paiai_ios/PaiAi/PaiaiDataKit/PresentLayer/Group/GroupViewModel.swift

//
//  GroupViewModel.swift
//  PaiAi
//
//  Created by zhengjianfei on 2017/1/4.
//  Copyright © 2017年 FFIB. All rights reserved.
//

import UIKit
import RxSwift
import RxCocoa
import RxDataSources

public protocol GroupViewModelDelegate: class {
    func didSelect(_ items: [PhotoItem], currIndex: Int)
    func navigateToGroupDetail(_ item: GroupItem)
}

public class GroupViewModel {
    
    private let disposeBag = DisposeBag()
    
    private var repository: GroupPhotoRepository
    
    
    private var _isLoading = PublishSubject<Void>()
    private let items = BehaviorRelay<[PhotoItem]>(value: [])
    private let _hasData = BehaviorRelay<Bool>(value: false)
    
    public var groupItem: BehaviorRelay<GroupItem>
    
    public var groupName: Observable<String> {
        return groupItem.asObservable().flatMapLatest({ (item) -> Observable<String> in
            return Observable.just(item.group_name)
        })
    }
    
    public var groupAvatar: Observable<String> {
        return groupItem.asObservable().flatMapLatest({ (item) -> Observable<String> in
            return Observable.just("Group\(item.group_default_avatar)")
        })
    }
    
    public var isLoading: Observable<Void> {
        return _isLoading.asObservable()
    }
    
    public var hasData: Observable<Bool> {
        return _hasData.asObservable()
    }

    public var contents: Observable<[AnimatableSectionModel<Int, PhotoItem>]> {
        return items.map({ model in
            return [AnimatableSectionModel(model: 0, items: model)]
        })
    }
    
    public weak var delegate: GroupViewModelDelegate?
    
    public init(groupItem: GroupItem) {
        self.repository = GroupPhotoRepository(groupId: groupItem.group_id)
        self.groupItem = BehaviorRelay<GroupItem>(value: groupItem)
        ShareRecentGroupInfo.add(groupItem)
    }
    
    public func reload() {
        repository.load()
            .subscribe(onSuccess: {[weak self] (result) in
                guard let `self` = self else { return }
                self._isLoading.onNext(())
                self.items.accept(result)
                self._hasData.accept(result.count > 0)
                }, onError: {[weak self] (error) in
                    guard let `self` = self else { return }
                    self._isLoading.onNext(())
            }).disposed(by: disposeBag)
    }

    public func submit(data: Data) {
        repository.upload(data: data).subscribe(onSuccess: { [weak self] result in
            guard let `self` = self else { return }
            self.items.accept(result)
            Toast.show(message: "照片已上传")
            self._isLoading.onNext(())
        }) {[weak self] (error) in
            guard let  `self` = self else { return }
            Toast.show(message: "照片失败")
            self._isLoading.onNext(())
        }.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)
    }
}

/// GroupViewModelDelegate
public extension GroupViewModel {
    func didSelect(_ index: Int) {
        delegate?.didSelect(items.value, currIndex: index)
    }
    
    @objc func navigateToGroupDetail() {
        delegate?.navigateToGroupDetail(groupItem.value)
    }
}