Add Epic Games Store finder

Author: 0x0ade

Everest.Installer.csproj

@@ -84,6 +84,7 @@
     <Compile Include="src\CustomControls\CustomTextBox.cs">
       <SubType>Component</SubType>
     </Compile>
+    <Compile Include="src\Finders\EpicFinder.cs" />
     <Compile Include="src\Finders\LocalFinder.cs" />
     <Compile Include="src\Infos\EverestInfo.Installer.cs" />
     <Compile Include="src\ProgressShapes.cs" />

Properties/AssemblyInfo.cs

@@ -34,5 +34,5 @@
 // You can specify all the values or you can default the Build and Revision Numbers 
 // by using the '*' as shown below:
 // [assembly: AssemblyVersion("1.0.*")]
-[assembly: AssemblyVersion("19.03.0.*")]
+[assembly: AssemblyVersion("19.08.0.*")]
 [assembly: AssemblyFileVersion("1.0.0.0")]

src/Finders/EpicFinder.cs

@@ -0,0 +1,71 @@
+using Microsoft.Win32;
+using MonoMod.Utils;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text;
+using System.Text.RegularExpressions;
+
+namespace MonoMod.Installer {
+    public class EpicFinder : GameFinder {
+
+        // "" -> "
+        public readonly static Regex DisplayNameRegex = new Regex(@"\s*""DisplayName"": ""(.*)"",", RegexOptions.Compiled);
+        public readonly static Regex InstallLocationRegex = new Regex(@"\s*""InstallLocation"": ""(.*)"",", RegexOptions.Compiled);
+
+        public override string ID => "epic";
+
+        public override string FindGameDir(string gameid) {
+            if ((PlatformHelper.Current & Platform.Windows) != Platform.Windows)
+                return null;
+
+            string regKey =
+                (PlatformHelper.Current & Platform.X64) == Platform.X64 ?
+                @"HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Epic Games\EpicGamesLauncher" :
+                @"HKEY_LOCAL_MACHINE\SOFTWARE\Epic Games\EpicGamesLauncher";
+            // Win32 is case-insensitive.
+            string appdata = (string) Registry.GetValue(regKey, "AppDataPath", null);
+            if (!Directory.Exists(appdata))
+                return null;
+
+            // path ends up pointing to f.e. C:\ProgramData\Epic\EpicGamesLauncher\Data\
+            // Manifest .item (pretty much .json) files are stored in the Manifests subdir.
+            // The filenames sadly aren't consistent across machines / accounts,
+            // meaning that we'll need to crawl through them to find the right one.
+
+            string manifests = Path.Combine(appdata, "Manifests");
+            if (!Directory.Exists(manifests))
+                return null;
+
+            foreach (string manifest in Directory.GetFiles(manifests)) {
+                if (!manifest.EndsWith(".item", StringComparison.InvariantCultureIgnoreCase))
+                    continue;
+
+                string displayName = null;
+                string installLocation = null;
+
+                using (StreamReader reader = new StreamReader(manifest))
+                    while (!reader.EndOfStream) {
+                        string line = reader.ReadLine().Trim();
+                        Match match;
+                        
+                        match = DisplayNameRegex.Match(line);
+                        if (match.Success)
+                            displayName = Regex.Unescape(match.Groups[1].Value);
+
+                        match = InstallLocationRegex.Match(line);
+                        if (match.Success)
+                            installLocation = Regex.Unescape(match.Groups[1].Value);
+                    }
+
+                if (!string.IsNullOrEmpty(displayName) && gameid.Equals(displayName, StringComparison.InvariantCultureIgnoreCase) &&
+                    !string.IsNullOrEmpty(installLocation) && Directory.Exists(installLocation))
+                    return installLocation;
+            }
+
+            return null;
+        }
+
+    }
+}

src/Infos/EverestInfo.cs

@@ -77,7 +77,8 @@ public override Dictionary<string, string> GameIDs {
             get {
                 return new Dictionary<string, string>() {
                     { "local", "Celeste.exe" },
-                    { "steam", "Celeste" }
+                    { "steam", "Celeste" },
+                    { "epic", "Celeste" }
                 };
             }
         }