From def58485c319e3c5b68ad29e2ad2bb6ff3293294 Mon Sep 17 00:00:00 2001
From: FrogAi <91348155+FrogAi@users.noreply.github.com>
Date: Sat, 8 Aug 2026 16:36:30 -0700
Subject: [PATCH] Preserve OSM one-way direction during generation

---
 maps/generate_offline.go | 19 ++++++++++++++++++-
 maps/way.go              |  3 +++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/maps/generate_offline.go b/maps/generate_offline.go
index 19d37a3..4fad079 100644
--- a/maps/generate_offline.go
+++ b/maps/generate_offline.go
@@ -7,6 +7,7 @@ import (
 	"math"
 	"os"
 	"runtime"
+	"slices"
 	"strconv"
 	"strings"
 
@@ -115,6 +116,22 @@ func generateAreas() []Area {
 	return areas
 }
 
+func normalizeWayDirection(tags map[string]string, way *TmpWay) {
+	switch tags["oneway"] {
+	case "yes", "1":
+		way.OneWay = true
+	case "-1":
+		way.OneWay = true
+		slices.Reverse(way.Nodes)
+		way.MaxSpeedForward, way.MaxSpeedBackward = way.MaxSpeedBackward, way.MaxSpeedForward
+		way.MaxSpeedForwardConditional, way.MaxSpeedBackwardConditional = way.MaxSpeedBackwardConditional, way.MaxSpeedForwardConditional
+	case "":
+		way.OneWay = tags["junction"] == "roundabout" || tags["highway"] == "motorway"
+	default:
+		way.OneWay = false
+	}
+}
+
 func GenerateOffline(s OfflineSettings) {
 	slog.Info("Generating Offline Map")
 	EnsureOfflineMapsDirectories(s)
@@ -160,7 +177,6 @@ func GenerateOffline(s OfflineSettings) {
 				MaxSpeedBackward: ParseMaxSpeed(tags["maxspeed:backward"]),
 				MaxSpeedAdvisory: ParseMaxSpeed(tags["maxspeed:advisory"]),
 				Lanes:            uint8(lanes),
-				OneWay:           tags["oneway"] == "yes",
 				Id:               int64(way.ID),
 				HighwayClass:     HighwayClassFromTag(tags["highway"]),
 
@@ -190,6 +206,7 @@ func GenerateOffline(s OfflineSettings) {
 				tmpWay.Nodes[i].Latitude = n.Lat
 				tmpWay.Nodes[i].Longitude = n.Lon
 			}
+			normalizeWayDirection(tags, &tmpWay)
 			tmpWay.Box.MinPos = m.NewPosition(minLat, minLon)
 			tmpWay.Box.MaxPos = m.NewPosition(maxLat, maxLon)
 			if minLat < allMinLat {
diff --git a/maps/way.go b/maps/way.go
index 62c2b11..f44cdcc 100644
--- a/maps/way.go
+++ b/maps/way.go
@@ -140,6 +140,9 @@ func (w *Way) IsForwardFrom(matchNode m.Position) bool {
 	}
 
 	lastNode := nodes[len(nodes)-1]
+	if nodes[0].Equals(lastNode) && lastNode.Equals(matchNode) && w.OneWay() {
+		return true
+	}
 	return !lastNode.Equals(matchNode)
 }