/*

    Copyright (C) 2016 Apple Inc. All Rights Reserved.

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    A `UIViewController` that implements the `UISearchResultsUpdating` protocol to display results from a `UISearchController` in a `UITableView`.

*/

import UIKit

class SearchResultsViewController: UIViewController {

    // MARK: State

    private enum State {

        case popularItems([SearchableItem])

        case searchResults([SearchableItem])

    }

    // MARK: Properties

    static let storyboardIdentifier = "SearchResultsViewController"

    static let tableViewCellIdentifier = "SearchResultsCell"

    private let searchableItems = SearchableItem.sampleItems

    private var state: State = .popularItems(SearchableItem.samplePopularItems) {

        didSet {

            guard isViewLoaded else { return }

            tableView.reloadData()

            updateHintLabel()

        }

    }

    fileprivate var tableViewItems: [SearchableItem] {

        switch state {

            case .popularItems(let items):

                return items

            case .searchResults(let items):

                return items

        }

    }

    @IBOutlet weak var tableView: UITableView!

    @IBOutlet weak var hintLabel: UILabel!

    var filterString = "" {

        didSet {

            // Return if the filter string hasn't changed.

            guard filterString != oldValue else { return }

            // Apply the filter or show all items if the filter string is empty.

            if filterString.isEmpty {

                state = .popularItems(SearchableItem.samplePopularItems)

            }

            else {

                let filteredItems = searchableItems.filter { $0.title.localizedCaseInsensitiveContains(filterString) }

                state = .searchResults(filteredItems)

            }

        }

    }

    // MARK: UIViewController

    override func viewDidLoad() {

        super.viewDidLoad()

        updateHintLabel()

    }

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {

        super.prepare(for: segue, sender: sender)

        if let mapViewController = segue.destination as? MapViewController, let selectedIndexPath = tableView.indexPathForSelectedRow {

            mapViewController.items = tableViewItems

            mapViewController.selectedItem = tableViewItems[selectedIndexPath.row]

        }

    }

    // MARK: Convenience

    private func updateHintLabel() {

        switch state {

            case .popularItems(_):

                return hintLabel.text = NSLocalizedString("Popular Bay Area Locations", comment: "")

            case .searchResults(let searchResults) where searchResults.isEmpty:

                return hintLabel.text = NSLocalizedString("No points of interest found", comment: "")

            case .searchResults(_):

                return hintLabel.text = NSLocalizedString("Matching Points Of Interest", comment: "")

        }

    }

}

extension SearchResultsViewController: UISearchResultsUpdating {

    func updateSearchResults(for searchController: UISearchController) {

        // Check of the change is due to user input in the search bar.

        guard searchController.searchBar.isFirstResponder else { return }

        // Update the filter string with the text in the search bar.

        filterString = searchController.searchBar.text ?? ""

    }

}

extension SearchResultsViewController: UITableViewDataSource {

    func numberOfSections(in tableView: UITableView) -> Int {

        return 1

    }

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {

        return tableViewItems.count

    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

        // Dequeue a cell from the table view and configure it with the item details.

        let cell = tableView.dequeueReusableCell(withIdentifier: SearchResultsViewController.tableViewCellIdentifier, for: indexPath)

        let item = tableViewItems[indexPath.row]

        cell.textLabel?.text = item.title

        return cell

    }

}