/*
 * Utility functions to decode/encode numbers and array's of numbers
 * to/from strings (Google maps polyline encoding)
 *
 * Extends the L.Polyline and L.Polygon object with methods to convert
 * to and create from these strings.
 *
 * Jan Pieter Waagmeester <jieter@jieter.nl>
 *
 * Original code from:
 * http://facstaff.unca.edu/mcmcclur/GoogleMaps/EncodePolyline/
 */

(function () {
	'use strict';

	var defaultOptions = function (options) {
		if (typeof options === 'number') {
			// Legacy
			options = { precision: options };
		} else {
			options = options || {};
		}

		options.precision = options.precision || 5;
		options.factor = options.factor || Math.pow(10, options.precision);
		options.dimension = options.dimension || 2;
		return options;
	};

	var PolylineUtil = {
		encode: function (points, options) {
			options = defaultOptions(options);

			var flatPoints = [];
			for (var i = 0, len = points.length; i < len; ++i) {
				var point = points[i];

				if (options.dimension === 2) {
					flatPoints.push(point.lat || point[0]);
					flatPoints.push(point.lng || point[1]);
				} else {
					for (var dim = 0; dim < options.dimension; ++dim) {
						flatPoints.push(point[dim]);
					}
				}
			}

			return this.encodeDeltas(flatPoints, options);
		},

		decode: function (encoded, options) {
			options = defaultOptions(options);

			var flatPoints = this.decodeDeltas(encoded, options);

			var points = [];
			for (var i = 0, len = flatPoints.length; i + (options.dimension - 1) < len;) {
				var point = [];

				for (var dim = 0; dim < options.dimension; ++dim) {
					point.push(flatPoints[i++]);
				}

				points.push(point);
			}

			return points;
		},

		encodeDeltas: function(numbers, options) {
			options = defaultOptions(options);

			var lastNumbers = [];

			for (var i = 0, len = numbers.length; i < len;) {
				for (var d = 0; d < options.dimension; ++d, ++i) {
					var num = numbers[i];
					var delta = num - (lastNumbers[d] || 0);
					lastNumbers[d] = num;

					numbers[i] = delta;
				}
			}

			return this.encodeFloats(numbers, options);
		},

		decodeDeltas: function(encoded, options) {
			options = defaultOptions(options);

			var lastNumbers = [];

			var numbers = this.decodeFloats(encoded, options);
			for (var i = 0, len = numbers.length; i < len;) {
				for (var d = 0; d < options.dimension; ++d, ++i) {
					numbers[i] = lastNumbers[d] = numbers[i] + (lastNumbers[d] || 0);
				}
			}

			return numbers;
		},

		encodeFloats: function(numbers, options) {
			options = defaultOptions(options);

			for (var i = 0, len = numbers.length; i < len; ++i) {
				numbers[i] = Math.round(numbers[i] * options.factor);
			}

			return this.encodeSignedIntegers(numbers);
		},

		decodeFloats: function(encoded, options) {
			options = defaultOptions(options);

			var numbers = this.decodeSignedIntegers(encoded);
			for (var i = 0, len = numbers.length; i < len; ++i) {
				numbers[i] /= options.factor;
			}

			return numbers;
		},

		/* jshint bitwise:false */

		encodeSignedIntegers: function(numbers) {
			for (var i = 0, len = numbers.length; i < len; ++i) {
				var num = numbers[i];
				numbers[i] = (num < 0) ? ~(num << 1) : (num << 1);
			}

			return this.encodeUnsignedIntegers(numbers);
		},

		decodeSignedIntegers: function(encoded) {
			var numbers = this.decodeUnsignedIntegers(encoded);

			for (var i = 0, len = numbers.length; i < len; ++i) {
				var num = numbers[i];
				numbers[i] = (num & 1) ? ~(num >> 1) : (num >> 1);
			}

			return numbers;
		},

		encodeUnsignedIntegers: function(numbers) {
			var encoded = '';
			for (var i = 0, len = numbers.length; i < len; ++i) {
				encoded += this.encodeUnsignedInteger(numbers[i]);
			}
			return encoded;
		},

		decodeUnsignedIntegers: function(encoded) {
			var numbers = [];

			var current = 0;
			var shift = 0;

			for (var i = 0, len = encoded.length; i < len; ++i) {
				var b = encoded.charCodeAt(i) - 63;

				current |= (b & 0x1f) << shift;

				if (b < 0x20) {
					numbers.push(current);
					current = 0;
					shift = 0;
				} else {
					shift += 5;
				}
			}

			return numbers;
		},

		encodeSignedInteger: function (num) {
			num = (num < 0) ? ~(num << 1) : (num << 1);
			return this.encodeUnsignedInteger(num);
		},

		// This function is very similar to Google's, but I added
		// some stuff to deal with the double slash issue.
		encodeUnsignedInteger: function (num) {
			var value, encoded = '';
			while (num >= 0x20) {
				value = (0x20 | (num & 0x1f)) + 63;
				encoded += (String.fromCharCode(value));
				num >>= 5;
			}
			value = num + 63;
			encoded += (String.fromCharCode(value));

			return encoded;
		}

		/* jshint bitwise:true */
	};

	// Export Node module
	if (typeof module === 'object' && typeof module.exports === 'object') {
		module.exports = PolylineUtil;
	}

	// Inject functionality into Leaflet
	if (typeof L === 'object') {
		if (!(L.Polyline.prototype.fromEncoded)) {
			L.Polyline.fromEncoded = function (encoded, options) {
				return new L.Polyline(PolylineUtil.decode(encoded), options);
			};
		}
		if (!(L.Polygon.prototype.fromEncoded)) {
			L.Polygon.fromEncoded = function (encoded, options) {
				return new L.Polygon(PolylineUtil.decode(encoded), options);
			};
		}

		var encodeMixin = {
			encodePath: function () {
				return PolylineUtil.encode(this.getLatLngs());
			}
		};

		if (!L.Polyline.prototype.encodePath) {
			L.Polyline.include(encodeMixin);
		}
		if (!L.Polygon.prototype.encodePath) {
			L.Polygon.include(encodeMixin);
		}

		L.PolylineUtil = PolylineUtil;
	}
})();
