//
//  AccountViewController.swift
//  MullvadVPN
//
//  Created by pronebird on 20/03/2019.
//  Copyright © 2019 Mullvad VPN AB. All rights reserved.
//

import MullvadLogging
import MullvadREST
import MullvadTypes
import Operations
import StoreKit
import UIKit

protocol AccountViewControllerDelegate: AnyObject {
    func accountViewControllerDidLogout(_ controller: AccountViewController)
}

class AccountViewController: UIViewController {
    private let interactor: AccountInteractor
    private let alertPresenter = AlertPresenter()

    private let contentView: AccountContentView = {
        let contentView = AccountContentView()
        contentView.translatesAutoresizingMaskIntoConstraints = false
        return contentView
    }()

    private var productState: ProductState = .none
    private var paymentState: PaymentState = .none

    weak var delegate: AccountViewControllerDelegate?

    init(interactor: AccountInteractor) {
        self.interactor = interactor

        super.init(nibName: nil, bundle: nil)
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    // MARK: - View lifecycle

    override var preferredStatusBarStyle: UIStatusBarStyle {
        return .lightContent
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        view.backgroundColor = .secondaryColor

        let scrollView = UIScrollView()
        scrollView.translatesAutoresizingMaskIntoConstraints = false
        scrollView.addSubview(contentView)
        view.addSubview(scrollView)

        NSLayoutConstraint.activate([
            scrollView.topAnchor.constraint(equalTo: view.topAnchor),
            scrollView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            scrollView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            scrollView.bottomAnchor.constraint(equalTo: view.bottomAnchor),

            contentView.topAnchor.constraint(equalTo: scrollView.topAnchor),
            contentView.bottomAnchor
                .constraint(greaterThanOrEqualTo: scrollView.safeAreaLayoutGuide.bottomAnchor),
            contentView.leadingAnchor.constraint(equalTo: scrollView.leadingAnchor),
            contentView.trailingAnchor.constraint(equalTo: scrollView.trailingAnchor),
            contentView.widthAnchor.constraint(equalTo: scrollView.widthAnchor),
        ])

        navigationItem.title = NSLocalizedString(
            "NAVIGATION_TITLE",
            tableName: "Account",
            value: "Account",
            comment: ""
        )

        contentView.accountTokenRowView.copyAccountNumber = { [weak self] in
            self?.copyAccountToken()
        }

        contentView.restorePurchasesButton.addTarget(
            self,
            action: #selector(restorePurchases),
            for: .touchUpInside
        )
        contentView.purchaseButton.addTarget(
            self,
            action: #selector(doPurchase),
            for: .touchUpInside
        )
        contentView.logoutButton.addTarget(self, action: #selector(doLogout), for: .touchUpInside)

        interactor.didReceiveDeviceState = { [weak self] newDeviceState in
            self?.updateView(from: newDeviceState)
        }

        interactor.didReceivePaymentEvent = { [weak self] event in
            self?.didReceivePaymentEvent(event)
        }

        updateView(from: interactor.deviceState)
        applyViewState(animated: false)

        if StorePaymentManager.canMakePayments {
            requestStoreProducts()
        } else {
            setProductState(.cannotMakePurchases, animated: false)
        }
    }

    // MARK: - Private

    private func requestStoreProducts() {
        let productKind = StoreSubscription.thirtyDays

        setProductState(.fetching(productKind), animated: true)

        _ = interactor.requestProducts(with: [productKind]) { [weak self] completion in
            let productState: ProductState = completion.value?.products.first
                .map { .received($0) } ?? .failed

            self?.setProductState(productState, animated: true)
        }
    }

    private func setPaymentState(_ newState: PaymentState, animated: Bool) {
        paymentState = newState

        applyViewState(animated: animated)
    }

    private func setProductState(_ newState: ProductState, animated: Bool) {
        productState = newState

        applyViewState(animated: animated)
    }

    private func updateView(from deviceState: DeviceState?) {
        guard case let .loggedIn(accountData, deviceData) = deviceState else {
            return
        }

        contentView.accountDeviceRow.deviceName = deviceData.name
        contentView.accountTokenRowView.accountNumber = accountData.number
        contentView.accountExpiryRowView.value = accountData.expiry
    }

    private func applyViewState(animated: Bool) {
        let isInteractionEnabled = paymentState.allowsViewInteraction
        let purchaseButton = contentView.purchaseButton
        let activityIndicator = contentView.accountExpiryRowView.activityIndicator

        if productState.isFetching || paymentState != .none {
            activityIndicator.startAnimating()
        } else {
            activityIndicator.stopAnimating()
        }

        purchaseButton.setTitle(productState.purchaseButtonTitle, for: .normal)
        contentView.purchaseButton.isLoading = productState.isFetching

        purchaseButton.isEnabled = productState.isReceived && isInteractionEnabled
        contentView.restorePurchasesButton.isEnabled = isInteractionEnabled
        contentView.logoutButton.isEnabled = isInteractionEnabled

        view.isUserInteractionEnabled = isInteractionEnabled
        isModalInPresentation = !isInteractionEnabled

        navigationItem.setHidesBackButton(!isInteractionEnabled, animated: animated)
    }

    private func didReceivePaymentEvent(_ event: StorePaymentEvent) {
        guard case let .makingPayment(payment) = paymentState,
              payment == event.payment else { return }

        switch event {
        case let .finished(completion):
            showTimeAddedConfirmationAlert(with: completion.serverResponse, context: .purchase)

        case let .failure(paymentFailure):
            switch paymentFailure.error {
            case .storePayment(SKError.paymentCancelled):
                break

            default:
                showPaymentErrorAlert(error: paymentFailure.error)
            }
        }

        setPaymentState(.none, animated: true)
    }

    private func showPaymentErrorAlert(error: StorePaymentManagerError) {
        let alertController = UIAlertController(
            title: NSLocalizedString(
                "CANNOT_COMPLETE_PURCHASE_ALERT_TITLE",
                tableName: "Account",
                value: "Cannot complete the purchase",
                comment: ""
            ),
            message: error.displayErrorDescription,
            preferredStyle: .alert
        )

        alertController.addAction(
            UIAlertAction(
                title: NSLocalizedString(
                    "CANNOT_COMPLETE_PURCHASE_ALERT_OK_ACTION",
                    tableName: "Account",
                    value: "OK",
                    comment: ""
                ), style: .cancel
            )
        )

        alertPresenter.enqueue(alertController, presentingController: self)
    }

    private func showRestorePurchasesErrorAlert(error: StorePaymentManagerError) {
        let alertController = UIAlertController(
            title: NSLocalizedString(
                "RESTORE_PURCHASES_FAILURE_ALERT_TITLE",
                tableName: "Account",
                value: "Cannot restore purchases",
                comment: ""
            ),
            message: error.displayErrorDescription,
            preferredStyle: .alert
        )
        alertController.addAction(
            UIAlertAction(title: NSLocalizedString(
                "RESTORE_PURCHASES_FAILURE_ALERT_OK_ACTION",
                tableName: "Account",
                value: "OK",
                comment: ""
            ), style: .cancel)
        )
        alertPresenter.enqueue(alertController, presentingController: self)
    }

    private func showTimeAddedConfirmationAlert(
        with response: REST.CreateApplePaymentResponse,
        context: REST.CreateApplePaymentResponse.Context
    ) {
        let alertController = UIAlertController(
            title: response.alertTitle(context: context),
            message: response.alertMessage(context: context),
            preferredStyle: .alert
        )
        alertController.addAction(
            UIAlertAction(
                title: NSLocalizedString(
                    "TIME_ADDED_ALERT_OK_ACTION",
                    tableName: "Account",
                    value: "OK",
                    comment: ""
                ),
                style: .cancel
            )
        )

        alertPresenter.enqueue(alertController, presentingController: self)
    }

    // MARK: - Actions

    @objc private func doLogout() {
        let message = NSLocalizedString(
            "LOGGING_OUT_ALERT_TITLE",
            tableName: "Account",
            value: "Logging out. Please wait...",
            comment: ""
        )

        let alertController = UIAlertController(
            title: nil,
            message: message,
            preferredStyle: .alert
        )

        alertPresenter.enqueue(alertController, presentingController: self) {
            self.interactor.logout {
                DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(1)) {
                    alertController.dismiss(animated: true) {
                        self.delegate?.accountViewControllerDidLogout(self)
                    }
                }
            }
        }
    }

    private func copyAccountToken() {
        guard let accountData = interactor.deviceState.accountData else {
            return
        }

        UIPasteboard.general.string = accountData.number
    }

    @objc private func doPurchase() {
        guard case let .received(product) = productState,
              let accountData = interactor.deviceState.accountData
        else {
            return
        }

        let payment = SKPayment(product: product)
        interactor.addPayment(payment, for: accountData.number)

        setPaymentState(.makingPayment(payment), animated: true)
    }

    @objc private func restorePurchases() {
        guard let accountData = interactor.deviceState.accountData else {
            return
        }

        setPaymentState(.restoringPurchases, animated: true)

        _ = interactor.restorePurchases(for: accountData.number) { [weak self] completion in
            guard let self = self else { return }

            switch completion {
            case let .success(response):
                self.showTimeAddedConfirmationAlert(with: response, context: .restoration)

            case let .failure(error as StorePaymentManagerError):
                self.showRestorePurchasesErrorAlert(error: error)

            default:
                break
            }

            self.setPaymentState(.none, animated: true)
        }
    }
}