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

namespace SqlServerTypes
{
	/// <summary>
	/// Utility methods related to CLR Types for SQL Server 
	/// </summary>
	public class Utilities
	{
		[DllImport("kernel32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
		private static extern IntPtr LoadLibrary(string libname);

		/// <summary>
		/// Loads the required native assemblies for the current architecture (x86 or x64)
		/// </summary>
		/// <param name="rootApplicationPath">
		/// Root path of the current application. Use Server.MapPath(".") for ASP.NET applications
		/// and AppDomain.CurrentDomain.BaseDirectory for desktop applications.
		/// </param>
		public static void LoadNativeAssemblies(string rootApplicationPath)
		{
			var nativeBinaryPath = IntPtr.Size > 4
				? Path.Combine(rootApplicationPath, @"SqlServerTypes\x64\")
				: Path.Combine(rootApplicationPath, @"SqlServerTypes\x86\");

			LoadNativeAssembly(nativeBinaryPath, "msvcr120.dll");
			LoadNativeAssembly(nativeBinaryPath, "SqlServerSpatial140.dll");
		}

		private static void LoadNativeAssembly(string nativeBinaryPath, string assemblyName)
		{
			var path = Path.Combine(nativeBinaryPath, assemblyName);
			var ptr = LoadLibrary(path);
			if (ptr == IntPtr.Zero)
			{
				throw new InvalidOperationException(string.Format(
					"Error loading {0} (ErrorCode: {1})",
					assemblyName,
					Marshal.GetLastWin32Error()));
			}
		}
	}
}
