gpx.studio/website/src/lib/components/toolbar/tools/routing/utils.svelte.ts

import type { Coordinates } from 'gpx';
import { TrackPoint, distance } from 'gpx';
import { settings } from '$lib/logic/settings';
import { getElevation } from '$lib/utils';

const { routing, routingProfile, privateRoads } = settings;

export const brouterProfiles: { [key: string]: string } = {
    bike: 'Trekking-dry',
    racing_bike: 'fastbike',
    gravel_bike: 'gravel',
    mountain_bike: 'MTB',
    foot: 'Hiking-Alpine-SAC6',
    motorcycle: 'Car-FastEco',
    water: 'river',
    railway: 'rail',
};

export function route(points: Coordinates[]): Promise<TrackPoint[]> {
    if (routing.value) {
        return getRoute(points, brouterProfiles[routingProfile.value], privateRoads.value);
    } else {
        return getIntermediatePoints(points);
    }
}

async function getRoute(
    points: Coordinates[],
    brouterProfile: string,
    privateRoads: boolean
): Promise<TrackPoint[]> {
    let url = `https://brouter.gpx.studio?lonlats=${points.map((point) => `${point.lon.toFixed(8)},${point.lat.toFixed(8)}`).join('|')}&profile=${brouterProfile + (privateRoads ? '-private' : '')}&format=geojson&alternativeidx=0`;

    let response = await fetch(url);

    // Check if the response is ok
    if (!response.ok) {
        throw new Error(`${await response.text()}`);
    }

    let geojson = await response.json();

    let route: TrackPoint[] = [];
    let coordinates = geojson.features[0].geometry.coordinates;
    let messages = geojson.features[0].properties.messages;

    const lngIdx = messages[0].indexOf('Longitude');
    const latIdx = messages[0].indexOf('Latitude');
    const tagIdx = messages[0].indexOf('WayTags');
    let messageIdx = 1;
    let tags = messageIdx < messages.length ? getTags(messages[messageIdx][tagIdx]) : {};

    for (let i = 0; i < coordinates.length; i++) {
        let coord = coordinates[i];
        route.push(
            new TrackPoint({
                attributes: {
                    lat: coord[1],
                    lon: coord[0],
                },
                ele: coord[2] ?? (i > 0 ? route[i - 1].ele : 0),
            })
        );

        if (
            messageIdx < messages.length &&
            coordinates[i][0] == Number(messages[messageIdx][lngIdx]) / 1000000 &&
            coordinates[i][1] == Number(messages[messageIdx][latIdx]) / 1000000
        ) {
            messageIdx++;

            if (messageIdx == messages.length) tags = {};
            else tags = getTags(messages[messageIdx][tagIdx]);
        }

        route[route.length - 1].setExtensions(tags);
    }

    return route;
}

function getTags(message: string): { [key: string]: string } {
    const fields = message.split(' ');
    let tags: { [key: string]: string } = {};
    for (let i = 0; i < fields.length; i++) {
        let [key, value] = fields[i].split('=');
        key = key.replace(/:/g, '_');
        tags[key] = value;
    }
    return tags;
}

function getIntermediatePoints(points: Coordinates[]): Promise<TrackPoint[]> {
    let route: TrackPoint[] = [];
    let step = 0.05;

    for (let i = 0; i < points.length - 1; i++) {
        // Add intermediate points between each pair of points
        let dist = distance(points[i], points[i + 1]) / 1000;
        for (let d = 0; d < dist; d += step) {
            let lat = points[i].lat + (d / dist) * (points[i + 1].lat - points[i].lat);
            let lon = points[i].lon + (d / dist) * (points[i + 1].lon - points[i].lon);
            route.push(
                new TrackPoint({
                    attributes: {
                        lat: lat,
                        lon: lon,
                    },
                })
            );
        }
    }

    route.push(
        new TrackPoint({
            attributes: {
                lat: points[points.length - 1].lat,
                lon: points[points.length - 1].lon,
            },
        })
    );

    return getElevation(route).then((elevations) => {
        route.forEach((point, i) => {
            point.ele = elevations[i];
        });
        return route;
    });
}