Add deserialization for ICS

LICENSE

@@ -1,5 +1,6 @@
 BSD 3-Clause License
 
+Copyright (c) 2020, Jonas Franz
 Copyright (c) 2020, Lukas Himsel
 All rights reserved.
 

example/pubspec.yaml

@@ -2,8 +2,8 @@ name: example
 environment:
   sdk: '>=2.1.0 <3.0.0'
 dependencies:
-  intl: ^0.15.7
-  nanoid: ^0.0.6
+  intl: any
+  nanoid: any
   ical:
     path: ..
 

lib/serializer.dart

@@ -2,6 +2,7 @@ export 'src/abstract.dart';
 export 'src/subcomponents.dart';
 export 'src/calendar.dart';
 export 'src/event.dart';
+export 'src/parser.dart';
 //export 'src/journal.dart';
 //export 'src/timezone.dart';
 //export 'src/todo.dart';

lib/src/abstract.dart

@@ -1,4 +1,5 @@
 import 'package:ical/serializer.dart';
+import 'package:ical/src/structure.dart';
 import 'package:ical/src/utils.dart';
 
 import 'utils.dart' as utils;
@@ -9,6 +10,10 @@ abstract class AbstractSerializer {
   String serialize();
 }
 
+abstract class AbstractDeserializer {
+  void deserialize(ICalStructure structure);
+}
+
 class IClass {
   final String _label;
   @override
@@ -105,7 +110,8 @@ class IOrganizer {
   }
 }
 
-abstract class ICalendarElement extends AbstractSerializer {
+abstract class ICalendarElement
+    implements AbstractSerializer, AbstractDeserializer {
   IOrganizer organizer;
   String uid;
   String summary;
@@ -143,12 +149,27 @@ abstract class ICalendarElement extends AbstractSerializer {
     if (summary != null) out.writeln('SUMMARY:${escapeValue(summary)}');
     if (url != null) out.writeln('URL:${url}');
     if (classification != null) out.writeln('CLASS:$classification');
-    if (description != null)
+    if (description != null) {
       out.writeln('DESCRIPTION:${escapeValue(description)}');
+    }
     if (rrule != null) out.write(rrule.serialize());
 
     return out.toString();
   }
+
+  @override
+  void deserialize(ICalStructure structure) {
+    uid = structure["UID"]?.value;
+    categories = structure["CATEGORIES"]?.value?.split(",");
+    comment = structure["COMMENT"]?.value;
+    summary = structure["SUMMARY"]?.value;
+    url = structure["URL"]?.value;
+    final classificationString = structure["CLASSIFICATION"]?.value;
+    if (classificationString != null)
+      classification = IClass._(classificationString);
+    // TODO support rrule
+  }
+
   // TODO ATTENDEE
   // TODO CONTACT
 }

lib/src/calendar.dart

@@ -1,7 +1,9 @@
-import 'abstract.dart';
+import 'package:ical/serializer.dart';
+import 'package:ical/src/structure.dart';
+
 import 'utils.dart' as utils;
 
-class ICalendar extends AbstractSerializer {
+class ICalendar implements AbstractSerializer, AbstractDeserializer {
   List<ICalendarElement> _elements = <ICalendarElement>[];
   String company;
   String product;
@@ -18,6 +20,8 @@ class ICalendar extends AbstractSerializer {
   addAll(List<ICalendarElement> elements) => _elements.addAll(elements);
   addElement(ICalendarElement element) => _elements.add(element);
 
+  List<IEvent> get events => _elements.whereType<IEvent>().toList();
+
   @override
   String serialize() {
     var out = StringBuffer()
@@ -37,4 +41,13 @@ class ICalendar extends AbstractSerializer {
     out.writeln('END:VCALENDAR');
     return out.toString();
   }
+
+  @override
+  void deserialize(ICalStructure structure) {
+    _elements = structure.children
+        .where((child) => child.type == "VEVENT")
+        .map((event) => IEvent()..deserialize(event))
+        .cast<ICalendarElement>()
+        .toList();
+  }
 }

lib/src/event.dart

@@ -1,3 +1,5 @@
+import 'package:ical/src/structure.dart';
+
 import 'abstract.dart';
 import 'subcomponents.dart';
 import 'utils.dart' as utils;
@@ -79,6 +81,27 @@ class IEvent extends ICalendarElement with EventToDo {
       ..writeln('END:VEVENT');
     return out.toString();
   }
+
+  @override
+  void deserialize(ICalStructure structure) {
+    super.deserialize(structure);
+    start = _parseDate(structure["DTSTART"]);
+    end = _parseDate(structure["DTEND"]);
+    // TODO support duration
+    transparency = structure["TRANSP"] != null
+      ? ITimeTransparency._(structure["TRANSP"].value)
+        : null;
+    status = structure["STATUS"] != null
+      ? IEventStatus._(structure["STATUS"].value)
+        : null;
+    // TODO support missing event to do;
+  }
+
+  DateTime _parseDate(ICalRow row) {
+    if(row == null || row.value == null) return null;
+    // TODO: add TZID support
+    return DateTime.parse(row.value);
+  }
 }
 
 class IEventStatus {

lib/src/parser.dart

@@ -0,0 +1,42 @@
+import 'dart:convert';
+
+import 'package:ical/serializer.dart';
+import 'package:ical/src/structure.dart';
+import 'package:ical/src/utils.dart';
+
+const _rowRegex = r"""^([\w-]+);?([\w-]+="[^"]*"|.*?):(.*)$""";
+const _middleRegex = r"""(?<key>[^=;]+)=(?<value>[^;]+)""";
+
+class ICalParser {
+  List<ICalRow> parseText(String text) {
+    // unfold strings
+    text = text.replaceAll("\r\n", "\n").replaceAll("\n ", "");
+    return LineSplitter()
+        .convert(text)
+        .map(_parseLine)
+        .where((element) => element != null)
+        .toList();
+  }
+
+  ICalRow _parseLine(String line) {
+    final regex = RegExp(_rowRegex);
+    final match = regex.firstMatch(line);
+    if(match == null) return null;
+    final String key = match.group(1);
+    final String middle = match.group(2);
+    final String value = unescapeValue(match.group(3));
+    return ICalRow(key, value, properties: _parseMiddlePart(middle));
+  }
+
+  Map<String, String> _parseMiddlePart(String middle) {
+    final matches = RegExp(_middleRegex).allMatches(middle);
+    final entries = matches
+        .map((match) => MapEntry(match.namedGroup("key"), unescapeValue(match.namedGroup("value"))));
+    return Map.fromEntries(entries);
+  }
+
+  ICalendar parseCalender(String text) {
+    final rows = parseText(text);
+    return ICalendar()..deserialize(ICalStructure.fromRows(rows));
+  }
+}

lib/src/structure.dart

@@ -0,0 +1,42 @@
+class ICalStructure {
+  final String type;
+  final List<ICalRow> rows;
+  final List<ICalStructure> children;
+
+  ICalRow operator [](String key) {
+    return rows.firstWhere((row) => row.key == key, orElse: () => null);
+  }
+
+  const ICalStructure(this.type, this.rows, this.children);
+
+  factory ICalStructure.fromRows(List<ICalRow> rows) {
+    final beginRow = rows.removeAt(0);
+    if(beginRow == null) throw Exception("No begin row found");
+    final type = beginRow.value;
+    final List<ICalStructure> children = [];
+
+    var beginIndex = rows.indexWhere((element) => element.key == "BEGIN");
+    while(beginIndex != -1) {
+      final subType = rows[beginIndex].value;
+      final endIndex = rows.indexWhere((element) => element.key == "END" && element.value == subType) + 1;
+      if(endIndex == 0) throw Exception("No END row found for type $subType");
+      final subStructure = rows.getRange(beginIndex, endIndex);
+      children.add(ICalStructure.fromRows(subStructure.toList()));
+      rows.removeRange(beginIndex, endIndex);
+      beginIndex = rows.indexWhere((element) => element.key == "BEGIN");
+    }
+    // remove END row
+    // TODO check if end row is valid
+    final endRow = rows.removeLast();
+    if(endRow.key != "END" || endRow.value != type) throw Exception("Invalid END row");
+    return ICalStructure(type, rows, children);
+  }
+}
+
+class ICalRow {
+  final String key;
+  final String value;
+  final Map<String, String> properties;
+
+  const ICalRow(this.key, this.value, {this.properties = const {}});
+}

lib/src/utils.dart

@@ -25,3 +25,10 @@ String escapeValue(String val) => val
     .replaceAll('\t', '\\t')
     .replaceAll(',', '\\,')
     .replaceAll(';', '\\;');
+
+String unescapeValue(String val) => val
+    .replaceAll('\\\\', '\\')
+    .replaceAll('\\n', '\n')
+    .replaceAll('\\t', '\t')
+    .replaceAll('\\,', ',')
+    .replaceAll('\\;', ';');

pubspec.yaml

@@ -9,10 +9,9 @@ environment:
   sdk: ">=2.0.0 <3.0.0"
 
 dependencies:
-  intl: ^0.16.0
-  nanoid: ^0.1.0
+  intl: ^0.17.0
+  nanoid: ^1.0.0
 
 dev_dependencies:
   test: ^1.5.1+1
   pedantic: ^1.8.0
-

test/parser.dart

@@ -0,0 +1,83 @@
+import 'package:ical/src/parser.dart';
+import 'package:test/test.dart';
+
+main() {
+  group('Parser', () {
+    ICalParser parser;
+    setUp(() {
+      parser = ICalParser();
+    });
+    test('parse single row', () {
+      const withMiddle = "DTSTART;VALUE=DATE:20200908";
+      const withoutMiddle = "CREATED:20200827T080438Z";
+
+      var result = parser.parseText(withMiddle);
+      var row = result.firstWhere((element) => element.key == "DTSTART");
+      expect(row?.value, "20200908");
+      expect(row?.properties["VALUE"], "DATE");
+
+      result = parser.parseText(withoutMiddle);
+      row = result.firstWhere((element) => element.key == "CREATED");
+      expect(row?.value, "20200827T080438Z");
+      expect(row?.properties?.length, 0);
+    });
+
+    test('parse multiple rows', () {
+      const testIcs = """CREATED:20200827T080438Z
+DTSTAMP:20200827T080438Z
+LAST-MODIFIED:20200827T080438Z
+DTSTART;VALUE=DATE:20200907
+DTEND;VALUE=DATE:20200908""";
+      final result = parser.parseText(testIcs);
+      expect(result.length, 5);
+      expect(result.map((e) => e.key),
+          ["CREATED", "DTSTAMP", "LAST-MODIFIED", "DTSTART", "DTEND"]);
+    });
+
+    test('parse calendar', () {
+      const foldedRow = """TEST:testtesttesttesttesttest
+ testtest""";
+      final row = parser
+          .parseText(foldedRow)
+          .firstWhere((element) => element.key == "TEST");
+      expect(row?.value, "testtesttesttesttesttesttesttest");
+    });
+
+    test('parse example ICalStructure', () {
+      const testIcs = """BEGIN:VCALENDAR
+VERSION:2.0
+CALSCALE:GREGORIAN
+BEGIN:VEVENT
+SUMMARY:Access-A-Ride Pickup
+DTSTART;TZID=America/New_York:20130802T103400
+DTEND;TZID=America/New_York:20130802T110400
+LOCATION:1000 Broadway Ave.\, Brooklyn
+DESCRIPTION: Access-A-Ride trip to 900 Jay St.\, Brooklyn
+STATUS:CONFIRMED
+SEQUENCE:3
+BEGIN:VALARM
+TRIGGER:-PT10M
+DESCRIPTION:Pickup Reminder
+ACTION:DISPLAY
+END:VALARM
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:Access-A-Ride Pickup
+DTSTART;TZID=America/New_York:20130802T200000
+DTEND;TZID=America/New_York:20130802T203000
+LOCATION:900 Jay St.\, Brooklyn
+DESCRIPTION: Access-A-Ride trip to 1000 Broadway Ave.\, Brooklyn
+STATUS:CONFIRMED
+SEQUENCE:3
+BEGIN:VALARM
+TRIGGER:-PT10M
+DESCRIPTION:Pickup Reminder
+ACTION:DISPLAY
+END:VALARM
+END:VEVENT
+END:VCALENDAR""";
+      final result = parser.parseCalender(testIcs);
+      expect(result.events.length, 2);
+    });
+  });
+}