SmallScreenRootViewController.swift

import UIKit
import CoreLocation
import ReSwift

struct SmallScreenRootViewControllerState: Equatable {
    var accessGranted: Bool
    var geocoderQueueCount: Int
    var mapContentListDetentIdentifer: UISheetPresentationController.Detent.Identifier
    var mapContentDetailsDetentIdentifer: UISheetPresentationController.Detent.Identifier
    var mapSelectedContact: MapContactSelection?
    var mapSelectedPersonLocationForEdit: PersonLocation?

    init(newState: AppState) {
        accessGranted = (
            newState.contactsAuthStatus == .authorized &&
            newState.locationAuthStatus == .authorized
        )
        geocoderQueueCount = newState.geocoderQueueCount
        mapContentListDetentIdentifer = newState.mapContactListDetentIdentifier
        mapContentDetailsDetentIdentifer = newState.mapContactDetailsDetentIdentifier
        mapSelectedContact = newState.mapSelection
        mapSelectedPersonLocationForEdit = newState.mapPersonLocationForEdit
    }
}

class SmallScreenRootViewController: UITabBarController, StoreSubscriber, UISheetPresentationControllerDelegate, UITabBarControllerDelegate {
    private var currentState: SmallScreenRootViewControllerState?
    private let mapVC = MapViewController()
    private let contactListVC = MapContactListViewController()
    private var contactDetailVC: ContactDetailViewController?
    private var personLocationEditVC: LocationEditViewController?
    private var onboardingVC: OnboardingViewController?

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

        let listVC = UINavigationController(rootViewController: ContactListViewController())
        listVC.navigationBar.prefersLargeTitles = true
        listVC.tabBarItem = UITabBarItem(title: "List", image: .init(systemName: "list.bullet"), selectedImage: .init(systemName: "list.bullet"))

        mapVC.tabBarItem = UITabBarItem(title: "Map", image: .init(systemName: "map"), selectedImage: .init(systemName: "map.fill"))

#if AFFINITES_ENABLED
        self.viewControllers = [listVC, mapVC]
        self.selectedViewController = listVC
#else
        self.viewControllers = [mapVC]
        self.selectedViewController = mapVC
#endif

        self.delegate = self
    }

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

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()

#if AFFINITES_ENABLED
            // TODO: this is so, so hacky
            view.window!.addSubview(self.tabBar)
#endif
    }

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)

        if selectedViewController == mapVC {
            presentContactsList()
        }

        presentOrDismissOnboarding()

        app.store.subscribe(self) { subscription in
            return subscription.select(SmallScreenRootViewControllerState.init)
        }
    }

    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)

        app.store.unsubscribe(self)
    }

    func tabBarController(_ tabBarController: UITabBarController, didSelect viewController: UIViewController) {
        if (viewController == mapVC) {
            presentContactsList()
        } else {
            contactListVC.view.isHidden = true;
            contactListVC.dismiss(animated: false) {
                self.contactListVC.view.isHidden = false;
            }
        }
    }

    func newState(state: SmallScreenRootViewControllerState) {
        let prevState = currentState
        currentState = state

        if state.mapContentListDetentIdentifer != prevState?.mapContentListDetentIdentifer {
            contactListVC.sheetPresentationController?.animateChanges {
                contactListVC.sheetPresentationController?.selectedDetentIdentifier = state.mapContentListDetentIdentifer
            }
        }
        if state.mapContentDetailsDetentIdentifer != prevState?.mapContentDetailsDetentIdentifer {
            contactDetailVC?.sheetPresentationController?.animateChanges {
                contactDetailVC?.sheetPresentationController?.selectedDetentIdentifier = state.mapContentDetailsDetentIdentifer
            }
        }
        if state.mapSelectedContact != prevState?.mapSelectedContact {
            if let mapSelectedPersonLocation = state.mapSelectedContact?.personLocation {
                presentContactDetails(mapSelectedPersonLocation)
            } else {
                dismissContactDetails()
            }
        }
        if state.mapSelectedPersonLocationForEdit != prevState?.mapSelectedPersonLocationForEdit {
            if let location = state.mapSelectedPersonLocationForEdit {
                presentPersonLocationForEdit(personLocation: location)
            } else {
                dismissPersonLocationForEdit()
            }
        }
        presentOrDismissOnboarding()
    }

    func sheetPresentationControllerDidChangeSelectedDetentIdentifier(_ sheetPresentationController: UISheetPresentationController) {
        if sheetPresentationController == contactListVC.sheetPresentationController {
            app.store.dispatch(MapContactListDetentChanged(detentIdentifier: sheetPresentationController.selectedDetentIdentifier!))
        } else if sheetPresentationController == contactDetailVC?.sheetPresentationController {
            app.store.dispatch(MapContactDetailsDetentChanged(detentIdentifier: sheetPresentationController.selectedDetentIdentifier!))
        }
    }

    private func presentOrDismissOnboarding() {
        var needsOnboarding = false
        if let currentState = currentState {
            needsOnboarding = (
                !currentState.accessGranted ||
                currentState.geocoderQueueCount > 3 ||
                (currentState.geocoderQueueCount > 0 && onboardingVC != nil)
            )
        }
        if needsOnboarding {
            presentOnboarding()
        } else {
            dismissOnboarding()
        }
    }

    private func presentOnboarding() {
        if self.onboardingVC != nil {
            return
        }

        let onboardingVC = OnboardingViewController()
        onboardingVC.modalPresentationStyle = .overFullScreen
        self.onboardingVC = onboardingVC

        let keyWindow = UIApplication.shared.connectedScenes
            .flatMap { ($0 as? UIWindowScene)?.windows ?? [] }
            .first { $0.isKeyWindow }
        guard let keyWindow = keyWindow else {
            fatalError("No key window")
        }

        guard var topVC = keyWindow.rootViewController else {
            fatalError("No top view controller")
        }
        while let presentedViewController = topVC.presentedViewController {
            topVC = presentedViewController
        }
        topVC.present(onboardingVC, animated: false)
    }

    private func dismissOnboarding() {
        if let onboardingVC = onboardingVC {
            onboardingVC.dismiss(animated: true)
            self.onboardingVC = nil
        }
    }

    private func presentContactsList() {
        contactListVC.isModalInPresentation = true // prevent dismissal
        if let sheet = contactListVC.sheetPresentationController {
            sheet.detents = [.collapsed, .small, .large()]
            sheet.selectedDetentIdentifier = app.store.state.mapContactListDetentIdentifier
            sheet.largestUndimmedDetentIdentifier = .small
            sheet.prefersGrabberVisible = true
            sheet.delegate = self
        }
        mapVC.present(contactListVC, animated: false)
    }

    private func presentContactDetails(_ personLocation: PersonLocation) {
        if let contactDetailVC = contactDetailVC {
            contactDetailVC.personLocation = personLocation
            return // already presented
        }
        let contactDetailVC = ContactDetailViewController(personLocation: personLocation)
        contactDetailVC.isModalInPresentation = true // prevent dismissal
        if let sheet = contactDetailVC.sheetPresentationController {
            sheet.detents = [.collapsed, .normal, .large()]
            sheet.selectedDetentIdentifier = .normal
            sheet.largestUndimmedDetentIdentifier = .normal
            sheet.prefersGrabberVisible = true
            sheet.delegate = self
        }
        contactListVC.present(contactDetailVC, animated: true)
        self.contactDetailVC = contactDetailVC
    }

    private func dismissContactDetails() {
        contactDetailVC?.dismiss(animated: true)
        contactDetailVC = nil
    }

    private func presentPersonLocationForEdit(personLocation: PersonLocation) {
        if personLocationEditVC != nil {
            return // already presented
        }
        guard let contactDetailVC = contactDetailVC else {
            fatalError("No contact details presented; cannot edit location")
        }
        let personLocationEditVC = LocationEditViewController(personLocation: personLocation)
        personLocationEditVC.isModalInPresentation = true // prevent dismissal
        if let sheet = personLocationEditVC.sheetPresentationController {
            sheet.detents = [.large()]
            sheet.delegate = self
        }
        contactDetailVC.present(personLocationEditVC, animated: true)
        self.personLocationEditVC = personLocationEditVC
    }

    private func dismissPersonLocationForEdit() {
        personLocationEditVC?.dismiss(animated: true)
        personLocationEditVC = nil
    }

}