/*

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

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    Application Lightbox view controller.

*/

import UIKit

import Photos

/**

        This UICollectionViewController displayes all images in

        a selected asset collection from the Photos library.

 */

class LightboxCollectionViewController: UICollectionViewController {

    // MARK: Properties

    let imageSegueName = "ImageSegue"

    var assetCollection : PHAssetCollection?

    var assets = [PHAsset]()

    /// Requests all image of the assetCollections to be fetched.

    override func viewDidLoad() {

        super.viewDidLoad()

        guard let assetCollection = assetCollection else {

            return

        }

        PHAsset.fetchKeyAssets(in: assetCollection, options: PHFetchOptions())!.enumerateObjects( {

            (item, idx, flag) in self.assets.append(item)

        })

    }

    // MARK: UICollectionViewController delegate methods

    override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {

        return assets.count

    }

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

        guard let cell = collectionView.dequeueReusableCell(withReuseIdentifier: LightboxCollectionViewCell.reuseIdentifier, for: indexPath) as? LightboxCollectionViewCell else { fatalError("Unable to dequeue a LightboxCollectionViewCell") }

        let asset = assets[indexPath.row]

        cell.imageView.image = nil

        let options = PHImageRequestOptions()

        options.isSynchronous = true

        PHCachingImageManager.default().requestImage(for: asset, targetSize: cell.bounds.size, contentMode: PHImageContentMode.aspectFit, options: options) {

            requestedImage, _ in cell.imageView.image = requestedImage

        }

        return cell

    }

    // MARK: Storyboard seque

    override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {

        performSegue(withIdentifier: imageSegueName, sender: assets[indexPath[1]])

    }

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

        guard let imageViewController = segue.destination as? ImageViewController else { return }

        guard let asset = sender as? PHAsset else { return }

        imageViewController.asset = asset

    }

}