using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.IO;

namespace MyApplication
{
    /// <summary>
    /// This class is a simple authentication/ticket submission program for ZenDesk.
    /// </summary>
    class ZenRequest
    {
        /// <summary>
        /// AppConfigFileSettings is class that reads/updates the App.Config file for
        /// simple transport of data. You should use more secure means to pass user sessions,
        /// this was necessary in my desktop app for GPO purposes.
        /// </summary>
        AppConfigFileSettings reg = new AppConfigFileSettings();
        /// <summary>
        /// ZenRequest is our constructor, and for security purposes, we do not allow null at
        /// build time.
        /// </summary>
        /// <param name="userName">Agent or Admin with all ticket access</param>
        /// <param name="password">In cleartext. This is a lament's example-- please secure your code!</param>
        /// <param name="debug">Are you using the sandbox URL, or the production?</param>
        public ZenRequest(String userName, String password, Boolean debug)
        {
            if (debug == true)
            {
                zenURL = "<sandbox_url>"; // Replace this string with the URL of your sandbox to test the app.
            }
            else if (debug == false)
            {
                zenURL = "<production_url>"; // Replace this string with the URL of your production helpdesk.
            }
            zenUserName = userName;
            zenPassword = password;

        }
        /// <summary>
        /// ZenAuth is a general authentication call for your application. This is essentially your
        /// "application login", and should be executed once before any commands are posted against the
        /// ZenDesk API to speed up the initial call.
        ///
        /// Remember, your user account must have "all ticket" access for this to work. This is the best
        /// method I've found for authenticating a user against ZenDesk.
        /// </summary>
        /// <returns>
        /// On a successful connection, return the ZenDesk Status code. You must handle the status
        /// outside of this class.
        ///
        /// Note: It is possible to get a Status response that does NOT authenticate you, make sure you stay
        /// current with the ZenDesk REST API.
        /// </returns>
        public string ZenAuth()
        {
            WebClient zenWeb = zenClient(); //  See zenClient below for further description.

            //  The next two lines formulate a GET request using the URL we specified at object creation
            //  as well as the "users.xml" file we use for simple authentication.
            String zenFile = "users.xml";
            String zenRequest = zenURL + zenFile;


            //  This gracefully executes a GET request, and will degrade without an application crash.
            try
            {
                zenWeb.DownloadData(zenRequest);    // Start the GET request.

                return zenWeb.ResponseHeaders["Status"];    //  Returns your status code. You want to be
                                                            //  Checking for a 200 OK.
            }
            catch (Exception e)
            {
                return "Error";                             //  Self explanatory. Handle your error properly.
            }

        }
        /// <summary>
        /// This method performs two functions: the first is to create a new ticket, using an XML-structured POST.
        /// The second function is to return the ticket number for application usage.
        /// </summary>
        /// <param name="userName">This is the email you will be creating a ticket for.</param>
        /// <param name="displayName">How do you want to display the name in ZenDesk?</param>
        /// <returns>Status Code for action.</returns>
        public String ZenSubmit(String userName, String displayName)
        {
            WebClient zenWeb = zenClient(); // See zenClient below for more information.

            //  The following lines structure a POST request against tickets.xml. I've also accounted
            //  for an additional custom ticket field you may have in your helpdesk.
            String zenFile = "tickets.xml";
            String zenRequest = zenURL + zenFile;
            String customTicketField = "";

            //  Remember, "reg" is reading from my app.config-- I strongly recommend using another
            //  method to store your user session.
            if (reg.ReturnAppSettings("userName") == "<specificUser1>") //  Check for specific user
                                                                        //  Enter user specific custom field.
            {
                customTicketField = @"<ticket-field-entry>
                                <ticket-field-id>[ID for custom ticket field.]</ticket-field-id>
                                <value>[tag for custom ticket field]</value>
                            </ticket-field-entry>";
            }
            else if (reg.ReturnAppSettings("userName") == "<specificUser2>")    // See above.
            {
                customTicketField = @"<ticket-field-entry>
                                <ticket-field-id>[ID for custom ticket field.]</ticket-field-id>
                                <value>[tag for custom ticket field]</value>
                            </ticket-field-entry>";
            }
            else
            {
                customTicketField = ""; //  Do not enter custom field.
            }

            //  The String Literal below constructs the XML needed for a successful POST, based on the
            //  fields we've already populated above.
            String createTicketXML = @"<ticket>
                                        <subject>[Ticket Subject]</subject>
                                        <description>[Body of ticket]</description>
                                        <requester-name>" + displayName + @"</requester-name>
                                        <requester-email>" + userName + @"</requester-email>
                                        <set-tags>[tag to set, if any]</set-tags>
                                        <ticket-field-entries type=""array"">
                                            " + customTicketField + @"
                                        </ticket-field-entries>
                                       </ticket>";
            zenWeb.UploadString(zenRequest, createTicketXML);   // Execute the POST request, and hopefully create ticket.


            //  If the ticket is created successfully, return the ticket number.
            //  Check the REST API frequently in case the location of the ticket changes.
            if (zenWeb.ResponseHeaders["Status"] == "201 Created")
            {
                zenTicketURL = zenWeb.ResponseHeaders["Location"];  //  Returns the ticket location in XML.
                //  The ticket number is extracted by removing the URL we are using, followed by the tickets/ URI,
                //  and finally by stripping ".xml" from the remaining string. Again, all of these locations are
                //  documented in the REST API for ZenDesk.

                int URLcount = CountChars(zenURL + "tickets/");

                String returnVar = zenTicketURL;
                returnVar = returnVar.Remove(0, URLcount);
                char[] xmlChar = { '.', 'x', 'm', 'l' };
                returnVar = returnVar.TrimEnd(xmlChar);
                return returnVar;
            }
            else
            {
                return "FAIL";  // Ticket creation unsuccessful.
            }

        }
        /// <summary>
        /// This is just an accessory method to get the last ticket created, should you ever need to.
        /// </summary>
        /// <returns>XML return of last ticket created.</returns>
        public String getTicket() {
            return zenTicketURL;
        }
        /// <summary>
        /// This method is the most important one in the entire class. Instead of creating a WebClient for every single
        /// action I had to take, I opted instead to set the basics up in zenClient, which can then be object referenced
        /// with every new call, and extended. This also promises proper garbage collection from the program, disposing of
        /// queries after they have been executed.
        /// </summary>
        /// <returns>Default settings for all WebClients</returns>
        private WebClient zenClient()
        {
            WebClient zenPrimaryClient = new WebClient();   // WebClient will provide transport for GET/POST commands.
            zenPrimaryClient.Credentials = new System.Net.NetworkCredential(zenUserName, zenPassword);  //  Secures UserName and Password for usage.
            zenPrimaryClient.Headers.Add("Content-Type", "application/xml");    //  Set your MIME type.

            zenPrimaryClient.BaseAddress = zenURL;  //  Set the Base URL for all commands.

            return zenPrimaryClient;    // Return all settings.
        }

        /// <summary>
        /// Generic method to count all characters in a string, and account for all spaces.
        /// Recommended for usage with URLs.
        /// </summary>
        /// <param name="value">URL to check</param>
        /// <returns>Characters in String/URL</returns>
        static int CountChars(string value)
        {
            int result = 0;
            bool lastWasSpace = false;

            foreach (char c in value)
            {
                if (char.IsWhiteSpace(c))
                {
                    if (lastWasSpace == false)
                    {
                        result++;
                    }
                    lastWasSpace = true;
                }
                else
                {
                    result++;
                    lastWasSpace = false;
                }
            }
            return result;
        }

#region Declarations
        private String zenTicketURL;
        private String zenUserName;
        private String zenPassword;
        private String zenURL;
#endregion
    }
}