OSMServer/Server/XmlImporter.cs

using System.Globalization;
using System.Xml;
using OSMDatastructure;
using OSMDatastructure.Graph;

namespace Server;

public static class XmlImporter
{
    private static readonly XmlReaderSettings readerSettings = new()
    {
        IgnoreWhitespace = true,
        IgnoreComments = true
    };

    public static HashSet<OsmNode> ImportXml(string filePath)
    {
        if (!File.Exists(filePath))
            throw new FileNotFoundException();
        
        Console.WriteLine(string.Format("[{0}] Getting highwayNodeIds...", DateTime.Now.ToLocalTime()));
        FileStream xmlFileStream = new FileStream(filePath, FileMode.Open);
        HashSet<ulong> requiredNodeIds = GetHighwayNodeIds(XmlReader.Create(xmlFileStream, readerSettings));
        xmlFileStream.Position = 0;

        Console.WriteLine(string.Format("[{0}] Importing Nodes...", DateTime.Now.ToLocalTime()));
        Dictionary<ulong, OsmNode> nodes =
            GetHighwayNodesFromIds(XmlReader.Create(xmlFileStream, readerSettings), requiredNodeIds);
        requiredNodeIds.Clear();
        xmlFileStream.Position = 0;
        
        Console.WriteLine(string.Format("[{0}] Importing Ways...", DateTime.Now.ToLocalTime()));
        HashSet<OsmNode> retNodes = ConnectNodes(XmlReader.Create(xmlFileStream, readerSettings), nodes);
        nodes.Clear();

        return retNodes;
    }

    public static HashSet<Region> SplitIntoRegions(HashSet<OsmNode> nodes)
    {
        Console.WriteLine(string.Format("[{0}] Splitting into Regions...", DateTime.Now.ToLocalTime()));
        Dictionary<int, Region> retRegions = new();
        foreach (OsmNode node in nodes)
        {
            int regionHash = Coordinates.GetRegionHashCode(node.coordinates);
            if(retRegions.ContainsKey(regionHash))
            {
                retRegions[regionHash].nodes.Add(node);
            }
            else
            {
                Region newRegion = new Region(regionHash);
                newRegion.nodes.Add(node);
                retRegions.Add(regionHash, newRegion);
            }
        }

        return retRegions.Values.ToHashSet();
    }

    private static readonly NumberFormatInfo decimalInfo = new()
    {
        NumberDecimalSeparator = "."
    };
    public static HashSet<ulong> GetHighwayNodeIds(XmlReader xmlReader)
    {
        HashSet<ulong> retSet = new();
        bool isHighway;
        HashSet<ulong> currentIds = new();
        while (xmlReader.ReadToFollowing("way"))
        {
            isHighway = false;
            currentIds.Clear();
            XmlReader wayReader = xmlReader.ReadSubtree();
            while (wayReader.Read())
            {
                if (xmlReader.Name == "tag" && xmlReader.GetAttribute("k")!.Equals("highway"))
                {
                    isHighway = true;
                }
                else if (xmlReader.Name == "nd")
                {
                    try
                    {
                        currentIds.Add(Convert.ToUInt64(xmlReader.GetAttribute("ref")));
                    }
                    catch (FormatException) { };
                }
            }
            if (isHighway)
            {
                retSet.UnionWith(currentIds);
            }
            wayReader.Close();
        }
        xmlReader.Close();

        return retSet;
    }

    private static Dictionary<ulong, OsmNode> GetHighwayNodesFromIds(XmlReader xmlReader, HashSet<ulong> ids)
    {
        Dictionary<ulong, OsmNode> retDict = new();

        while (xmlReader.ReadToFollowing("node"))
        {
            ulong id = Convert.ToUInt64(xmlReader.GetAttribute("id"));
            if (ids.Contains(id))
            {
                float lat = Convert.ToSingle(xmlReader.GetAttribute("lat")!, decimalInfo);
                float lon = Convert.ToSingle(xmlReader.GetAttribute("lon")!, decimalInfo);
                retDict.Add(id, new OsmNode(lat, lon));
            }
        }
        xmlReader.Close();
        
        return retDict;
    }
    
    private static HashSet<OsmNode> ConnectNodes(XmlReader xmlReader, Dictionary<ulong, OsmNode> dict)
    {
        while (xmlReader.ReadToFollowing("way"))
        {
            Dictionary<OsmEdge.tagType, object> tags = new();
            List<ulong> wayNodeIds = new();
            XmlReader wayReader = xmlReader.ReadSubtree();
            while (wayReader.Read())
            {
                if (xmlReader.Name == "tag")
                {
                    KeyValuePair<OsmEdge.tagType, object> tag =
                        OsmEdge.ConvertToTag(wayReader.GetAttribute("k")!, wayReader.GetAttribute("v")!);
                    tags.TryAdd(tag.Key, tag.Value);
                }
                else if (xmlReader.Name == "nd")
                {
                    wayNodeIds.Add(Convert.ToUInt64(xmlReader.GetAttribute("ref")));
                }
            }
            if (tags.ContainsKey(OsmEdge.tagType.highway))
            {
                ulong[] ids = wayNodeIds.Where(dict.ContainsKey).ToArray();
                for (int i = 0; i < ids.Length - 1; i++)
                {
                    OsmNode n1 = dict[ids[i]];
                    OsmNode n2 = dict[ids[i + 1]];
                    if (tags.ContainsKey(OsmEdge.tagType.oneway) && (bool)tags[OsmEdge.tagType.oneway])
                    {
                        if (tags.ContainsKey(OsmEdge.tagType.forward) && !(bool)tags[OsmEdge.tagType.forward])
                        {
                            n2.edges.Add(new OsmEdge(n1.coordinates, tags));
                        }
                        else
                        {
                            n1.edges.Add(new OsmEdge(n2.coordinates, tags));
                        }
                    }
                    else
                    {
                        n1.edges.Add(new OsmEdge(n2.coordinates, tags));
                        n2.edges.Add(new OsmEdge(n1.coordinates, tags));
                    }
                }
            }
            wayReader.Close();
        }
        xmlReader.Close();

        return dict.Values.ToHashSet();
    }
}