LeadKit/Sources/Protocols/Loading/PaginationLoading/PaginationLoadingViewModelConfiguration.swift

//
//  Copyright (c) 2017 Touch Instinct
//
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the Software), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the Software is
//  furnished to do so, subject to the following conditions:
//
//  The above copyright notice and this permission notice shall be included in
//  all copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED AS IS, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
//  THE SOFTWARE.
//

import RxSwift
import RxCocoa

public final class PaginationLoadingViewModelConfiguration<C: ResettableCursorDataSource>: LoadingConfiguration
    where C.ResultType == [C.Element] {

    public typealias DataSourceType = C
    public typealias LoadingStateType = PaginationLoadingState<DataSourceType>

    public private(set) var dataSource: DataSourceType
    private let stateVariable = Variable<LoadingStateType>(.initialState)
    public let scheduler = SerialDispatchQueueScheduler(qos: .default)

    private var currentRequestDisposable: Disposable?

    public init(dataSource: DataSourceType) {
        self.dataSource = dataSource
    }

    public var loadingObservable: Single<C.ResultType> {
        return dataSource.loadNextBatch()
    }

    public func isEmptyResult(result: C.ResultType) -> Bool {
        return result.isEmpty
    }

    public var stateDriver: Driver<LoadingStateType> {
        return stateVariable.asDriver()
    }

    public var state: LoadingStateType {
        get {
            return stateVariable.value
        }
        set {
            stateVariable.value = newValue
        }
    }

    public func resetDataSource() {
        currentRequestDisposable?.dispose()
        dataSource = dataSource.reset()
    }

    public func storeCurrentRequestDisposable(_ disposable: Disposable) {
        currentRequestDisposable = disposable
    }

}