move validation logic out of Manifest model

This avoids tightly coupling higher logic to the implementation class, since we can validate the interface.

1 files changed, 101 insertions, 0 deletions

diff --git a/src/SMAPI.Toolkit/Framework/ManifestValidator.cs b/src/SMAPI.Toolkit/Framework/ManifestValidator.cs
new file mode 100644
index 00000000..62cfd8e9
--- /dev/null
+++ b/src/SMAPI.Toolkit/Framework/ManifestValidator.cs
@@ -0,0 +1,101 @@
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using StardewModdingAPI.Toolkit.Utilities;
+
+namespace StardewModdingAPI.Toolkit.Framework
+{
+    /// <summary>Validates manifest fields.</summary>
+    public static class ManifestValidator
+    {
+        /// <summary>Try to validate a manifest's fields. Fails if any invalid field is found.</summary>
+        /// <param name="manifest">The manifest to validate.</param>
+        /// <param name="error">The error message to display to the user.</param>
+        /// <returns>Returns whether the manifest was validated successfully.</returns>
+        public static bool TryValidate(IManifest manifest, out string error)
+        {
+            // validate DLL / content pack fields
+            bool hasDll = !string.IsNullOrWhiteSpace(manifest.EntryDll);
+            bool isContentPack = manifest.ContentPackFor != null;
+
+            // validate field presence
+            if (!hasDll && !isContentPack)
+            {
+                error = $"manifest has no {nameof(IManifest.EntryDll)} or {nameof(IManifest.ContentPackFor)} field; must specify one.";
+                return false;
+            }
+            if (hasDll && isContentPack)
+            {
+                error = $"manifest sets both {nameof(IManifest.EntryDll)} and {nameof(IManifest.ContentPackFor)}, which are mutually exclusive.";
+                return false;
+            }
+
+            // validate DLL filename format
+            if (hasDll && manifest.EntryDll!.Intersect(Path.GetInvalidFileNameChars()).Any())
+            {
+                error = $"manifest has invalid filename '{manifest.EntryDll}' for the EntryDLL field.";
+                return false;
+            }
+
+            // validate content pack ID
+            else if (isContentPack && string.IsNullOrWhiteSpace(manifest.ContentPackFor!.UniqueID))
+            {
+                error = $"manifest declares {nameof(IManifest.ContentPackFor)} without its required {nameof(IManifestContentPackFor.UniqueID)} field.";
+                return false;
+            }
+
+            // validate required fields
+            {
+                List<string> missingFields = new List<string>(3);
+
+                if (string.IsNullOrWhiteSpace(manifest.Name))
+                    missingFields.Add(nameof(IManifest.Name));
+                if (manifest.Version == null || manifest.Version.ToString() == "0.0.0")
+                    missingFields.Add(nameof(IManifest.Version));
+                if (string.IsNullOrWhiteSpace(manifest.UniqueID))
+                    missingFields.Add(nameof(IManifest.UniqueID));
+
+                if (missingFields.Any())
+                {
+                    error = $"manifest is missing required fields ({string.Join(", ", missingFields)}).";
+                    return false;
+                }
+            }
+
+            // validate ID format
+            if (!PathUtilities.IsSlug(manifest.UniqueID))
+            {
+                error = "manifest specifies an invalid ID (IDs must only contain letters, numbers, underscores, periods, or hyphens).";
+                return false;
+            }
+
+            // validate dependencies
+            foreach (IManifestDependency? dependency in manifest.Dependencies)
+            {
+                // null dependency
+                if (dependency == null)
+                {
+                    error = $"manifest has a null entry under {nameof(IManifest.Dependencies)}.";
+                    return false;
+                }
+
+                // missing ID
+                if (string.IsNullOrWhiteSpace(dependency.UniqueID))
+                {
+                    error = $"manifest has a {nameof(IManifest.Dependencies)} entry with no {nameof(IManifestDependency.UniqueID)} field.";
+                    return false;
+                }
+
+                // invalid ID
+                if (!PathUtilities.IsSlug(dependency.UniqueID))
+                {
+                    error = $"manifest has a {nameof(IManifest.Dependencies)} entry with an invalid {nameof(IManifestDependency.UniqueID)} field (IDs must only contain letters, numbers, underscores, periods, or hyphens).";
+                    return false;
+                }
+            }
+
+            error = "";
+            return true;
+        }
+    }
+}