using System;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Text;
using System.Windows.Forms;
using System.Xml;
using Microsoft.Win32;
using System.Diagnostics;

namespace sharpupdater
{
    public class SharpUpdater
    {
        public static string DefaultLatestVersionMessage = "Congratulations, you are running the latest version.";
        public static string DefaultUpdateMessage = "You are running an outdated version. Please update to latest version.";
        public static string DefaultUpdateQuestion = "You are running an outdated version. Would you like to udpate?";

        public string Url { get; set; }
        public Update UpdateInfo { get; set; }

        public SharpUpdater(string url)
        {
            this.Url = url;
        }

        private string GetLatestVersionFile()
        {
            string ret = string.Empty;

            try
            {
                WebRequest request = HttpWebRequest.Create(Url);

                request.Proxy = WebRequest.DefaultWebProxy;
                request.Proxy.Credentials = CredentialCache.DefaultCredentials;

                HttpWebResponse response = (HttpWebResponse)request.GetResponse();
                if (response.StatusCode == HttpStatusCode.OK)
                {
                    Stream stream = response.GetResponseStream();

                    TextReader reader = new StreamReader(stream);
                    ret = reader.ReadToEnd();
                    reader.Close();
                }
                response.Close();
            }
            catch (WebException ex)
            {
                throw new UnableToRetrieveVersionException(ex.Message);
            }

            return ret;
        }

        private List<Product> GetProductInfos()
        {
            List<Product> products = new List<Product>();

            XmlDocument document = new XmlDocument();

            string versionFile = GetLatestVersionFile();

            if (string.IsNullOrEmpty(versionFile))
            {
                return null;
            }

            document.LoadXml(versionFile);

            foreach (XmlNode productsNode in document.ChildNodes)
            {
                if (productsNode.Name == "products")
                {
                    foreach (XmlNode productNode in productsNode.ChildNodes)
                    {
                        Product product = new Product(
                            productNode.Attributes["name"].Value,
                            productNode.Attributes["version"].Value);
                        products.Add(product);

                        foreach (XmlNode node in productNode.ChildNodes)
                        {
                            switch (node.Name)
                            {
                                case "update":
                                    Update.UpdateType updateType = Update.UpdateType.Url;
                                    switch (node.Attributes["type"].Value)
                                    {
                                        case "setup":
                                            updateType = Update.UpdateType.Setup;
                                            break;
                                        case "package":
                                            updateType = Update.UpdateType.Package;
                                            break;
                                    }
                                    Update update = new Update(updateType, node.InnerText);
                                    product.Update = update;
                                    break;
                                case "info":
                                    Info.InfoType infoType = Info.InfoType.Url;
                                    switch (node.Attributes["type"].Value)
                                    {
                                        case "file":
                                            infoType = Info.InfoType.File;
                                            break;
                                        case "notes":
                                            infoType = Info.InfoType.Notes;
                                            break;
                                    }
                                    Info info = new Info(infoType, node.InnerText);
                                    product.Info = info;
                                    break;
                            }
                        }
                    }
                }
            }

            return products;
        }

        public Product GetProductInfo(string productName)
        {
            List<Product> products = GetProductInfos();

            if (products == null)
            {
                return null;
            }

            foreach (Product product in products)
            {
                if (product.Name == productName)
                {
                    return product;
                }
            }
            return null;
        }

        public bool IsLatestVersion(string productName, string version)
        {
            bool ret = false;

            Product product = GetProductInfo(productName);
            if (product != null)
            {
                ret = product.Version.CompareTo(version) <= 0;
            }

            return ret;
        }

        public void UpdateProduct(string productName, string version)
        {
            if (!IsLatestVersion(productName, version))
            {
                Product product = GetProductInfo(productName);
                if (product != null)
                {
                    bool updateRequired = false;

                    if (product.Update != null)
                    {
                        updateRequired =
                            MessageBox.Show(DefaultUpdateQuestion, "Update", MessageBoxButtons.YesNo, MessageBoxIcon.Question) == DialogResult.Yes;

                        if (updateRequired)
                        {
                            switch (product.Update.Type)
                            {
                                case Update.UpdateType.Url:
                                    Process p = new Process();
                                    p.StartInfo.FileName = GetDefaultBrowserPath();
                                    p.StartInfo.Arguments = product.Update.Url;
                                    p.Start();
                                    break;
                                case Update.UpdateType.Setup:
                                    break;
                                case Update.UpdateType.Package:
                                    break;
                            }
                        }
                    }
                    // No update strategy has been specified
                    else
                    {
                        MessageBox.Show(DefaultUpdateMessage, "Update", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    }
                }
            }
        }

        private string GetDefaultBrowserPath()
        {
            string key = @"htmlfile\shell\open\command";
            RegistryKey registryKey = Registry.ClassesRoot.OpenSubKey(key, false);
            return ((string)registryKey.GetValue(null, null)).Split('"')[1];
        }
    }
}