/**
 * Utilities for Intaleq Map SDK.
 */
export class PolylineUtils {
    /**
     * Decodes a Google-encoded polyline string into an array of [lng, lat] coordinates.
     * Note: MapLibre and GeoJSON use [lng, lat] while Google/Flutter use [lat, lng].
     */
    static decode(encoded: string): [number, number][] {
        const points: [number, number][] = [];
        let index = 0;
        const len = encoded.length;
        let lat = 0;
        let lng = 0;

        while (index < len) {
            let b: number;
            let shift = 0;
            let result = 0;
            do {
                b = encoded.charCodeAt(index++) - 63;
                result |= (b & 0x1f) << shift;
                shift += 5;
            } while (b >= 0x20);
            const dlat = ((result & 1) !== 0 ? ~(result >> 1) : (result >> 1));
            lat += dlat;

            shift = 0;
            result = 0;
            do {
                b = encoded.charCodeAt(index++) - 63;
                result |= (b & 0x1f) << shift;
                shift += 5;
            } while (b >= 0x20);
            const dlng = ((result & 1) !== 0 ? ~(result >> 1) : (result >> 1));
            lng += dlng;

            // MapLibre uses [lng, lat]
            points.push([lng / 1E5, lat / 1E5]);
        }
        return points;
    }
}