// 
// 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
import Reusable
import WysiwygComposer
import SwiftUI
import Combine
import UIKit
import CoreGraphics

class SelfSizingHostingController<Content>: UIHostingController<Content> where Content: View {

    var heightSubject = CurrentValueSubject<CGFloat, Never>(0)
    
    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        let height = sizeThatFits(in: CGSize(width: self.view.frame.width, height: 800)).height
        heightSubject.send(height)
    }
}

@objc protocol HtmlRoomInputToolbarViewProtocol: RoomInputToolbarViewProtocol {
    @objc var htmlContent: String { get set }
}

class WysiwygInputToolbarView: MXKRoomInputToolbarView, NibLoadable, HtmlRoomInputToolbarViewProtocol {
    var htmlContent: String {
        get {
            self.hostingViewController.rootView.wysiwygViewModel.content.html
        }
        set {
            self.hostingViewController.rootView.wysiwygViewModel.setHtmlContent(newValue)
        }
    }
    
    var eventSenderDisplayName: String! {
        get {
            viewModel.eventSenderDisplayName
        }
        set {
            viewModel.eventSenderDisplayName = newValue
        }
    }
    
    var sendMode: RoomInputToolbarViewSendMode {
        get {
            viewModel.sendMode.legacySendMode
        }
        set {
            viewModel.sendMode = ComposerSendMode(from: newValue)
        }
    }
    
    override class func instantiate() -> MXKRoomInputToolbarView! {
        return loadFromNib()
    }
    
    private weak var toolbarViewDelegate: RoomInputToolbarViewDelegate? {
        return (delegate as? RoomInputToolbarViewDelegate) ?? nil
    }
    
    private var cancellables = Set<AnyCancellable>()
    private var heightConstraint: NSLayoutConstraint!
    private var hostingViewController: SelfSizingHostingController<Composer>!
    private var viewModel: ComposerViewModelProtocol =  ComposerViewModel(initialViewState: ComposerViewState())
    private static let minToolbarHeight: CGFloat = 100
    
    override func awakeFromNib() {
        super.awakeFromNib()
        viewModel.callback = { [weak self] result in
            guard let self = self else { return }
            switch result {
            case .cancel:
                self.toolbarViewDelegate?.roomInputToolbarViewDidTapCancel(self)
            }
        }
        
        let wysiwygViewModel = WysiwygComposerViewModel()
        let composer = Composer(viewModel: viewModel.context,
            wysiwygViewModel: wysiwygViewModel,
            sendMessageAction: { [weak self] content in
            guard let self = self else { return }
            self.sendWysiwygMessage(content: content)
        }, showSendMediaActions: { [weak self]  in
            guard let self = self else { return }
            self.showSendMediaActions()
        })
        
        hostingViewController = SelfSizingHostingController(rootView: composer)
        let height = hostingViewController.sizeThatFits(in: CGSize(width: self.frame.width, height: 800)).height
        let subView: UIView = hostingViewController.view
        self.addSubview(subView)
        
        hostingViewController.view.translatesAutoresizingMaskIntoConstraints = false
        subView.translatesAutoresizingMaskIntoConstraints = false
        heightConstraint = subView.heightAnchor.constraint(equalToConstant: height)
        NSLayoutConstraint.activate([
            heightConstraint,
            subView.leadingAnchor.constraint(equalTo: self.leadingAnchor),
            subView.trailingAnchor.constraint(equalTo: self.trailingAnchor),
            subView.bottomAnchor.constraint(equalTo: self.bottomAnchor)
        ])
        cancellables = [
            hostingViewController.heightSubject
                .removeDuplicates()
                .sink(receiveValue: { [weak self] idealHeight in
                    guard let self = self else { return }
                    let h = self.hostingViewController.sizeThatFits(in: CGSize(width: self.frame.width, height: 800)).height
                    self.updateToolbarHeight(wysiwygHeight: h)
                })
        ]
        
        update(theme: ThemeService.shared().theme)
        registerThemeServiceDidChangeThemeNotification()
    }

    override func customizeRendering() {
        super.customizeRendering()
        self.backgroundColor = .clear
    }
    
    func setVoiceMessageToolbarView(_ voiceMessageToolbarView: UIView!) {
        //TODO embed the voice messages UI
    }
    
    func toolbarHeight() -> CGFloat {
        return heightConstraint.constant
    }
    
   private func updateToolbarHeight(wysiwygHeight: CGFloat) {
       self.heightConstraint.constant = wysiwygHeight
       toolbarViewDelegate?.roomInputToolbarView?(self, heightDidChanged: wysiwygHeight, completion: nil)
    }
    
    private func sendWysiwygMessage(content: WysiwygComposerContent) {
        delegate?.roomInputToolbarView?(self, sendFormattedTextMessage: content.html, withRawText: content.plainText)
    }
    

    private func showSendMediaActions() {
        delegate?.roomInputToolbarViewShowSendMediaActions?(self)
    }
    
    private func registerThemeServiceDidChangeThemeNotification() {
        NotificationCenter.default.addObserver(self, selector: #selector(themeDidChange), name: .themeServiceDidChangeTheme, object: nil)
    }
    
    @objc private func themeDidChange() {
        self.update(theme: ThemeService.shared().theme)
    }
    
    private func update(theme: Theme) {
        hostingViewController.view.backgroundColor = theme.colors.background
    }
}

fileprivate extension ComposerSendMode {
    init(from sendMode: RoomInputToolbarViewSendMode) {
        switch sendMode {
        case .reply: self = .reply
        case .edit: self = .edit
        case .createDM: self = .createDM
        default: self = .send
        }
    }
    
    var legacySendMode: RoomInputToolbarViewSendMode {
        switch self {
        case .createDM: return .createDM
        case .reply: return .reply
        case .edit: return .edit
        case .send: return .send
        }
    }
}