Allow for editing event titles:

- Add frontend for editing
- Save the original iCal properties when loading
- Use these to closely reproduce the original iCal for PUT'ing

BlazorApp/BlazorApp.csproj

@@ -15,4 +15,10 @@
     <PackageReference Include="Microsoft.EntityFrameworkCore.Tools.DotNet" Version="2.0.3" />
   </ItemGroup>
 
+  <ItemGroup>
+    <None Update="Pages\Event.razor.scss">
+      <DependentUpon>Event.razor</DependentUpon>
+    </None>
+  </ItemGroup>
+
 </Project>

BlazorApp/Data/Calendar.cs

@@ -3,24 +3,13 @@ using System.Collections.Generic;
 using System.ComponentModel.DataAnnotations;
 using System.Globalization;
 using System.Net.Http;
+using System.Net.Http.Headers;
 using System.Text;
 using System.Threading.Tasks;
 using System.Xml;
 
 namespace BlazorApp.Data
 {
-    public class Event
-    {
-        public string Uid { get; set; }
-        public string Summary { get; set; }
-        public DateTime? DtStart { get; set; }
-        public DateTime? DtEnd { get; set; }
-        public string Description { get; set; }
-        public TimeSpan? Duration { get; set; }
-
-        public DateTime? CalculatedEnd => DtEnd ?? DtStart + Duration;
-    }
-
     public class Calendar
     {
         public int Id { get; set; }
@@ -127,17 +116,22 @@ namespace BlazorApp.Data
                     continue;
                 }
 
+                if (name == "END" && value == "VEVENT")
+                {
+                    // End of the current event, add it to the list
+                    events.Add(@event);
+                    @event = null;
+                    continue;
+                }
+
+                var parameters = left.Length == 2 ? left[1] : null;
+                
+                // Add property to the RawProperties list.
+                // Used for rebuilding the full iCal for updating the event on the server.
+                @event.RawProperties.Add((name, parameters, value));
+
                 switch (name)
                 {
-                    case "END":
-                        if (value == "VEVENT")
-                        {
-                            // End of the current event, add it to the list
-                            events.Add(@event);
-                            @event = null;
-                        }
-
-                        break;
                     case "UID":
                         @event.Uid = value;
                         break;
@@ -162,18 +156,8 @@ namespace BlazorApp.Data
             return events;
         }
 
-        /**
+        private static List<Event> _filterSortEvents(List<Event> events)
-         * <summary>Retrieves and parses all events from the CalDav server.</summary>
-         */
-        public async Task<List<Event>> GetEvents()
         {
-            var client = new HttpClient();
-            if (AuthorizationHeader != null)
-                client.DefaultRequestHeaders.Add("Authorization", AuthorizationHeader);
-
-            var body = await client.GetStringAsync(Url);
-            var events = ParseICal(body);
-
             var now = DateTime.Now;
             events = events.FindAll(@event => @event.DtStart > now || @event.DtEnd > now);
 
@@ -190,6 +174,26 @@ namespace BlazorApp.Data
             return events;
         }
 
+        /**
+         * <summary>Retrieves and parses all events from the CalDav server.</summary>
+         */
+        public async Task<List<Event>> GetEvents()
+        {
+            var client = new HttpClient();
+            if (AuthorizationHeader != null)
+                client.DefaultRequestHeaders.Add("Authorization", AuthorizationHeader);
+
+            var response = await client.GetAsync(Url);
+            var eTag = response.Headers.ETag?.Tag;
+            var body = await response.Content.ReadAsStringAsync();
+
+            var events = ParseICal(body);
+            foreach (var @event in events)
+                @event.ETag = eTag;
+                    
+            return _filterSortEvents(events);
+        }
+
         /**
          * <summary>Retrieves and parses an event with UID <code>uid</code> from the CalDav server.</summary>
          */
@@ -199,6 +203,7 @@ namespace BlazorApp.Data
             if (AuthorizationHeader != null)
                 client.DefaultRequestHeaders.Add("Authorization", AuthorizationHeader);
 
+            // Request the event with UID `uid`.
             var request = new HttpRequestMessage(new HttpMethod("REPORT"), Url);
             request.Headers.Add("Depth", "1");
 
@@ -225,13 +230,53 @@ namespace BlazorApp.Data
             var result = await client.SendAsync(request);
             var body = await result.Content.ReadAsStreamAsync();
 
+            // Parse the received XML
             var reader = new XmlTextReader(body);
             var document = new XmlDocument();
             document.Load(reader);
 
-            var node = document.GetElementsByTagName("C:calendar-data")[0]?.InnerText;
+            // Extract and parse the ICal data
-            var events = ParseICal(node);
+            var dataNode = document.GetElementsByTagName("C:calendar-data")[0]?.InnerText;
-            return events.Count > 0 ? events[0] : null;
+            var events = ParseICal(dataNode);
+            if (events.Count == 0)
+                return null;
+            var @event = events[0];
+            
+            // Extract the ETag and event collection href.
+            @event.ETag = document.GetElementsByTagName("getetag")[0]?.InnerText;
+            @event.Href = document.GetElementsByTagName("href")[0]?.InnerText;
+            
+            return @event;
+        }
+
+        public async Task<Event> UpdateEvent(Event @event)
+        {
+            var client = new HttpClient();
+            if (AuthorizationHeader != null)
+                client.DefaultRequestHeaders.Add("Authorization", AuthorizationHeader);
+            
+            // Setting If-Match header to the ETag is required when updating an event.
+            if (@event.ETag != null)
+                client.DefaultRequestHeaders.IfMatch.Add(new EntityTagHeaderValue(@event.ETag));
+
+            // Build a new URL based on the calendar's URL and the event's collection href.
+            var url = new Uri(new Uri(Url), @event.Href);
+
+            var content = new StringContent(@event.ToICal(), Encoding.UTF8, "text/calendar");
+            var response = await client.PutAsync(url, content);
+            
+            // Parse the newly updated event.
+            var body = await response.Content.ReadAsStringAsync();
+
+            var events = ParseICal(body);
+            if (events.Count == 0)
+                return null;
+            var newEvent = events[0];
+            
+            // Extract the updated ETag
+            newEvent.ETag = response.Headers.ETag?.Tag;
+            
+            return newEvent;
         }
     }
 }

BlazorApp/Data/Event.cs

@@ -0,0 +1,59 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace BlazorApp.Data
+{
+    public class Event
+    {
+        public string Uid { get; set; }
+        public string Summary { get; set; }
+        public DateTime? DtStart { get; set; }
+        public DateTime? DtEnd { get; set; }
+        public string Description { get; set; }
+        public TimeSpan? Duration { get; set; }
+
+        public List<(string, string, string)> RawProperties { get; } = new();
+        public string ETag { get; set; }
+        public string Href { get; set; }
+
+        public DateTime? CalculatedEnd => DtEnd ?? DtStart + Duration;
+
+        private static string _escape(string s)
+        {
+            return s
+                .Replace(@"\", @"\\")
+                .Replace(",", @"\,")
+                .Replace(";", @"\;")
+                .Replace("\n", @"\n");
+        }
+
+        public string ToICal()
+        {
+            var sb = new StringBuilder();
+            sb.Append("BEGIN:VCALENDAR\r\n");
+            sb.Append("VERSION:2.0\r\n");
+            sb.Append("PRODID:-//Sijmen//blazor-calendar//EN\r\n");
+            sb.Append("BEGIN:VEVENT\r\n");
+
+            foreach (var (name, parameters, oldValue) in RawProperties)
+            {
+                sb.Append(name);
+                if (parameters != null)
+                    sb.Append($";{parameters}");
+
+                var value = name switch
+                {
+                    "SUMMARY" => _escape(Summary),
+                    _ => oldValue
+                };
+
+                sb.Append($":{value}\r\n");
+            }
+
+            sb.Append("END:VEVENT\r\n");
+            sb.Append("END:VCALENDAR\r\n");
+            return sb.ToString();
+        }
+    }
+}

BlazorApp/Pages/Event.razor

@@ -13,7 +13,21 @@
 }
 else
 {
-    <h1>@_event.Summary</h1>
+    @if (!_editTitle)
+    {
+        <h1 class="event-summary">
+            <span @onclick="() => _editTitle = true">@_event.Summary</span>
+        </h1>
+    }
+    else
+    {
+        <input @bind="@_event.Summary">
+        <button @onclick="UpdateEvent">Save</button>
+    }
+
+    <div>
+        <strong>ETag:</strong> @_event.ETag
+    </div>
 
     @if (_event.DtStart != null)
     {
@@ -40,11 +54,18 @@ else
     [Parameter]
     public string EventUid { get; set; }
 
+    private Data.Calendar _calendar;
     private Data.Event _event;
+    private bool _editTitle;
 
     protected override async Task OnInitializedAsync()
     {
-        var calendar = await Data.CalendarService.GetCalendarById(CalendarId);
+        _calendar = await Data.CalendarService.GetCalendarById(CalendarId);
-        _event = await calendar.GetEventByUid(EventUid);
+        _event = await _calendar.GetEventByUid(EventUid);
+    }
+
+    private async void UpdateEvent()
+    {
+        _event = await _calendar.UpdateEvent(_event);
     }
 }

BlazorApp/Pages/Event.razor.css

@@ -0,0 +1,3 @@
+.event-summary > span:hover {
+    border: 1px solid rgba(0, 0, 0, 0.2);
+}

BlazorApp/Properties/launchSettings.json

@@ -18,7 +18,7 @@
     "BlazorApp": {
       "commandName": "Project",
       "dotnetRunMessages": "true",
-      "launchBrowser": true,
+      "launchBrowser": false,
       "applicationUrl": "http://localhost:5000",
       "environmentVariables": {
         "ASPNETCORE_ENVIRONMENT": "Development"