add smapi.io shortcut URLs (#375)

1 files changed, 61 insertions, 0 deletions

diff --git a/src/SMAPI.Web/Framework/RewriteRules/RedirectToUrlRule.cs b/src/SMAPI.Web/Framework/RewriteRules/RedirectToUrlRule.cs
new file mode 100644
index 00000000..0719e311
--- /dev/null
+++ b/src/SMAPI.Web/Framework/RewriteRules/RedirectToUrlRule.cs
@@ -0,0 +1,61 @@
+using System;
+using System.Net;
+using System.Text.RegularExpressions;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Rewrite;
+
+namespace StardewModdingAPI.Web.Framework.RewriteRules
+{
+    /// <summary>Redirect requests to an external URL if they match a condition.</summary>
+    internal class RedirectToUrlRule : IRule
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <summary>A predicate which indicates when the rule should be applied.</summary>
+        private readonly Func<HttpRequest, bool> ShouldRewrite;
+
+        /// <summary>The new URL to which to redirect.</summary>
+        private readonly string NewUrl;
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="shouldRewrite">A predicate which indicates when the rule should be applied.</param>
+        /// <param name="url">The new URL to which to redirect.</param>
+        public RedirectToUrlRule(Func<HttpRequest, bool> shouldRewrite, string url)
+        {
+            this.ShouldRewrite = shouldRewrite ?? (req => true);
+            this.NewUrl = url;
+        }
+
+        /// <summary>Construct an instance.</summary>
+        /// <param name="pathRegex">A case-insensitive regex to match against the path.</param>
+        /// <param name="url">The external URL.</param>
+        public RedirectToUrlRule(string pathRegex, string url)
+        {
+            Regex regex = new Regex(pathRegex, RegexOptions.IgnoreCase | RegexOptions.Compiled);
+            this.ShouldRewrite = req => req.Path.HasValue && regex.IsMatch(req.Path.Value);
+            this.NewUrl = url;
+        }
+
+        /// <summary>Applies the rule. Implementations of ApplyRule should set the value for <see cref="RewriteContext.Result" /> (defaults to RuleResult.ContinueRules).</summary>
+        /// <param name="context">The rewrite context.</param>
+        public void ApplyRule(RewriteContext context)
+        {
+            HttpRequest request = context.HttpContext.Request;
+
+            // check condition
+            if (!this.ShouldRewrite(request))
+                return;
+
+            // redirect request
+            HttpResponse response = context.HttpContext.Response;
+            response.StatusCode = (int)HttpStatusCode.Redirect;
+            response.Headers["Location"] = this.NewUrl;
+            context.Result = RuleResult.EndResponse;
+        }
+    }
+}