swfit

//
//  ViewController.swift
//  VendingMachine
//
//  Created by Pasan Premaratne on 1/19/16.
//  Copyright © 2016 Treehouse. All rights reserved.
//

import UIKit

private let reuseIdentifier = "vendingItem"
private let screenWidth = UIScreen.mainScreen().bounds.width

class ViewController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegate {

    @IBOutlet weak var collectionView: UICollectionView!
    @IBOutlet weak var totalLabel: UILabel!
    @IBOutlet weak var balanceLabel: UILabel!
    @IBOutlet weak var quantityLabel: UILabel!

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        setupCollectionViewCells()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    // MARK: - UICollectionView

    func setupCollectionViewCells() {
        let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
// https://developer.apple.com/library/prerelease/ios/documentation/UIKit/Reference/UICollectionViewFlowLayout_class/
// it works with collection view objects to adjust layout information dynamically.

        layout.sectionInset = UIEdgeInsets(top: 20, left: 0, bottom: 10, right: 0) // sets margins(paddings)
        let padding: CGFloat = 10
        layout.itemSize = CGSize(width: (screenWidth / 3) - padding, height: (screenWidth / 3) - padding)
        layout.minimumInteritemSpacing = 10
        layout.minimumLineSpacing = 10

        collectionView.collectionViewLayout = layout
    }

    func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 12
    }

    func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifier, forIndexPath: indexPath) as! VendingItemCell

        return cell
    }

    func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
        updateCellBackgroundColor(indexPath, selected: true)

    }

    func collectionView(collectionView: UICollectionView, didDeselectItemAtIndexPath indexPath: NSIndexPath) {
        updateCellBackgroundColor(indexPath, selected: false)
    }

    func collectionView(collectionView: UICollectionView, didHighlightItemAtIndexPath indexPath: NSIndexPath) {
        updateCellBackgroundColor(indexPath, selected: true)
    }

    func collectionView(collectionView: UICollectionView, didUnhighlightItemAtIndexPath indexPath: NSIndexPath) {
        updateCellBackgroundColor(indexPath, selected: false)
    }

    func updateCellBackgroundColor(indexPath: NSIndexPath, selected: Bool) {
        if let cell = collectionView.cellForItemAtIndexPath(indexPath) {
            cell.contentView.backgroundColor = selected ? UIColor(red: 41/255.0, green: 211/255.0, blue: 241/255.0, alpha: 1.0) : UIColor.clearColor()
        }
    }

    // MARK: - Helper Methods
}