Backend: Move pluscode package to /pkg/geo/pluscode

Signed-off-by: Michael Mayer <michael@photoprism.app>

pkg/geo/pluscode/pluscode.go

@@ -0,0 +1,80 @@
+/*
+Package pluscode provides an abstraction for Google's Open Location Code package.
+
+Copyright (c) 2018 - 2024 PhotoPrism UG. All rights reserved.
+
+	This program is free software: you can redistribute it and/or modify
+	it under Version 3 of the GNU Affero General Public License (the "AGPL"):
+	<https://docs.photoprism.app/license/agpl>
+
+	This program is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU Affero General Public License for more details.
+
+	The AGPL is supplemented by our Trademark and Brand Guidelines,
+	which describe how our Brand Assets may be used:
+	<https://www.photoprism.app/trademark>
+
+Feel free to send an email to hello@photoprism.app if you have questions,
+want to support our work, or just want to say hello.
+
+Additional information can be found in our Developer Guide:
+<https://docs.photoprism.app/developer-guide/>
+*/
+package pluscode
+
+import (
+	"fmt"
+
+	olc "github.com/google/open-location-code/go"
+	"github.com/photoprism/photoprism/pkg/geo/s2"
+)
+
+var defaultLen = 8
+
+// Encode returns the plus code for the given coordinates using the default length.
+func Encode(lat, lng float64) string {
+	result, _ := EncodeLength(lat, lng, defaultLen)
+
+	return result
+}
+
+// EncodeLength returns the plus code for the given coordinates.
+func EncodeLength(lat, lng float64, length int) (plusCode string, err error) {
+	if lat < -90 || lat > 90 {
+		return "", fmt.Errorf("latitude out of range (%f)", lat)
+	}
+
+	if lng < -180 || lng > 180 {
+		return "", fmt.Errorf("longitude out of range (%f)", lng)
+	}
+
+	return olc.Encode(lat, lng, length), nil
+}
+
+// LatLng returns the coordinates for a plus code token.
+func LatLng(token string) (lat, lng float64) {
+	if token == "" || token == "-" {
+		return lat, lng
+	}
+
+	c, err := olc.Decode(token)
+
+	if err != nil {
+		return lat, lng
+	}
+
+	lat, lng = c.Center()
+
+	return lat, lng
+}
+
+// S2 returns the S2 cell token for the plus code using the default cell level.
+func S2(plusCode string) string {
+	lat, lng := LatLng(plusCode)
+
+	s2Token := s2.Token(lat, lng)
+
+	return s2Token
+}