feat(geobase): define TemporalRefSys and TemporalRefSysResolver basic…

… implementations #196

BREAKING CHANGE: meta classes changes type of trs parameter

dart/geobase/lib/coordinates.dart

@@ -35,5 +35,7 @@ export 'src/coordinates/projection/projection.dart';
 export 'src/coordinates/projection/projection_adapter.dart';
 export 'src/coordinates/reference/coord_ref_sys.dart';
 export 'src/coordinates/reference/coord_ref_sys_resolver.dart';
+export 'src/coordinates/reference/temporal_ref_sys.dart';
+export 'src/coordinates/reference/temporal_ref_sys_resolver.dart';
 export 'src/coordinates/scalable/scalable.dart';
 export 'src/coordinates/scalable/scalable2i.dart';

dart/geobase/lib/geobase.dart

@@ -52,6 +52,8 @@ export 'src/coordinates/projection/projection.dart';
 export 'src/coordinates/projection/projection_adapter.dart';
 export 'src/coordinates/reference/coord_ref_sys.dart';
 export 'src/coordinates/reference/coord_ref_sys_resolver.dart';
+export 'src/coordinates/reference/temporal_ref_sys.dart';
+export 'src/coordinates/reference/temporal_ref_sys_resolver.dart';
 export 'src/coordinates/scalable/scalable.dart';
 export 'src/coordinates/scalable/scalable2i.dart';
 

dart/geobase/lib/src/coordinates/reference/coord_ref_sys_resolver.dart

@@ -14,13 +14,13 @@ import '/src/codes/geo_representation.dart';
 /// custom instance using [register]).
 ///
 /// NOTE: The current version of this resolver class provides only methods
-/// [normalizeId], [axisOrder] and [epsg]. In future other methods might be
-/// added.
+/// [normalizeId], [isGeographic], [axisOrder], [swapXY] and [epsg]. In future
+/// other methods might be added.
 abstract class CoordRefSysResolver {
   const CoordRefSysResolver._();
 
   /// Normalizes the coordinate reference system identifier to the template
-  /// `http://www.opengis.net/def/crs/EPSG/0/4326`.
+  /// `http://www.opengis.net/def/crs/{authority}/{version}/{code}`.
   ///
   /// Examples:
   /// * `http://www.opengis.net/def/crs/EPSG/0/4326`

dart/geobase/lib/src/coordinates/reference/temporal_ref_sys.dart

@@ -0,0 +1,73 @@
+// Copyright (c) 2020-2023 Navibyte (https://navibyte.com). All rights reserved.
+// Use of this source code is governed by a “BSD-3-Clause”-style license that is
+// specified in the LICENSE file.
+//
+// Docs: https://github.com/navibyte/geospatial
+
+import 'package:meta/meta.dart';
+
+import 'temporal_ref_sys_resolver.dart';
+
+/// Metadata about a temporal coordinate reference system (TRS) identified and
+/// specified by [id].
+@immutable
+class TemporalRefSys {
+  /// Metadata about a temporal coordinate reference system (TRS) identified and
+  /// specified by [id].
+  ///
+  /// No normalization of identifiers is done.
+  ///
+  /// See also [TemporalRefSys.normalized].
+  const TemporalRefSys.id(this.id);
+
+  /// Metadata about a temporal coordinate reference system (TRS) identified and
+  /// specified by the normalized identifier of [id].
+  ///
+  /// Normalization: `TemporalRefSysResolver.registry.normalizeId(id)`.
+  ///
+  /// The default implementation returns [id] unmodified (however when necessary
+  /// a custom logic can be registered for [TemporalRefSysResolver]).
+  TemporalRefSys.normalized(String id)
+      : id = TemporalRefSysResolver.registry.normalizeId(id);
+
+  /// The temporal coordinate reference system (TRS) identifier.
+  ///
+  /// The identifier is authorative, it identifies a well known or referenced
+  /// specification that defines properties for a temporal coordinate reference
+  /// system.
+  ///
+  /// Examples:
+  /// * `http://www.opengis.net/def/uom/ISO-8601/0/Gregorian`: dates or
+  ///    timestamps are in the Gregorian calendar and conform to
+  ///    [RFC 3339](https://www.rfc-editor.org/rfc/rfc3339.html).
+  final String id;
+
+  /// The temporal coordinate reference system resolved in this order:
+  /// 1. [temporalRefSys] if it's non-null
+  /// 2. otherwise `TemporalRefSys.normalized(trs)` if [trs] is non-null
+  /// 3. otherwise `TemporalRefSys.gregorian`
+  factory TemporalRefSys.from({
+    TemporalRefSys? temporalRefSys,
+    String? trs,
+  }) =>
+      temporalRefSys ??
+      (trs != null ? TemporalRefSys.normalized(trs) : gregorian);
+
+  /// The temporal coordinate reference system identified by
+  /// 'http://www.opengis.net/def/uom/ISO-8601/0/Gregorian'.
+  ///
+  /// References temporal coordinates, dates or timestamps, that are in the
+  /// Gregorian calendar and conform to
+  /// [RFC 3339](https://www.rfc-editor.org/rfc/rfc3339.html).
+  static const TemporalRefSys gregorian =
+      TemporalRefSys.id('http://www.opengis.net/def/uom/ISO-8601/0/Gregorian');
+
+  @override
+  String toString() => id;
+
+  @override
+  bool operator ==(Object other) => other is TemporalRefSys && id == other.id;
+
+  @override
+  int get hashCode => id.hashCode;
+}

dart/geobase/lib/src/coordinates/reference/temporal_ref_sys_resolver.dart

@@ -0,0 +1,50 @@
+// Copyright (c) 2020-2023 Navibyte (https://navibyte.com). All rights reserved.
+// Use of this source code is governed by a “BSD-3-Clause”-style license that is
+// specified in the LICENSE file.
+//
+// Docs: https://github.com/navibyte/geospatial
+
+// NOTE: implement normalization for the template
+//       `http://www.opengis.net/def/uom/{authority}/{version}/{code}`.
+
+/// An abstract class for resolving temporal coordinate reference system
+/// information.
+///
+/// A resolver can be accessed using [registry] that is initially instantiated
+/// with the basic default implementation. It be customized by registering a
+/// custom instance using [register]).
+///
+/// NOTE: The current version of this resolver class provides only the method
+/// [normalizeId]. In future other methods might be added.
+abstract class TemporalRefSysResolver {
+  const TemporalRefSysResolver._();
+
+  /// Normalizes the temporal coordinate reference system identifier.
+  ///
+  /// The normalization logic depends on the resolver of [registry].
+  String normalizeId(String id);
+
+  /// The current instance of [TemporalRefSysResolver], initially instantiated
+  /// with the basic default implementation.
+  ///
+  /// Currently the basic default implemention returns identifiers unmodified.
+  ///
+  /// NOTE: In future the basic implementation is going to be extended to
+  /// support also other identifier and more wide normalization logic.
+  static TemporalRefSysResolver registry = const _BasicTemporalRefSysRegistry();
+
+  /// Registers a custom instance of [TemporalRefSysResolver], available at
+  /// static [registry] after calling this.
+  // ignore: use_setters_to_change_properties
+  static void register(TemporalRefSysResolver resolver) =>
+      TemporalRefSysResolver.registry = resolver;
+}
+
+class _BasicTemporalRefSysRegistry implements TemporalRefSysResolver {
+  const _BasicTemporalRefSysRegistry();
+
+  @override
+  String normalizeId(String id) {
+    return id;
+  }
+}

dart/geobase/lib/src/meta/extent/geo_extent.dart

@@ -8,6 +8,7 @@ import 'package:meta/meta.dart';
 
 import '/src/coordinates/geographic/geobox.dart';
 import '/src/coordinates/reference/coord_ref_sys.dart';
+import '/src/coordinates/reference/temporal_ref_sys.dart';
 import '/src/meta/time/interval.dart';
 
 import 'spatial_extent.dart';
@@ -31,12 +32,12 @@ class GeoExtent {
   /// A geospatial extent of one [bbox] and optional [interval].
   ///
   /// A coordinate reference system can be specified by [crs], and a
-  /// temporal reference system by [trs].
+  /// temporal coordinate reference system by [trs].
   GeoExtent.single({
     required GeoBox bbox,
     Interval? interval,
     CoordRefSys crs = CoordRefSys.CRS84,
-    String trs = 'http://www.opengis.net/def/uom/ISO-8601/0/Gregorian',
+    TemporalRefSys trs = TemporalRefSys.gregorian,
   })  : _spatial = SpatialExtent<GeoBox>.single(
           bbox,
           crs: crs,
@@ -51,12 +52,12 @@ class GeoExtent {
   /// A geospatial extent of [boxes] and optional [intervals].
   ///
   /// A coordinate reference system can be specified by [crs], and a
-  /// temporal reference system by [trs].
+  /// temporal coordinate reference system by [trs].
   GeoExtent.multi({
     required Iterable<GeoBox> boxes,
     Iterable<Interval>? intervals,
     CoordRefSys crs = CoordRefSys.CRS84,
-    String trs = 'http://www.opengis.net/def/uom/ISO-8601/0/Gregorian',
+    TemporalRefSys trs = TemporalRefSys.gregorian,
   })  : _spatial = SpatialExtent<GeoBox>.multi(
           boxes,
           crs: crs,

dart/geobase/lib/src/meta/extent/temporal_extent.dart

@@ -6,27 +6,31 @@
 
 import 'package:meta/meta.dart';
 
+import '/src/coordinates/reference/temporal_ref_sys.dart';
 import '/src/meta/time/interval.dart';
 
-/// An extent with 1 to N intervals in defined temporal reference system.
+/// An extent with 1 to N intervals in defined temporal coordinate reference
+/// system.
 @immutable
 class TemporalExtent {
   final Interval _first;
   final Iterable<Interval>? _intervals;
-  final String _trs;
+  final TemporalRefSys _trs;
 
-  /// A temporal extent of one [interval] (temporal reference system in [trs]).
+  /// A temporal extent of one [interval] (temporal coordinate reference system
+  /// in [trs]).
   const TemporalExtent.single(
     Interval interval, {
-    String trs = 'http://www.opengis.net/def/uom/ISO-8601/0/Gregorian',
+    TemporalRefSys trs = TemporalRefSys.gregorian,
   })  : _first = interval,
         _intervals = null,
         _trs = trs;
 
-  /// A temporal extent of [intervals] (temporal reference system in [trs]).
+  /// A temporal extent of [intervals] (temporal coordinate reference system in
+  /// [trs]).
   TemporalExtent.multi(
     Iterable<Interval> intervals, {
-    String trs = 'http://www.opengis.net/def/uom/ISO-8601/0/Gregorian',
+    TemporalRefSys trs = TemporalRefSys.gregorian,
   })  : _intervals = _validate(intervals),
         _first = intervals.first,
         _trs = trs;
@@ -44,12 +48,12 @@ class TemporalExtent {
   /// All intervals for this extent.
   Iterable<Interval> get intervals => _intervals ?? [_first];
 
-  /// The temporal reference system for intervals of this extent.
-  String get trs => _trs;
+  /// The temporal coordinate reference system for intervals of this extent.
+  TemporalRefSys get trs => _trs;
 
   /// Copy this temporal extent with optional [interval] and/or [trs]
   /// parameters changed.
-  TemporalExtent copyWith({Interval? interval, String? trs}) {
+  TemporalExtent copyWith({Interval? interval, TemporalRefSys? trs}) {
     if (interval != null) {
       return TemporalExtent.single(interval, trs: trs ?? _trs);
     } else {

dart/geobase/test/meta/extent_test.dart

@@ -64,7 +64,7 @@ void main() {
       );
       expect(extent1.temporal!.first, interval1);
       expect(
-        extent1.temporal!.trs,
+        extent1.temporal!.trs.toString(),
         'http://www.opengis.net/def/uom/ISO-8601/0/Gregorian',
       );
       expect(