Random book story generator refactor (#28082)

* Randomized book overhaul

* Fix prototype names

* Improved setting paper content

* Praise Ratvar

Content.Shared/StoryGen/EntitySystems/StoryGeneratorSystem.cs

@@ -0,0 +1,54 @@
+using System.Diagnostics.CodeAnalysis;
+using Robust.Shared.Collections;
+using Robust.Shared.Prototypes;
+using Robust.Shared.Random;
+
+namespace Content.Shared.StoryGen;
+
+/// <summary>
+/// Provides functionality to generate a story from a <see cref="StoryTemplatePrototype"/>.
+/// </summary>
+public sealed partial class StoryGeneratorSystem : EntitySystem
+{
+    [Dependency] private readonly IPrototypeManager _protoMan = default!;
+    [Dependency] private readonly IRobustRandom _random = default!;
+
+    /// <summary>
+    /// Tries to generate a random story using the given template, picking a random word from the referenced
+    /// datasets for each variable and passing them into the localization system with template.
+    /// If <paramref name="seed"/> is specified, the randomizer will be seeded with it for consistent story generation;
+    /// otherwise the variables will be randomized.
+    /// Fails if the template prototype cannot be loaded.
+    /// </summary>
+    /// <returns>true if the template was loaded, otherwise false.</returns>
+    public bool TryGenerateStoryFromTemplate(ProtoId<StoryTemplatePrototype> template, [NotNullWhen(true)] out string? story, int? seed = null)
+    {
+        // Get the story template prototype from the ID
+        if (!_protoMan.TryIndex(template, out var templateProto))
+        {
+            story = null;
+            return false;
+        }
+
+        // If given a seed, use it
+        if (seed != null)
+            _random.SetSeed(seed.Value);
+
+        // Pick values for all of the variables in the template
+        var variables = new ValueList<(string, object)>(templateProto.Variables.Count);
+        foreach (var (name, list) in templateProto.Variables)
+        {
+            // Get the prototype for the world list dataset
+            if (!_protoMan.TryIndex(list, out var listProto))
+                continue; // Missed one, but keep going with the rest of the story
+
+            // Pick a random word from the dataset and localize it
+            var chosenWord = Loc.GetString(_random.Pick(listProto.Values));
+            variables.Add((name, chosenWord));
+        }
+
+        // Pass the variables to the localization system and build the story
+        story = Loc.GetString(templateProto.LocId, variables.ToArray());
+        return true;
+    }
+}