paiai_ios/PaiAi/PaiaiDataKit/PresentLayer/Home/HomeViewModel.swift

//
//  HomeViewModel.swift
//  PaiaiDataKit
//
//  Created by FFIB on 2016/12/29.
//  Copyright © 2016年 FFIB. All rights reserved.
//

import Foundation
import RxSwift
import RxCocoa
import RxDataSources

public protocol HomeViewModelDelegate: class {
    func scanQR()
    func createGroup()
    func didSelect(_ _items: [PhotoItem], currIndex: Int)
}

public class HomeViewModel {
    
    private var page: Int = 1
    private let disposeBag = DisposeBag()
    
    private var repository: HomeRepository
    
    private var _isLoading = PublishSubject<Bool>()
    private var _hasMoreData = BehaviorRelay<Bool>(value: true)
    private let _items = BehaviorRelay<[PhotoItem]>(value: [])
    
    public var scanBtnTapped = PublishSubject<Void>()
    public var createBtnTapped = PublishSubject<Void>()
    
    
    public var isLoading: Observable<Bool> {
        return _isLoading.asObservable()
    }
    
    public var hasMoreData: Observable<Bool> {
        return _hasMoreData.asObservable()
    }
    
    public var contents: Observable<[AnimatableSectionModel<Int, PhotoItem>]> {
        return _items.map({ model in
            return [AnimatableSectionModel(model: 0, items: model)]
        })
    }
    
    public weak var delegate: HomeViewModelDelegate?
    
    public init() {
        self.repository = HomeRepository()
        
        scanBtnTapped.subscribe({
            [weak self] (_) in
            guard let `self` = self else { return }
            self.delegate?.scanQR()
        }).disposed(by: disposeBag)
        
        createBtnTapped.subscribe({
            [weak self] (_) in
            guard let `self` = self else { return }
            self.delegate?.createGroup()
        }).disposed(by: disposeBag)
        
        setNotification()
    }

    public func reload() {
        page = 1
        repository.load(page: page)
            .subscribe(onSuccess: {[weak self] (result) in
                guard let `self` = self else { return }
                self._isLoading.onNext(true)
                self._items.accept(result.data)
                self._hasMoreData.accept(result.hasMore)
            }, onError: {[weak self] (_) in
                guard let `self` = self else { return }
                self._isLoading.onNext(true)
            }).disposed(by: disposeBag)
    }
    
    public func preload() {
        guard _hasMoreData.value else { return }
        page += 1
        repository.load(page: page)
            .subscribe(onSuccess: {[weak self] (result) in
                guard let `self` = self else { return }
                self._isLoading.onNext(false)
                self._hasMoreData.accept(result.hasMore)
                self._items.accept(self._items.value + result.data)
                }, onError: {[weak self] (_) in
                    guard let `self` = self else { return }
                    self._isLoading.onNext(false)
            }).disposed(by: disposeBag)
    }
    
    public func layoutSizeForIndexPath(_ indexPath: IndexPath) -> CGSize {
        let item = _items.value[indexPath.row]
        let w = item.photo_thumbnail_w
        let h = item.photo_thumbnail_h
        
//        header 42, footer: 32
        return CGSize(width: w, height: h + 74)
    }
    
    private func setNotification() {
        NotificationCenter.default.rx.notification(.GroupItemsChanged).subscribe(onNext: { (notification) in
            guard let itemOperator = notification.userInfo?[GroupItemsOperator.key] as? GroupItemsOperator else { return }
            var items = self._items.value
            switch itemOperator {
            case let .update(id, v):
                items = items.map({ (item) -> PhotoItem in
                    
                    if item.group_id == id {
                        var tmp = item
                        tmp.group_name = v.group_name
                        
                        return tmp
                    }
                    return item
                })
                self._items.accept(items)
                break
            case let .remove(id):
                items.removeAll(where: { $0.group_id == id })
                self._items.accept(items)
            }
        }).disposed(by: disposeBag)
        
        NotificationCenter.default.rx.notification(.PhotoItemsChanged).subscribe(onNext: { (notification) in
            guard let itemOperator = notification.userInfo?[PhotoItemsOperator.key] as? PhotoItemsOperator,
                case let .update(id, v) = itemOperator,
                let index = self._items.value.firstIndex(where: { $0.photo_id == id }) else { return }
            var items = self._items.value
            items[index] = v
            self._items.accept(items)
        }).disposed(by: disposeBag)
    }
}

//coordinator delegate
extension HomeViewModel {
    public func scanQR() {
        delegate?.scanQR()
    }
    
    public func createGroup() {
        delegate?.createGroup()
    }
    
    public func didSelect(_ currIndex: Int) {
        delegate?.didSelect(_items.value, currIndex: currIndex)
    }
}