import UIKit

private let listReuseIdentifier = "ListCell"
private let gridReuseIdentifier = "GridCell"

class MainListCollectionViewController: UICollectionViewController {

    private let movies = Movie.dummyMovies
    private var layoutOption: LayoutOption = .list

    override func viewDidLoad() {
        super.viewDidLoad()
        setupCollectionView()
        setupNavigationBarItem()
        setupLayout(with: view.bounds.size)
    }

    private func setupCollectionView() {
        collectionView.register(UINib(nibName: "MovieLayoutListCollectionViewCell", bundle: nil), forCellWithReuseIdentifier: listReuseIdentifier)
        collectionView.register(UINib(nibName: "MovieLayoutGridCollectionViewCell", bundle: nil), forCellWithReuseIdentifier: gridReuseIdentifier)
    }

    private func setupLayout(with containerSize: CGSize) {
        guard let flowLayout = collectionView.collectionViewLayout as? UICollectionViewFlowLayout else {
            return
        }

        switch layoutOption {
        case .list:
            break

        case .largeGrid, .smallGrid:
            break
        }

        collectionView.reloadData()
    }

    private func setupNavigationBarItem() {
        let barButtonItem = UIBarButtonItem(title: "Layout", style: .plain, target: self, action: #selector(layoutTapped(_:)))
        navigationItem.rightBarButtonItem = barButtonItem
    }

    @objc private func layoutTapped(_ sender: Any) {
        let alertController = UIAlertController(title: "Select Layout", message: nil, preferredStyle: .actionSheet)
        alertController.popoverPresentationController?.barButtonItem = navigationItem.rightBarButtonItem
        alertController.addAction(UIAlertAction(title: "List", style: .default, handler: { (_) in
            self.layoutOption = .list
        }))

        alertController.addAction(UIAlertAction(title: "Large Grid", style: .default, handler: { (_) in
            self.layoutOption = .largeGrid
        }))

        alertController.addAction(UIAlertAction(title: "Small Grid", style: .default, handler: { (_) in
            self.layoutOption = .smallGrid
        }))

        alertController.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))
        present(alertController, animated: true, completion: nil)
    }
}

extension MainListCollectionViewController {

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

    override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        switch layoutOption {
        case .list:
            let cell = collectionView.dequeueReusableCell(withReuseIdentifier: listReuseIdentifier, for: indexPath) as! MovieLayoutListCollectionViewCell
            let movie = movies[indexPath.item]
            cell.setup(with: movie)
            return cell

        case .largeGrid:
            let cell = collectionView.dequeueReusableCell(withReuseIdentifier: gridReuseIdentifier, for: indexPath) as! MovieLayoutGridCollectionViewCell
            let movie = movies[indexPath.item]
            cell.setup(with: movie)
            return cell

        case .smallGrid:
            let cell = collectionView.dequeueReusableCell(withReuseIdentifier: gridReuseIdentifier, for: indexPath) as! MovieLayoutGridCollectionViewCell
            let movie = movies[indexPath.item]
            cell.setup(with: movie)
            return cell
        }
    }
}