add extremely basic support for opening files in more modes then reading

The "storage path" idea needs to be fleshed out quite a lot more still.
Ideally it should be pointing to OS-specific application-writeable
locations (e.g. ~/Library/Application Support/$APP_NAME/)

Blarg.GameFramework.SDL2/IO/SDLFileSystem.cs

@@ -7,51 +7,65 @@ namespace Blarg.GameFramework.IO
 {
 	public class SDLFileSystem : IFileSystem
 	{
-		string _assetsPath;
+		ILogger _logger;
+
+		public string AssetsPath { get; private set; }
+		public string StoragePath { get; private set; }
 
 		public SDLFileSystem(ILogger logger)
+		{
+			_logger = logger;
+
+			AssetsPath = GetAssetsPath();
+			StoragePath = GetStoragePath();
+
+			if (!Directory.Exists(AssetsPath))
+				logger.Warn("SDL_FILESYSTEM", "Attempting to use assets directory {0} which doesn't exist.", AssetsPath);
+		}
+
+		public Stream Open(string filename, FileOpenMode mode)
+		{
+			string realPath = TranslateFilePath(filename);
+			return new FileStream(realPath, (FileMode)mode);
+		}
+
+		public string TranslateFilePath(string path)
+		{
+			if (path.StartsWith("assets://"))
+				return Path.Combine(AssetsPath, path.Substring(9));
+			else if (path.StartsWith("storage://"))
+				return Path.Combine(StoragePath, path.Substring(10));
+			else
+				return path;
+		}
+
+		private string GetAssetsPath()
 		{
 			string envAssetsPath = Environment.GetEnvironmentVariable("ASSETS_DIR");
 			string workingDirPath = Path.Combine(Environment.CurrentDirectory, "assets");
 
 			if (!String.IsNullOrEmpty(envAssetsPath))
 			{
-				logger.Info("SDL_FILESYSTEM", "Environment variable ASSETS_DIR value found.");
-				_assetsPath = envAssetsPath;
+				_logger.Info("SDL_FILESYSTEM", "Environment variable ASSETS_DIR value found.");
+				return envAssetsPath;
 			}
 			else if (Directory.Exists(workingDirPath))
 			{
-				logger.Info("SDL_FILESYSTEM", "'Assets' found under the current working directory.");
-				_assetsPath = workingDirPath;
+				_logger.Info("SDL_FILESYSTEM", "'Assets' found under the current working directory.");
+				return workingDirPath;
 			}
 			else
 			{
 				// fallback to the default otherwise
-				logger.Info("SDL_FILESYSTEM", "Assuming 'Assets' directory located next to application executable.");
-				_assetsPath = Path.Combine(Path.GetDirectoryName(Assembly.GetEntryAssembly().Location), "assets");
+				_logger.Info("SDL_FILESYSTEM", "Assuming 'Assets' directory located next to application executable.");
+				return Path.Combine(Path.GetDirectoryName(Assembly.GetEntryAssembly().Location), "assets");
 			}
-
-			if (!Directory.Exists(_assetsPath))
-				logger.Warn("SDL_FILESYSTEM", "Attempting to use assets directory {0} which doesn't exist.", _assetsPath);
 		}
 
-		public Stream Open(string filename)
+		private string GetStoragePath()
 		{
-			string realPath = TranslateFilePath(filename);
-			return new FileStream(realPath, FileMode.Open);
-		}
-
-		public string TranslateFilePath(string path)
-		{
-			if (path.StartsWith("assets://"))
-				return Path.Combine(_assetsPath, path.Substring(9));
-			else
-				return path;
-		}
-
-		public string AssetsPath
-		{
-			get { return _assetsPath; }
+			// TODO: set a proper path
+			return Path.GetDirectoryName(Assembly.GetEntryAssembly().Location);
 		}
 	}
 }

Blarg.GameFramework/Blarg.GameFramework.csproj

@@ -221,6 +221,7 @@
     <Compile Include="TileMap\TileDataSerializer.cs" />
     <Compile Include="TileMap\Json\JsonTileMap.cs" />
     <Compile Include="TileMap\Json\TileMapLoader.cs" />
+    <Compile Include="IO\FileOpenMode.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildExtensionsPath32)\Microsoft\Portable\$(TargetFrameworkVersion)\Microsoft.Portable.CSharp.targets" />
   <ItemGroup>

Blarg.GameFramework/IO/FileOpenMode.cs

@@ -0,0 +1,14 @@
+using System;
+
+namespace Blarg.GameFramework.IO
+{
+	public enum FileOpenMode
+	{
+		CreateNew = 1,
+		Create,
+		Open,
+		OpenOrCreate,
+		Truncate,
+		Append
+	}
+}

Blarg.GameFramework/IO/IFileSystem.cs

@@ -5,9 +5,10 @@ namespace Blarg.GameFramework.IO
 {
 	public interface IFileSystem
 	{
-		Stream Open(string filename);
+		Stream Open(string filename, FileOpenMode mode = FileOpenMode.Open);
 		string TranslateFilePath(string path);
 
 		string AssetsPath { get; }
+		string StoragePath { get; }
 	}
 }