using System;
using Microsoft.Win32;

namespace Developpez.Dotnet.System.Providers.Windows
{
    /// <summary>
    /// Infrastructure (Interop)
    /// </summary>
    internal static class FrameworkVersionRegistryHelper
    {
        #region Nom des clefs du registre

        const string g_szNetfx20RegKeyName = "Software\\Microsoft\\NET Framework Setup\\NDP\\v2.0.50727";
        const string g_szNetfx30RegKeyName = "Software\\Microsoft\\NET Framework Setup\\NDP\\v3.0\\Setup";
        const string g_szNetfx30SpRegKeyName = "Software\\Microsoft\\NET Framework Setup\\NDP\\v3.0";
        const string g_szNetfx30RegValueName = "InstallSuccess";
        const string g_szNetfx35RegKeyName = "Software\\Microsoft\\NET Framework Setup\\NDP\\v3.5";
        const string g_szNetfxStandardRegValueName = "Install";
        const string g_szNetfxStandardSPxRegValueName = "SP";
        const string g_szNetfxStandardVersionRegValueName = "Version";

        #endregion

        #region Utilitaires du registre

        internal static bool RegistryTryGetValue(RegistryKey root, string key_name, string value_name, out object value)
        {
            if (root == null)
                throw new ArgumentNullException("root");

            value = null;

            RegistryKey key = root;
            if (!String.IsNullOrEmpty(key_name))
            {
                key = root.OpenSubKey(key_name, false);
            }

            if (key == null)
                return false;
            else
            {
                try
                {
                    /* il faut bien vérifier si la clef existe */
                    foreach (string item in key.GetValueNames())
                    {
                        if ((String.IsNullOrEmpty(item) && String.IsNullOrEmpty(value_name)) ||
                            item.Equals(value_name, StringComparison.OrdinalIgnoreCase))
                        {
                            /* la valeur existe bien */
                            value = key.GetValue(value_name);

                            return true;
                        }
                    }
                }
                finally
                {
                    if (key != root)
                        key.Close(); /* si key == root ça veux dire que key_name était vide */
                }
            }

            return false;
        }

        #endregion

        internal static bool IsFX35Installed()
        {
            object value = null;

            if (RegistryTryGetValue(Registry.LocalMachine, g_szNetfx35RegKeyName, g_szNetfxStandardRegValueName, out value))
            {
                /* un peux sale */
                try
                {
                    return (value != null) && (Convert.ToInt32(value) == 1);
                }
                catch
                {
                    return false;
                }
            }

            return false;
        }

        internal static bool IsFX30Installed()
        {
            object value = null;

            if (RegistryTryGetValue(Registry.LocalMachine, g_szNetfx30RegKeyName, g_szNetfxStandardRegValueName, out value))
            {
                /* un peux sale */
                try
                {
                    return (value != null) && (Convert.ToInt32(value) == 1);
                }
                catch
                {
                    return false;
                }
            }

            return false;
        }

        internal static bool IsFX20Installed()
        {
            object value = null;

            if (RegistryTryGetValue(Registry.LocalMachine, g_szNetfx20RegKeyName, g_szNetfxStandardRegValueName, out value))
            {
                /* un peux sale */
                try
                {
                    return (value != null) && (Convert.ToInt32(value) == 1);
                }
                catch
                {
                    return false;
                }
            }

            return false;
        }

        internal static int GetFX35SPLevel()
        {
            return GetFXSpLevel(g_szNetfx35RegKeyName, g_szNetfxStandardSPxRegValueName);
        }

        internal static int GetFX30SPLevel()
        {
            return GetFXSpLevel(g_szNetfx35RegKeyName, g_szNetfxStandardSPxRegValueName);
        }

        internal static int GetFX20SPLevel()
        {
            return GetFXSpLevel(g_szNetfx35RegKeyName, g_szNetfxStandardSPxRegValueName);
        }

        private static int GetFXSpLevel(string regKeyName, string regValueName)
        {
            object value = null;
            if (RegistryTryGetValue(Registry.LocalMachine, regKeyName, regValueName, out value))
            {
                try
                {
                    return (int)value;
                }
                catch
                {
                    return 0;
                }
            }

            return 0;
        }
    }
}