/**
 * Creates a circular arc, of a circle of the given radius and center point, between bearing1 and bearing2;
 * 0 bearing is North of center point, positive clockwise.
 *
 * @name lineArc
 * @param {Coord} center center point
 * @param {number} radius radius of the circle
 * @param {number} bearing1 angle, in decimal degrees, of the first radius of the arc
 * @param {number} bearing2 angle, in decimal degrees, of the second radius of the arc
 * @param {Object} [options={}] Optional parameters
 * @param {number} [options.steps=64] number of steps
 * @param {string} [options.units='kilometers'] miles, kilometers, degrees, or radians
 * @returns {Feature<LineString>} line arc
 * @example
 * var center = turf.point([-75, 40]);
 * var radius = 5;
 * var bearing1 = 25;
 * var bearing2 = 47;
 *
 * var arc = turf.lineArc(center, radius, bearing1, bearing2);
 *
 * //addToMap
 * var addToMap = [center, arc]
 */
export default function lineArc(center: Coord, radius: number, bearing1: number, bearing2: number, options: {
    steps?: number,
    units?: Units,
} = {}): Feature<LineString> {
    // default params
    const steps = options.steps || 64;

    const angle1 = convertAngleTo360(bearing1);
    const angle2 = convertAngleTo360(bearing2);
    const properties = (!Array.isArray(center) && center.type === "Feature")  ? center.properties : {};

    // handle angle parameters
    if (angle1 === angle2) {
        return lineString(circle(center, radius, options).geometry.coordinates[0], properties);
    }
    const arcStartDegree = angle1;
    const arcEndDegree = (angle1 < angle2) ? angle2 : angle2 + 360;

    let alfa = arcStartDegree;
    const coordinates = [];
    let i = 0;

    while (alfa < arcEndDegree) {
        coordinates.push(destination(center, radius, alfa, options).geometry.coordinates);
        i++;
        alfa = arcStartDegree + i * 360 / steps;
    }
    if (alfa > arcEndDegree) {
        coordinates.push(destination(center, radius, arcEndDegree, options).geometry.coordinates);
    }
    return lineString(coordinates, properties);
}

/**
 * Takes a {@link LineString} and returns a {@link Point} at a specified distance along the line.
 *
 * @name along
 * @param {Feature<LineString>} line input line
 * @param {number} distance distance along the line
 * @param {Object} [options] Optional parameters
 * @param {string} [options.units="kilometers"] can be degrees, radians, miles, or kilometers
 * @returns {Feature<Point>} Point `distance` `units` along the line
 * @example
 * var line = turf.lineString([[-83, 30], [-84, 36], [-78, 41]]);
 * var options = {units: 'miles'};
 *
 * var along = turf.along(line, 200, options);
 *
 * //addToMap
 * var addToMap = [along, line]
 */
export default function along(
    line: Feature<LineString> | LineString,
    distance: number,
    options: {units?: Units} = {},
): Feature<Point> {
    // Get Coords
    const geom = getGeom(line);
    const coords = geom.coordinates;
    let travelled = 0;
    for (let i = 0; i < coords.length; i++) {
        if (distance >= travelled && i === coords.length - 1) { break;
        } else if (travelled >= distance) {
            const overshot = distance - travelled;
            if (!overshot) { return point(coords[i]);
            } else {
                const direction = bearing(coords[i], coords[i - 1]) - 180;
                const interpolated = destination(coords[i], overshot, direction, options);
                return interpolated;
            }
        } else {
            travelled += measureDistance(coords[i], coords[i + 1], options);
        }
    }
    return point(coords[coords.length - 1]);
}

/**
 * Takes a {@link Point} and calculates the circle polygon given a radius in degrees, radians, miles, or kilometers; and steps for precision.
 *
 * @name circle
 * @param {Feature<Point>|number[]} center center point
 * @param {number} radius radius of the circle
 * @param {Object} [options={}] Optional parameters
 * @param {number} [options.steps=64] number of steps
 * @param {string} [options.units='kilometers'] miles, kilometers, degrees, or radians
 * @param {Object} [options.properties={}] properties
 * @returns {Feature<Polygon>} circle polygon
 * @example
 * var center = [-75.343, 39.984];
 * var radius = 5;
 * var options = {steps: 10, units: 'kilometers', properties: {foo: 'bar'}};
 * var circle = turf.circle(center, radius, options);
 *
 * //addToMap
 * var addToMap = [turf.point(center), circle]
 */
function circle<P = Properties>(center: number[] | Point | Feature<Point, P>, radius: number, options: {
    steps?: number,
    units?: Units,
    properties?: P
} = {}): Feature<Polygon, P> {
    // default params
    const steps = options.steps || 64;
    const properties: any = options.properties ? options.properties : (!Array.isArray(center) && center.type === 'Feature' && center.properties) ? center.properties : {};

    // main
    const coordinates = [];
    for (let i = 0; i < steps; i++) {
        coordinates.push(destination(center, radius, i * -360 / steps, options).geometry.coordinates);
    }
    coordinates.push(coordinates[0]);

    return polygon([coordinates], properties);
}

function getMeanLineString(centroidOfLine: number[], angle: number, lenOfLine: number, isPlanar: boolean) {
    if (isPlanar) {
        const [averageX, averageY]: number[] = centroidOfLine;
        let beginX: number;
        let beginY: number;
        let endX: number;
        let endY: number;
        const r: number = angle * Math.PI / 180;
        const sin: number = Math.sin(r);
        const cos: number = Math.cos(r);
        beginX = averageX - lenOfLine / 2 * cos;
        beginY = averageY - lenOfLine / 2 * sin;
        endX = averageX + lenOfLine / 2 * cos;
        endY = averageY + lenOfLine / 2 * sin;
        return [
            [beginX, beginY],
            [endX, endY],
        ];
    } else {
        const end = destination(point(centroidOfLine), lenOfLine / 2, angle, { units: "meters" });
        const begin = destination(point(centroidOfLine), -lenOfLine / 2, angle, { units: "meters" });
        return [
            getCoord(begin), getCoord(end),
        ];
    }
}

/**
 * Takes a {@link LineString} and returns a {@link Point} at a specified distance along the line.
 *
 * @name along
 * @param {Feature<LineString>} line input line
 * @param {number} distance distance along the line
 * @param {Object} [options] Optional parameters
 * @param {string} [options.units="kilometers"] can be degrees, radians, miles, or kilometers
 * @returns {Feature<Point>} Point `distance` `units` along the line
 * @example
 * var line = turf.lineString([[-83, 30], [-84, 36], [-78, 41]]);
 * var options = {units: 'miles'};
 *
 * var along = turf.along(line, 200, options);
 *
 * //addToMap
 * var addToMap = [along, line]
 */
function along(line: Feature<LineString>| LineString, distance: number, options: {
    units?: Units
} = {}): Feature<Point> {
    // Optional parameters
    if (!isObject(options)) throw new Error('options is invalid');

    // Validation
    let coords;
    if (line.type === 'Feature') coords = line.geometry.coordinates;
    else if (line.type === 'LineString') coords = line.coordinates;
    else throw new Error('input must be a LineString Feature or Geometry');
    if (!isNumber(distance)) throw new Error('distance must be a number');

    let travelled = 0;
    for (let i = 0; i < coords.length; i++) {
        if (distance >= travelled && i === coords.length - 1) break;
        else if (travelled >= distance) {
            const overshot = distance - travelled;
            if (!overshot) return point(coords[i]);
            else {
                const direction = bearing(coords[i], coords[i - 1]) - 180;
                const interpolated = destination(coords[i], overshot, direction, options);
                return interpolated;
            }
        } else {
            travelled += measureDistance(coords[i], coords[i + 1], options);
        }
    }
    return point(coords[coords.length - 1]);
}

    flattenEach(lines, function (line: any) {
        const coords: any = getCoords(line);

        for (let i = 0; i < coords.length - 1; i++) {
            //start
            const start = point(coords[i]);
            start.properties.dist = distance(pt, start, options);
            //stop
            const stop = point(coords[i + 1]);
            stop.properties.dist = distance(pt, stop, options);
            // sectionLength
            const sectionLength = distance(start, stop, options);
            //perpendicular
            const heightDistance = Math.max(start.properties.dist, stop.properties.dist);
            const direction = bearing(start, stop);
            const perpendicularPt1 = destination(pt, heightDistance, direction + 90, options);
            const perpendicularPt2 = destination(pt, heightDistance, direction - 90, options);
            const intersect = lineIntersects(
                lineString([perpendicularPt1.geometry.coordinates, perpendicularPt2.geometry.coordinates]),
                lineString([start.geometry.coordinates, stop.geometry.coordinates])
            );
            let intersectPt = null;
            if (intersect.features.length > 0) {
                intersectPt = intersect.features[0];
                intersectPt.properties.dist = distance(pt, intersectPt, options);
                intersectPt.properties.location = length + distance(start, intersectPt, options);
            }

            if (start.properties.dist < closestPt.properties.dist) {
                closestPt = start;
                closestPt.properties.index = i;
                closestPt.properties.location = length;
            }
            if (stop.properties.dist < closestPt.properties.dist) {
                closestPt = stop;
                closestPt.properties.index = i + 1;
                closestPt.properties.location = length + sectionLength;
            }
            if (intersectPt && intersectPt.properties.dist < closestPt.properties.dist) {
                closestPt = intersectPt;
                closestPt.properties.index = i;
            }
            // update length
            length += sectionLength;
        }

    });