using System;
using System.IO;
using System.Runtime.InteropServices;

namespace FlashExtractor
{
	/// <summary>
	/// Summary description for Class1.
	/// </summary>
	class Class1
	{
		/// <summary>
		/// The main entry point for the application.
		/// </summary>
		[STAThread]
		static void Main(string[] args)
		{
			//assume param 1 is the location of the shockwave file
			byte[] file = new byte[Marshal.SizeOf(typeof(swf))];

			FileStream fs = File.Open(args[0], FileMode.Open, FileAccess.Read,FileShare.Read);
			int i=0;
			//go through the file byte by byte 
			//could I have seeked this?
			while (i<fs.Length-8)
			{
				//set the position in the file
				fs.Position = i;
				//read off 8 bytes worth of data to put into the swf struct
				fs.Read(file,0, 8);
				IntPtr ptr = Marshal.AllocHGlobal(file.Length);
				Marshal.Copy(file, 0x0, ptr, file.Length);
				swf s = (swf) Marshal.PtrToStructure(ptr, typeof(swf));

				// if the struct header is FWS then we may have a flash file
				if (s.header1==0x46 && s.header2==0x57 && s.header3==0x53)
				{
					//we have the identity of a flash file
					Console.WriteLine("Found the header of a flash file");
					Console.WriteLine("Version: {0}", s.version);
					Console.WriteLine("Size: {0}", s.size);

					//if the size of the fws is < length of the file
					if (s.size + i<=fs.Length)
					{
						Console.WriteLine("Attempting to write the file to {0}", args[1]);
						FileStream fw = File.OpenWrite(args[1]);
						
						Console.WriteLine("Allocation byte array of {0} length", s.size);
						byte[] b=new byte[s.size];
						
						Console.WriteLine("Reseting the file back to position: {0}", i);
						fs.Position = i;
						
						Console.WriteLine("Reading from {0} to {1}", i, s.size);
						fs.Read(b,0,(int)s.size);

						Console.WriteLine("Writing byte array back to disk");
						fw.Write(b, 0, b.Length);

						fw.Close();
						break;
					}
					else
					{
						Console.WriteLine("The file is not of the correct size file: {0}, {1}", s.size, fs.Length);
					}

				}
				i++;
			}
			fs.Close();

		
		}
	
	}
	
	[StructLayout (LayoutKind.Sequential, Pack = 0x1)]
	struct swf
	{
		public byte header1;
		public byte header2;
		public byte header3;
		public byte version;
		public UInt32 size;
	}
}