VPNFeedbackFormViewModel.swift

//
//  VPNFeedbackFormViewModel.swift
//
//  Copyright © 2023 DuckDuckGo. All rights reserved.
//
//  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 Foundation
import Combine
import SwiftUI

protocol VPNFeedbackFormViewModelDelegate: AnyObject {
    func vpnFeedbackViewModelDismissedView(_ viewModel: VPNFeedbackFormViewModel)
}

final class VPNFeedbackFormViewModel: ObservableObject {

    enum ViewState {
        case feedbackPending
        case feedbackSending
        case feedbackSendingFailed
        case feedbackSent

        var canSubmit: Bool {
            switch self {
            case .feedbackPending: return true
            case .feedbackSending: return false
            case .feedbackSendingFailed: return true
            case .feedbackSent: return false
            }
        }
    }

    enum ViewAction {
        case cancel
        case submit
    }

    @Published var viewState: ViewState {
        didSet {
            updateSubmitButtonStatus()
        }
    }

    @Published var feedbackFormText: String = "" {
        didSet {
            updateSubmitButtonStatus()
        }
    }

    @Published private(set) var submitButtonEnabled: Bool = false
    @Published var selectedFeedbackCategory: VPNFeedbackCategory

    weak var delegate: VPNFeedbackFormViewModelDelegate?

    private let metadataCollector: VPNMetadataCollector
    private let feedbackSender: VPNFeedbackSender

    init(metadataCollector: VPNMetadataCollector,
         feedbackSender: VPNFeedbackSender = DefaultVPNFeedbackSender()) {
        self.viewState = .feedbackPending
        self.selectedFeedbackCategory = .landingPage

        self.metadataCollector = metadataCollector
        self.feedbackSender = feedbackSender
    }

    @MainActor
    func process(action: ViewAction) async {
        switch action {
        case .cancel:
            delegate?.vpnFeedbackViewModelDismissedView(self)
        case .submit:
            self.viewState = .feedbackSending

            do {
                let metadata = await self.metadataCollector.collectVPNMetadata()
                try await self.feedbackSender.send(metadata: metadata, category: selectedFeedbackCategory, userText: feedbackFormText)
                self.viewState = .feedbackSent
            } catch {
                self.viewState = .feedbackSendingFailed
            }
        }
    }

    private func updateSubmitButtonStatus() {
        self.submitButtonEnabled = viewState.canSubmit && !feedbackFormText.isEmpty
    }

}