//
//  EQNBaseMapViewController.swift
//  Earthquake Network
//
//  Created by Andrea Busi on 06/03/21.
//  Copyright © 2021 Earthquake Network. All rights reserved.
//

import Foundation
import MapKit


class EQNBaseMapViewController: EQNBaseViewController, MKMapViewDelegate {
    
    /// Current filter
    var filter = EQNBaseMapFilter.oneDay {
        didSet {
            updateUI()
        }
    }
    /// Available filters
    var availableFilters: [EQNBaseMapFilter] {
        [.oneDay, .twelveHours, .sixHours, .twoHours, .oneHour, .tenMinutes]
    }
    /// If `true`, the filter view is visible. Could be overridden by a subclass with a custom filter view
    var isFilterViewVisible: Bool {
        !availableFilters.isEmpty
    }
    
    /// If `true` the close button will be shown on top of the map view
    var isCloseButtonVisible: Bool {
        true
    }
    
    // MARK: - Internal
    
    /// Annotations displayed on the map
    private(set) var mapAnnotations = [MKAnnotation]()
    /// If `true`, the initial filter has been already evaluated
    private var initialFilterEvaluated = false
    
    // MARK: - UI
    
    lazy var closeButton: EQNBlurredCloseButton = {
        let button = EQNBlurredCloseButton()
        button.translatesAutoresizingMaskIntoConstraints = false
        button.addTarget(self, action: #selector(closeTapped(_:)), for: .touchUpInside)
        button.setTitleColor(.darkGray, for: .normal)
        return button
    }()
    
    lazy var mapView: MKMapView = {
        let mapView = MKMapView()
        mapView.translatesAutoresizingMaskIntoConstraints = false
        mapView.showsUserLocation = true
        mapView.delegate = self
        return mapView
    }()
    
    private lazy var containerView: UIView = {
        let view = UIView()
        view.translatesAutoresizingMaskIntoConstraints = false
        return view
    }()
    
    override var bannerContainerView: UIView? {
        return containerView
    }
    
    lazy var filtersView: UIView = {
        let view = UIView()
        view.translatesAutoresizingMaskIntoConstraints = false
        view.backgroundColor = AppTheme.Colors.lightGray
        
        // label with current selecte filter
        view.addSubview(filterLabel)
        filterLabel.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
        filterLabel.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
        filterLabel.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 8.0).isActive = true
        
        let imageView = UIImageView(image: UIImage(named: "icon-arrow-down"))
        imageView.translatesAutoresizingMaskIntoConstraints = false
        imageView.tintColor = .black
        imageView.contentMode = .scaleAspectFit
        
        view.addSubview(imageView)
        imageView.widthAnchor.constraint(equalTo: imageView.heightAnchor).isActive = true
        imageView.topAnchor.constraint(equalTo: view.topAnchor, constant: 8.0).isActive = true
        imageView.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -8.0).isActive = true
        imageView.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -8.0).isActive = true
        imageView.leadingAnchor.constraint(equalTo: filterLabel.trailingAnchor, constant: 8.0).isActive = true

        // tap recognizer
        let tapRecognizer = UITapGestureRecognizer(target: self, action: #selector(filtersTapped(_:)))
        view.addGestureRecognizer(tapRecognizer)
        
        return view
    }()
    
    private lazy var filterLabel: UILabel = {
        let label = UILabel()
        label.translatesAutoresizingMaskIntoConstraints = false
        label.text = filter.title
        return label
    }()
    
    // app icon and name displayed on the screenshot
    private lazy var watermarkView: UIView = {
        let view = UIView()
        view.translatesAutoresizingMaskIntoConstraints = false
        
        let logo = UIImageView(image: .init(named: "eq_icon_transparent"))
        logo.translatesAutoresizingMaskIntoConstraints = false
        logo.contentMode = .scaleAspectFit
        view.addSubview(logo)
        logo.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
        logo.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
        logo.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
        logo.widthAnchor.constraint(equalTo: logo.heightAnchor).isActive = true
        
        let title = UILabel()
        title.translatesAutoresizingMaskIntoConstraints = false
        title.text = NSLocalizedString("app_name", comment: "") + " App"
        title.textColor = AppTheme.Colors.red
        title.font = .preferredFont(forTextStyle: .title3, weight: .semibold)
        view.addSubview(title)
        title.leadingAnchor.constraint(equalTo: logo.trailingAnchor, constant: 10.0).isActive = true
        title.centerYAnchor.constraint(equalTo: logo.centerYAnchor).isActive = true
        title.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
        
        return view
    }()

    
    // MARK: - Init
    
    init() {
        super.init(nibName: nil, bundle: nil)
        setupUI()
    }
    
    required init?(coder: NSCoder) {
        super.init(coder: coder)
        setupUI()
    }
    
    // MARK: - Private
    
    private func setupUI() {
        view.backgroundColor = .white
        view.addSubview(mapView)
        view.addSubview(containerView)
        if isFilterViewVisible {
            view.addSubview(filtersView)
        }
        if isCloseButtonVisible {
            view.addSubview(closeButton)
            closeButton.addDefaultConstraint(to: view)
        }
        
        containerView.bottomAnchor.constraint(equalTo: view.layoutMarginsGuide.bottomAnchor).isActive = true
        containerView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
        containerView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
        bannerContainerHeightConstraint = containerView.heightAnchor.constraint(equalToConstant: 55.0)
        bannerContainerHeightConstraint?.isActive = true
        
        if isFilterViewVisible {
            filtersView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
            filtersView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
            filtersView.bottomAnchor.constraint(equalTo: containerView.topAnchor).isActive = true
            filtersView.heightAnchor.constraint(equalToConstant: 40.0).isActive = true
        }
        
        if isFilterViewVisible && !isBannerVisible {
            view.backgroundColor = filtersView.backgroundColor // trick to simulate a bigger filters view
        }
        
        mapView.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
        mapView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
        mapView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
        mapView.bottomAnchor.constraint(equalTo: (isFilterViewVisible ? filtersView : containerView).topAnchor).isActive = true
        
        extraUI()
    }
    
    private func addWatermarkView() {
        view.addSubview(watermarkView)
        
        watermarkView.topAnchor.constraint(equalTo: mapView.topAnchor, constant: 10.0).isActive = true
        watermarkView.leadingAnchor.constraint(equalTo: mapView.leadingAnchor, constant: 10.0).isActive = true
        watermarkView.heightAnchor.constraint(equalToConstant: 40.0).isActive = true
    }
    
    private func removeWatermarkView() {
        watermarkView.removeFromSuperview()
    }
    
    // MARK: - View Lifecycle
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        configureUI()
        registerMapAnnotationViews()
        loadDataSource()
    }
    
    override func didReceiveDownloadComplete(_ notification: Notification) {
        super.didReceiveDownloadComplete(notification)
        
        // when data is download, reload data source
        DispatchQueue.main.async {
            self.loadDataSource()
        }
    }
    
    // MARK: - Public
    
    /// Add extra UI not available in the base class
    func extraUI() {
        // nope, subclass will implement some logic
    }
    
    /// Configure UI after view initialization
    func configureUI() {
        // nope, subclass will implement some logic
    }
    
    /// Load data to display on the map
    func loadDataSource() {
        // nope, subclass will implement some logic
    }
    
    /// Register annotation views for the current map
    func registerMapAnnotationViews() {
        // nope, subclass will implement some logic
    }
    
    func elaborateMapCenter() {
        // nope, subclass will center map with it's own logic
    }
    
    func setDefaultFilter(for items: [EQNBaseMapRepresentable]) {
        // initial filter will be the upper nearest of the newest item
        // this logic has to be evaluated only one time, to keep user filter change working
        guard !initialFilterEvaluated, let newest = items.sorted(by: { $0.date > $1.date }).first else {
            return
        }
        
        // find the filter that include the newest item
        let difference = Date().timeIntervalSince(newest.date) / 60.0
        let betterFilter = availableFilters
            .filter { $0.minutes > difference }
            .sorted()
            .first
        
        // use the filter found, or the first available
        if let betterFilter = betterFilter {
            filter = betterFilter
        } else if let firstFilter = availableFilters.first {
            filter = firstFilter
        }
        
        initialFilterEvaluated = true
    }
    
    /// Update the map with a set of annotations
    func updateMap(with annotations: [MKAnnotation]) {
        // remove previous annotations
        mapView.removeAnnotations(mapAnnotations)
        
        // set new annotations and reload map
        mapAnnotations = annotations
        
        mapView.addAnnotations(mapAnnotations)
        mapView.showAnnotations(mapAnnotations, animated: true)
        
        elaborateMapCenter()
    }
    
    func reloadMap() {
        // remove and re-add annotations, to force redrawn
        mapView.removeAnnotations(mapAnnotations)
        mapView.addAnnotations(mapAnnotations)
    }
    
    /// Changes the center coordinate of the map to a given location
    func setMapCenter(for location: CLLocation, span: MKCoordinateSpan = MKCoordinateSpan(latitudeDelta: 8, longitudeDelta: 8)) {
        let region = MKCoordinateRegion(center: location.coordinate, span: span)
        mapView.setCenter(location.coordinate, animated: false)
        mapView.setRegion(region, animated: true)
    }
    
    func didTapAnnotation(_ annotation: MKAnnotation) {
        // nope, subclass will implement logic
    }
    
    func zPriority(for annotation: MKAnnotation) -> MKAnnotationViewZPriority {
        // subclass will impelement its own logic to define annotation priority
        .min
    }
    
    func createSnapshot(
        prepare: () -> Void = { },
        restore: () -> Void = { }
    ) -> UIImage {
        prepare()
        addWatermarkView()
        
        // riduciamo la porzione da salvare alla sola mappa (eliminiamo i filtri)
        let size = CGSize(width: view.bounds.width, height: mapView.bounds.maxY)
        let renderer = UIGraphicsImageRenderer(size: size)
        let image = renderer.image { ctx in
            view.drawHierarchy(in: view.bounds, afterScreenUpdates: true)
        }

        restore()
        removeWatermarkView()
        
        return image
    }
    
    // MARK: - Private
    
    private func updateUI() {
        filterLabel.text = filter.title
    }
    
    // MARK: - Actions
    
    @objc func closeTapped(_ sender: Any) {
        dismiss(animated: true)
    }
    
    @objc func filtersTapped(_ sender: UIGestureRecognizer) {
        let sheet = UIAlertController(title: nil, message: nil, preferredStyle: .actionSheet)
        availableFilters.forEach { (filter) in
            sheet.addAction(UIAlertAction(title: filter.title, style: .default, handler: { _ in
                self.applyFilter(filter)
            }))
        }
        sheet.addAction(UIAlertAction(title: NSLocalizedString("status_cancel", comment: ""), style: .cancel, handler: nil))
        present(sheet, animated: true, completion: nil)
    }
    
    private func applyFilter(_ filter: EQNBaseMapFilter) {
        self.filter = filter
        loadDataSource()
    }
    
    // MARK: - MKMapViewDelegate

    func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
        guard !annotation.isKind(of: MKUserLocation.self) else {
            // Make a fast exit if the annotation is the `MKUserLocation`, as it's not an annotation view we wish to customize.
            return nil
        }
        
        let annotationView = setupAnnotationView(for: annotation, on: mapView)
        annotationView?.zPriority = zPriority(for: annotation)
        return annotationView
    }
    
    func setupAnnotationView(for annotation: MKAnnotation, on mapView: MKMapView) -> MKAnnotationView? {
        return nil
    }
    
    func mapView(_ mapView: MKMapView, didSelect view: MKAnnotationView) {
        guard let annotation = view.annotation else { return }
        didTapAnnotation(annotation)
    }
}