import Messages
import SwiftUI
import UIKit

class MessagesViewController: MSMessagesAppViewController {
    private let gameController = GameController()
    private var hostingController: UIHostingController<RootView>?
    private var currentSession: MSSession?

    override func viewDidLoad() {
        super.viewDidLoad()
        gameController.onRequestExpand = { [weak self] in
            self?.requestPresentationStyle(.expanded)
        }
        gameController.onRequestCollapse = { [weak self] in
            self?.requestPresentationStyle(.compact)
        }
        gameController.onShareGame = { [weak self] gameID, password, caption, newSession in
            self?.insertGameMessage(
                gameID: gameID,
                password: password,
                caption: caption,
                newSession: newSession
            )
        }
        embedRootIfNeeded()
    }

    override func willBecomeActive(with conversation: MSConversation) {
        apply(conversation: conversation, style: presentationStyle)
        embedRootIfNeeded()
    }

    override func didResignActive(with conversation: MSConversation) {
        gameController.stopPolling()
    }

    override func didReceive(_ message: MSMessage, conversation: MSConversation) {
        apply(conversation: conversation, style: presentationStyle)
    }

    override func didCancelSending(_ message: MSMessage, conversation: MSConversation) {
        apply(conversation: conversation, style: presentationStyle)
    }

    override func willTransition(to presentationStyle: MSMessagesAppPresentationStyle) {
        gameController.presentationStyle = chrome(for: presentationStyle)
    }

    override func didTransition(to presentationStyle: MSMessagesAppPresentationStyle) {
        gameController.presentationStyle = chrome(for: presentationStyle)
    }

    private func apply(conversation: MSConversation, style: MSMessagesAppPresentationStyle) {
        if let selected = conversation.selectedMessage {
            currentSession = selected.session
        }
        gameController.configureMessages(
            style: chrome(for: style),
            remoteParticipantCount: conversation.remoteParticipantIdentifiers.count,
            gameURL: conversation.selectedMessage?.url
        )
    }

    private func chrome(for style: MSMessagesAppPresentationStyle) -> PresentationChrome {
        style == .expanded ? .expanded : .compact
    }

    private func insertGameMessage(
        gameID: Int,
        password: String?,
        caption: String,
        newSession: Bool
    ) {
        guard let conversation = activeConversation else {
            gameController.errorMessage = "No active conversation to send into."
            return
        }
        let session = newSession ? nil : (conversation.selectedMessage?.session ?? currentSession)
        let message = MSMessage(session: session ?? MSSession())
        message.url = MessageGameID.url(gameID: gameID, password: password)
        message.summaryText = caption

        let layout = MSMessageTemplateLayout()
        layout.caption = "Six Card Golf"
        layout.subcaption = caption
        layout.trailingCaption = "#\(gameID)"
        message.layout = layout

        currentSession = message.session
        // `send` delivers immediately (no compose-field Send tap), like Game Pigeon.
        conversation.send(message) { [weak self] error in
            DispatchQueue.main.async {
                if let error {
                    self?.gameController.errorMessage = error.localizedDescription
                }
            }
        }
    }

    private func embedRootIfNeeded() {
        guard hostingController == nil else { return }
        let hosting = UIHostingController(rootView: RootView(controller: gameController))
        hostingController = hosting
        addChild(hosting)
        hosting.view.translatesAutoresizingMaskIntoConstraints = false
        hosting.view.backgroundColor = .clear
        view.addSubview(hosting.view)
        NSLayoutConstraint.activate([
            hosting.view.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            hosting.view.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            hosting.view.topAnchor.constraint(equalTo: view.topAnchor),
            hosting.view.bottomAnchor.constraint(equalTo: view.bottomAnchor)
        ])
        hosting.didMove(toParent: self)
    }
}