//
//  UICollectionViewLeftAlignedLayout.swift
//  MVMCoreUI
//
//  Created by Dhamodaram Nandi on 05/06/20.
//  Copyright © 2020 Verizon Wireless. All rights reserved.
//

import Foundation

class UICollectionViewLeftAlignedLayout: UICollectionViewFlowLayout {
    override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
        guard let attributes = super.layoutAttributesForElements(in: rect) else {
            return nil
        }
        var newAttributesForElementsInRect = [UICollectionViewLayoutAttributes]()
        var leftMargin: CGFloat = 0.0;
        let leftPadding: CGFloat = 0
        let interItemSpacing = minimumInteritemSpacing
        var maxY: CGFloat = -1.0
        for attribute in attributes {
            if attribute.frame.origin.y >= maxY {
                leftMargin = leftPadding
            } else {
                var newLeftAlignedFrame = attribute.frame
                newLeftAlignedFrame.origin.x = leftMargin
                attribute.frame = newLeftAlignedFrame
            }
            attribute.frame.origin.x = leftMargin
            leftMargin += attribute.frame.width + interItemSpacing
            maxY = max(attribute.frame.maxY, maxY)
            newAttributesForElementsInRect.append(attribute)
        }
        return newAttributesForElementsInRect
    }
}