using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Windows.Markup;

namespace Developpez.Dotnet.Windows
{
    internal class AssemblyManager
    {
        public static Assembly GetEntryAssembly()
        {
            Assembly asm = Assembly.GetEntryAssembly();

            // Mode design
            if (asm == null)
            {
                // En mode design, Assembly.GetEntryAssembly ne fonctionne pas
                // On cherche donc un assembly avec un point d'entrée qui contient
                // une classe héritée de System.Windows.Application
                asm = (
                       from a in AppDomain.CurrentDomain.GetAssemblies()
                       where a.EntryPoint != null
                       && a.GetTypes().Any(t => t.IsSubclassOf(typeof(System.Windows.Application)))
                       select a
                      ).FirstOrDefault();
            }

            return asm;
        }

        public static Uri GetRootUri(IUriContext uriContext)
        {
            string authority = uriContext.BaseUri.GetLeftPart(UriPartial.Authority);
            if (uriContext.BaseUri.Segments.Length > 1)
            {
                string path = uriContext.BaseUri.Segments[0] + uriContext.BaseUri.Segments[1];
                return new Uri(authority + path);
            }
            else return null;
        }

        private static Dictionary<Uri, Assembly> _assembliesByUri = new Dictionary<Uri, Assembly>();

        public static Assembly GetAssembly(IUriContext uriContext)
        {
            Uri baseUri = GetRootUri(uriContext);
            Assembly assembly = null;

            if (_assembliesByUri.TryGetValue(baseUri, out assembly))
            {
                return assembly;
            }
            else
            {
                if (baseUri.Authority == "application:,,," && baseUri.Segments.Length > 1)
                {
                    string seg1 = baseUri.Segments[1];
                    int idx = seg1.IndexOf(";component");
                    if (idx >= 0)
                    {
                        string assemblySpec = seg1.Substring(0, idx);
                        string[] assemblyParts = assemblySpec.Split(';');
                        string uriAsmName = assemblyParts[0];
                        string uriAsmVersion = null;
                        string uriAsmPubKeyToken = null;
                        if (assemblyParts.Length > 1)
                            uriAsmVersion = assemblyParts[1];
                        if (assemblyParts.Length > 2)
                            uriAsmPubKeyToken = assemblyParts[2];

                        System.Reflection.Assembly[] assemblies = AppDomain.CurrentDomain.GetAssemblies();
                        foreach (System.Reflection.Assembly asm in assemblies)
                        {
                            System.Reflection.AssemblyName asmName = asm.GetName();
                            string pubKeyToken =asmName.GetPublicKeyToken().ToHexString();
                            if (asmName.Name == uriAsmName
                                && (uriAsmVersion == null || asmName.Version.ToString() == uriAsmVersion)
                                && (uriAsmPubKeyToken == null || pubKeyToken == uriAsmPubKeyToken))
                            {
                                _assembliesByUri.Add(baseUri, asm);
                                return asm;
                            }
                        }
                    }
                }
            }

            return null;
        }
    }
}