Implement out-of-route navigation

package.json

@@ -3,7 +3,7 @@
   "version": "0.1.0",
   "type": "module",
   "scripts": {
-    "back": "node src/back",
+    "back": "node --experimental-json-modules src/back",
     "front:dev": "vite src/front",
     "front:prod": "vite build src/front",
     "lint": "eslint ."

script/show-courses.js

@@ -1,14 +1,10 @@
-#!/usr/bin/env node
+#!/usr/bin/env -S node --experimental-json-modules
 
-import * as courses from '../src/tam/courses.js';
-import {displayTime} from '../src/util.js';
-import process from 'process';
-import path from 'path';
-import { readFile } from 'fs/promises';
-
-const network = JSON.parse(await readFile(
-    new URL('../src/tam/network.json', import.meta.url)
-));
+import * as courses from "../src/tam/courses.js";
+import network from "../src/tam/network.json";
+import {displayTime} from "../src/util.js";
+import process from "process";
+import path from "path";
 
 /**
  * Convert stop ID to human-readable stop name.

src/tam/courses.js

@@ -6,11 +6,8 @@
  */
 
 import * as tam from "./sources/tam.js";
-import { readFile } from 'fs/promises';
-
-const network = JSON.parse(await readFile(
-    new URL('./network.json', import.meta.url)
-));
+import * as routing from "./routing.js";
+import network from "./network.json";
 
 /**
  * Information about the course of a vehicle.
@@ -24,8 +21,7 @@ const network = JSON.parse(await readFile(
  */
 
 /** Parse time information relative to the current date. */
-const parseTime = (time, reference) =>
-{
+const parseTime = (time, reference) => {
     const [hours, minutes, seconds] = time.split(':').map(x => parseInt(x, 10));
     const result = new Date(reference);
 
@@ -41,6 +37,32 @@ const parseTime = (time, reference) =>
     return result;
 };
 
+/** Guess whether a stop comes directly before another one. */
+const isPenultimateStop = (stop, finalStop) => {
+    // If there is a standard segment linking both stops, it’s certainly
+    // the penultimate stop
+    if ((stop + "-" + finalStop) in network.segments) {
+        return true;
+    }
+
+    const route = routing.findRoute(stop, finalStop);
+
+    // If there is no way to link both stops, it can’t be
+    if (route === null) {
+        return false;
+    }
+
+    // If there is another stop in the way, it can’t be either
+    for (const node of route.slice(1, -1)) {
+        if (node in network.stops) {
+            return false;
+        }
+    }
+
+    // Otherwise, assume it’s the penultimate stop
+    return true;
+};
+
 /**
  * Fetch information about courses in the TaM network.
  *
@@ -127,7 +149,9 @@ export const fetch = async (kind = 'realtime') => {
         if (course.finalStopId === undefined) {
             course.finalStopId = lastPassing[0];
         } else if (course.finalStopId !== lastPassing[0]) {
-            course.passings.push([course.finalStopId, lastPassing[1] + 60000]);
+            if (isPenultimateStop(lastPassing[0], course.finalStopId)) {
+                course.passings.push([course.finalStopId, lastPassing[1] + 60000]);
+            }
         }
     }
 

src/tam/network.js

@@ -26,11 +26,21 @@ export const fetch = async lineRefs => {
     // Retrieve routes, ways and stops from OpenStreetMap
     const rawData = await osm.runQuery(`[out:json];
 
-// Find the public transport line bearing the requested reference
+// Find the public transport lines bearing the requested references
 relation[network="TaM"][type="route_master"][ref~"^(${lineRefs.join("|")})$"];
 
-// Recursively fetch routes, ways and stops inside the line
-(._; >>;);
+(
+    ._;
+
+    // Recursively fetch routes, ways and stops inside the lines
+    >>;
+
+    // Find adjacent tracks (used for out-of-route navigation)
+    complete {
+        way(around:0)[railway="tram"];
+    };
+    >;
+);
 
 out body qt;
 `);
@@ -47,20 +57,25 @@ out body qt;
         return prev;
     }, {});
 
-    // All stops in the network
+    // Graph for out-of-route navigation
+    const navigation = {};
+
+    // Stops in the network indexed by reference
     const stops = {};
 
-    // All transport lines of the network
+    // Stops indexed by OSM identifier
+    const stopsReverse = {};
+
+    // Transport lines of the network indexed by name
     const lines = {};
 
-    // All segments leading from one stop to another
+    // Segments leading from stop to stop in the planned route for each line
     const segments = {};
 
+    // Extract lines, associated stops and planned routes
     for (const routeMaster of routeMasters) {
         const lineRef = routeMaster.tags.ref;
         const color = routeMaster.tags.colour || "#000000";
-
-        // Extract all routes for the given line
         const routes = [];
 
         for (const [routeRef, data] of routeMaster.members.entries()) {
@@ -87,8 +102,9 @@ a “ref” tag`);
                         ], {
                             name: stop.tags.name,
                             routes: [[lineRef, routeRef]],
-                            successors: []
                         });
+
+                        stopsReverse[ref] = stop.tags.ref;
                     } else {
                         stops[stop.tags.ref].properties.routes.push([
                             lineRef,
@@ -163,13 +179,11 @@ but there are ${nextNodeCandidates.length}`);
                 }
 
                 if (curNodeIndex < nextNodeIndex) {
-
                     // Use the way in its normal direction
                     path = path.concat(
                         wayNodes.slice(curNodeIndex, nextNodeIndex)
                     );
                 } else {
-
                     // Use the way in the reverse direction
                     if (osm.isOneWay(way)) {
                         throw new Error(`Way n°${wayIndex} in
@@ -215,14 +229,12 @@ different sequence of nodes in two or more lines.`);
                             elements[nodeId].lat
                         ]
                     ), {
-
                         // Keep track of the original sequence of nodes to
                         // compare with duplicates
                         nodesIds,
                         routes: [[lineRef, routeRef]]
                     });
 
-                    stops[begin].properties.successors.push(end);
                     segments[id].properties.length = (
                         1000 * turfLength(segments[id]));
                 }
@@ -248,5 +260,47 @@ different sequence of nodes in two or more lines.`);
         delete segment.properties.nodesIds;
     }
 
-    return { stops, lines, segments };
+    // Create out-of-route navigation graph
+    const navigationId = objId => (
+        objId in stopsReverse
+        ? stopsReverse[objId]
+        : objId.toString()
+    );
+
+    for (const obj of elementsList) {
+        if (obj.type === "node") {
+            const id = navigationId(obj.id);
+
+            navigation[id] = {
+                // Position of this node
+                lon: obj.lon,
+                lat: obj.lat,
+
+                // List of other nodes that can be accessed from this node
+                successors: [],
+            };
+        }
+    }
+
+    for (const obj of elementsList) {
+        if (obj.type === "way") {
+            const oneWay = osm.isOneWay(obj);
+            const pairs = obj.nodes.slice(0, -1).map(
+                (node, i) => [
+                    navigationId(node),
+                    navigationId(obj.nodes[i + 1]),
+                ]
+            );
+
+            for (const [from, to] of pairs) {
+                navigation[from].successors.push(to);
+
+                if (!oneWay) {
+                    navigation[to].successors.push(from);
+                }
+            }
+        }
+    }
+
+    return { navigation, stops, lines, segments };
 };

src/tam/routing.js

@@ -0,0 +1,40 @@
+import network from "./network.json";
+
+/**
+ * Find a route linking two nodes or stops.
+ * @param {string} from ID of the starting stop or node.
+ * @param {string} to ID of the ending stop or node.
+ * @return {lineString?} If it exists, a segment linking the two nodes that has
+ * the least number of nodes possible.
+ */
+export const findRoute = (from, to) => {
+    const queue = [from];
+    const parent = {from: from};
+
+    while (queue.length > 0 && !(to in parent)) {
+        const current = queue.shift();
+
+        for (const successor of network.navigation[current].successors) {
+            if (!(successor in parent)) {
+                queue.push(successor);
+                parent[successor] = current;
+            }
+        }
+    }
+
+    if (!(to in parent)) {
+        return null;
+    }
+
+    const path = [];
+    let current = to;
+
+    while (current !== from) {
+        path.push(current);
+        current = parent[current];
+    }
+
+    path.push(from);
+    path.reverse();
+    return path;
+};

src/tam/simulation.js

@@ -3,6 +3,7 @@ import turfAlong from "@turf/along";
 import turfLength from "@turf/length";
 import * as turfHelpers from "@turf/helpers";
 import * as turfProjection from "@turf/projection";
+import * as routing from "./routing.js";
 import network from "./network.json";
 
 const server = "http://localhost:4321";
@@ -81,6 +82,7 @@ class Course {
 
         const name = `${this.departureStop}-${this.arrivalStop}`;
 
+        // Use predefined segment if it exists
         if (name in network.segments) {
             this.segment = network.segments[name];
             return;
@@ -98,11 +100,21 @@ class Course {
             return;
         }
 
-        this.segment = turfHelpers.lineString([
-            network.stops[this.departureStop].geometry.coordinates,
-            network.stops[this.arrivalStop].geometry.coordinates,
-        ]);
-        this.segment.properties.length = turfLength(this.segment);
+        // Compute a custom route between two stops
+        const route = routing.findRoute(this.departureStop, this.arrivalStop);
+
+        if (route === null) {
+            console.warn(`No route from ${this.departureStop} \
+to ${this.arrivalStop}`);
+        }
+
+        this.segment = turfHelpers.lineString(
+            route.map(node => [
+                network.navigation[node].lon,
+                network.navigation[node].lat,
+            ])
+        );
+        this.segment.properties.length = 1000 * turfLength(this.segment);
     }
 
     /** Merge data received from the server. */