$(function() {

	// Return a string safe to display in HTML
	var safe = function(html) {
	    return String(html)
			.replace(/&/g, '&')
			.replace(/</g, '&lt;')
			.replace(/>/g, '&gt;')
			.replace(/"/g, '&quot;');
	};

	// Return a uniquer identifier
	var uniqueId = function() {
		return 'xxxxxxxxxxxx4xxxyxxxxxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
			var r, v;
			r = Math.random() * 16 | 0;
		    v = c === 'x' ? r : (r & 0x3 | 0x8);
	    	return v.toString(16);
		});
	};

	// MessageBus ENTER callback
	var enter = function(name, opts) {
		if (opts && opts.check) {
		    var found = false;
	    	$('#walkers li').each(function() {
				found = found || ($(this).text().trim() === name.trim());
				if (found && opts.me) {
				    $(this).remove();
		    		found = false;
				}
				return !found;
		    });
		    if (found) {
				return;
	    	}
		}

		var li = $('<li></li>');
		li.text(name);
		if (opts && opts.me) {
	    	li.addClass("me");
	    	$('#walkers').prepend(li);
		} else {
	    	$('#walkers').append(li);
		}
    };

	// MessageBus LEAVE callback
	var leave = function(name) {
		$.post('/leave', { name: name });
		MessageBus.stop();
		$('#bus-status').text('stopped');
	};

	// Assign player to a team
	var assign_random_team = function() {
		var teams = ['cavity', 'musclel', 'muscler', 'stringl', 'stringr', 'wingl', 'wingr'];
		var team = teams[Math.floor(Math.random()*teams.length)];
		$('#team').text(team);
		return team;
	};


	// When the DOM is fully loaded, start playing
	$(document).ready(function() {

		var name      = uniqueId(),	// Uniquely identify client
			n_walkers = 0,			// Number of clients
			n_steps   = 0,			// Number of steps for this client
			last_step = $.now(),	// Timestamp for last step
			has_accel = false,		// Whether this device has an accelerometer
			accel_n   = 0,			// Acceleration (vector norm)
			accel     = { x: 0, y: 0, z: 0, n: 0 }, // Acceleration with Kalman filter
			MIN_N     = 10.3, 		// Minimum threshold for step detection
			MAX_N     = 20;			// Maximum threshold

		// SVG animation
		var map, cavity, cavity_b, musclel, musclel_b, muscler, muscler_b,
			stringl, stringl_b, stringr, stringr_b, wingl, wingl_b, wingr, wingr_b, flight_path, flight_path_l, last_point;

		var team  = assign_random_team();
		var svgp, bbox;
		
		map           = Snap('#left-bits');
/*
		cavity        = map.select('#cavity');
		cavity_b      = cavity.getBBox();
		musclel       = map.select('#musclel');
		musclel_b     = musclel.getBBox();
		muscler       = map.select('#muscler');
		musclel_b     = muscler.getBBox();
		stringl       = map.select('#stringl');
		stringl_b     = stringl.getBBox();
		stringr       = map.select('#stringr');
		stringl_b     = stringr.getBBox();
		wingl         = map.select('#wingl');
		wingl_b       = wingl.getBBox();
		wingr         = map.select('#wingr');
		wingr_b       = wingr.getBBox();		
*/		flight_path   = map.select('#path');
		flight_path_l = Snap.path.getTotalLength(flight_path);
		
//		console.log('flight_path_length ' + flight_path_l);
		last_point    = flight_path.getPointAtLength(flight_path_l);

		// Start/pause MessageBus when clicking on status
		$('#bus-status').click(function() {
			switch($('#bus-status').text()) {
			case 'started':
				MessageBus.pause();
				break;
			case 'paused':
				MessageBus.resume();
				break;
			case 'stopped':
				MessageBus.start();
				break;
			default:
				break;
			}
		});

	var play_move = function(jump, team=false) {
		if (svgp = map.select('#' + (team || $('#team').text()))) {
			bbox = svgp.getBBox();

			if (jump > flight_path_l) {
//				console.log('GAME OVER');
				return;
			}
		
			Snap.animate(jump, flight_path_l, function() {
				var p = Snap.path.getPointAtLength( flight_path, jump );
				x = p.x;
				y = p.y;
				svgp.transform('translate(' + x + ',' + y + ') rotate(' + (p.alpha - 90) + ', ' + bbox.cx + ', ' + bbox.cy + ')');
			},1000, mina.easeout);
		}
	}

		// Update MessageBus status (debug)
		var statusInfo = setInterval(function() {
			$('#bus-status').text(MessageBus.status());
			$('#name').text(name); // should be static
		}, 2000);

		// Configuration
	    MessageBus.headers["X-NAME"] = name;

		// Who's connected
/*		MessageBus.subscribe("/presence", function(msg) {
	    	if (msg.enter) {
				enter(msg.enter, { check: true });
	    	}
		    if (msg.leave) {
				$('#walkers li').each(function() {
	    			if ($(this).text() === msg.leave) {
						$(this).remove();
						leave(msg.leave);
	    			}
				});
		    }
		});
*/
		// Count clients
/*		MessageBus.subscribe('/n-walkers', function(data) {
			if (data && data.count) {
				n_walkers = data.count;
				$('#n-walkers').text(n_walkers);
			}
		}, n_walkers);
*/
		// Update client steps
		MessageBus.subscribe("/walk", function(data) {
			if (data.name) {
				jump = data.n * data.step;
				if (data.name == name) {
					$('#accel-n').text(data.n);
					$('#n-steps').text(data.step);
					$('#current-team').text(data.team);
				}
				if (jump >  flight_path_l) {
					$.post('/walk', { n: data.n, name: data.name, step: 0, team: data.team });
				} else {
					play_move(jump, data.team);
				}
			}
		}); // last id is zero, so getting backlog

	    // If we have accelerometer, play the game
	    if (window.DeviceMotionEvent != undefined) {

			// Enter the game
/*			$.post("/enter", { name: name }, null, "json" ).success(function(data) {
				$.each(data.walkers, function(idx, name) {
			    	enter(name);
				});
				name = data.name;
				enter(name, { check: true, me: true });
	    	});

			// Leave the game
			window.onbeforeunload = function() {
			    $.post("/leave", { name: name });
			};
*/
			// Compute acceleration or simulate it
			var accel_norm = function(e) {

				//	has_accel = (window.DeviceMotionEvent != undefined && e != undefined && e.type == 'devicemotion' && e.acceleration.x != null);
				var norm;

				if (!has_accel) {
//					console.log("This device does not support DeviceMotionEvent");
					var min = 5, max = 15;
				    norm = Math.floor(Math.random()*(max-min+1)+min);
				} else {
					var ax, ay, az;
					ax = e.accelerationIncludingGravity.x;
					ay = e.accelerationIncludingGravity.y;
					az = e.accelerationIncludingGravity.z;

					accel = detect_footstep(ax, ay, az);

					norm = Math.sqrt(ax * ax + ay * ay + az * az);
				}
				$('#accel-n').text(safe(norm));
//				console.log("accel-n " + norm);
				return norm;
			}

			// Detect footsteps with a Kalman filter
			var detect_footstep = function(ax, ay, az) {

				var acc = {
					x: ax,
					y: ay,
					z: az
				};
				var cnt = 0;

				var x_0 = $V([acc.x, acc.y, acc.z]); // vector. Initial accelerometer values

				// P prior knowledge of state
				var P_0 = $M([
            		[1,0,0],
				    [0,1,0],
           			[0,0,1]
				]); // identity matrix. Initial covariance. Set to 1
				var F_k = $M([
				    [1,0,0],
				    [0,1,0],
        			[0,0,1]
        		]); // identity matrix. How change to model is applied. Set to 1
				var Q_k = $M([
				    [0,0,0],
    				[0,0,0],
        			[0,0,0]
        		]); // empty matrix. Noise in system is zero

				var KM = new KalmanModel(x_0,P_0,F_k,Q_k);

				var z_k = $V([acc.x, acc.y, acc.z]); // Updated accelerometer values
				var H_k = $M([
				    [1,0,0],
				    [0,1,0],
        			[0,0,1]
        		]); // identity matrix. Describes relationship between model and observation
				var R_k = $M([
				    [2,0,0],
				    [0,2,0],
        			[0,0,2]
       			]); // 2x Scalar matrix. Describes noise from sensor. Set to 2 to begin

				var KO = new KalmanObservation(z_k,H_k,R_k);

				// each 1/10th second take new reading from accelerometer to update
				var getNewPos = window.setInterval(function() {
				    KO.z_k = $V([acc.x, acc.y, acc.z]); //vector to be new reading from x, y, z
				    KM.update(KO);

					accel = { x: KM.x_k.elements[0], y: KM.x_k.elements[1], z: KM.x_k.elements[2], n: accel.n };
					accel.n = Math.sqrt(accel.x * accel.x + accel.y * accel.y + accel.z * accel.z);
					$('#accel-n-kalman').text(accel.n);
				}, 100);

				return accel;
			};

			// If we can use the accelerometer, use it...
			window.ondevicemotion = function(e) {
//				console.log('ondevicemotion');
				has_accel = (window.DeviceMotionEvent != undefined && e != undefined && e.type == 'devicemotion' && e.acceleration.x != null);
				if (has_accel) {
//					console.log('has_accel');
					$('#accel-support').text("with accelerometer support");
					walk(e);
				} else {
					$('#accel-support').text('with simulated accelerometer');
					setInterval(walk, 100);
				}
			}
			// ... otherwise simulate it
//			if (!has_accel) {
//				$('#accel-support').text('with simulated accelerometer');
//				setInterval(walk, 100);
//			}

			// Count steps (ballpark figure)
			var walk = function(e) {
				var val = accel_norm(e);
//				console.log('walk setting val to ' + safe(val));
				if (has_accel) {
					// Use Kalman filter
					val = accel.n;
//					console.log('walk setting val to ' + safe(val) + ' (K)');
				}
//				console.log("walk " + (has_accel?'ACCEL ':'NOCEL ') + val);
				// Avoid noise
				if (val < MIN_N || val > MAX_N) {
//					console.log('walk NOISE');
					return;
				}
				// Take step frequency into account
				if (($.now() - last_step) > 400) {
					n_steps += 1;
					$.post('/walk', { n: val, name: name, step: n_steps, team: $('#team').text() });
					last_step = $.now();
				}
			};
		} 	// DeviceMotionEvent
	}); 	// DOM Ready
});			// Anonymous function