import UIKit
import ChameleonFramework
import Alamofire
import AlamofireImage

extension ViewController: UICollectionViewDelegate, UICollectionViewDataSource, UIScrollViewDelegate {

    //MARK: Collection View Delegate Methods
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return latestMovies.count
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "mCell", for: indexPath) as! MovieCollectionViewCell

        let cachedImage = imageCache.image(withIdentifier: latestMovies[indexPath.row].getFullImageURL())
        if  cachedImage != nil {
            cell.coverView.image = cachedImage
            colorTracker = cachedImage!
            self.calculateBackgroundColor() // PEPPE
            //print("using the cache")
        }
        else {
            downloadPoster(from: latestMovies[indexPath.row].getFullImageURL(), cell: cell)
        }


        cell.movieName.text = latestMovies[indexPath.row].title
        cell.releaseDate.text = "Release date: " + latestMovies[indexPath.row].release_date
        //setViewColors(from: colorTracker)
        cell.changeCellColorAttributes(with: UIColor(averageColorFrom: colorTracker))
        setShadows(to: cell)
        return cell
    }

    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        performSegue(withIdentifier: "showDetails", sender: latestMovies[indexPath.row])
    }


    // Set the Collection View Cells to be 'always centered':
    func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
        let layout = self.moviesCollection.collectionViewLayout as! UICollectionViewFlowLayout
        let cellWidthIncludingSpacing = layout.itemSize.width + layout.minimumLineSpacing
        var offset = targetContentOffset.pointee
        let index = (offset.x + scrollView.contentInset.left) / cellWidthIncludingSpacing
        let roundedIndex = round(index)
        offset = CGPoint(x: roundedIndex * cellWidthIncludingSpacing - scrollView.contentInset.left, y: -scrollView.contentInset.top)
        targetContentOffset.pointee = offset
    }

    func scrollViewDidEndDragging(_ scrollView: UIScrollView, willDecelerate decelerate: Bool) {

    }

    func scrollViewWillBeginDragging(_ scrollView: UIScrollView) {

    }

    //MARK: Networking & API Request
    func downloadPoster(from url: String, cell: MovieCollectionViewCell) {

        Alamofire.request(url).responseImage { [weak self] (response) in
            guard let self = self else { return }
            guard let image = response.value else { return }

            DispatchQueue.main.async {
                cell.coverView.image = image
                self.imageCache.add(image, withIdentifier: url)
                self.colorTracker = image
                self.imagesArray.append(image)

                self.calculateBackgroundColor() // PEPPE
            }
        }
    }

    // PEPPE
    func calculateBackgroundColor() {
        DispatchQueue.main.async {
            let indexPaths: [IndexPath] = self.moviesCollection.indexPathsForVisibleItems.reversed()
            print(indexPaths)
            print(indexPaths[0].row)
            let cell = self.moviesCollection.cellForItem(at: indexPaths[0]) as! MovieCollectionViewCell
            guard let image = cell.coverView.image else { return }
            self.setViewColors(from: image)
        }
    }

    //MARK: Customization & Appearence:

    func setViewColors(from image: UIImage) {

        self.view.backgroundColor = UIColor(averageColorFrom: image)
        if let backColor = self.view.backgroundColor, let navBar = navigationController?.navigationBar {
            self.moviesCollection.backgroundColor = backColor
            navBar.barTintColor = backColor
            navBar.tintColor = ContrastColorOf(backColor, returnFlat: true)
            navBar.largeTitleTextAttributes = [NSAttributedString.Key.foregroundColor : ContrastColorOf(backColor, returnFlat: true)]
        }
    }

    func setShadows(to cell: MovieCollectionViewCell) {
        cell.layer.cornerRadius = 3.0
        cell.layer.shadowRadius = 10
        cell.layer.shadowOpacity = 0.4
        cell.layer.shadowOffset = CGSize(width: 5, height: 10)
        cell.clipsToBounds = false
    }

}