PhotoViewController.swift

//
//  PhotoViewController.swift
//  SolarSystem
//
//  Created by Neha Thakore on 11/8/17.
//  Copyright © 2017 Neha Thakore. All rights reserved.
//

import UIKit

class PhotoViewController: UIViewController {
    @IBOutlet weak var photoCollectionView: UICollectionView!
    var imageCellModels = [PlanetImageCellModel]()
    var startingIndexPath: IndexPath?

    @IBAction func closeButton(_ sender: Any) {
        dismiss(animated: true, completion: nil)
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        photoCollectionView.delegate = self
        photoCollectionView.dataSource = self
    }
    
    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        
        if let index = startingIndexPath {
            photoCollectionView.scrollToItem(at: index, at: .centeredHorizontally, animated: false)
        }
    }
}

extension PhotoViewController: UICollectionViewDataSource {
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return imageCellModels.count
    }
    
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        guard let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "PhotoCollectionViewCell", for: indexPath) as? PhotoCollectionViewCell else {
            return UICollectionViewCell()
        }
        let imageModel = imageCellModels[indexPath.item]
        cell.cellModel = imageModel
        return cell
    }
}

extension PhotoViewController: UICollectionViewDelegateFlowLayout {
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        return CGSize(width: photoCollectionView.bounds.width, height: photoCollectionView.bounds.height)
    }
}