From 7015e4ee8777c4a1c3934c1f3e9c3ceefcc1295d Mon Sep 17 00:00:00 2001
From: Jesse Plamondon-Willard <github@jplamondonw.com>
Date: Thu, 15 Mar 2018 20:58:43 -0400
Subject: show prerelease SMAPI updates when updating from an older prerelease
 of the same version (#457)

---
 src/SMAPI/Program.cs | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

(limited to 'src')

diff --git a/src/SMAPI/Program.cs b/src/SMAPI/Program.cs
index 4bd40710..e4b279f7 100644
--- a/src/SMAPI/Program.cs
+++ b/src/SMAPI/Program.cs
@@ -541,8 +541,10 @@ namespace StardewModdingAPI
                         this.Monitor.Log("Couldn't check for a new version of SMAPI. This won't affect your game, but you may not be notified of new versions if this keeps happening.", LogLevel.Warn);
                         this.Monitor.Log($"Error: {response.Error}");
                     }
-                    else if (new SemanticVersion(response.Version).IsNewerThan(Constants.ApiVersion))
+                    else if (this.IsValidUpdate(Constants.ApiVersion, new SemanticVersion(response.Version)))
                         this.Monitor.Log($"You can update SMAPI to {response.Version}: {response.Url}", LogLevel.Alert);
+                    else if (response.PreviewVersion != null && this.IsValidUpdate(Constants.ApiVersion, new SemanticVersion(response.PreviewVersion)))
+                        this.Monitor.Log($"You can update SMAPI to {response.PreviewVersion}: {response.Url}", LogLevel.Alert);
                     else
                         this.Monitor.Log("   SMAPI okay.", LogLevel.Trace);
                 }
@@ -656,6 +658,27 @@ namespace StardewModdingAPI
             }).Start();
         }
 
+        /// <summary>Get whether a given version should be offered to the user as an update.</summary>
+        /// <param name="currentVersion">The current semantic version.</param>
+        /// <param name="newVersion">The target semantic version.</param>
+        private bool IsValidUpdate(ISemanticVersion currentVersion, ISemanticVersion newVersion)
+        {
+            // basic eligibility
+            bool isNewer = newVersion.IsNewerThan(currentVersion);
+            bool isPrerelease = newVersion.Build != null;
+            bool isEquallyStable = !isPrerelease || currentVersion.Build != null; // don't update stable => prerelease
+            if (!isNewer || !isEquallyStable)
+                return false;
+            if (!isPrerelease)
+                return true;
+
+            // prerelease eligible if same version (excluding prerelease tag)
+            return
+                newVersion.MajorVersion == currentVersion.MajorVersion
+                && newVersion.MinorVersion == currentVersion.MinorVersion
+                && newVersion.PatchVersion == currentVersion.PatchVersion;
+        }
+
         /// <summary>Create a directory path if it doesn't exist.</summary>
         /// <param name="path">The directory path.</param>
         private void VerifyPath(string path)
-- 
cgit