//
//  PopupQueueManager.swift
//  QuickLocation
//
//  Created by 八条 on 2026/7/3.
//

import UIKit

class PopupQueueManager {

    private weak var sourceVC: UIViewController?
    private var currentStep = 0
    private var stepGeneration = 0
    private var countdownTimer: Timer?
    private var isPaused = false

    init() {
        NotificationCenter.default.addObserver(self,
                                               selector: #selector(handlePause),
                                               name: .pausePopupQueue,
                                               object: nil)
        NotificationCenter.default.addObserver(self,
                                               selector: #selector(handleResume),
                                               name: .resumePopupQueue,
                                               object: nil)
        NotificationCenter.default.addObserver(self,
                                               selector: #selector(handleInvalidate),
                                               name: .invalidatePopupQueue,
                                               object: nil)
    }

    deinit {
        NotificationCenter.default.removeObserver(self)
    }

    func start(from vc: UIViewController) {
        sourceVC = vc
        currentStep = 0
        executeNextStep()
    }

    @objc private func handlePause() {
        countdownTimer?.invalidate()
        countdownTimer = nil
        isPaused = true
    }

    @objc private func handleResume() {
        guard isPaused else { return }
        isPaused = false
        executeNextStep()
    }

    @objc private func handleInvalidate() {
        countdownTimer?.invalidate()
        countdownTimer = nil
        isPaused = true
        currentStep = 3
    }

    private func executeNextStep() {
        guard AppContextManager.shared.systemConfig?.isIntercept == false else { return }
        switch currentStep {
        case 0:
            tryStartPromotionalActivities()
        case 1:
            tryStartSearchPopup()
        case 2:
            tryStartRegisterOrVipPopup()
        default:
            break
        }
    }

    // MARK: - Step 0: PromotionalActivities

    private func tryStartPromotionalActivities() {
        guard let config = AppContextManager.shared.systemConfig else {
            skipToNext()
            return
        }
        guard config.popupConfig?.pay_pop == true,
              AppContextManager.shared.vip == 1,
              let timeConfig = config.timeConfig else {
            skipToNext()
            return
        }
        let gen = stepGeneration
        startCountdown(seconds: timeConfig.pay_pop_time) { [weak self] in
            guard let self = self, self.currentStep == 0, self.stepGeneration == gen else { return }
            let vc = PromotionalActivitiesVC()
            vc.onDismiss = { [weak self] in
                self?.skipToNext()
            }
            self.push(vc)
        }
    }

    // MARK: - Step 1: Search PopupWindow

    private func tryStartSearchPopup() {
        guard let config = AppContextManager.shared.systemConfig else {
            skipToNext()
            return
        }
        guard config.popupConfig?.search_phone == true,
              let timeConfig = config.timeConfig else {
            skipToNext()
            return
        }
        let gen = stepGeneration
        startCountdown(seconds: timeConfig.search_phone) {
            guard self.currentStep == 1, self.stepGeneration == gen else { return }
            PopupWindow.show(popupType: .search) {
                self.skipToNext()
            }
        }
    }

    // MARK: - Step 2: Register or VIP PopupWindow (mutually exclusive)

    private func tryStartRegisterOrVipPopup() {
        guard let config = AppContextManager.shared.systemConfig,
              let timeConfig = config.timeConfig else {
            return
        }

        if AppContextManager.shared.isGuest {
            let gen = stepGeneration
            startCountdown(seconds: timeConfig.signup_tip) {
                guard self.currentStep == 2, self.stepGeneration == gen else { return }
                PopupWindow.show(popupType: .register) {
                    // done
                }
            }
        } else if AppContextManager.shared.vip == 1 {
            let gen = stepGeneration
            startCountdown(seconds: timeConfig.buy_vip_tip) {
                guard self.currentStep == 2, self.stepGeneration == gen else { return }
                PopupWindow.show(popupType: .vip) {
                    // done
                }
            }
        }
    }

    // MARK: - Helpers

    private func skipToNext() {
        stepGeneration += 1
        currentStep += 1
        executeNextStep()
    }

    private func startCountdown(seconds: Int, onExpired: @escaping () -> Void) {
        guard seconds > 0 else {
            onExpired()
            return
        }
        countdownTimer?.invalidate()
        var remaining = seconds
        countdownTimer = Timer.scheduledTimer(withTimeInterval: 1, repeats: true) { [weak self] timer in
            remaining -= 1
            if remaining <= 0 {
                timer.invalidate()
                self?.countdownTimer = nil
                onExpired()
            }
        }
    }

    private func push(_ vc: UIViewController) {
        let topVC = topViewController()
        guard let nav = topVC?.navigationController else { return }
        if nav.viewControllers.contains(where: { type(of: $0) == type(of: vc) }) {
            return
        }
        nav.pushViewController(vc, animated: true)
    }

    private func topViewController() -> UIViewController? {
        guard let rootVC = kKeyWindow?.rootViewController else { return nil }
        return topViewController(from: rootVC)
    }

    private func topViewController(from root: UIViewController) -> UIViewController {
        if let presented = root.presentedViewController {
            return topViewController(from: presented)
        }
        if let nav = root as? UINavigationController, let visible = nav.visibleViewController {
            return topViewController(from: visible)
        }
        if let tab = root as? UITabBarController, let selected = tab.selectedViewController {
            return topViewController(from: selected)
        }
        return root
    }
}