Search for webmap by keyword

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//
// 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.
//

import UIKit
import ArcGIS

class SearchForWebmapByKeywordViewController: UICollectionViewController {
    private var portal: AGSPortal?
    private var resultPortalItems: [AGSPortalItem] = [] {
        didSet {
            collectionView.reloadData()
        }
    }

    private var lastQueryCancelable: AGSCancelable?

    override func viewDidLoad() {
        super.viewDidLoad()

        // register to be notified about authentication challenges
        AGSAuthenticationManager.shared().delegate = self

        // create the portal
        portal = AGSPortal(url: URL(string: "https://arcgis.com")!, loginRequired: false)

        (navigationItem.rightBarButtonItem as! SourceCodeBarButtonItem).filenames = ["SearchForWebmapByKeywordViewController", "WebMapCell", "WebMapViewController"]

        addSearchController()
    }

    private func addSearchController() {
        // create the search controller
        let searchController = UISearchController(searchResultsController: nil)
        searchController.obscuresBackgroundDuringPresentation = false
        // Setting hidesNavigationBarDuringPresentation to false causes issues on iOS 13 - 13.1.2,
        // so we hide the navigation bar during search.
        searchController.hidesNavigationBarDuringPresentation = true
        // send search query updates to the results controller
        searchController.searchResultsUpdater = self

        let searchBar = searchController.searchBar
        searchBar.autocapitalizationType = .none

        // Change the backgroundColor to differentiate from nav bar color.
        searchBar.searchTextField.backgroundColor = .tertiarySystemBackground
        // Set the color of the insertion cursor as well as the text.
        // The text is default to black color whereas the cursor is white.
        searchBar.searchTextField.tintColor = .label

        // embed the search bar under the title in the navigation bar
        navigationItem.searchController = searchController
        navigationItem.hidesSearchBarWhenScrolling = false
    }

    let dateFormatter: DateFormatter = {
        let formatter = DateFormatter()
        formatter.dateStyle = .medium
        return formatter
    }()

    private func startWebMapSearch(query: String) {
        // if the last search hasn't returned yet, cancel it
        lastQueryCancelable?.cancel()

        // webmaps authored prior to July 2nd, 2014 are not supported - so
        // search only from that date to the current time
        let dateRange = dateFormatter.date(from: "July 2, 2014")!...Date()
        let uploadedRange = dateRange.lowerBound.millisecondsSince1970...dateRange.upperBound.millisecondsSince1970
        let dateString = String(format: "uploaded:[%ld TO %ld]", uploadedRange.lowerBound, uploadedRange.upperBound)

        // create query parameters looking for items of type .webMap and
        // with our keyword and date string
        let queryParams = AGSPortalQueryParameters(forItemsOf: .webMap, withSearch: "\(query) AND \(dateString)")
        lastQueryCancelable = portal?.findItems(with: queryParams) { [weak self] (resultSet: AGSPortalQueryResultSet?, error: Error?) in
            if let error = error {
                if (error as NSError).code != NSUserCancelledError {
                    print(error.localizedDescription)
                }
            } else {
                // if our results are an array of portal items, set it on our web maps collection ViewController
                if let portalItems = resultSet?.results as? [AGSPortalItem] {
                    self?.resultPortalItems = portalItems
                } else {
                    self?.resultPortalItems = []
                }
            }
        }
    }

    // MARK: - Navigation

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if let controller = segue.destination as? WebMapViewController,
            let selectedIndex = collectionView.indexPathsForSelectedItems?.first?.row {
            controller.portalItem = resultPortalItems[selectedIndex]
        }
    }

    // MARK: - UICollectionViewDataSource

    override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return resultPortalItems.count
    }

    override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath) as! WebMapCell
        let portalItem = resultPortalItems[indexPath.row]

        cell.titleLabel.text = portalItem.title
        cell.ownerLabel.text = portalItem.owner

        // imageview border
        cell.thumbnail.layer.borderColor = UIColor.darkGray.cgColor
        cell.thumbnail.layer.borderWidth = 1

        // date label
        cell.timerLabel.text = dateFormatter.string(from: portalItem.modified!)

        if let image = portalItem.thumbnail?.image {
            cell.thumbnail.image = image
        } else {
            cell.thumbnail.image = UIImage(named: "Placeholder")
            portalItem.thumbnail?.load { [weak self] (error: Error?) in
                if let error = error {
                    print("Error downloading thumbnail :: \(error.localizedDescription)")
                } else {
                    self?.collectionView.reloadItems(at: [indexPath])
                }
            }
        }

        return cell
    }
}

extension SearchForWebmapByKeywordViewController: UISearchResultsUpdating {
    func updateSearchResults(for searchController: UISearchController) {
        if let query = searchController.searchBar.text?.trimmingCharacters(in: .whitespacesAndNewlines),
            !query.isEmpty {
            startWebMapSearch(query: query)
        } else {
            lastQueryCancelable?.cancel()
            resultPortalItems = []
        }
    }
}

extension SearchForWebmapByKeywordViewController: AGSAuthenticationManagerDelegate {
    func authenticationManager(_ authenticationManager: AGSAuthenticationManager, didReceive challenge: AGSAuthenticationChallenge) {
        // if a challenge is received, then the portal item is not fully public and cannot be displayed

        // don't present this challenge
        challenge.cancel()

        if let mapController = navigationController?.topViewController as? WebMapViewController {
            // stop attempts at map loading
            mapController.mapView.map = nil

            // close the view controller
            navigationController?.popViewController(animated: true)
        }

        // notify the user
        presentAlert(message: "Web map access denied")
    }
}

private extension Date {
    /// The milliseconds between the date value and 00:00:00 UTC on 1 January 1970.
    var millisecondsSince1970: Int64 {
        return Int64(timeIntervalSince1970 * 1_000)
    }
}