//
//  MineGroupViewModel.swift
//  PaiaiDataKit
//
//  Created by FFIB on 2017/5/8.
//  Copyright © 2017年 FFIB. All rights reserved.
//

import Foundation
import RxSwift
import RxCocoa
import RxDataSources

public protocol MineGroupViewModelDelegate: class {
    func didSelect(_ item: GroupItem)
}

public class MineGroupViewModel {

    private let repository: GroupRepository
    private var disposeBag = DisposeBag()
    private var page = 1

    private var _isLoading = PublishSubject<Bool>()
    private var _isEmpty = BehaviorRelay<Bool>(value: false)
    private var _hasMoreData = PublishSubject<Bool>()
    private var _showMessage = PublishSubject<String>()
    private let _items = BehaviorRelay<[GroupItem]>(value: [])

    public weak var delegate: MineGroupViewModelDelegate?

    public var isEmpty: Observable<Bool> {
        return _isEmpty.asObservable()
    }

    public var hasMoreData: Observable<Bool> {
        return _hasMoreData.asObservable()
    }

    public var isLoading: Observable<Bool> {
        return _isLoading.asObserver()
    }

    public var showMessage: Observable<String> {
        return _showMessage.asObservable()
    }

    public var contents: Observable<[AnimatableSectionModel<Int, GroupItem>]> {
        return _items.map({ model in
            return [AnimatableSectionModel(model: 0, items: model)]
        })
    }

    public init() {
        self.repository = PhotoGroupRepository()
        setNotification()
    }

    public func reload() {
        page = 1
        repository.load(page: page)
            .asDriver(onErrorJustReturn: NetworkArrayData<GroupItem>.empty())
            .drive(onNext: {[weak self] (model) in
                guard let `self` = self else { return }
                self._hasMoreData.onNext(model.hasMore)
                self._isEmpty.accept(!model.data.isEmpty)

                self._items.accept(model.data)
                }, onDisposed: {[weak self] in
                    guard let `self` = self else { return }
                    self._isLoading.onNext(true)
            }).disposed(by: disposeBag)
    }

    public func preload() {
        page += 1

        repository.load(page: page)
            .asDriver(onErrorJustReturn: NetworkArrayData<GroupItem>.empty())
            .drive(onNext: {[weak self] (model) in
                guard let `self` = self else { return }
                self._hasMoreData.onNext(model.hasMore)
                self._items.accept(self._items.value + model.data)
                }, onDisposed: {[weak self] in
                    guard let `self` = self else { return }
                    self._isLoading.onNext(false)
            }).disposed(by: disposeBag)
    }

    public func remove(of index: Int) {
        Toast.showActivity(message: "正在删除此群")
        repository.remove(groupId: _items.value[index].group_id)
            .subscribe(onCompleted: {[weak self] in
                guard let `self` = self else { return }
                var items = self._items.value
                items.remove(at: index)
                self._items.accept(items)
                self._showMessage.onNext("群已删除")
            }).disposed(by: disposeBag)
    }

    private func setNotification() {
        NotificationCenter.default.rx.notification(.GroupItemsChanged).subscribe(onNext: { (notification) in
            guard let userInfo = notification.userInfo,
                let itemOperator = userInfo[GroupItemsOperator.key] as? GroupItemsOperator else { return }

            switch itemOperator {
            case let .update(groupId, val):
                guard let index = self._items.value.firstIndex(where: { $0.group_id == groupId }) else { return }
                var items = self._items.value
                items[index] = val
                self._items.accept(items)
            case let .remove(groupId):
                var items = self._items.value
                items.removeAll(where: { $0.group_id == groupId })
                self._items.accept(items)
            }
        }).disposed(by: disposeBag)
    }
}

/// ViewModel delegate
public extension MineGroupViewModel {
    func didSelect(_ item: GroupItem) {
        delegate?.didSelect(item)
    }
}