Collection view with blocks

collectionViewCustom.swift

//
//  CollectionView.swift
//  Trendyol
//
//  Created by aybek can kaya on 12/06/2018.
//  Copyright © 2018 aybek can kaya. All rights reserved.
//

import UIKit

// Model conforms this protocol
protocol Listable {
    var className:String { get }
    static var className:String { get }
}

extension Listable {
    var className: String { return String(describing: type(of: self)) }
    static var className: String { return String(describing: self) }
}

protocol HeaderViewListable {
    var subModels:[Listable] { get set }
}

protocol ViewControllerAssignable {
    func assignedViewOnTap(parameters:HeaderViewListable...)
}


class CollectionView: UICollectionView, UICollectionViewDelegate , UICollectionViewDataSource , UICollectionViewDelegateFlowLayout {
    
    static let defaultInsets : UIEdgeInsets = UIEdgeInsetsMake(4, 4, 4, 4)
    static let defaultMinimumSpacing : CGFloat = 4
    
    fileprivate var cellAtIndexPath:((IndexPath)->(UICollectionViewCell)?)? = nil
    fileprivate var sizeAtIndexPath:((IndexPath)->(CGSize)?)? = nil
    fileprivate var didSelectItem:((IndexPath)->Void)? = nil
    fileprivate var headerViewAtIndexPath: ((IndexPath)->(UICollectionReusableView )?)? = nil
    fileprivate var edgeInsetsAtIndexPath: ((Int)->(UIEdgeInsets )?)? = nil
    fileprivate var headerSizeAtIndex: ((Int)->(CGSize)?)? = nil
    
    
    fileprivate var items:[Listable] = []
    fileprivate var headerViewItems:[HeaderViewListable] = []
    
    fileprivate var sizeItem:CGSize = CGSize.zero
    fileprivate var insetsSection:UIEdgeInsets = UIEdgeInsets.zero
    fileprivate var minimumSpacing:CGFloat = 0
    
    fileprivate var pagingCollectionViewEnabled:Bool = false
    fileprivate var isLoadingData:Bool = false
    fileprivate var currentPage:Int = 1
    fileprivate var shouldLoadPage: ((Int)->Void)? = nil
    
    // getters
    var pageCurrent:Int {
        return currentPage
    }
    
    fileprivate enum CollectionViewType {
        case undefined
        case threeRowCellsWithHeader // instagram style :)
    }
    
    fileprivate var type:CollectionViewType = CollectionViewType.undefined
    
    func collectionViewWithHeaderThreeRowCells<G:HeaderViewListable>(items:[G] , headerViewAtIndexPath:@escaping (_ indexPath:IndexPath)->(UICollectionReusableView),  cellAtIndexPath:@escaping (_ indexPath:IndexPath)->(UICollectionViewCell?) , sizeAtIndexPath: @escaping (_ indexPath:IndexPath)->(CGSize)  , headerSize:@escaping (_ section:Int)->(CGSize), edgeInsets:@escaping (_ section:Int)->(UIEdgeInsets) , didSelectItem: @escaping (_ indexPath:IndexPath)->Void ) {
        
        minimumSpacing = CollectionView.defaultMinimumSpacing
        self.type = CollectionViewType.threeRowCellsWithHeader
        self.headerSizeAtIndex = headerSize
        self.cellAtIndexPath = cellAtIndexPath
        self.headerViewItems = items
        self.sizeAtIndexPath = sizeAtIndexPath
        self.didSelectItem = didSelectItem
        self.edgeInsetsAtIndexPath = edgeInsets
        self.headerViewAtIndexPath = headerViewAtIndexPath
        setUp()
        self.reloadData()
    }
    
    
    func pagingEnabled(shouldLoadNewPage: @escaping (_ pageIndex:Int)->Void) {
        pagingCollectionViewEnabled = true
        self.shouldLoadPage = shouldLoadNewPage
    }
    
    func startLoadingNewPage() {
        isLoadingData = true
    }
    
    func finishLoadingNewPage() {
        if isLoadingData == false { return }
        isLoadingData = false
    }
    
    
    private func setUp() {
        self.delegate = self
        self.dataSource = self
    }
    
    func numberOfSections(in collectionView: UICollectionView) -> Int {
        if self.type == .threeRowCellsWithHeader {
            return self.headerViewItems.count
        }
        return 1
    }
    
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        if self.type == .threeRowCellsWithHeader {
            return headerViewItems[section].subModels.count
        }
        return items.count
    }
    
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        if let collectionViewCell = cellAtIndexPath!(indexPath) {
            return collectionViewCell
        }
        return UICollectionViewCell()
    }
    
    
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
        
        if self.type == .threeRowCellsWithHeader {
            return self.edgeInsetsAtIndexPath!(section)!
        }
        return insetsSection
    }
    
    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        guard let selectionBlock = didSelectItem else { return }
        selectionBlock(indexPath)
    }
    
    func collectionView(_ collectionView: UICollectionView,
                        layout collectionViewLayout: UICollectionViewLayout,
                        sizeForItemAt indexPath: IndexPath) -> CGSize {
        return sizeAtIndexPath!(indexPath)!
    }
    

    func collectionView(_ collectionView: UICollectionView,
                        layout collectionViewLayout: UICollectionViewLayout,
                        minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
        //return 100
        return minimumSpacing
    }
    
    func collectionView(_ collectionView: UICollectionView, layout
        collectionViewLayout: UICollectionViewLayout,
                        minimumLineSpacingForSectionAt section: Int) -> CGFloat {
        //return 100
        return minimumSpacing
    }
    
    func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
        if self.type == .threeRowCellsWithHeader {
            return headerViewAtIndexPath!(indexPath as IndexPath)!
        }
        return UICollectionReusableView()
    }
    
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
        // return CGSize(width:100 , height:100)
        if self.type == .threeRowCellsWithHeader {
            return headerSizeAtIndex!(section)!
        }
        return CGSize.zero
    }
    
    func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
        guard pagingCollectionViewEnabled == true , isLoadingData == false else { return }
        print("item Count: \(items.count) , indexPathRow: \(indexPath.row)")
        if indexPath.row + 1 >= items.count {
            currentPage += 1
            shouldLoadPage!(currentPage)
        }
    }
    
}


// Registrable
extension CollectionView {
    func registerCollectionViewCell(cellIndentifier:String) {
        let nib = UINib(nibName: cellIndentifier, bundle: nil)
        self.register(nib, forCellWithReuseIdentifier: cellIndentifier)
    }
    
    func registerCollectionHeaderView(identifier:String) {
        let nib = UINib(nibName: identifier, bundle: nil)
        self.register(nib, forSupplementaryViewOfKind: UICollectionElementKindSectionHeader , withReuseIdentifier: identifier)
    }
}