OSMServer/Pathfinding/Pathfinder.cs

using OSMDatastructure;
using OSMDatastructure.Graph;
using WayType = OSMDatastructure.Tag.WayType;

namespace Pathfinding;

public static partial class Pathfinder
{

    private static ValueTuple<OsmNode?, OsmNode?> SetupNodes(Coordinates startCoordinates, Coordinates goalCoordinates, RegionManager regionManager )
    {
        ValueTuple<OsmNode?, OsmNode?> retTuple = new();
        retTuple.Item1 = regionManager.ClosestNodeToCoordinates(startCoordinates, Tag.SpeedType.any);
        retTuple.Item2 = regionManager.ClosestNodeToCoordinates(goalCoordinates, Tag.SpeedType.any);
        if (retTuple.Item1 is null || retTuple.Item2 is null)
            return retTuple;
        retTuple.Item1.currentPathWeight = 0;
        retTuple.Item1.currentPathLength = 0;
        retTuple.Item1.directDistanceToGoal =  Utils.DistanceBetween(retTuple.Item1, retTuple.Item2);
        return retTuple;
    }

    private static double EdgeWeight(OsmNode node1, OsmEdge edge, Tag.SpeedType vehicle, RegionManager regionManager)
    {
        OsmNode? node2 = regionManager.GetNode(edge.neighborId, edge.neighborRegion);
        if (node2 is null)
            return double.MaxValue;
        double distance = Utils.DistanceBetween(node1, node2);
        byte speed = regionManager.GetSpeedForEdge(node1, edge.wayId, vehicle);
        return speed is 0 ? double.MaxValue : distance / speed;
    }

    private static double GetPriority(OsmNode current, OsmNode? previous, OsmEdge edge, Tag.SpeedType vehicle, RegionManager regionManager)
    {
        if (vehicle == Tag.SpeedType.any)
            return 1;
        const double roadPriorityFactor = 1; 
        const double junctionFactor = 2; 
        const double wayChangeFactor = 2; 
        Region r = regionManager.GetRegion(current.coordinates)!;
        
        double roadPriority = GetPriorityVehicleRoad(edge, vehicle, r) * 0.1 * roadPriorityFactor;
        double roadSpeed = regionManager.GetSpeedForEdge(current, edge.wayId, vehicle);
        
        if(vehicle == Tag.SpeedType.pedestrian)
            return (current.directDistanceToGoal / roadSpeed) * roadPriority; 
        
        ulong previousWayId = UInt64.MaxValue;
        if (previous?.edges is not null)
        {
            foreach (OsmEdge e in previous.edges)
                if (e.neighborId.Equals(current.nodeId))
                {
                    previousWayId = e.wayId;
                    break;
                }
        }

        double junctionPriority = (current.edges.Count > 2 ? 1 : 0) * junctionFactor;
        double wayChange = (previousWayId != edge.wayId ? 1 : 0) * wayChangeFactor;
        
        if(vehicle == Tag.SpeedType.car)
            return (current.directDistanceToGoal / roadSpeed) * roadPriority * ((junctionPriority + wayChange) / 2);

        return double.MaxValue;
    }

    private static double GetPriorityVehicleRoad(OsmEdge edge, Tag.SpeedType vehicle, Region region)
    {
        if (vehicle == Tag.SpeedType.any)
            return 1;
        WayType? wayType = (WayType?)region.tagManager.GetTag(edge.wayId, Tag.TagType.highway);
        if(wayType is null)
            return double.MaxValue;
        if (vehicle == Tag.SpeedType.car)
        {
            switch (wayType)
            {
                case WayType.motorway:
                case WayType.motorway_link:
                case WayType.motorroad:
                case WayType.trunk:
                case WayType.trunk_link:
                case WayType.primary:
                case WayType.primary_link:
                    return 1;
                case WayType.secondary:
                case WayType.secondary_link:
                    return 2;
                case WayType.tertiary:
                case WayType.tertiary_link:
                    return 3;
                case WayType.unclassified:
                case WayType.residential:
                case WayType.road:
                    return 4;
                case WayType.living_street:
                case WayType.service:
                case WayType.track:
                    return 5;
                default:
                    return 100;
            }
        }
        if (vehicle == Tag.SpeedType.pedestrian)
        {
            switch (wayType)
            {
                case WayType.pedestrian:
                case WayType.corridor:
                case WayType.footway:
                case WayType.path:
                case WayType.steps:
                case WayType.residential: 
                case WayType.living_street:
                    return 1;
                case WayType.service:
                case WayType.cycleway:
                case WayType.bridleway:
                case WayType.road:
                case WayType.track:
                case WayType.unclassified:
                    return 2;
                case WayType.tertiary:
                case WayType.tertiary_link:
                case WayType.escape:
                    return 5;
                default:
                    return 100;
            }
        }

        return 100;

    }

    private static List<PathNode> GetRouteFromCalc(OsmNode goalNode, RegionManager regionManager)
    {
        List<PathNode> path = new();
        OsmNode? currentNode = goalNode;
        while (currentNode is not null)
        {
            HashSet<Tag>? tags = null;
            double pathDistanceDelta = 0;
            double pathWeightDelta = 0;
            double directDistanceDelta = 0;
            if (currentNode.previousPathNode is not null)
            {
                OsmEdge edge = currentNode.previousPathNode!.edges.First(e => e.neighborId.Equals(currentNode.nodeId));
                tags = regionManager.GetRegion(currentNode.coordinates)!.tagManager.GetTagsForWayId(edge.wayId);
                pathDistanceDelta = currentNode.currentPathLength - currentNode.previousPathNode.currentPathLength;
                pathWeightDelta = currentNode.currentPathWeight - currentNode.previousPathNode.currentPathWeight;
                directDistanceDelta =
                    currentNode.directDistanceToGoal - currentNode.previousPathNode.directDistanceToGoal;
            }

            PathNode? pn = PathNode.FromOsmNode(currentNode, tags, pathDistanceDelta, pathWeightDelta, directDistanceDelta);
            if(pn is not null)
                path.Add(pn!);
            currentNode = currentNode.previousPathNode;
        }

        path.Reverse();
        return path;
    }
}