using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security;
using Microsoft.SharePoint.Client;

namespace SPOSearchNav
{
    class Program
    {
        private class Configuration
        {
            public static string ServiceSiteUrl = "https://<tenant>.sharepoint.com/Sites/<site>";
            public static string ServiceUserName = "<admin>@<tenant>.onmicrosoft.com";
            public static string ServicePassword = "<password>";
        }

        static ClientContext GetonlineContext()
        {
            var securePassword = new SecureString();
            foreach (char c in Configuration.ServicePassword)
            {
                securePassword.AppendChar(c);
            }
            var onlineCredentials = new SharePointOnlineCredentials(Configuration.ServiceUserName, securePassword);
            var context = new ClientContext(Configuration.ServiceSiteUrl);
            context.Credentials = onlineCredentials;
            return context;
        }

        static void Main(string[] args)
        {
            var clientContext = GetonlineContext();
            Web web = clientContext.Web;

            // Get the search navigation node collection.
            NavigationNode searchNav = web.Navigation.GetNodeById(1040);
            NavigationNodeCollection nodeCollection = searchNav.Children;
            clientContext.Load(nodeCollection);
            clientContext.ExecuteQuery();

            //delete all node in search navigation
            nodeCollection.ToList().ForEach(node => node.DeleteObject());
            clientContext.ExecuteQuery();

            // create
            // Set properties for a new navigation node.
            NavigationNodeCreationInformation node1 = new NavigationNodeCreationInformation();
            node1.Title = "This Site";
            node1.Url = "/sites/<site>/_layouts/15/osssearchresults.aspx?u={contexturl}";
            node1.AsLastNode = true; //be created as the last node in the collection
            nodeCollection.Add(node1);
            clientContext.Load(nodeCollection);
            clientContext.ExecuteQuery();

            NavigationNodeCreationInformation node2 = new NavigationNodeCreationInformation();
            node2.Title = "Everything";
            node2.Url = "https://<tenant>.sharepoint.com/search/Pages/results.aspx";
            node2.IsExternal = true;
            node2.AsLastNode = true; //be created as the last node in the collection
            //node2.PreviousNode = nodeCollection[0]; //be created after the first node in the navigation node collection
            nodeCollection.Add(node2);
            clientContext.Load(nodeCollection);
            clientContext.ExecuteQuery();

            NavigationNodeCreationInformation node3 = new NavigationNodeCreationInformation();
            node3.Title = "People";
            node3.Url = "https://<tenant>.sharepoint.com/search/Pages/peopleresults.aspx";
            node3.IsExternal = true;
            node3.AsLastNode = true; //be created as the last node in the collection
            //node3.PreviousNode = nodeCollection[1]; //be created after the second node in the navigation node collection
            nodeCollection.Add(node3);
            clientContext.Load(nodeCollection);
            clientContext.ExecuteQuery();

            foreach (NavigationNode navNode in nodeCollection)
            { Console.WriteLine(navNode.Title);}

        }
    }
}