introduce PlaylistRef.TryParse, improve validation

Author: hyperblast

src/Client/Infrastructure/ArgumentValidator.cs

@@ -7,7 +7,7 @@ namespace Beefweb.Client.Infrastructure;
 internal static partial class ArgumentValidator
 {
     [GeneratedRegex("^[a-z0-9_]+$")]
-    private static partial Regex IdMatcher();
+    public static partial Regex IdMatcher();
 
     public static void ValidatePlaylistId(string? id,
         [CallerArgumentExpression(nameof(id))] string parameterName = "")

src/Client/PlaylistRef.cs

@@ -14,7 +14,7 @@ namespace Beefweb.Client;
     /// <summary>
     /// <see cref="PlaylistRef"/> referencing currently selected playlist.
     /// </summary>
-    public static PlaylistRef Current { get; } = new("current");
+    public static PlaylistRef Current { get; } = new(false, "current");
 
     /// <summary>
     /// Playlist identifier.
@@ -36,6 +36,7 @@ namespace Beefweb.Client;
     public PlaylistRef(string id)
     {
         ArgumentValidator.ValidatePlaylistId(id);
+
         Id = id;
         Index = -1;
     }
@@ -53,6 +54,18 @@ public PlaylistRef(int index)
         Index = index;
     }
 
+    private PlaylistRef(bool unused, int index)
+    {
+        Id = null;
+        Index = index;
+    }
+
+    private PlaylistRef(bool unused, string id)
+    {
+        Id = id;
+        Index = -1;
+    }
+
     /// <summary>
     /// Implicitly converts <paramref name="index"/> to <see cref="PlaylistRef"/>.
     /// </summary>
@@ -89,9 +102,40 @@ public object GetValue()
     /// <returns>Parsed value of <paramref name="value"/>.</returns>
     public static PlaylistRef Parse(string value)
     {
-        return int.TryParse(value, NumberStyles.Integer, CultureInfo.InvariantCulture, out var index)
-            ? new PlaylistRef(index)
-            : new PlaylistRef(value);
+        if (TryParse(value, out var playlistRef))
+            return playlistRef;
+
+        throw new ArgumentException($"Invalid playlist reference '{value}'.", nameof(value));
+    }
+
+    /// <summary>
+    /// Tries to create <see cref="PlaylistRef"/> from string representation.
+    /// </summary>
+    /// <param name="value">String representation of playlist reference.</param>
+    /// <param name="playlistRef">Parsed value.</param>
+    /// <returns>Parsed value of <paramref name="value"/>.</returns>
+    public static bool TryParse(string? value, out PlaylistRef playlistRef)
+    {
+        if (int.TryParse(value, NumberStyles.Integer, CultureInfo.InvariantCulture, out var index))
+        {
+            if (index < 0)
+            {
+                playlistRef = default;
+                return false;
+            }
+
+            playlistRef = new PlaylistRef(false, index);
+            return true;
+        }
+
+        if (value != null && ArgumentValidator.IdMatcher().IsMatch(value))
+        {
+            playlistRef = new PlaylistRef(false, value);
+            return true;
+        }
+
+        playlistRef = default;
+        return false;
     }
 
     /// <inheritdoc />

src/CommandLineTool/Services/Extensions.cs

@@ -36,7 +36,7 @@ public static PlaylistInfo Get(this IList<PlaylistInfo> playlists, string playli
         {
             if (!zeroBasedIndices && playlistRef == "0")
             {
-                throw new InvalidRequestException("Playlist index (0) is out of range.");
+                throw IndexIsOutOfRange();
             }
 
             return playlists.FirstOrDefault(p => p.Id == playlistRef) ??
@@ -46,10 +46,15 @@ public static PlaylistInfo Get(this IList<PlaylistInfo> playlists, string playli
         var realIndex = index.GetOffsetInclusive(playlists.Count);
         if (realIndex < 0 || realIndex >= playlists.Count)
         {
-            throw new InvalidRequestException($"Playlist index ({playlistRef}) is out of range.");
+            throw IndexIsOutOfRange();
         }
 
         return playlists[realIndex];
+
+        InvalidRequestException IndexIsOutOfRange()
+        {
+            return new InvalidRequestException($"Playlist index ({playlistRef}) is out of range.");
+        }
     }
 
     public static IEnumerable<int> GetItems(this Range range, int totalCount)

tests/Client.Tests/PlaylistRefTests.cs

@@ -18,4 +18,24 @@ public void ShouldParse()
         PlaylistRef.Parse("123").Should().Be(new PlaylistRef(123));
         PlaylistRef.Parse("p321").Should().Be(new PlaylistRef("p321"));
     }
+
+    [Fact]
+    public void ShouldTryParse()
+    {
+        PlaylistRef.TryParse("p1", out var pl).Should().BeTrue();
+        pl.Should().Be(new PlaylistRef("p1"));
+
+        PlaylistRef.TryParse("current", out pl).Should().BeTrue();
+        pl.Should().Be(PlaylistRef.Current);
+
+        PlaylistRef.TryParse("0", out pl).Should().BeTrue();
+        pl.Should().Be(new PlaylistRef(0));
+
+        PlaylistRef.TryParse("1", out pl).Should().BeTrue();
+        pl.Should().Be(new PlaylistRef(1));
+
+        PlaylistRef.TryParse("", out _).Should().BeFalse();
+        PlaylistRef.TryParse("-1", out _).Should().BeFalse();
+        PlaylistRef.TryParse("invalid?", out _).Should().BeFalse();
+    }
 }