//
// Copyright 2022 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 Foundation

enum ServerSelectionScreenViewModelAction {
    /// The user would like to use the homeserver at the given address.
    case confirm(homeserverAddress: String)
    /// Dismiss the view without using the entered address.
    case dismiss
}

struct ServerSelectionScreenViewState: BindableState {
    /// The message to be shown in the text field footer when no error has occurred.
    private let regularFooterMessage = {
        let linkPlaceholder = "{link}"
        var message = AttributedString(L10n.screenChangeServerFormNotice(linkPlaceholder))
        message.replace(linkPlaceholder,
                        with: L10n.actionLearnMore,
                        asLinkTo: ServiceLocator.shared.settings.slidingSyncLearnMoreURL)
        return message
    }()
    
    /// View state that can be bound to from SwiftUI.
    var bindings: ServerSelectionScreenBindings
    /// An error message to be shown in the text field footer.
    var footerErrorMessage: String?
    /// Whether the screen is presented modally or within a navigation stack.
    var isModallyPresented: Bool
    
    /// The message to show in the text field footer.
    var footerMessage: AttributedString {
        footerErrorMessage.map(AttributedString.init) ?? regularFooterMessage
    }
    
    /// The title shown on the confirm button.
    var buttonTitle: String {
        isModallyPresented ? L10n.actionContinue : L10n.actionNext
    }
    
    /// The text field is showing an error.
    var isShowingFooterError: Bool {
        footerErrorMessage != nil
    }
    
    /// Whether it is possible to continue when tapping the confirmation button.
    var hasValidationError: Bool {
        bindings.homeserverAddress.isEmpty || isShowingFooterError
    }
}

struct ServerSelectionScreenBindings {
    /// The homeserver address input by the user.
    var homeserverAddress: String
    /// Information describing the currently displayed alert.
    var alertInfo: AlertInfo<ServerSelectionScreenErrorType>?
}

enum ServerSelectionScreenViewAction {
    /// The user would like to use the homeserver at the input address.
    case confirm
    /// Dismiss the view without using the entered address.
    case dismiss
    /// Clear any errors shown in the text field footer.
    case clearFooterError
}

enum ServerSelectionScreenErrorType: Hashable {
    /// An error message to be shown in the text field footer.
    case footerMessage(String)
    /// An alert that allows the user to learn about sliding sync.
    case slidingSyncAlert
}