//
//  UITableViewExt+rx.swift
//  PaiAi
//
//  Created by LISA on 2017/5/18.
//  Copyright © 2017年 yb. All rights reserved.
//

import UIKit
import RxSwift
import RxCocoa

class FFTableViewReactiveArrayDataSource<Element>
    : NSObject, UITableViewDataSource, SectionedViewDataSourceType{
    var itemModels: [Element]? = nil
    var isInsert = false
    var isDelete = true
    typealias CellFactory = (UITableView, Int, Element) -> UITableViewCell
    var cellFactory: CellFactory
    
    init(cellFactory: @escaping CellFactory) {
        self.cellFactory = cellFactory
    }
    func modelAtIndex(_ index: Int) -> Element? {
        return itemModels?[index]
    }
    
    func model(at indexPath: IndexPath) throws -> Any {
        precondition(indexPath.section == 0)
        guard let item = itemModels?[indexPath.item] else {
            throw RxCocoaError.itemsNotYetBound(object: self)
        }
        return item
    }
    
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return itemModels?.count ?? 0
    }
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        return cellFactory(tableView, indexPath.row, itemModels![indexPath.row])
    }
    func tableView(_ tableView: UITableView, observedElements: [Element]) {
        if self.itemModels?.count ?? 0 > observedElements.count {
            self.itemModels = observedElements
        }else {
            self.itemModels = observedElements
            tableView.reloadData()
            
        }
    
    }
    
    
}
class FFTableViewReactiveArrayDataSourceSequenceWrapper<S: Sequence>
    : FFTableViewReactiveArrayDataSource<S.Iterator.Element>
, RxTableViewDataSourceType {
    typealias Element = S
    
    override init(cellFactory: @escaping CellFactory) {
        super.init(cellFactory: cellFactory)
    }
    
    func tableView(_ tableView: UITableView, observedEvent: Event<S>) {
        UIBindingObserver(UIElement: self) { tableViewDataSource, sectionModels in
            let sections = Array(sectionModels)
            tableViewDataSource.tableView(tableView, observedElements: sections)
            }.on(observedEvent)
    }
}

extension Reactive where Base: UITableView {
    public func items<S: Sequence, Cell: UITableViewCell, O : ObservableType>
        (cellIdentifier: String, cellType: Cell.Type = Cell.self)
        -> (_ source: O)
        -> (_ configureCell: @escaping (Int, S.Iterator.Element, Cell) -> Void)
        -> Disposable
        where O.E == S {
            return { source in
                return { configureCell in
                    let dataSource = FFTableViewReactiveArrayDataSourceSequenceWrapper<S> { (tv, i, item) in
                        let indexPath = IndexPath(item: i, section: 0)
                        let cell = tv.dequeueReusableCell(withIdentifier: cellIdentifier, for: indexPath) as! Cell
                        configureCell(i, item, cell)
                        return cell
                    }
                    return self.items(dataSource: dataSource)(source)
                }
            }
    }
}