element-ios/RiotSwiftUI/Modules/Room/PollHistory/MockPollHistoryScreenState.swift

//
// Copyright 2021 New Vector Ltd
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

import Combine
import Foundation
import SwiftUI

/// Using an enum for the screen allows you define the different state cases with
/// the relevant associated data for each case.
enum MockPollHistoryScreenState: MockScreenState, CaseIterable {
    // A case for each state you want to represent
    // with specific, minimal associated data that will allow you
    // mock that screen.
    case active
    case past
    case activeEmpty
    case pastEmpty
    case loading
    
    /// The associated screen
    var screenType: Any.Type {
        PollHistory.self
    }
    
    /// Generate the view struct for the screen state.
    var screenView: ([Any], AnyView) {
        let pollHistoryMode: PollHistoryMode
        let pollService = MockPollHistoryService()
        
        switch self {
        case .active:
            pollHistoryMode = .active
        case .past:
            pollHistoryMode = .past
        case .activeEmpty:
            pollHistoryMode = .active
            pollService.nextPublisher = Empty(completeImmediately: true,
                                              outputType: TimelinePollDetails.self,
                                              failureType: Error.self).eraseToAnyPublisher()
        case .pastEmpty:
            pollHistoryMode = .past
            pollService.nextPublisher = Empty(completeImmediately: true,
                                              outputType: TimelinePollDetails.self,
                                              failureType: Error.self).eraseToAnyPublisher()
        case .loading:
            pollHistoryMode = .active
            pollService.nextPublisher = Empty(completeImmediately: false,
                                              outputType: TimelinePollDetails.self,
                                              failureType: Error.self).eraseToAnyPublisher()
        }
        
        let viewModel = PollHistoryViewModel(mode: pollHistoryMode, pollService: pollService)
        
        // can simulate service and viewModel actions here if needs be.
        
        return (
            [pollHistoryMode, viewModel],
            AnyView(PollHistory(viewModel: viewModel.context)
                .environmentObject(AvatarViewModel.withMockedServices()))
        )
    }
}