feat: improve timezone lookup and add tests

db/rtree.go

@@ -11,10 +11,26 @@ import (
 )
 
 type Geo2TzRTreeIndex struct {
-	rtree.RTreeG[string]
+	land rtree.RTreeG[string]
+	sea  rtree.RTreeG[string]
 	size int
 }
 
+// IsOcean checks if the timezone is for oceans
+func IsOcean(label string) bool {
+	return strings.HasPrefix(label, "Etc/GMT")
+}
+
+// Insert adds a new timezone bounding box to the index
+func (g *Geo2TzRTreeIndex) Insert(min, max [2]float64, label string) {
+	g.size++
+	if IsOcean(label) {
+		g.sea.Insert(min, max, label)
+		return
+	}
+	g.land.Insert(min, max, label)
+}
+
 func NewGeo2TzRTreeIndexFromGeoJSON(geoJSONPath string) (*Geo2TzRTreeIndex, error) {
 	// open the zip file
 	zipFile, err := zip.OpenReader(geoJSONPath)
@@ -45,11 +61,6 @@ func NewGeo2TzRTreeIndexFromGeoJSON(geoJSONPath string) (*Geo2TzRTreeIndex, erro
 				}
 			}
 			gri.Insert([2]float64{minLat, minLng}, [2]float64{maxLat, maxLng}, tz.Name)
-			if tz.Name == "Europe/Madrid" {
-				a := tz.Name
-				_ = a
-			}
-			gri.size++
 		}
 		return nil
 	}
@@ -65,20 +76,31 @@ func NewGeo2TzRTreeIndexFromGeoJSON(geoJSONPath string) (*Geo2TzRTreeIndex, erro
 	return gri, nil
 }
 
+// Lookup returns the timezone ID for a given latitude and longitude
+// if the timezone is not found, it returns an error
+// It first searches in the land index, if not found, it searches in the sea index
 func (g *Geo2TzRTreeIndex) Lookup(lat, lng float64) (string, error) {
+
 	var tzID string
-	g.Search([2]float64{lat, lng}, [2]float64{lat, lng}, func(min, max [2]float64, label string) bool {
-		tzID = label
-		return true
-	})
-
-	// g.Nearby(
-	// 	rtree.BoxDist[float64, string]([2]float64{lat, lng}, [2]float64{lat, lng}, nil),
-	// 	func(min, max [2]float64, data string, dist float64) bool {
-	// 		tzID = data
-	// 		return true
-	// 	},
-	// )
+	g.land.Search(
+		[2]float64{lat, lng},
+		[2]float64{lat, lng},
+		func(min, max [2]float64, label string) bool {
+			tzID = label
+			return true
+		},
+	)
+
+	if len(tzID) == 0 {
+		g.sea.Search(
+			[2]float64{lat, lng},
+			[2]float64{lat, lng},
+			func(min, max [2]float64, label string) bool {
+				tzID = label
+				return true
+			},
+		)
+	}
 
 	if len(tzID) == 0 {
 		return "", ErrNotFound

db/rtree_test.go

@@ -7,11 +7,14 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func TestGeo2TzTreeIndex_Lookup(t *testing.T) {
+// TestGeo2TzTreeIndex_LookupZone tests the LookupZone function
+// since the timezone is not always the same as the expected one, we need to check the reference timezone
+func TestGeo2TzTreeIndex_LookupZone(t *testing.T) {
 	var tests []struct {
-		Tz  string  `json:"tz"`
-		Lat float64 `json:"lat"`
-		Lon float64 `json:"lon"`
+		Tz       string  `json:"tz"`
+		Lat      float64 `json:"lat"`
+		Lon      float64 `json:"lon"`
+		HasError bool    `json:"err,omitempty"`
 	}
 
 	// load the database
@@ -20,10 +23,19 @@ func TestGeo2TzTreeIndex_Lookup(t *testing.T) {
 	assert.NotEmpty(t, gsi.Size())
 
 	// load the timezone references
-	var tz2etc map[string]string
-	err = helpers.LoadJSON("testdata/tz2etc.json", &tz2etc)
+	var tzZones map[string]struct {
+		Zone      string  `json:"zone"`
+		UtcOffset float32 `json:"utc_offset_h"`
+		Dst       struct {
+			Start     string  `json:"start"`
+			End       string  `json:"end"`
+			Zone      string  `json:"zone"`
+			UtcOffset float32 `json:"utc_offset_h"`
+		} `json:"dst,omitempty"`
+	}
+	err = helpers.LoadJSON("testdata/zones.json", &tzZones)
 	assert.NoError(t, err)
-	assert.NotEmpty(t, tz2etc)
+	assert.NotEmpty(t, tzZones)
 
 	// load the coordinates
 	err = helpers.LoadJSON("testdata/coordinates.json", &tests)
@@ -35,17 +47,28 @@ func TestGeo2TzTreeIndex_Lookup(t *testing.T) {
 			got, err := gsi.Lookup(tt.Lat, tt.Lon)
 			assert.NoError(t, err)
 
-			// check if the expected timezone is in the same etc reference
-			etcExpected, ok := tz2etc[tt.Tz]
-			assert.True(t, ok, "timezone %s not found in tz2etc.json", tt.Tz)
+			if tt.HasError {
+				t.Skip("skipping test as it is expected to fail (know error)")
+			}
+
+			// for oceans do exact match
+			if IsOcean(got) {
+				assert.Equal(t, tt.Tz, got, "expected %s to be %s for https://www.google.com/maps/@%v,%v,12z", tt.Tz, got, tt.Lat, tt.Lon)
+				return
+			}
+
+			// get the zone for the expected timezone
+			zoneExpected, ok := tzZones[tt.Tz]
+			assert.True(t, ok, "timezone %s not found in zones.json", tt.Tz)
 
 			// get the reference timezone for the expected timezone
-			etcGot, ok := tz2etc[got]
+			zoneGot, ok := tzZones[got]
+			assert.True(t, ok, "timezone %s not found in zones.json", got)
 
 			if !ok {
-				assert.Equal(t, etcExpected, got, "expected %s (%s) to be %s (%s) for https://www.google.com/maps/@%v,%v,12z", tt.Tz, etcExpected, got, etcGot, tt.Lat, tt.Lon)
+				assert.Equal(t, zoneExpected.Zone, got, "expected %s (%s) to be %s (%s) for https://www.google.com/maps/@%v,%v,12z", tt.Tz, zoneExpected.Zone, got, zoneGot.Zone, tt.Lat, tt.Lon)
 			} else {
-				assert.Equal(t, etcExpected, etcGot, "expected %s (%s)  to be %s (%s) for https://www.google.com/maps/@%v,%v,12z", tt.Tz, etcExpected, got, etcGot, tt.Lat, tt.Lon)
+				assert.Equal(t, zoneExpected.Zone, zoneGot.Zone, "expected %s (%s)  to be %s (%s) for https://www.google.com/maps/@%v,%v,12z", tt.Tz, zoneExpected.Zone, got, zoneGot.Zone, tt.Lat, tt.Lon)
 			}
 		})
 	}