SearchPortalMaps.cs

// Copyright 2017 Esri.
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License.
// You may obtain a copy of the License at: http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an 
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific 
// language governing permissions and limitations under the License.

using Android.App;
using Android.OS;
using Android.Views;
using Android.Widget;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Portal;
using Esri.ArcGISRuntime.Security;
using Esri.ArcGISRuntime.UI.Controls;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Esri.ArcGISRuntime;
using Xamarin.Auth;

namespace ArcGISRuntime.Samples.SearchPortalMaps
{
    [Activity]
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        "Search a portal for maps",
        "Map",
        "This sample demonstrates searching a portal for web maps and loading them in the map view. You can search ArcGIS Online public web maps using tag values or browse the web maps in your account. OAuth is used to authenticate with ArcGIS Online to access items in your account.",
        "1. When the sample starts, you will be presented with a dialog for entering OAuth settings. If you need to create your own settings, sign in with your developer account and use the [ArcGIS for Developers dashboard](https://developers.arcgis.com/dashboard) to create an Application to store these settings.\n2. Enter values for the following OAuth settings.\n\t1. **Client ID**: a unique alphanumeric string identifier for your application\n\t2. **Redirect URL**: a URL to which a successful OAuth login response will be sent\n3. If you do not enter OAuth settings, you will be able to search public web maps on ArcGIS Online. Browsing the web map items in your ArcGIS Online account will be disabled, however.")]
    public class SearchPortalMaps : Activity, IOAuthAuthorizeHandler
    {
        // Create and hold reference to the used MapView
        private MapView _myMapView = new MapView();

        // Dictionary to hold URIs to web maps
        private Dictionary<string, Uri> _webMapUris;

        // Use a TaskCompletionSource to track the completion of the authorization
        private TaskCompletionSource<IDictionary<string, string>> _taskCompletionSource;

        // Store the OAuth dialog and controls for updating OAuth configuration
        private AlertDialog _configOAuthDialog = null;
        private EditText _clientIdText;
        private EditText _redirectUrlText;

        // Variables for OAuth config and default values ...
        // URL of the server to authenticate with
        private const string ServerUrl = "https://www.arcgis.com/sharing/rest";

        // TODO: Add Client ID for an app registered with the server
        private string _appClientId = "2Gh53JRzkPtOENQq";

        // TODO: Add URL for redirecting after a successful authorization
        //       Note - this must be a URL configured as a valid Redirect URI with your app
        private string _oAuthRedirectUrl = "https://developers.arcgis.com";

        // Button layout at the top of the page
        private LinearLayout _buttonPanel;

        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);

            Title = "Search a portal for maps";

            // Set up AuthenticationManager (prompt user for OAuth config first)
            ShowOAuthConfigDialog();
            // Note: the code above calls UpdateAuthenticationManager() to store OAuth configuration

            // Create the UI, setup the control references and execute initialization 
            CreateLayout();
            Initialize();
        }

        private void Initialize()
        {
            // Create a new Map instance
            Map myMap = new Map(Basemap.CreateLightGrayCanvas());

            // Provide default Map to the MapView
            _myMapView.Map = myMap;
        }

        private void SearchMapsClicked(object sender, EventArgs e)
        {
            // Create a dialog to show save options (title, description, and tags)
            SearchMapsDialogFragment searchMapsDialog = new SearchMapsDialogFragment();
            searchMapsDialog.OnSearchClicked += OnSearchMapsClicked;

            // Begin a transaction to show a UI fragment (the search dialog)
            FragmentTransaction trans = FragmentManager.BeginTransaction();
            searchMapsDialog.Show(trans, "search maps");
        }

        private async void MyMapsClicked(object sender, EventArgs e)
        {
            try
            {
                // Get web map portal items in the current user's folder
                IEnumerable<PortalItem> mapItems = null;

                // Call a sub that will force the user to log in to ArcGIS Online (if they haven't already)
                bool loggedIn = await EnsureLoggedInAsync();
                if (!loggedIn) { return; }

                // Connect to the portal (will connect using the provided credentials)
                ArcGISPortal portal = await ArcGISPortal.CreateAsync(new Uri(ServerUrl));

                // Get the user's content (items in the root folder and a collection of sub-folders)
                PortalUserContent myContent = await portal.User.GetContentAsync();

                // Get the web map items in the root folder
                mapItems = from item in myContent.Items where item.Type == PortalItemType.WebMap select item;

                // Loop through all sub-folders and get web map items, add them to the mapItems collection
                foreach (PortalFolder folder in myContent.Folders)
                {
                    IEnumerable<PortalItem> folderItems = await portal.User.GetContentAsync(folder.FolderId);
                    mapItems = mapItems.Concat(from item in folderItems where item.Type == PortalItemType.WebMap select item);
                }

                // Show the map results
                ShowMapList(mapItems);
            }
            catch (Exception ex)
            {
                new AlertDialog.Builder(this).SetMessage(ex.ToString()).SetTitle("Error").Show();
            }
        }

        private async void OnSearchMapsClicked(object sender, OnSearchMapEventArgs e)
        {
            try
            {
                // Get web map portal items from a keyword search
                IEnumerable<PortalItem> mapItems = null;

                // Connect to the portal (anonymously)
                ArcGISPortal portal = await ArcGISPortal.CreateAsync(new Uri(ServerUrl));

                // Create a query expression that will get public items of type 'web map' with the keyword(s) in the items tags
                string queryExpression = $"tags:\"{e.SearchText}\" access:public type: (\"web map\" NOT \"web mapping application\")";
            
                // Create a query parameters object with the expression and a limit of 10 results
                PortalQueryParameters queryParams = new PortalQueryParameters(queryExpression, 10);

                // Search the portal using the query parameters and await the results
                PortalQueryResultSet<PortalItem> findResult = await portal.FindItemsAsync(queryParams);
            
                // Get the items from the query results
                mapItems = findResult.Results;

                // Show the map results
                ShowMapList(mapItems);
            }
            catch (Exception ex)
            {
                new AlertDialog.Builder(this).SetMessage(ex.ToString()).SetTitle("Error").Show();
            }
        }

        private void ShowMapList(IEnumerable<PortalItem> webmapItems)
        {
            // Create menu to show map results
            PopupMenu mapsMenu = new PopupMenu(this, _buttonPanel);
            mapsMenu.MenuItemClick += OnMapsMenuItemClicked;

            // Create a dictionary of web maps and show the titles in the menu
            _webMapUris = new Dictionary<string, Uri>();
            foreach (PortalItem item in webmapItems)
            {
                if (!_webMapUris.ContainsKey(item.Title)){
                    _webMapUris.Add(item.Title, item.Url);
                    mapsMenu.Menu.Add(item.Title);
                }
            }

            //Show menu in the view
            mapsMenu.Show();
        }

        private void OnMapsMenuItemClicked(object sender, PopupMenu.MenuItemClickEventArgs e)
        {
            // Get the selected web map item URI from the dictionary
            string mapTitle = e.Item.TitleCondensedFormatted.ToString();
            Uri selectedMapUri = _webMapUris[mapTitle];

            if (selectedMapUri == null) { return; }

            // Create a new map, pass the web map portal item to the constructor
            Map webMap = new Map(selectedMapUri);

            // Handle change in the load status (to report load errors)
            webMap.LoadStatusChanged += WebMapLoadStatusChanged;

            // Show the web map in the map view
            _myMapView.Map = webMap;
        }

        private void WebMapLoadStatusChanged(object sender, Esri.ArcGISRuntime.LoadStatusEventArgs e)
        {
            // Report errors if map failed to load
            if (e.Status == LoadStatus.FailedToLoad)
            {
                Map map = (Map)sender;
                Exception err = map.LoadError;
                if (err != null)
                {
                    AlertDialog.Builder alertBuilder = new AlertDialog.Builder(this);
                    alertBuilder.SetTitle("Map Load Error");
                    alertBuilder.SetMessage(err.Message);
                    alertBuilder.Show();
                }
            }
        }

        private void CreateLayout()
        {
            // Create a new vertical layout for the app
            LinearLayout mainLayout = new LinearLayout(this) { Orientation = Orientation.Vertical };

            // Create a layout for app buttons
            _buttonPanel = new LinearLayout(this) { Orientation = Orientation.Horizontal };

            // Create button to show search UI
            Button searchMapsButton = new Button(this)
            {
                Text = "Search Maps"
            };
            searchMapsButton.Click += SearchMapsClicked;

            // Create another button to show maps from user's ArcGIS Online account
            Button myMapsButton = new Button(this)
            {
                Text = "My Maps"
            };
            myMapsButton.Click += MyMapsClicked;

            // Add buttons to the horizontal layout panel
            _buttonPanel.AddView(searchMapsButton);
            _buttonPanel.AddView(myMapsButton);

            // Add button panel to the main layout
            mainLayout.AddView(_buttonPanel);

            // Add the map view to the layout
            mainLayout.AddView(_myMapView);

            // Show the layout in the app
            SetContentView(mainLayout);
        }

        #region OAuth helpers
        // Prompt for portal item information 
        private void ShowOAuthConfigDialog()
        {
            // Create a dialog to get OAuth information (client id, redirect url, etc.)
            AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(this);

            // Create the layout
            LinearLayout dialogLayout = new LinearLayout(this)
            {
                Orientation = Orientation.Vertical
            };

            // Create a text box for entering the client id
            LinearLayout clientIdLayout = new LinearLayout(this)
            {
                Orientation = Orientation.Horizontal
            };
            TextView clientIdLabel = new TextView(this)
            {
                Text = "Client ID:"
            };
            _clientIdText = new EditText(this);
            if (!String.IsNullOrEmpty(_appClientId)) { _clientIdText.Text = _appClientId; }
            clientIdLayout.AddView(clientIdLabel);
            clientIdLayout.AddView(_clientIdText);

            // Create a text box for entering the redirect url
            LinearLayout redirectUrlLayout = new LinearLayout(this)
            {
                Orientation = Orientation.Horizontal
            };
            
            TextView redirectUrlLabel = new TextView(this)
            {
                Text = "Redirect:"
            };
            
            _redirectUrlText = new EditText(this)
            {
                Hint = "https://my.redirect/url"
            };

            if (!String.IsNullOrEmpty(_oAuthRedirectUrl))
            {
                _redirectUrlText.Text = _oAuthRedirectUrl;
            }

            redirectUrlLayout.AddView(redirectUrlLabel);
            redirectUrlLayout.AddView(_redirectUrlText);

            // Create a button to dismiss the dialog (and proceed with updating the values)
            Button okButton = new Button(this)
            {
                Text = "Save"
            };

            // Handle the click event for the OK button
            okButton.Click += OnCloseOAuthDialog;

            // Add the controls to the dialog
            dialogLayout.AddView(clientIdLayout);
            dialogLayout.AddView(redirectUrlLayout);
            dialogLayout.AddView(okButton);
            dialogBuilder.SetView(dialogLayout);
            dialogBuilder.SetTitle("Configure OAuth");

            // Show the dialog
            _configOAuthDialog = dialogBuilder.Show();
        }

        // Click event for the OK button on the save map dialog
        private void OnCloseOAuthDialog(object sender, EventArgs e)
        {
            if (_configOAuthDialog != null)
            {
                // Get title and description text
                _appClientId = _clientIdText.Text;
                _oAuthRedirectUrl = _redirectUrlText.Text;

                // Dismiss the dialog
                _configOAuthDialog.Dismiss();

                // Update the OAuth settings
                UpdateAuthenticationManager();
            }
        }

        private void UpdateAuthenticationManager()
        {
            // Register the server information with the AuthenticationManager
            ServerInfo portalServerInfo = new ServerInfo
            {
                ServerUri = new Uri(ServerUrl),
                OAuthClientInfo = new OAuthClientInfo
                {
                    ClientId = _appClientId,
                    RedirectUri = new Uri(_oAuthRedirectUrl)
                },
                // Specify OAuthAuthorizationCode if you need a refresh token (and have specified a valid client secret)
                // Otherwise, use OAuthImplicit
                TokenAuthenticationType = TokenAuthenticationType.OAuthImplicit
            };

            // Get a reference to the (singleton) AuthenticationManager for the app
            AuthenticationManager thisAuthenticationManager = AuthenticationManager.Current;

            // Register the server information
            thisAuthenticationManager.RegisterServer(portalServerInfo);

            // Assign the method that AuthenticationManager will call to challenge for secured resources
            thisAuthenticationManager.ChallengeHandler = new ChallengeHandler(CreateCredentialAsync);

            // Set the OAuth authorization handler to this class (Implements IOAuthAuthorize interface)
            thisAuthenticationManager.OAuthAuthorizeHandler = this;
        }

        private async Task<bool> EnsureLoggedInAsync()
        {
            bool loggedIn = false;

            try
            {
                // Create a challenge request for portal credentials (OAuth credential request for arcgis.com)
                CredentialRequestInfo challengeRequest = new CredentialRequestInfo
                {

                    // Use the OAuth implicit grant flow
                    GenerateTokenOptions = new GenerateTokenOptions
                    {
                        TokenAuthenticationType = TokenAuthenticationType.OAuthImplicit
                    },

                    // Indicate the url (portal) to authenticate with (ArcGIS Online)
                    ServiceUri = new Uri(ServerUrl)
                };

                // Call GetCredentialAsync on the AuthenticationManager to invoke the challenge handler
                Credential cred = await AuthenticationManager.Current.GetCredentialAsync(challengeRequest, false);
                loggedIn = cred != null;
            }
            catch (System.OperationCanceledException)
            {
                // Login was canceled
                // .. ignore, user can still search public maps without logging in
            }
            catch (Exception ex)
            {
                // Login failure
                AlertDialog.Builder alertBuilder = new AlertDialog.Builder(this);
                alertBuilder.SetTitle("Login Error");
                alertBuilder.SetMessage(ex.Message);
                alertBuilder.Show();
            }

            return loggedIn;
        }

        // ChallengeHandler function for AuthenticationManager, called whenever access to a secured resource is attempted
        private async Task<Credential> CreateCredentialAsync(CredentialRequestInfo info)
        {
            OAuthTokenCredential credential = null;

            try
            {
                // Create generate token options if necessary
                if (info.GenerateTokenOptions == null)
                {
                    info.GenerateTokenOptions = new GenerateTokenOptions();
                }

                // AuthenticationManager will handle challenging the user for credentials
                credential = await AuthenticationManager.Current.GenerateCredentialAsync
                    (
                            info.ServiceUri,
                            info.GenerateTokenOptions
                    ) as OAuthTokenCredential;
            }
            catch (TaskCanceledException) { return credential; }
            catch (Exception)
            {
                // Exception will be reported in calling function
                throw;
            }

            return credential;
        }

        // IOAuthAuthorizeHandler.AuthorizeAsync implementation
        public Task<IDictionary<string, string>> AuthorizeAsync(Uri serviceUri, Uri authorizeUri, Uri callbackUri)
        {
            // If the TaskCompletionSource is not null, authorization may already be in progress and should be cancelled
            if (_taskCompletionSource != null)
            {
                // Try to cancel any existing authentication task
                _taskCompletionSource.TrySetCanceled();
            }

            // Create a task completion source
            _taskCompletionSource = new TaskCompletionSource<IDictionary<string, string>>();

            // Create a new Xamarin.Auth.OAuth2Authenticator using the information passed in
            Xamarin.Auth.OAuth2Authenticator authenticator = new OAuth2Authenticator(
                clientId: _appClientId,
                scope: "",
                authorizeUrl: authorizeUri,
                redirectUrl: callbackUri)
            {
                ShowErrors = false
            };

            // Allow the user to cancel the OAuth attempt
            authenticator.AllowCancel = true;

            // Define a handler for the OAuth2Authenticator.Completed event
            authenticator.Completed += (sender, authArgs) =>
            {
                try
                {
                    // Check if the user is authenticated
                    if (authArgs.IsAuthenticated)
                    {
                        // If authorization was successful, get the user's account
                        Xamarin.Auth.Account authenticatedAccount = authArgs.Account;

                        // Set the result (Credential) for the TaskCompletionSource
                        _taskCompletionSource.SetResult(authenticatedAccount.Properties);
                    }
                }
                catch (Exception ex)
                {
                    // If authentication failed, set the exception on the TaskCompletionSource
                    _taskCompletionSource.TrySetException(ex);

                    // Cancel authentication
                    authenticator.OnCancelled();
                }
                finally
                {
                    // End the OAuth login activity
                    FinishActivity(99);
                }
            };

            // If an error was encountered when authenticating, set the exception on the TaskCompletionSource
            authenticator.Error += (sndr, errArgs) =>
            {
                // If the user cancels, the Error event is raised but there is no exception ... best to check first
                if (errArgs.Exception != null)
                {
                    _taskCompletionSource.TrySetException(errArgs.Exception);
                }
                else
                {
                    // Login canceled: end the OAuth login activity
                    if (_taskCompletionSource != null)
                    {
                        _taskCompletionSource.TrySetCanceled();
                        FinishActivity(99);
                    }
                }

                // Cancel authentication
                authenticator.OnCancelled();
            };

            // Present the OAuth UI (Activity) so the user can enter user name and password
            Android.Content.Intent intent = authenticator.GetUI(this);
            StartActivityForResult(intent, 99);

            // Return completion source task so the caller can await completion
            return _taskCompletionSource.Task;
        }

        private static IDictionary<string, string> DecodeParameters(Uri uri)
        {
            // Create a dictionary of key value pairs returned in an OAuth authorization response URI query string
            string answer = "";

            // Get the values from the URI fragment or query string
            if (!String.IsNullOrEmpty(uri.Fragment))
            {
                answer = uri.Fragment.Substring(1);
            }
            else
            {
                if (!String.IsNullOrEmpty(uri.Query))
                {
                    answer = uri.Query.Substring(1);
                }
            }

            // Parse parameters into key / value pairs
            Dictionary<string,string> keyValueDictionary = new Dictionary<string, string>();
            string[] keysAndValues = answer.Split(new[] { '&' }, StringSplitOptions.RemoveEmptyEntries);
            foreach (string kvString in keysAndValues)
            {
                string[] pair = kvString.Split('=');
                string key = pair[0];
                string value = string.Empty;
                if (key.Length > 1)
                {
                    value = Uri.UnescapeDataString(pair[1]);
                }

                keyValueDictionary.Add(key, value);
            }

            // Return the dictionary of string keys/values
            return keyValueDictionary;
        }
        #endregion
    }

    #region UI for entering web map search text
    // A custom DialogFragment class to show input controls for searching for maps
    public class SearchMapsDialogFragment : DialogFragment
    {
        // Inputs for portal item search text
        private EditText _mapSearchTextbox;

        // Raise an event so the listener can access the input search text value when the form has been completed
        public event EventHandler<OnSearchMapEventArgs> OnSearchClicked;

        public SearchMapsDialogFragment() { }

        public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
        {
            // Dialog to display
            LinearLayout dialogView = null;

            // Get the context for creating the dialog controls
            Android.Content.Context ctx = Activity.ApplicationContext;

            // Set a dialog title
            Dialog.SetTitle("Search Portal");

            try
            {
                base.OnCreateView(inflater, container, savedInstanceState);

                // The container for the dialog is a vertical linear layout
                dialogView = new LinearLayout(ctx)
                {
                    Orientation = Orientation.Vertical
                };

                // Add a text box for entering web map search text
                _mapSearchTextbox = new EditText(ctx)
                {
                    Hint = "Search text"
                };
                dialogView.AddView(_mapSearchTextbox);

                // Add a button to complete search
                Button searchMapsButton = new Button(ctx)
                {
                    Text = "Search"
                };
                searchMapsButton.Click += SearchMapsButtonClick;
                dialogView.AddView(searchMapsButton);
            }
            catch (Exception ex)
            {
                // Show the exception message 
                AlertDialog.Builder alertBuilder = new AlertDialog.Builder(Activity);
                alertBuilder.SetTitle("Error");
                alertBuilder.SetMessage(ex.Message);
                alertBuilder.Show();
            }

            // Return the new view for display
            return dialogView;
        }

        // A click handler for the search button
        private void SearchMapsButtonClick(object sender, EventArgs e)
        {
            try
            {
                // Get information for the new portal item
                string search = _mapSearchTextbox.Text;

                // Create a new OnSaveMapEventArgs object to store the information entered by the user
                OnSearchMapEventArgs mapSearchArgs = new OnSearchMapEventArgs(search);

                // Raise the OnSaveClicked event so the main activity can handle the event and save the map
                OnSearchClicked?.Invoke(this, mapSearchArgs);

                // Close the dialog
                Dismiss();
            }
            catch (Exception ex)
            {
                // Show the exception message (dialog will stay open so user can try again)
                AlertDialog.Builder alertBuilder = new AlertDialog.Builder(Activity);
                alertBuilder.SetTitle("Error");
                alertBuilder.SetMessage(ex.Message);
                alertBuilder.Show();
            }
        }
    }

    // Custom EventArgs class for containing map search expression text
    public class OnSearchMapEventArgs : EventArgs
    {
        // Search text
        public string SearchText { get; set; }

        public OnSearchMapEventArgs(string searchText) : base()
        {
            // Store the web map search text
            SearchText = searchText;
        }
    }
    #endregion
}