//
//  EditListSearchResultsContainerViewController.swift
//  Tusker
//
//  Created by Shadowfacts on 11/11/22.
//  Copyright © 2022 Shadowfacts. All rights reserved.
//

import UIKit
import Combine

class EditListSearchResultsContainerViewController: UIViewController {
    
    private let mastodonController: MastodonController
    private let didSelectAccount: (String) -> Void
    
    private let searchResultsController: SearchResultsViewController
    private let searchFollowingController: EditListSearchFollowingViewController
    
    var mode = Mode.search {
        willSet {
            currentViewController.removeViewAndController()
        }
        didSet {
            embedChild(currentViewController)
        }
    }
    var currentViewController: UIViewController {
        switch mode {
        case .search:
            return searchResultsController
        case .following:
            return searchFollowingController
        }
    }
    
    private var currentQuery: String?
    private var searchSubject = PassthroughSubject<String?, Never>()
    private var cancellables = Set<AnyCancellable>()
    
    init(mastodonController: MastodonController, didSelectAccount: @escaping (String) -> Void) {
        self.mastodonController = mastodonController
        self.didSelectAccount = didSelectAccount
        
        self.searchResultsController = SearchResultsViewController(mastodonController: mastodonController, resultTypes: [.accounts])
        self.searchFollowingController = EditListSearchFollowingViewController(mastodonController: mastodonController, didSelectAccount: didSelectAccount)
        
        super.init(nibName: nil, bundle: nil)
        
        self.searchResultsController.delegate = self
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()

        embedChild(currentViewController)
        
        searchSubject
            .debounce(for: .milliseconds(500), scheduler: RunLoop.main)
            .sink { [unowned self] in self.performSearch(query: $0) }
            .store(in: &cancellables)
    }
    
    func performSearch(query: String?) {
        guard var query = query?.trimmingCharacters(in: .whitespacesAndNewlines) else {
            return
        }
        if query.starts(with: "@") {
            query = String(query.dropFirst())
        }
        guard query != self.currentQuery else {
            return
        }
        self.currentQuery = query
        
        switch mode {
        case .search:
            searchResultsController.performSearch(query: query)
        case .following:
            searchFollowingController.updateQuery(query)
        }
    }
    
    enum Mode: Equatable {
        case search, following
    }

}

extension EditListSearchResultsContainerViewController: UISearchResultsUpdating {
    func updateSearchResults(for searchController: UISearchController) {
        searchSubject.send(searchController.searchBar.text)
    }
}

extension EditListSearchResultsContainerViewController: UISearchBarDelegate {
    func searchBarTextDidEndEditing(_ searchBar: UISearchBar) {
        performSearch(query: searchBar.text)
    }
    
    func searchBar(_ searchBar: UISearchBar, selectedScopeButtonIndexDidChange selectedScope: Int) {
        mode = selectedScope == 0 ? .search : .following
        performSearch(query: searchBar.text)
    }
}

extension EditListSearchResultsContainerViewController: SearchResultsViewControllerDelegate {
    func selectedSearchResult(account accountID: String) {
        didSelectAccount(accountID)
    }
}