var imageSet = false;
var calibrationDone = false;
var calibrationData = { x1: null, y1: null, lat1: null, lon1: null, x2: null, y2: null, lat2: null, lon2: null};
getImage = function() {
	try {
		g('image').src = g('imageURL').value;
		if(!imageSet) {
			g('image').style.borderWidth = "1px";
			g('image').style.borderStyle = "solid";
			g('image').style.borderColor = "#000000";
			g('divCalibrate').style.display = "block";
			imageStyleSet = true;
		}
	} catch(e) {
		alert("An exception occurred in the script.\nError name: " + e.name + ".\nError description: " + e.description + ".\nError number: " + e.number+ ".\nError message: " + e.message);
	}
	return false;
}
imageLoaded = function() {
	try {
		var size = document.getElementSize(g('image'));
		//var pos =  document.getElementPosition(g('image'));
		//alert(size.w+','+size.h);
		//alert(pos.x +','+pos.y);
		g('divCalibrate').style.top = size.h + 20 + 'px';
		g('divTC').style.top = size.h + 20 + 'px';
		g('divRef').style.top = size.h + 20 + 'px';
		g('divCalcResult').style.top = size.h + 20 + 'px';
		return true;
	} catch(e) {
		alert("An exception occurred in the script.\nError name: " + e.name + ".\nError description: " + e.description + ".\nError number: " + e.number+ ".\nError message: " + e.message);
	}
	return false;
}
choosePlace = function() {
	try {
		g('divXY4').style.display = "none";
		g('divLaLo4').style.display = "block";
		g('imageLat4').value = null;
		g('imageLon4').value = null;
	} catch(e) {
		alert("An exception occurred in the script.\nError name: " + e.name + ".\nError description: " + e.description + ".\nError number: " + e.number+ ".\nError message: " + e.message);
	}
	return false;
}
chooseHK = function() {
	try {
		g('divXY4').style.display = "none";
		g('divLaLo4').style.display = "block";
		g('imageLat4').value = 22.3;
		g('imageLon4').value = 114.17;
	} catch(e) {
		alert("An exception occurred in the script.\nError name: " + e.name + ".\nError description: " + e.description + ".\nError number: " + e.number+ ".\nError message: " + e.message);
	}
	return false;
}
getImageXY = function(n) {
	try { 
		g('divXY'+n).style.display = "block"; g('divLaLo'+n).style.display = "none";
		var postClickHandler = null;
		var oldX = g('imageX'+n).value;
		var oldY = g('imageY'+n).value;
		var moveMouse = function (e) {
			var mousePos = document.getMousePos(e);
			var imagePos =  document.getElementPosition(g('image'));
			g('imageX'+n).value = mousePos.x - imagePos.x;
			g('imageY'+n).value = mousePos.y - imagePos.y;
			document.body.style.cursor = 'crosshair';
		}
		var mouseClick = function (e) {
			stopCalibration();
			postClickHandler(n);
		}
		var keyDown = function (e) {
			if(!e) e = window.event;
			var k = e.keyCode;
			if(k == 27) { //Esc
				stopCalibration();
				g('imageX'+n).value = oldX;
				g('imageY'+n).value = oldY;
			}
		}
		var stopCalibration = function () {
			unhookevent(document, 'mousemove', moveMouse);
			unhookevent(document, 'keydown', keyDown);
			unhookevent(document, 'click', mouseClick);
			document.body.style.cursor = '';
			g('divLaLo'+n).style.display = "block";
		}
		var finishCalibration = function(n) {
			g('imageLat'+n).focus();
			g('imageLat'+n).select();
		}
		postClickHandler = finishCalibration;
		if(getImageXY.arguments.length > 1 && typeof getImageXY.arguments[1] == 'function')
			postClickHandler = getImageXY.arguments[1];
		hookevent(document, 'mousemove', moveMouse);
		hookevent(document, 'keydown', keyDown);
		setTimeout(function(){hookevent(document, 'click', mouseClick);}, 0);
	} catch(e) {
		try { unhookevent(document, 'mousemove', moveMouse); } catch(e) {}
		try { unhookevent(document, 'keydown', keyDown); } catch(e) {}
		try { unhookevent(document, 'click', mouseClick); } catch(e) {}
		
		alert("An exception occurred in the script.\nError name: " + e.name + ".\nError description: " + e.description + ".\nError number: " + e.number+ ".\nError message: " + e.message);
	}
}
calibrationFinish = function() {
	try {
		calibrationDone = true;
		var errmsg = '';
		if(!isNaN(g('imageX1').value) || (calibrationDone = false)) {
			calibrationData.x1 = Number(g('imageX1').value);
		}
		if(!isNaN(g('imageY1').value) || (calibrationDone = false)) {
			calibrationData.y1 = Number(g('imageY1').value);
		}
		if(!isNaN(g('imageLat1').value) || (calibrationDone = false)) {
			calibrationData.lat1 = Number(g('imageLat1').value);
		}
		if(!isNaN(g('imageLon1').value) || (calibrationDone = false)) {
			calibrationData.lon1 = Number(g('imageLon1').value);
		}
		if(!isNaN(g('imageX2').value) || (calibrationDone = false)) {
			calibrationData.x2 = Number(g('imageX2').value);
		}
		if(!isNaN(g('imageY2').value) || (calibrationDone = false)) {
			calibrationData.y2 = Number(g('imageY2').value);
		}
		if(!isNaN(g('imageLat2').value) || (calibrationDone = false)) {
			calibrationData.lat2 = Number(g('imageLat2').value);
		}
		if(!isNaN(g('imageLon2').value) || (calibrationDone = false)) {
			calibrationData.lon2 = Number(g('imageLon2').value);
		}
		if(!calibrationDone) {
			errmsg += '校準出現錯誤！\n';
		} else if(calibrationData.lat1 == calibrationData.lat2 || calibrationData.lon1 == calibrationData.lon2 || Math.abs(calibrationData.x1 - calibrationData.x2) < 5 || Math.abs(calibrationData.y1 - calibrationData.y2) < 5) {
			errmsg += '用作校準工作的兩點不能位於同一經度或者緯度！\n';
			calibrationDone = false;
		} else if((calibrationData.x1 == 0 && calibrationData.y1 == 0) || (calibrationData.x2 == 0 && calibrationData.y2 == 0)) {
			errmsg += '需要尚餘一點以進行校準工作！\n';
			calibrationDone = false;
		}
		if(calibrationDone) {
			g('divTC').style.display = "block"; g('divRef').style.display = "block";
		} else {
			alert(errmsg);
		}
		//alert('calibrationDone = ' + calibrationDone + '\n(' + calibrationData.x1 + ', ' + calibrationData.y1 + ') = (' + calibrationData.lat1 + '\xb0N, ' + calibrationData.lon1 + '\xb0E)\n(' + calibrationData.x2 + ', ' + calibrationData.y2 + ') = (' + calibrationData.lat2 + '\xb0N, ' + calibrationData.lon2 + '\xb0E)\n');
	} catch(e) {
		calibrationDone = false;
		alert("An exception occurred in the script.\nError name: " + e.name + ".\nError description: " + e.description + ".\nError number: " + e.number+ ".\nError message: " + e.message);
	}
	return false;
}
getImageLatLonFromXY = function(n) {
	try {
		if(calibrationDone) {
			var x = Number(g('imageX'+n).value);
			var y = Number(g('imageY'+n).value);
			if(isNaN(x) || isNaN(y)) {
				return false;
			}
			with (calibrationData) {
				var lon = lon1 + (lon2 - lon1) * (x - x1) / (x2 - x1);
				var lat = lat1 + (lat2 - lat1) * (y - y1) / (y2 - y1);
			}
			g('imageLat'+n).value = Math.round(lat * 100) / 100; //round to 2 decimal places;
			g('imageLon'+n).value = Math.round(lon * 100) / 100; //round to 2 decimal places;
		}
	} catch(e) {
		alert("An exception occurred in the script.\nError name: " + e.name + ".\nError description: " + e.description + ".\nError number: " + e.number+ ".\nError message: " + e.message);
	}
	return false;
}
calc = function() {
	try {
		var inrange = function(num, lowerlimit, upperlimit) {
			return !isNaN(num) && lowerlimit <= num && num <= upperlimit;
		}
		var tcpos = new LatLon(g('imageLat3').value.parseDeg(), g('imageLon3').value.parseDeg());
		var refpos = new LatLon(g('imageLat4').value.parseDeg(), g('imageLon4').value.parseDeg());
		if(inrange(tcpos.lat, -90, 90) && inrange(tcpos.lon, -180, 180) && inrange(refpos.lat, -90, 90) && inrange(refpos.lon, -180, 180)) {
			//Great circle distances & bearings
			var distanceHaversine = LatLon.distHaversine(refpos.lat, refpos.lon, tcpos.lat, tcpos.lon);
			var distanceCosineLaw = LatLon.distCosineLaw(refpos.lat, refpos.lon, tcpos.lat, tcpos.lon);
			var ref2tcInitBearing = LatLon.bearing(refpos.lat, refpos.lon, tcpos.lat, tcpos.lon);
			var tc2refInitBearing = LatLon.bearing(tcpos.lat, tcpos.lon, refpos.lat, refpos.lon); //not necessarily 180 degrees apart
			//Rhumb line distance & bearing
			var distanceRhumbline = LatLon.distRhumb(refpos.lat, refpos.lon, tcpos.lat, tcpos.lon);
			var ref2tcRhumbBearing = LatLon.brngRhumb(refpos.lat, refpos.lon, tcpos.lat, tcpos.lon);
			
			var formatAngle = function(degrees, decimalPlaces, leadingZero) {
				var output = '<span class="degreesDecimal">';
				if(decimalPlaces > 0) {
					var dp = Math.round(Math.abs(degrees) % 1 * Math.pow(10, decimalPlaces)).toString();
					while(dp.length < decimalPlaces)
						dp += '0';
					output += (leadingZero ? ('000' + Math.floor(degrees)).slice(-3) : Math.floor(degrees).toString()) + '.' + dp;
				} else {
					output += (leadingZero) ? ('000' + Math.round(degrees)).slice(-3) : Math.round(degrees).toString();
				}
				output += '&#176;</span><span class="degreesDMS">(' + (leadingZero ? degrees.toDMS() : degrees.toDMS().replace(/^0+(?!\u00B0)/g, '')) + ')</span>';
				return output;
			}
			var formatDistance = function(dist) {
				return Math.round(dist) + ' km / ' + Math.round(dist / 1.852) + ' nm / ' + Math.round(dist * 0.621) + ' miles';
			}
			var ihtml = '<p>　</p><p>計算結果：</p>';
			ihtml += '<table>';
			ihtml += '<tr><td><b>Reference position</b>:</td><td>' + formatAngle(Math.abs(refpos.lat), 2, false) + (refpos.lat < 0 ? ' S' : ' N') + ', </td><td>' + formatAngle(Math.abs(refpos.lon), 2, false) + (refpos.lon < 0 ? ' W' : ' E') + '</td></tr>';
			ihtml += '<tr><td><b>TC position</b>:</td><td>' + formatAngle(Math.abs(tcpos.lat), 2, false) + (tcpos.lat < 0 ? ' S' : ' N') + ', </td><td>' + formatAngle(Math.abs(tcpos.lon), 2, false) + (tcpos.lon < 0 ? ' W' : ' E') + '</td></tr>';
			ihtml += '</table>';
			ihtml += '<table>';
			ihtml += '<tr><td><b>Distance method</b></td><td><b>Initial Bearing</b></td><td><b>Final Bearing</b></td><td><b>Distance</b></td></tr>';
			ihtml += '<tr><td>Great Circle:</td><td>[Ref&rarr;TC]: ' + formatAngle(ref2tcInitBearing, 0, true) + '</td><td>[Ref&rarr;TC]: ' + formatAngle((tc2refInitBearing + 180) % 360, 0, true) + '</td><td>' + Math.round(distanceHaversine) + ' km / ' + Math.round(distanceHaversine / 1.852) + ' nm / ' + Math.round(distanceHaversine * 0.621) + ' miles (Haversine formula)</td></tr>';
			ihtml += '<tr><td></td><td>[TC&rarr;Ref]: ' + formatAngle(tc2refInitBearing, 0, true) + '</td><td>[TC&rarr;Ref]: ' + formatAngle((ref2tcInitBearing + 180) % 360, 0, true) + '</td><td>' + Math.round(distanceCosineLaw) + ' km / ' + Math.round(distanceCosineLaw / 1.852) + ' nm / ' + Math.round(distanceCosineLaw * 0.621) + ' miles (cosine law)</td></tr>';
			ihtml += '<tr><td>Rhumb line:</td><td>[Ref&rarr;TC]: ' + formatAngle(ref2tcRhumbBearing, 0, true) + '</td><td>[TC&rarr;Ref]: ' + formatAngle((ref2tcRhumbBearing + 180) % 360, 0, true) + '</td><td>' + Math.round(distanceRhumbline) + ' km / ' + Math.round(distanceRhumbline / 1.852) + ' nm / ' + Math.round(distanceRhumbline * 0.621) + ' miles</td></tr>';
			ihtml += '</table>';
			
			g('divCalcResult').innerHTML = ihtml;
		} else {
			alert('資料出現錯誤！');
		}
	} catch(e) {
		alert("An exception occurred in the script.\nError name: " + e.name + ".\nError description: " + e.description + ".\nError number: " + e.number+ ".\nError message: " + e.message);
	}
	return false;
}