using System;
using System.Collections;
using System.Reflection;
using Emergent.Gamebryo.SceneDesigner.PluginAPI;

namespace Emergent.Gamebryo.SceneDesigner.GUI.Utility
{
	/// <summary>
	/// Summary description for AssemblyUtilities.
	/// </summary>
	public class AssemblyUtilities
	{
		public AssemblyUtilities()
		{
		}

        public static bool CheckForInitAndShutDown(Assembly assembly)
        {
            bool found = true;
            found = found && 
                (FindAttributedMethod(assembly, typeof(DllInitAttribute)) 
                != null);
            found = found && 
                (FindAttributedMethod(assembly, typeof(DllShutdownAttribute)) 
                != null);
            return found;
        }

        public static bool FindAllCallInitMethod(Assembly assembly)
        {            
            return FindAndCallAttributedMethod(assembly, 
                typeof(DllInitAttribute));
        }

        public static bool FindAndCallShutdownMethod(Assembly assembly)
        {
            return FindAndCallAttributedMethod(assembly, 
                typeof(DllShutdownAttribute));            
        }

	    private static bool FindAndCallAttributedMethod(Assembly assembly, 
            Type type)
	    {
            MethodInfo method = FindAttributedMethod(assembly, type);
            if (method != null)
            {
                method.Invoke(null, new object[] {} );
                return true;
            }
            else
            {
                return false;
            }
	    }                

	    private static MethodInfo FindAttributedMethod(Assembly assembly,
            Type attributeType)
        {
            Type[] types = assembly.GetTypes();
            //there should only be one per assembly
            ArrayList initMethodList = new ArrayList();
            foreach (Type type in types)
            {
                BindingFlags bindingInfo = BindingFlags.Public 
                    | BindingFlags.NonPublic | BindingFlags.Static | 
                    BindingFlags.Instance | BindingFlags.DeclaredOnly;
                MethodInfo[] methods = type.GetMethods(bindingInfo);
                foreach(MethodInfo method in methods)
                {
                    object[] methodAttributes = 
                        method.GetCustomAttributes(
                        attributeType, false);
                    if (methodAttributes.Length > 0)
                    {
                        if (!method.IsStatic)
                        {
                            //Then fail, we have no instance to use
                            return null;
                        }
                        ParameterInfo[] parameters = method.GetParameters();
                        if (parameters.Length != 0)
                        {
                            //Then fail, we have no parameters to pass
                            return null;
                        }
                        initMethodList.Add(method);
                    }                    
                }
            }
            if (initMethodList.Count == 1)
            {
                MethodInfo method = initMethodList[0] as MethodInfo;
                //method.Invoke(null, new object[]{});                
                return method;
            }
            else
            {
                //Assembly should have one and only one attributed
                return null;
            }
           
        }
	}
}