Allow ImageRequest.Parse to optionally reject bad parameters

src/IIIF/IIIF.Tests/ImageApi/ImageRequestXTests.cs

@@ -1,6 +1,6 @@
-using FluentAssertions;
+using System;
+using FluentAssertions;
 using IIIF.ImageApi;
-using Xunit;
 
 namespace IIIF.Tests.ImageApi;
 
@@ -221,4 +221,88 @@ public void Parse_CorrectPercentageScaled()
         // Assert
         result.Should().BeEquivalentTo(expected);
     }
+
+    [Theory]
+    [InlineData("my-asset")]
+    [InlineData("my-asset/")]
+    public void Parse_IsBase(string path)
+    {
+        // Arrange and Act
+        const string prefix = "iiif-img/27/1/";
+        var result = ImageRequest.Parse($"{prefix}{path}", prefix);
+
+        // Assert
+        result.IsBase.Should().BeTrue();
+    }
+
+    [Fact]
+    public void Parse_InfoJson()
+    {
+        // Arrange and Act
+        const string prefix = "iiif-img/27/1/";
+        var result = ImageRequest.Parse($"{prefix}my-asset/info.json", prefix);
+
+        // Assert
+        result.IsInformationRequest.Should().BeTrue();
+    }
+
+    [Fact]
+    public void Parse_Fails_WhenInfoHasInvalidExtension()
+    {
+        // Arrange and Act
+        const string prefix = "iiif-img/27/1/";
+        var action = () => ImageRequest.Parse($"{prefix}my-asset/info.jsonll", prefix);
+
+        // Assert
+        action.Should().ThrowExactly<ArgumentException>();
+    }
+
+    [Theory]
+    [InlineData("iiif-img/27/1/")]
+    [InlineData("/iiif-img/27/1/")]
+    [InlineData("/iiif-img/27/1")]
+    [InlineData("iiif-img/27/1")]
+    public void Parse_Validate_HandlesPrefixFormats(string prefix)
+    {
+        // Arrange and Act
+        const string request = $"iiif-img/27/1/my-asset/full/800,/0/default.jpg";
+        var action = () => ImageRequest.Parse(request, prefix, true);
+
+        // Assert
+        action.Should().NotThrow<ArgumentException>();
+    }
+
+    [Theory]
+    [InlineData("my-asset//full/800,/0/default.jpg")]
+    [InlineData("my-asset/full//800,/0/default.jpg")]
+    [InlineData("my-asset/full/800,//0/default.jpg")]
+    [InlineData("my-asset/full/800,/0//default.jpg")]
+    public void Parse_Validate_Fails_WhenGivenExtraSegments(string path)
+    {
+        // Arrange and Act
+        const string prefix = "iiif-img/27/1/";
+        var action = () => ImageRequest.Parse($"{prefix}{path}", prefix, true);
+
+        // Assert
+        action.Should().ThrowExactly<ArgumentException>()
+            .WithMessage("Path contains empty or an invalid number of segments");
+    }
+
+    [Theory]
+    [InlineData("my-asset//800,/0/default.jpg")]
+    [InlineData("my-asset/full//0/default.jpg")]
+    [InlineData("my-asset/full/800,//default.jpg")]
+    [InlineData("my-asset/full/800,/0/")]
+    [InlineData("my-asset////default.jpg")]
+    [InlineData("my-asset////")]
+    public void Parse_Validate_Fails_WhenGivenEmptyParameters(string path)
+    {
+        // Arrange and Act
+        const string prefix = "iiif-img/27/1/";
+        var action = () => ImageRequest.Parse($"{prefix}{path}", prefix, true);
+
+        // Assert
+        action.Should().ThrowExactly<ArgumentException>()
+            .WithMessage("Path contains empty or an invalid number of segments");
+    }
 }

src/IIIF/IIIF/ImageApi/ImageRequest.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Linq;
 
 namespace IIIF.ImageApi;
 
@@ -25,7 +26,15 @@ public class ImageRequest
     /// </summary>
     public string ImageRequestPath => OriginalPath.Replace(Identifier, string.Empty);
 
-    public static ImageRequest Parse(string path, string prefix)
+    /// <summary>
+    /// Parses an image request path as a IIIF ImageRequest object
+    /// </summary>
+    /// <returns>A ImageRequest object</returns>
+    /// <param name="path">The image request path</param>
+    /// <param name="prefix">The image request prefix</param>
+    /// <param name="validateSegments">If true, throws an ArgumentException if the image request contains empty values,
+    /// or an invalid number of segments</param>
+    public static ImageRequest Parse(string path, string prefix, bool validateSegments = false)
     {
         if (path[0] == '/') path = path[1..];
 
@@ -35,12 +44,16 @@ public static ImageRequest Parse(string path, string prefix)
             if (prefix != path[..prefix.Length])
                 throw new ArgumentException("Path does not start with prefix", nameof(prefix));
             path = path[prefix.Length..];
+            if (path[0] == '/') path = path[1..];
         }
 
         var request = new ImageRequest { Prefix = prefix };
+
         var parts = path.Split('/');
+
         request.Identifier = parts[0];
-        if (parts.Length == 1 || parts[1] == string.Empty)
+
+        if (parts.Length == 1 || (parts.Length == 2 && parts[1] == string.Empty))
         {
             // likely the server will want to redirect this
             request.IsBase = true;
@@ -52,6 +65,11 @@ public static ImageRequest Parse(string path, string prefix)
             request.IsInformationRequest = true;
             return request;
         }
+
+        if (validateSegments && (parts.Length != 5 || parts.Any(string.IsNullOrEmpty)))
+        {
+            throw new ArgumentException("Path contains empty or an invalid number of segments");
+        }
 
         request.OriginalPath = path;
         request.Region = RegionParameter.Parse(parts[1]);