Fix TimeZone parsing

.github/workflows/build.yml

@@ -25,7 +25,7 @@ jobs:
     - uses: actions/checkout@v3
 
     - name: Test
-      run: dotnet test --configuration Release
+      run: dotnet test -c Release
 
     - name: Test - Compiled
       run: dotnet test --configuration Release /p:Compiled=true

Fluid.Tests/Fluid.Tests.csproj

@@ -1,11 +1,9 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>netcoreapp3.1;net5.0;net6.0;net7.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net7.0</TargetFrameworks>
     <LangVersion>latest</LangVersion>
     <DefineConstants Condition="'$(Compiled)' == 'true'">$(DefineConstants);COMPILED</DefineConstants>
-    <!-- Ignore: The target framework '...' is out of support and will not receive security updates in the future -->
-    <NoWarn>NETSDK1138</NoWarn>
   </PropertyGroup>
 
   <ItemGroup>

Fluid.Tests/MiscFiltersTests.cs

@@ -1,9 +1,10 @@
-using System;
+using Fluid.Filters;
+using Fluid.Values;
+using System;
 using System.Globalization;
 using System.Linq;
 using System.Threading.Tasks;
-using Fluid.Filters;
-using Fluid.Values;
+using TimeZoneConverter;
 using Xunit;
 
 namespace Fluid.Tests
@@ -302,6 +303,27 @@ public async Task ChangeTimeZone(string initialDateTime, string timeZone, string
             Assert.Equal(expected, ((DateTimeOffset)result.ToObjectValue()).ToString("yyyy-MM-ddTHH:mm:ssK"));
         }
 
+        [Theory]
+        [InlineData("2022-12-13T21:02:18.399+00:00", "utc", "2022-12-13T21:02:18.399+00:00")]
+        [InlineData("2022-12-13T21:02:18.399+00:00", "America/New_York", "2022-12-13T21:02:18.399+00:00")]
+        [InlineData("2022-12-13T21:02:18.399+00:00", "Australia/Adelaide", "2022-12-13T21:02:18.399+00:00")]
+        [InlineData("2022-12-13T21:02:18.399", "utc", "2022-12-13T21:02:18.399+00:00")]
+        [InlineData("2022-12-13T21:02:18.399", "America/New_York", "2022-12-13T21:02:18.399-05:00")]
+        [InlineData("2022-12-13T21:02:18.399", "Australia/Adelaide", "2022-12-13T21:02:18.399+10:30")]
+        [InlineData("2022-12-13T21:02:18.399+01:00", "utc", "2022-12-13T21:02:18.399+01:00")] // Parsed as UTC+1, converted to UTC
+        public async Task DateFilterUsesContextTimezone(string initialDateTime, string timeZone, string expected)
+        {
+            // - When a TZ is provided in the source string, the resulting DateTimeOffset uses it
+            // - When no TZ is provided, we assume the local offset (context.TimeZone)
+
+            var input = new StringValue(initialDateTime);
+            var context = new TemplateContext { TimeZone = TZConvert.GetTimeZoneInfo(timeZone) };
+
+            var date = await MiscFilters.Date(input, new FilterArguments(new StringValue(RoundTripDateTimePattern)), context);
+
+            Assert.Equal(expected, date.ToStringValue());
+        }
+
         [Theory]
         [InlineData("2020-05-18T02:13:09+00:00", "America/New_York", "%l:%M%P", "10:13pm")]
         [InlineData("2020-05-18T02:13:09+00:00", "Europe/London", "%l:%M%P", "3:13am")]

Fluid/Values/FluidValueExtensions.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Globalization;
+using TimeZoneConverter;
 
 namespace Fluid.Values
 {
@@ -8,10 +9,13 @@ public static class FluidValueExtensions
         private const string Now = "now";
         private const string Today = "today";
 
+        // The K specifier is optional when used in TryParseExact, so
+        // if a TZ is not specified, it will still match
+
         private static readonly string[] DefaultFormats = {
-            "yyyy-MM-ddTHH:mm:ss.FFF",
-            "yyyy-MM-ddTHH:mm:ss",
-            "yyyy-MM-ddTHH:mm",
+            "yyyy-MM-ddTHH:mm:ss.FFFK",
+            "yyyy-MM-ddTHH:mm:ssK",
+            "yyyy-MM-ddTHH:mmK",
             "yyyy-MM-dd",
             "yyyy-MM",
             "yyyy"
@@ -53,6 +57,8 @@ public static bool TryGetDateTimeInput(this FluidValue input, TemplateContext co
 
             if (input.Type == FluidValues.String)
             {
+                var timeZoneProvided = false;
+
                 var stringValue = input.ToStringValue();
 
                 if (stringValue == Now || stringValue == Today)
@@ -63,30 +69,52 @@ public static bool TryGetDateTimeInput(this FluidValue input, TemplateContext co
                 {
                     var success = true;
 
-                    if (!DateTime.TryParseExact(stringValue, DefaultFormats, context.CultureInfo, DateTimeStyles.None, out var dateTime))
+                    // Use DateTimeOffset.Parse to extract the TZ if it's specified.
+                    // We then verify if a TZ was set in the source string by using DateTime.Parse's Kind which will return Unspecified if not set.
+
+                    if (!DateTimeOffset.TryParseExact(stringValue, DefaultFormats, context.CultureInfo, DateTimeStyles.AssumeUniversal, out result))
                     {
-                        if (!DateTime.TryParseExact(stringValue, SecondaryFormats, context.CultureInfo, DateTimeStyles.None, out dateTime))
+                        if (!DateTimeOffset.TryParseExact(stringValue, SecondaryFormats, context.CultureInfo, DateTimeStyles.AssumeUniversal, out result))
                         {
-                            if (!DateTime.TryParse(stringValue, context.CultureInfo, DateTimeStyles.None, out dateTime))
+                            if (!DateTimeOffset.TryParse(stringValue, context.CultureInfo, DateTimeStyles.AssumeUniversal, out result))
                             {
-                                if (!DateTime.TryParse(stringValue, CultureInfo.InvariantCulture, DateTimeStyles.None, out dateTime))
+                                if (!DateTimeOffset.TryParse(stringValue, CultureInfo.InvariantCulture, DateTimeStyles.AssumeUniversal, out result))
                                 {
                                     success = false;
                                 }
+                                else
+                                {
+                                    timeZoneProvided = DateTime.TryParse(stringValue, CultureInfo.InvariantCulture, DateTimeStyles.None, out var timeZoneDateTime) && timeZoneDateTime.Kind != DateTimeKind.Unspecified;
+                                }
+                            }
+                            else
+                            {
+                                timeZoneProvided = DateTime.TryParse(stringValue, context.CultureInfo, DateTimeStyles.None, out var timeZoneDateTime) && timeZoneDateTime.Kind != DateTimeKind.Unspecified;
                             }
                         }
+                        else
+                        {
+                            timeZoneProvided = DateTime.TryParseExact(stringValue, SecondaryFormats, context.CultureInfo, DateTimeStyles.None, out var timeZoneDateTime) && timeZoneDateTime.Kind != DateTimeKind.Unspecified;
+                        }
+                    }
+                    else
+                    {
+                        timeZoneProvided = DateTime.TryParseExact(stringValue, DefaultFormats, context.CultureInfo, DateTimeStyles.None, out var timeZoneDateTime) && timeZoneDateTime.Kind != DateTimeKind.Unspecified;
                     }
 
-                    // If no timezone is specified, assume local using the configured timezone
                     if (success)
                     {
-                        if (dateTime.Kind == DateTimeKind.Unspecified)
-                        {
-                            result = new DateTimeOffset(dateTime, context.TimeZone.GetUtcOffset(dateTime));
-                        }
-                        else
+                        // If no timezone is specified in the source string, only use the date time part of the result
+                        if (!timeZoneProvided)
                         {
-                            result = new DateTimeOffset(dateTime);
+                            // A timezone is represented as a UTC offset, but this can vary based on daylight saving times.
+                            // Hence we don't use context.TimeZone.BaseUtcOffset which is fixed, but TimeZone.GetUtcOffset
+                            // to get the actual timezone offset at the moment of the parsed date and time
+
+                            var dateTime = result.DateTime;
+                            var offset = context.TimeZone.GetUtcOffset(dateTime);
+
+                            result = new DateTimeOffset(dateTime, offset);
                         }
                     }
 

README.md

@@ -372,10 +372,12 @@ Tuesday, August 1, 2017
 
 ### System time zone
 
-`TemplateOptions` and `TemplateContext` provides a property to define a default time zone to use when parsing date and times. The default value is the current system's time zone.
-When dates and times are parsed and don't specify a time zone, the default one is assumed. Setting a custom one can also prevent different environments (data centers) from
+`TemplateOptions` and `TemplateContext` provides a property to define a default time zone to use when parsing date and times. The default value is the current system's time zone. Setting a custom one can also prevent different environments (data centers) from
 generating different results.
 
+- When dates and times are parsed and don't specify a time zone, the configured one is assumed. 
+- When a time zone is provided in the source string, the resulting date time uses it.
+
 > Note: The `date` filter conforms to the Ruby date and time formats https://ruby-doc.org/core-3.0.0/Time.html#method-i-strftime. To use the .NET standard date formats, use the `format_date` filter.
 
 #### Source