me.isMultiPage() ? '+' : ' ';
				inverseBarString ~= me.pageNames[i] ~ sep ~ me.pageIndex[1];
				barString ~= '     '; # 5 spaces
			} else {
				barString ~= ' ' ~ me.pageNames[i];
				if (i < activePage)
					inverseBarString ~= '    '; # 4 spaces
			}
		}
		
		me._pageBarText.setText(barString);
		me._pageBarInverseText.setText(inverseBarString);
	},
	
	_setInverted: func(line, firstcol, numcols=1)
	{
		var t = me._pageAreaInverted;
		var cellW = 20.0;
		var lineH = (KLN94.canvas_settings.view[1] - KLN94.PAGE_BAR_HEIGHT) / 5;
		t.setTranslation(firstcol * cellW, (line + 0.5) * lineH);        
		t.setText(substr(me._pageAreaLines[line].getText(), firstcol, numcols));
		t.setVisible(1);
	},
	
	_setBlink: func(line, firstcol, numcols=1)
	{
		
	},
	
	isPageActive: func(nm, idx) 
	{
		if (me._page == nil) return 0;
		return (me._page.section == nm) and (me._page.index == idx);
	},
	
	isMultiPage: func { return me._page.isMulti(); },
	
	
	toggleCursor: func
	{
		me._cursorActive = !me._cursorActive;
		if (me._cursorActive) {
			me._cursorField = 0;
		}
		
		me._updatePageBar();
	},
	
	_buildMessageScreen: func
	{
		
	},
	
	# Nav4 mode is special
	inNav4Mode: func { return me.isPageActive(NAV, 4); },
	
	formatDuration: func(timeInSeconds)
	{
		if (timeInSeconds > 60) {
			return sprintf("0:%02d", timeInSeconds);
		}
		
		if (timeInSeconds > 3600) {
			var mins = int(timeInSeconds / 60);
			var secs = timeInSeconds - (mins * 60);
			return sprintf("%d:%02d", mins, secs);
		}
		
		var hours = int(timeInSeconds / 3600);
		timeInSeconds -= (hours * 3600);
		var mins = int(timeInSeconds / 60);
		var secs = timeInSeconds - (mins * 60);
		return sprintf("%d:%02d:%02d", hours, mins, secs); 
	},
	
	formatLatitude: func(lat)
	{
		var north = (lat >= 0.0);
		var latDeg = int(lat);
		var latMinutes = math.abs(lat - latDeg) * 60;
		return sprintf('%s%02d*%04.1f', north ? "N" : "S", abs(latDeg), latMinutes);
	},
	
	formatLongitude: func(lon)
	{
		var east = (lon >= 0.0);
		var lonDeg = int(lon);
		var lonMinutes = math.abs(lon - lonDeg) * 60;
		sprintf("%s%03d*%04.1f", east ? 'E' : 'W', abs(lonDeg), lonMinutes);        
	},
	
	##	Input Handling
	
	enter: func{
		# Enter Button Functionality	
	},

	toggleCursorMode: func{
		# Cursor Button Functionality
	},

	nearestButton: func{
		# Nearest Button Functionality
	},

	directTo: func{
		# Direct To (DTO) Button Functionality
	},

	obsButton: func{
		# OBS Button Functionality
	},

	messageButton: func{
		# Messages Button Functionality
		if (me._messageScreenActive) {
			me._messages = me._messages[1:]; # pop front
			if (size(me._messages) == 0) {
				me._messageScreenActive = 0;
				# refresh normal screen
				return;
			}
			
			me._buildMessageScreen();
			return;
		}
		
		if (size(me._messages) == 0) {
			debug.dump('no messages to show');
			return;
		}
		
		me._messageScreenActive = 1;
		me._buildMessageScreen();
	},

	procedureButton: func{
		# Procedure Button Functionality
	},

	altitudeButton: func{
		# Altitude Button Functionality
	},

	clearButton: func{
		# Clear Button Functionality
	},

	menuButton: func{
		# Menu Button Functionality
	},

	rangeButton: func( dir ){
		# Range Button Functionality
		# variable dir:
		#	-1 = down (decrease)
		#	 0 = not pressed
		#	 1 = up (increase)
	},

	innerKnob: func( offset ){
		# Inner Knob Functionality
	},

	outerKnob: func( offset ){
		# Outer Knob Functionality
	},

	powerButton: func{
		# Power Button Functionality
		#  Power Button equals to pushing in the brightness knob
	},
};


reload_gps = func 
{    
	kln94._setActivePage(nil); # force existing page to be undisplayed cleanly
	
	# make the cdu instance available inside the module namespace
	# we are going to load into.
	# for a reload this also wipes the existing namespace, which we want
	globals['kln94_NS'] = { gps: kln94, KLN94:KLN94 };
	
	var pages = ['navPages.nas', 'flightplanPages.nas', 'settingPages.nas', 'auxPages.nas'];
	# , 'infoPages.nas'
	
	#var settings = props.globals.getNode('/instrumentation/cdu/settings');
	foreach (var path; pages) {        
		# resolve the path in FG_ROOT, and --fg-aircraft dir, etc
		var abspath = resolvepath('Aircraft/Instruments-3d/kln94/' ~ path);
		if (io.stat(abspath) == nil) {
			debug.dump('KLN94 page not found:', path, abspath);
			continue;
		}
		
		# load pages code into a seperate namespace which we defined above
		# also means we can clean out that namespace later
		io.load_nasal(abspath, 'kln94_NS');
	}
	#   cdu.displayPageByTag(getprop('/instrumentation/cdu/settings/boot-page'));
};

setlistener("/nasal/canvas/loaded", func 
{
	# create base PGS
	kln94 = KLN94.new('/instrumentation/gps', {"node": "screen"});
	reload_gps();
}, 1);