RxDataSource 动画数据源

//
//  ViewController.swift
//  RxSwiftTest
//
//  Created by xiaoP on 2017/3/15.
//  Copyright © 2017年 Chicv. All rights reserved.
//

import UIKit
import RxSwift
import RxCocoa
import SnapKit
import RxGesture
import RxOptional
import RxDataSources

class ViewController: UIViewController {

    let tableView = UITableView(frame: CGRect.zero)
    let dataSource = RxTableViewSectionedAnimatedDataSource<PriceSectionModel>()
    let bag = DisposeBag()
    fileprivate var heightConstraint: Constraint?
    
    
    override func viewDidLoad() {
        super.viewDidLoad()
        configUI()
        bind()
    }
    
    fileprivate func configUI() {
        automaticallyAdjustsScrollViewInsets = false
        
        let rightItem = UIBarButtonItem(title: "insert/delete", style: .done, target: nil, action: nil)
        navigationItem.rightBarButtonItem = rightItem
        
        view.backgroundColor = UIColor.black
        view.addSubview(tableView)
        
        tableView.snp.makeConstraints { (make: ConstraintMaker) in
            make.left.right.bottom.equalToSuperview()
            self.heightConstraint = make.height.equalTo(0).constraint
        }
        tableView.delegate = self
        tableView.tableFooterView = UIView()
        tableView.register(UINib(nibName: "PriceCell", bundle: nil), forCellReuseIdentifier: "PriceCell")
        tableView.register(UINib(nibName: "PayCell", bundle: nil), forCellReuseIdentifier: "PayCell")
        
        dataSource.configureCell = { (ds, tv, ip, item) in
            switch item {
            case let .price(title, value):
                let cell = tv.dequeueReusableCell(withIdentifier: "PriceCell", for: ip) as! PriceCell
                cell.fillData(title: title, value: value)
                return cell
            case .pay:
                let cell = tv.dequeueReusableCell(withIdentifier: "PayCell", for: ip) as! PayCell
                return cell
            }
        }
    }
    
    fileprivate func bind() {
        let items: Variable<[PriceItem]> = Variable([
            .price(title: "Sub Total", value: "$135.50"),
            .price(title: "Quantity", value: "6"),
            .price(title: "Standard Delivery", value: "$10.00"),
            .price(title: "Total", value: "$145.50"),
            .pay
        ])
        
        let rightItem = navigationItem.rightBarButtonItem!
        rightItem.rx.tap
            .map{ _-> PriceItem in
                let count = Int(arc4random() % 1000)
                return .price(title: "Inserted\(count)", value: "$0.00")
            }
            .bindNext { (item: PriceItem) in
                let index = Int(arc4random() % UInt32(items.value.count))
                if index % 2 == 0 && items.value.isNotEmpty {
                    items.value.remove(at: index)
                } else {
                    items.value.insert(item, at: index)
                }
            }
            .disposed(by: bag)
        
        let data = items
            .asObservable()
            .map { (items: [PriceItem]) -> [PriceSectionModel] in
                return [PriceSectionModel(header: "", prices: items)]
            }
            
        data
            .delay(1.5, scheduler: MainScheduler.instance)
            .bindTo(tableView.rx.items(dataSource: dataSource))
            .disposed(by: bag)
        
        data
            .map { (sections: [PriceSectionModel]) -> CGFloat in
                return sections.reduce(0){ (sum, section) in
                    return sum + section.items.reduce(0){ (sum, item) in
                        switch item {
                        case .price:
                            return sum + 44
                        case .pay:
                            return sum + 50
                        }
                    }
                }
            }
            .bindNext { [weak self] (height: CGFloat) in
                self?.heightConstraint?.update(offset: height)
                UIView.animate(withDuration: 1, animations: { [weak self] in
                    self?.view.layoutIfNeeded()
                })
            }
            .disposed(by: bag)
    }
    
}

extension ViewController: UITableViewDelegate {
    
    func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
        let item = dataSource[indexPath]
        switch item {
        case .price:
            return 44
        case .pay:
            return 50
        }
    }
    
}

struct PriceSectionModel {
    var header: String
    var prices: [PriceItem]
    
    init(header: String, prices: [Item]) {
        self.header = header
        self.prices = prices
    }
    
}

extension PriceSectionModel: AnimatableSectionModelType {
    typealias Item = PriceItem
    typealias Identity = String
    
    var identity: String {
        return header
    }
    
    var items: [Item] {
        return prices
    }
    
    init(original: PriceSectionModel, items: [Item]) {
        self = original
        self.prices = items
    }
}

enum PriceItem: IdentifiableType, Equatable {
    typealias Identity = String
    
    case price(title: String, value: String)
    case pay
    
    var identity: String {
        switch self {
        case let .price(title, _):
            return "price-\(title)"
        case .pay:
            return "pay"
        }
    }
    
    static func ==(l: PriceItem, r: PriceItem)-> Bool {
        return l.identity == r.identity
    }
    
}