LeftAlignedCollectionViewFlowLayout

//
//  Created by Akash Soni on 1/13/21.
//  Copyright © 2021 buzzyears. All rights reserved.
//
import UIKit

class LeftAlignedCollectionViewFlowLayout: UICollectionViewFlowLayout {

    override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
        self.headerReferenceSize = CGSize(width: self.collectionView?.frame.size.width ?? 300, height: 60)

        let attributes = super.layoutAttributesForElements(in: rect)

        var leftMargin = sectionInset.left
        var maxY: CGFloat = -1.0
        attributes?.forEach { layoutAttribute in
            if layoutAttribute.frame.origin.y >= maxY {
                leftMargin = sectionInset.left
            }

            layoutAttribute.frame.origin.x = leftMargin

            leftMargin += layoutAttribute.frame.width + minimumInteritemSpacing
            maxY = max(layoutAttribute.frame.maxY , maxY)
        }

        return attributes
    }
    
    override func prepare() {
        super.prepare()
    }

    override func layoutAttributesForDecorationView(ofKind elementKind: String, at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
        let attributes = UICollectionViewLayoutAttributes(forSupplementaryViewOfKind: elementKind, with: indexPath)
        attributes.frame = CGRect(x: 0, y: 0, width: self.collectionView?.frame.size.width ?? 300, height: 60)

        return attributes

    }
}