From 7ee9d3637ce228ba7f3047bf46ea134a081190b3 Mon Sep 17 00:00:00 2001
From: Oliver Booth <me@olivr.me>
Date: Tue, 15 Aug 2023 17:04:43 +0100
Subject: [PATCH] feat: add support for template variants

---
 .../Configuration/TemplateConfiguration.cs    |  5 ++-
 OliverBooth/Data/Web/ITemplate.cs             |  8 +++-
 OliverBooth/Data/Web/Template.cs              |  9 +++--
 .../Markdown/Template/TemplateInline.cs       |  6 +++
 .../Markdown/Template/TemplateInlineParser.cs | 14 +++++++
 OliverBooth/Services/ITemplateService.cs      | 25 ++++++++++++
 OliverBooth/Services/TemplateService.cs       | 40 ++++++++++++++-----
 7 files changed, 92 insertions(+), 15 deletions(-)

diff --git a/OliverBooth/Data/Web/Configuration/TemplateConfiguration.cs b/OliverBooth/Data/Web/Configuration/TemplateConfiguration.cs
index 9cf5d8b..512b5ab 100644
--- a/OliverBooth/Data/Web/Configuration/TemplateConfiguration.cs
+++ b/OliverBooth/Data/Web/Configuration/TemplateConfiguration.cs
@@ -11,9 +11,10 @@ internal sealed class TemplateConfiguration : IEntityTypeConfiguration<Template>
     public void Configure(EntityTypeBuilder<Template> builder)
     {
         builder.ToTable("Template");
-        builder.HasKey(e => e.Name);
+        builder.HasKey(e => new { e.Name, e.Variant });
 
-        builder.Property(e => e.Name).IsRequired();
+        builder.Property(e => e.Name).HasMaxLength(50).IsRequired();
+        builder.Property(e => e.Variant).HasMaxLength(50).IsRequired();
         builder.Property(e => e.FormatString).IsRequired();
     }
 }
diff --git a/OliverBooth/Data/Web/ITemplate.cs b/OliverBooth/Data/Web/ITemplate.cs
index 25c0e21..50ad893 100644
--- a/OliverBooth/Data/Web/ITemplate.cs
+++ b/OliverBooth/Data/Web/ITemplate.cs
@@ -1,4 +1,4 @@
-namespace OliverBooth.Data;
+namespace OliverBooth.Data.Web;
 
 /// <summary>
 ///     Represents a template.
@@ -15,4 +15,10 @@ public interface ITemplate
     ///     Gets the name of the template.
     /// </summary>
     string Name { get; }
+
+    /// <summary>
+    ///     Gets the variant of the template.
+    /// </summary>
+    /// <value>The variant of the template.</value>
+    string Variant { get; }
 }
diff --git a/OliverBooth/Data/Web/Template.cs b/OliverBooth/Data/Web/Template.cs
index 74347e4..cf029a1 100644
--- a/OliverBooth/Data/Web/Template.cs
+++ b/OliverBooth/Data/Web/Template.cs
@@ -11,6 +11,9 @@ public sealed class Template : ITemplate, IEquatable<Template>
     /// <inheritdoc />
     public string Name { get; private set; } = string.Empty;
 
+    /// <inheritdoc />
+    public string Variant { get; private set; } = string.Empty;
+
     /// <summary>
     ///     Returns a value indicating whether two instances of <see cref="Template" /> are equal.
     /// </summary>
@@ -46,7 +49,7 @@ public sealed class Template : ITemplate, IEquatable<Template>
     {
         if (ReferenceEquals(null, other)) return false;
         if (ReferenceEquals(this, other)) return true;
-        return Name == other.Name;
+        return Name == other.Name && Variant == other.Variant;
     }
 
     /// <summary>
@@ -68,7 +71,7 @@ public sealed class Template : ITemplate, IEquatable<Template>
     /// <returns>The hash code.</returns>
     public override int GetHashCode()
     {
-        // ReSharper disable once NonReadonlyMemberInGetHashCode
-        return Name.GetHashCode();
+        // ReSharper disable NonReadonlyMemberInGetHashCode
+        return HashCode.Combine(Name, Variant);
     }
 }
diff --git a/OliverBooth/Markdown/Template/TemplateInline.cs b/OliverBooth/Markdown/Template/TemplateInline.cs
index 34be9ad..a50f3b8 100644
--- a/OliverBooth/Markdown/Template/TemplateInline.cs
+++ b/OliverBooth/Markdown/Template/TemplateInline.cs
@@ -30,4 +30,10 @@ public sealed class TemplateInline : Inline
     /// </summary>
     /// <value>The template parameters.</value>
     public IReadOnlyDictionary<string, string> Params { get; set; } = null!;
+
+    /// <summary>
+    ///     Gets the variant of the template.
+    /// </summary>
+    /// <value>The variant of the template.</value>
+    public string Variant { get; set; } = string.Empty;
 }
diff --git a/OliverBooth/Markdown/Template/TemplateInlineParser.cs b/OliverBooth/Markdown/Template/TemplateInlineParser.cs
index 283ae49..b96907f 100644
--- a/OliverBooth/Markdown/Template/TemplateInlineParser.cs
+++ b/OliverBooth/Markdown/Template/TemplateInlineParser.cs
@@ -1,6 +1,7 @@
 using Cysharp.Text;
 using Markdig.Helpers;
 using Markdig.Parsers;
+using Serilog;
 
 namespace OliverBooth.Markdown.Template;
 
@@ -37,11 +38,23 @@ public sealed class TemplateInlineParser : InlineParser
 
         template = template[2..^2]; // trim {{ and }}
         ReadOnlySpan<char> name = ReadTemplateName(template, out ReadOnlySpan<char> argumentSpan);
+        int variantIndex = name.IndexOf(':');
+        bool hasVariant = variantIndex > -1;
+        var variant = ReadOnlySpan<char>.Empty;
+
+        if (hasVariant)
+        {
+            Log.Debug("Index of variant: {Index}", variantIndex);
+            variant = name[(variantIndex + 1)..];
+            name = name[..variantIndex];
+        }
+
         if (argumentSpan.IsEmpty)
         {
             processor.Inline = new TemplateInline
             {
                 Name = name.ToString(),
+                Variant = hasVariant ? variant.ToString() : string.Empty,
                 ArgumentString = string.Empty,
                 ArgumentList = ArraySegment<string>.Empty,
                 Params = EmptyParams
@@ -60,6 +73,7 @@ public sealed class TemplateInlineParser : InlineParser
         processor.Inline = new TemplateInline
         {
             Name = name.ToString(),
+            Variant = hasVariant ? variant.ToString() : string.Empty,
             ArgumentString = argumentSpan.ToString(),
             ArgumentList = argumentList.AsReadOnly(),
             Params = paramsList.AsReadOnly()
diff --git a/OliverBooth/Services/ITemplateService.cs b/OliverBooth/Services/ITemplateService.cs
index 77e2e0d..82202fa 100644
--- a/OliverBooth/Services/ITemplateService.cs
+++ b/OliverBooth/Services/ITemplateService.cs
@@ -1,4 +1,6 @@
+using System.Diagnostics.CodeAnalysis;
 using OliverBooth.Data;
+using OliverBooth.Data.Web;
 using OliverBooth.Markdown.Template;
 
 namespace OliverBooth.Services;
@@ -28,4 +30,27 @@ public interface ITemplateService
     ///     <paramref name="templateInline" /> is <see langword="null" />.
     /// </exception>
     string RenderTemplate(TemplateInline templateInline, ITemplate? template);
+
+    /// <summary>
+    ///     Attempts to get the template with the specified name.
+    /// </summary>
+    /// <param name="name">The name of the template.</param>
+    /// <param name="template">
+    ///     When this method returns, contains the template with the specified name, if the template is found;
+    ///     otherwise, <see langword="null" />.
+    /// </param>
+    /// <returns><see langword="true" /> if the template exists; otherwise, <see langword="false" />.</returns>
+    bool TryGetTemplate(string name, [NotNullWhen(true)] out ITemplate? template);
+
+    /// <summary>
+    ///     Attempts to get the template with the specified name and variant.
+    /// </summary>
+    /// <param name="name">The name of the template.</param>
+    /// <param name="variant">The variant of the template.</param>
+    /// <param name="template">
+    ///     When this method returns, contains the template with the specified name and variant, if the template is
+    ///     found; otherwise, <see langword="null" />.
+    /// </param>
+    /// <returns><see langword="true" /> if the template exists; otherwise, <see langword="false" />.</returns>
+    bool TryGetTemplate(string name, string variant, [NotNullWhen(true)] out ITemplate? template);
 }
diff --git a/OliverBooth/Services/TemplateService.cs b/OliverBooth/Services/TemplateService.cs
index d8668d6..dd7cbb8 100644
--- a/OliverBooth/Services/TemplateService.cs
+++ b/OliverBooth/Services/TemplateService.cs
@@ -1,4 +1,5 @@
 using System.Buffers.Binary;
+using System.Diagnostics.CodeAnalysis;
 using Microsoft.EntityFrameworkCore;
 using OliverBooth.Data;
 using OliverBooth.Data.Web;
@@ -40,17 +41,17 @@ internal sealed class TemplateService : ITemplateService
     {
         if (templateInline is null) throw new ArgumentNullException(nameof(templateInline));
 
-        using WebContext context = _webContextFactory.CreateDbContext();
-        Template? template = context.Templates.Find(templateInline.Name);
-        return RenderTemplate(templateInline, template);
+        return TryGetTemplate(templateInline.Name, templateInline.Variant, out ITemplate? template)
+            ? RenderTemplate(templateInline, template)
+            : GetDefaultRender(templateInline);
     }
 
     /// <inheritdoc />
-    public string RenderTemplate(TemplateInline inline, ITemplate? template)
+    public string RenderTemplate(TemplateInline templateInline, ITemplate? template)
     {
         if (template is null)
         {
-            return $"{{{{{inline.Name}}}}}";
+            return GetDefaultRender(templateInline);
         }
 
         Span<byte> randomBytes = stackalloc byte[20];
@@ -58,9 +59,9 @@ internal sealed class TemplateService : ITemplateService
 
         var formatted = new
         {
-            inline.ArgumentList,
-            inline.ArgumentString,
-            inline.Params,
+            templateInline.ArgumentList,
+            templateInline.ArgumentString,
+            templateInline.Params,
             RandomInt = BinaryPrimitives.ReadInt32LittleEndian(randomBytes[..4]),
             RandomGuid = new Guid(randomBytes[4..]).ToString("N"),
         };
@@ -71,7 +72,28 @@ internal sealed class TemplateService : ITemplateService
         }
         catch
         {
-            return $"{{{{{inline.Name}|{inline.ArgumentString}}}}}";
+            return GetDefaultRender(templateInline);
         }
     }
+
+    /// <inheritdoc />
+    public bool TryGetTemplate(string name, [NotNullWhen(true)] out ITemplate? template)
+    {
+        return TryGetTemplate(name, string.Empty, out template);
+    }
+
+    /// <inheritdoc />
+    public bool TryGetTemplate(string name, string variant, [NotNullWhen(true)] out ITemplate? template)
+    {
+        using WebContext context = _webContextFactory.CreateDbContext();
+        template = context.Templates.FirstOrDefault(t => t.Name == name && t.Variant == variant);
+        return template is not null;
+    }
+
+    private static string GetDefaultRender(TemplateInline templateInline)
+    {
+        return string.IsNullOrWhiteSpace(templateInline.ArgumentString)
+            ? $"{{{{{templateInline.Name}}}}}"
+            : $"{{{{{templateInline.Name}|{templateInline.ArgumentString}}}}}";
+    }
 }