1 files changed, 70 insertions, 0 deletions
diff --git a/src/SMAPI.ModBuildConfig/BuildTasks/ValidateInstallTask.cs b/src/SMAPI.ModBuildConfig/BuildTasks/ValidateInstallTask.cs
new file mode 100644
index 00000000..2cc7dc9c
--- /dev/null
+++ b/src/SMAPI.ModBuildConfig/BuildTasks/ValidateInstallTask.cs
@@ -0,0 +1,70 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using Microsoft.Build.Framework;
+using Microsoft.Build.Utilities;
+using StardewModdingAPI.ModBuildConfig.Framework;
+
+namespace StardewModdingAPI.ModBuildConfig.BuildTasks
+{
+    /// <summary>A build task which validates the install context.</summary>
+    public class ValidateInstallTask : Task
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <summary>The MSBuild platforms recognised by the build configuration.</summary>
+        private readonly HashSet<string> ValidPlatforms = new HashSet<string>(new[] { "OSX", "Unix", "Windows_NT" }, StringComparer.InvariantCultureIgnoreCase);
+
+        /// <summary>The name of the game's main executable file.</summary>
+        private string GameExeName => this.Platform == "Windows_NT"
+            ? "Stardew Valley.exe"
+            : "StardewValley.exe";
+
+        /// <summary>The name of SMAPI's main executable file.</summary>
+        private readonly string SmapiExeName = "StardewModdingAPI.exe";
+
+
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>The folder containing the game files.</summary>
+        public string GameDir { get; set; }
+
+        /// <summary>The MSBuild OS value.</summary>
+        public string Platform { get; set; }
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>When overridden in a derived class, executes the task.</summary>
+        /// <returns>true if the task successfully executed; otherwise, false.</returns>
+        public override bool Execute()
+        {
+            try
+            {
+                if (!this.ValidPlatforms.Contains(this.Platform))
+                    throw new UserErrorException($"The mod build package doesn't recognise OS type '{this.Platform}'.");
+                if (!Directory.Exists(this.GameDir))
+                    throw new UserErrorException("The mod build package can't find your game path. See https://github.com/Pathoschild/SMAPI/blob/develop/docs/mod-build-config.md for help specifying it.");
+                if (!File.Exists(Path.Combine(this.GameDir, this.GameExeName)))
+                    throw new UserErrorException($"The mod build package found a game folder at {this.GameDir}, but it doesn't contain the {this.GameExeName} file. If this folder is invalid, delete it and the package will autodetect another game install path.");
+                if (!File.Exists(Path.Combine(this.GameDir, this.SmapiExeName)))
+                    throw new UserErrorException($"The mod build package found a game folder at {this.GameDir}, but it doesn't contain SMAPI. You need to install SMAPI before building the mod.");
+
+                return true;
+            }
+            catch (UserErrorException ex)
+            {
+                this.Log.LogErrorFromException(ex);
+                return false;
+            }
+            catch (Exception ex)
+            {
+                this.Log.LogError($"The mod build package failed trying to deploy the mod.\n{ex}");
+                return false;
+            }
+        }
+    }
+}