client side of package downloader; incomplete

OpenRa.Game/PackageDownloader.cs

@@ -0,0 +1,73 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using OpenRa.FileFormats;
+using System.IO;
+using System.Security.Cryptography;
+
+namespace OpenRa.Game
+{
+	static class PackageDownloader
+	{
+		static string[] allPackages = { };
+		static List<string> missingPackages = new List<string>();
+		static string currentPackage = null;
+		static MemoryStream content = null;
+
+		public static void SetPackageList(string[] packages)
+		{
+			allPackages = packages;
+			missingPackages = allPackages.Where(p => !HavePackage(p)).ToList();
+
+			if (currentPackage == null || !missingPackages.Contains(currentPackage))
+				BeginDownload();
+		}
+
+		public static void ReceiveChunk(string data)
+		{
+			
+		}
+
+		static void BeginDownload()
+		{
+			if (missingPackages.Count == 0)
+			{	// we're finished downloading resources!
+				currentPackage = null;
+				return;
+			}
+
+			currentPackage = missingPackages[0];
+			missingPackages.RemoveAt(0);
+
+			content = new MemoryStream();
+		}
+
+		static void EndDownload()
+		{
+			File.WriteAllBytes(currentPackage.Split(':')[0], content.ToArray());
+			currentPackage = null;
+
+			BeginDownload();
+		}
+
+		public static bool IsIdle()
+		{
+			return currentPackage == null 
+				&& missingPackages.Count == 0;
+		}
+
+		static bool HavePackage(string p)
+		{
+			var parts = p.Split(':');
+			return File.Exists(parts[0]) && CalculateSHA1(parts[0]) == parts[1];
+		}
+
+		public static string CalculateSHA1(string filename)
+		{
+			using (var csp = SHA1.Create())
+				return new string(csp.ComputeHash(File.ReadAllBytes(filename))
+					.SelectMany(a => a.ToString("x2")).ToArray());
+		}
+	}
+}