//
//  AddSavedHashtagViewController.swift
//  Tusker
//
//  Created by Shadowfacts on 12/19/19.
//  Copyright © 2019 Shadowfacts. All rights reserved.
//

import UIKit
import Pachyderm

class AddSavedHashtagViewController: EnhancedTableViewController {

    weak var mastodonController: MastodonController!
    
    var resultsController: SearchResultsViewController!
    var searchController: UISearchController!
    
    var dataSource: UITableViewDiffableDataSource<Section, Item>!
    
    init(mastodonController: MastodonController) {
        self.mastodonController = mastodonController
        
        super.init(style: .grouped)
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()

        title = NSLocalizedString("Search", comment: "search screen title")
        
        tableView.register(UINib(nibName: "TrendingHashtagTableViewCell", bundle: .main), forCellReuseIdentifier: "trendingTagCell")
        tableView.rowHeight = 60 // 44 for content + 2 * 8 spacing

        dataSource = DataSource(tableView: tableView, cellProvider: { (tableView, indexPath, item) -> UITableViewCell? in
            switch item {
            case let .tag(hashtag):
                let cell = tableView.dequeueReusableCell(withIdentifier: "trendingTagCell", for: indexPath) as! TrendingHashtagTableViewCell
                cell.updateUI(hashtag: hashtag)
                return cell
            }
        })
        
        resultsController = HashtagSearchResultsViewController(mastodonController: mastodonController)
        resultsController.delegate = self
        resultsController.exploreNavigationController = self.navigationController!
        
        searchController = UISearchController(searchResultsController: resultsController)
        searchController.obscuresBackgroundDuringPresentation = true
        searchController.hidesNavigationBarDuringPresentation = false
        searchController.searchResultsUpdater = resultsController
        searchController.searchBar.autocapitalizationType = .none
        searchController.searchBar.placeholder = NSLocalizedString("Search for hashtags to save", comment: "add saved hashtag search field placeholder")
        searchController.searchBar.delegate = resultsController
        searchController.searchBar.showsCancelButton = false
        
        definesPresentationContext = true
        
        navigationItem.searchController = searchController
        navigationItem.hidesSearchBarWhenScrolling = false
        
        navigationItem.leftBarButtonItem = UIBarButtonItem(barButtonSystemItem: .cancel, target: self, action: #selector(cancelButtonPressed))
    }
    
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        
        let request = Client.getTrends(limit: 10)
        mastodonController.run(request) { (response) in
            var snapshot = NSDiffableDataSourceSnapshot<Section, Item>()
            
            guard case let .success(hashtags, _) = response,
                  hashtags.count > 0 else {
                self.dataSource.apply(snapshot)
                return
            }
            
            snapshot.appendSections([.trendingTags])
            snapshot.appendItems(hashtags.map { .tag($0) })
            self.dataSource.apply(snapshot, animatingDifferences: false)
        }
    }
    
    private func selectHashtag(_ hashtag: Hashtag) {
        SavedDataManager.shared.add(hashtag: hashtag, for: mastodonController.accountInfo!)
        presentingViewController!.dismiss(animated: true)
    }
    
    // MARK: - Table View Delegate
    
    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        switch dataSource.itemIdentifier(for: indexPath) {
        case nil:
            return
        case let .tag(hashtag):
            selectHashtag(hashtag)
        }
    }
    
    // MARK: - Interaction
    
    @objc func cancelButtonPressed() {
        dismiss(animated: true)
    }

}

extension AddSavedHashtagViewController {
    enum Section {
        case trendingTags
    }
    
    enum Item: Hashable {
        case tag(Hashtag)
    }
    
    class DataSource: UITableViewDiffableDataSource<Section, Item> {
        override func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
            return NSLocalizedString("Trending Hashtags", comment: "trending hashtags seciton title")
        }
    }
}

extension AddSavedHashtagViewController: SearchResultsViewControllerDelegate {
    func selectedSearchResult(hashtag: Hashtag) {
        selectHashtag(hashtag)
    }
}