//
// 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 Combine
import UIKit

enum RoomScreenViewModelAction {
    case displayVideo(videoURL: URL)
    case displayFile(fileURL: URL, title: String?)
    case displayEmojiPicker(itemId: String)
}

enum RoomScreenComposerMode: Equatable {
    case `default`
    case reply(id: String, displayName: String)
    case edit(originalItemId: String)
}

enum RoomScreenViewAction {
    case displayEmojiPicker(itemId: String)
    case paginateBackwards
    case itemAppeared(id: String)
    case itemDisappeared(id: String)
    case itemTapped(id: String)
    case linkClicked(url: URL)
    case sendMessage
    case sendReaction(key: String, eventID: String)
    case cancelReply
    case cancelEdit
    case displayReactionsMenuForItemId(itemId: String)
}

struct RoomScreenViewState: BindableState {
    var roomId: String
    var roomTitle = ""
    var roomAvatar: UIImage?
    var items: [RoomTimelineViewProvider] = []
    var isBackPaginating = false
    var showLoading = false
    var bindings: RoomScreenViewStateBindings
    var displayReactionsMenuForItemId = ""
    
    var contextMenuBuilder: (@MainActor (_ itemId: String) -> TimelineItemContextMenu)?
    
    var composerMode: RoomScreenComposerMode = .default
    
    var sendButtonDisabled: Bool {
        bindings.composerText.count == 0
    }
    
    let scrollToBottomPublisher = PassthroughSubject<Void, Never>()
    
    /// Returns the opacity that the supplied timeline item's cell should be.
    func opacity(for item: RoomTimelineViewProvider) -> CGFloat {
        guard case let .reply(selectedItemID, _) = composerMode else { return 1.0 }
        return selectedItemID == item.id ? 1.0 : 0.5
    }
}

struct RoomScreenViewStateBindings {
    var composerText: String
    var composerFocused: Bool
    
    var scrollToBottomButtonVisible = false
    
    /// Information describing the currently displayed alert.
    var alertInfo: AlertInfo<RoomScreenErrorType>?
    
    var debugInfo: DebugScreen.DebugInfo?
}

enum RoomScreenErrorType: Hashable {
    /// A specific error message shown in an alert.
    case alert(String)
}