@siva-sub/mcp-public-transport/dist/esm/services/polylines.js

A Model Context Protocol server for Singapore transport data with real-time information and routing

import polyline from '@mapbox/polyline';
export class PolylineService {
    /**
     * Decode a polyline string to coordinates
     */
    decode(encoded) {
        const decodedCoordinates = polyline.decode(encoded);
        // Convert to [lng, lat] format for GeoJSON and calculate bounds
        const coordinates = decodedCoordinates.map(coord => [coord[1], coord[0]]);
        const bounds = this.calculateBounds(coordinates);
        return {
            coordinates,
            bounds
        };
    }
    /**
     * Process polyline data from OneMap response
     */
    processPolylines(response) {
        const polylines = [];
        // Handle direct routing polyline
        if (response.route_geometry) {
            const decoded = this.decode(response.route_geometry);
            polylines.push({
                encoded: response.route_geometry,
                decoded,
                geojson: this.createGeoJSON(decoded.coordinates),
                coordinateCount: decoded.coordinates.length
            });
        }
        // Handle transit leg polylines
        if (response.plan?.itineraries?.[0]?.legs) {
            response.plan.itineraries[0].legs.forEach((leg, index) => {
                if (leg.legGeometry?.points) {
                    const decoded = this.decode(leg.legGeometry.points);
                    polylines.push({
                        encoded: leg.legGeometry.points,
                        decoded,
                        geojson: this.createGeoJSON(decoded.coordinates),
                        coordinateCount: decoded.coordinates.length
                    });
                }
            });
        }
        return polylines;
    }
    /**
     * Create GeoJSON LineString from coordinates
     */
    createGeoJSON(coordinates) {
        return {
            type: 'LineString',
            coordinates
        };
    }
    /**
     * Calculate bounding box for coordinates
     */
    calculateBounds(coordinates) {
        if (coordinates.length === 0) {
            return { north: 0, south: 0, east: 0, west: 0 };
        }
        let north = coordinates[0][1];
        let south = coordinates[0][1];
        let east = coordinates[0][0];
        let west = coordinates[0][0];
        coordinates.forEach(([lng, lat]) => {
            north = Math.max(north, lat);
            south = Math.min(south, lat);
            east = Math.max(east, lng);
            west = Math.min(west, lng);
        });
        return { north, south, east, west };
    }
    /**
     * Estimate coordinate count from encoded polyline
     */
    estimateCoordinateCount(encoded) {
        return Math.floor(encoded.length / 10);
    }
    /**
     * Create step markers for instructions
     */
    createStepMarkers(instructions) {
        return instructions
            .filter(inst => inst.coordinates)
            .map(inst => ({
            step: inst.step,
            coordinates: [inst.coordinates.lng, inst.coordinates.lat],
            instruction: inst.instruction
        }));
    }
}