DynamicSection

import Foundation
import UIKit
import DataSources
import EasyPeasy

protocol ModelNew {
    var title: String { get }
}

struct ModelM : ModelNew, Diffable {
    
    var diffIdentifier: AnyHashable {
        return AnyHashable(identity)
    }
    
    let identity: String
    let title: String
}


final class Header : UICollectionReusableView {
    
    let label = UILabel()
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        
        addSubview(label)
        
        //label.frame = self.frame
        
        label <- Edges(8)
        
        label.textAlignment = .center
        label.font = UIFont.boldSystemFont(ofSize: 20)
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

final class Cell : UICollectionViewCell {
    
    let label = UILabel()
    private let paddingView = UIView()
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        
        contentView.addSubview(paddingView)
        contentView.addSubview(label)
        label <- Center()
        paddingView <- Edges(2)
        
        //label.frame = self.frame
        //label.center = self.center
        //paddingView.frame = self.frame
        
        label.textAlignment = .center
        label.font = UIFont.systemFont(ofSize: 20)
        
        paddingView.backgroundColor = UIColor(white: 0.95, alpha: 1)
        paddingView.layer.cornerRadius = 4
        paddingView.layer.shouldRasterize = true
        paddingView.layer.rasterizationScale = UIScreen.main.scale
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

extension String{
    static func randomEmoji() -> String{
        let range = 0x1F601...0x1F64F
        let ascii = range.lowerBound + Int(arc4random_uniform(UInt32(range.count)))
        
        var view = UnicodeScalarView()
        view.append(UnicodeScalar(ascii)!)
        
        let emoji = String(view)
        
        return emoji
    }
}


final class ViewController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout  {
    
    var collectionView: UICollectionView = {
        let layout = UICollectionViewFlowLayout()
        layout.sectionInset = .zero
        layout.minimumLineSpacing = 0
        layout.minimumInteritemSpacing = 0
        
        let collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
        collectionView.register(Cell.self, forCellWithReuseIdentifier: "Cell")
        collectionView.register(Header.self, forSupplementaryViewOfKind: UICollectionElementKindSectionHeader, withReuseIdentifier: "Header")
        collectionView.backgroundColor = .white
        return collectionView
    }()
    
    private lazy var _dataSource: DataController<CollectionViewAdapter> = .init(adapter: .init(collectionView: self.collectionView))    
    var sectionModels = NSMutableArray()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        collectionView.delegate = self
        collectionView.dataSource = self
        
        
        for _ in 0..<5 {
            let section0 = Section(ModelM.self, isEqual: { $0.identity == $1.identity })
            var section0Models: [ModelM] = [] {
                didSet {
                    _dataSource.update(
                        in: section0,
                        items: section0Models,
                        updateMode: .partial(animated: true),
                        completion: {
                            print(self._dataSource.numberOfItems(in: 0))
                    })
                }
            }
            _dataSource.add(section: section0)
            for _ in 0..<20 {
                section0Models.append(ModelM(identity: UUID().uuidString, title: String.randomEmoji()))
            }
            sectionModels.add(section0)
        }
        
        
        
        view.addSubview(collectionView)
        collectionView.frame = self.view.bounds
        collectionView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
        
        //This return zero items even though section0Models has 20 items
        print(_dataSource.numberOfItems(in: 0))
        self.navigationController?.title = "This is title"
        self.navigationController?.navigationItem.rightBarButtonItem = UIBarButtonItem(title: "Add", style: .plain, target: self, action: #selector(addTapped))
        
    }
    @IBAction func AddItem(_ sender: Any) {
        let section0 = Section(ModelM.self, isEqual: { $0.identity == $1.identity })
        var section0Models: [ModelM] = [] {
            didSet {
                _dataSource.update(
                    in: section0,
                    items: section0Models,
                    updateMode: .partial(animated: true),
                    completion: {
                        print(self._dataSource.numberOfItems(in: 0))
                })
            }
        }
        _dataSource.add(section: section0)
        for _ in 0..<20 {
            section0Models.append(ModelM(identity: UUID().uuidString, title: String.randomEmoji()))
        }
    
    }
    @objc func addTapped() {
        let section0 = Section(ModelM.self, isEqual: { $0.identity == $1.identity })
        var section0Models: [ModelM] = [] {
            didSet {
                _dataSource.update(
                    in: section0,
                    items: section0Models,
                    updateMode: .partial(animated: true),
                    completion: {
                        print(self._dataSource.numberOfItems(in: 0))
                })
            }
        }
        _dataSource.add(section: section0)
        for _ in 0..<20 {
            section0Models.append(ModelM(identity: UUID().uuidString, title: String.randomEmoji()))
        }
    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    
    func numberOfSections(in collectionView: UICollectionView) -> Int {
        return _dataSource.numberOfSections()
    }
    
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return _dataSource.numberOfItems(in: section)
    }
    
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath) as! Cell
        if sectionModels.count > indexPath.section {
            let section0: Section<ModelM> = sectionModels.object(at: indexPath.section) as! Section<ModelM>
            let m = _dataSource.item(at: indexPath, in: section0)
            cell.label.text = m.title
        }

        return cell
    }
    
    func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
        if kind == UICollectionElementKindSectionHeader {
            let view = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "Header", for: indexPath) as! Header
            view.label.text = "Section " + indexPath.section.description
            return view
        }
        fatalError()
    }
    
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
        
        return CGSize(width: collectionView.bounds.width, height: 50)
    }
    
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        
        return CGSize(width: collectionView.bounds.width / 6, height: 50)
    }
}