//
//  TableView.swift
//  CapFinder
//
//  Created by User on 22.04.18.
//  Copyright © 2018 User. All rights reserved.
//

import UIKit

import JGProgressHUD

class TableView: UITableViewController {
    
    @IBOutlet weak var infoButton: UIBarButtonItem!
    
    private var classifier: Classifier?
    
    private var accessory: SearchAndDisplayAccessory?
    
    private var titleLabel: UILabel!
    
    private var subtitleLabel: UILabel!
    
    private var caps = [Cap]()

    private var shownCaps = [Cap]()
    
    private var matches: [Int : Float]?
    
    private var sortType: SortCriteria = .id
    
    private var searchText: String? = nil
    
    private var sortAscending: Bool = false

    /// This will be set to a cap id when adding a cap to it
    private var capToAddImageTo: Int?
    
    private var isUnlocked = false
    
    private var processingScreenHud: JGProgressHUD?
    
    // MARK: Computed properties
    
    private var titleText: String {
        let recognized = app.database.recognizedCapCount
        let all = app.database.capCount
        switch all {
        case 0:
            return "No caps"
        case 1:
            return "1 cap"
        case recognized:
            return "\(all) caps"
        default:
            return "\(all) caps (\(all - recognized) new)"
        }
    }
    
    private var subtitleText: String {
        let capCount = app.database.capCount
        guard capCount > 0, isUnlocked else {
            return ""
        }
        let allImages = app.database.imageCount
        
        let ratio = Float(allImages) / Float(capCount)
        return String(format: "%d images (%.2f per cap)", allImages, ratio)
    }
    
    // MARK: Overrides
    
    override var inputAccessoryView: UIView? {
        get { return accessory }
    }
    
    override var canBecomeFirstResponder: Bool {
        return true
    }

    // MARK: - Actions
    
    @IBAction func updateInfo(_ sender: UIBarButtonItem, forEvent event: UIEvent) {
        guard let touch = event.allTouches?.first, touch.tapCount > 0, !app.database.isInOfflineMode else {
            showOfflineDialog()
            return
        }
        downloadCapNames()
    }
    
    @IBAction func showMosaic(_ sender: UIBarButtonItem) {
        checkThumbnailsAndColorsBeforShowingGrid()
    }
    
    func showCameraView() {
        let storyboard = UIStoryboard(name: "Main", bundle: nil)
        let controller = storyboard.instantiateViewController(withIdentifier: "NewImageController") as! CameraController
        controller.delegate = self
        self.present(controller, animated: true)
    }
    
    @objc private func titleWasTapped() {
        let storyboard = UIStoryboard(name: "Main", bundle: nil)
        let controller = storyboard.instantiateViewController(withIdentifier: "SortController") as! SortController
        controller.selected = sortType
        controller.ascending = sortAscending
        controller.delegate = self
        
        controller.options = [.id, .name]
        if isUnlocked { controller.options.append(.count) }
        if matches != nil { controller.options.append(.match) }
        
        let presentationController = AlwaysPresentAsPopover.configurePresentation(forController: controller)
        
        presentationController.sourceView = navigationItem.titleView!
        presentationController.permittedArrowDirections = [.up]
        self.present(controller, animated: true)
    }
    
    // MARK: - Life cycle

    override func viewDidLoad() {
        super.viewDidLoad()

        tableView.rowHeight = 100
        
        accessory = SearchAndDisplayAccessory(width: self.view.frame.width)
        accessory?.delegate = self
        
        initInfoButton()
        
        app.database.delegate = self
        let count = app.database.capCount
        if count == 0 {
            log("No caps found, downloading names")
            downloadCapNames()
            showProcessingScreen()
        } else {
            log("Loaded \(count) caps")
            reloadCapsFromDatabase()
            loadClassifier()
        }
    }
    
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        
        (navigationController as? NavigationController)?.allowLandscape = false
        isUnlocked = app.isUnlocked
        log(isUnlocked ? "App is unlocked" : "App is locked")
    }

    override func didMove(toParent parent: UIViewController?) {
        super.didMove(toParent: parent)

        guard parent != nil && self.navigationItem.titleView == nil else {
            return
        }
        initNavigationItemTitleView()
    }
    
    private func initInfoButton() {
        let offline = app.database.isInOfflineMode
        setInfoButtonIcon(offline: offline)
    }
    
    private func setInfoButtonIcon(offline: Bool) {
        let symbol = offline ? "icloud.slash" : "arrow.clockwise.icloud"
        infoButton.image = UIImage(systemName: symbol)
    }
    
    private func initNavigationItemTitleView() {
        self.titleLabel = UILabel()
        titleLabel.text = titleText
        titleLabel.font = .preferredFont(forTextStyle: .headline)
        titleLabel.textColor = .label

        self.subtitleLabel = UILabel()
        subtitleLabel.text = subtitleText
        subtitleLabel.font = .preferredFont(forTextStyle: .footnote)
        subtitleLabel.textColor = .secondaryLabel

        let stackView = UIStackView(arrangedSubviews: [titleLabel, subtitleLabel])
        stackView.distribution = .equalCentering
        stackView.alignment = .center
        stackView.axis = .vertical

        self.navigationItem.titleView = stackView
        
        let recognizer = UITapGestureRecognizer(target: self, action: #selector(titleWasTapped))
        stackView.isUserInteractionEnabled = true
        stackView.addGestureRecognizer(recognizer)
        
        let longPress = UILongPressGestureRecognizer(target: self, action: #selector(attemptChangeOfUserPermissions))
        stackView.addGestureRecognizer(longPress)
    }

    private func updateNavigationItemTitleView() {
        DispatchQueue.main.async {
            self.titleLabel.text = self.titleText
            self.subtitleLabel.text = self.subtitleText
        }
    }
    
    // MARK: Starting updates
    
    private func checkThumbnailsAndColorsBeforShowingGrid() {
        let missingImageCount = app.database.capCountWithoutImages
        guard missingImageCount == 0 else {
            askUserToDownload(capImages: missingImageCount)
            return
        }
        createMissingThumbnailsBeforeShowingGrid()
    }
    
    private func createMissingThumbnailsBeforeShowingGrid() {
        let missing = app.database.capsWithoutThumbnails.map { $0.id }
        guard missing.count > 0 else {
            log("No thumbnails missing, checking colors")
            checkColorsBeforeShowingGrid()
            return
        }
        log("Generating \(missing.count) thumbnails")
        let hud = JGProgressHUD(style: traitCollection.userInterfaceStyle == .dark ? .dark : .light)
        hud.indicatorView = JGProgressHUDPieIndicatorView()
        hud.detailTextLabel.text = "0 % complete (0 / \(missing.count)"
        hud.textLabel.text = "Generating thumbnails"
        hud.show(in: self.view)
        
        let group = DispatchGroup()
        var done = 0
        let split = 50
        DispatchQueue.global(qos: .background).async {
            for part in missing.split(intoPartsOf: split) {
                for id in part {
                    group.enter()
                    defer {
                        done += 1
                        let ratio = Float(done) / Float(missing.count)
                        let percent = Int((ratio * 100).rounded())
                        DispatchQueue.main.async {
                            hud.progress = ratio
                            hud.detailTextLabel.text = "\(percent) % complete (\(done) / \(missing.count))"
                        }
                        group.leave()
                    }
                    guard let image = app.storage.image(for: id) else {
                        return
                    }
                    let thumbnail = Cap.thumbnail(for: image)
                    app.storage.save(thumbnail: thumbnail, for: id)
                }
                if group.wait(timeout: .now() + .seconds(30)) != .success {
                    self.log("Timed out waiting for thumbnails to be generated")
                }
            }
            DispatchQueue.main.async {
                hud.dismiss()
                self.checkColorsBeforeShowingGrid()
            }
        }
    }
    
    private func checkColorsBeforeShowingGrid() {
        let missing = Array(app.database.capsWithoutColors)
        
        guard missing.count > 0 else {
            log("No missing colors, showing grid")
            showGrid()
            return
        }
        log("Generating \(missing.count) colors")
        let hud = JGProgressHUD(style: traitCollection.userInterfaceStyle == .dark ? .dark : .light)
        hud.indicatorView = JGProgressHUDPieIndicatorView()
        hud.detailTextLabel.text = "0 % complete (0 / \(missing.count)"
        hud.textLabel.text = "Generating colors"
        hud.show(in: self.view)
        
        let group = DispatchGroup()
        var done = 0
        let split = 50
        let context = CIContext(options: [.workingColorSpace: kCFNull!])
        
        DispatchQueue.global(qos: .background).async {
            for part in missing.split(intoPartsOf: split) {
                for id in part {
                    group.enter()
                    defer {
                        done += 1
                        let ratio = Float(done) / Float(missing.count)
                        let percent = Int((ratio * 100).rounded())
                        DispatchQueue.main.async {
                            hud.progress = ratio
                            hud.detailTextLabel.text = "\(percent) % complete (\(done) / \(missing.count))"
                        }
                        group.leave()
                    }
                    guard let image = app.storage.ciImage(for: id) else {
                        return
                    }
                    guard let color = image.averageColor(context: context) else {
                        return
                    }
                    app.database.set(color: color, for: id)
                }
                if group.wait(timeout: .now() + .seconds(30)) != .success {
                    self.log("Timed out waiting for colors to be generated")
                }
                context.clearCaches()
            }
            DispatchQueue.main.async {
                hud.dismiss()
                self.showGrid()
            }
        }
    }
    
    private func showGrid() {
        let vc = app.mainStoryboard.instantiateViewController(withIdentifier: "GridView") as! GridViewController
        guard let nav = navigationController as? NavigationController else {
            return
        }
        if let tileImage = app.database.tileImage(named: "default") {
            log("Showing existing tile image")
            vc.load(tileImage: tileImage)
        } else {
            let tileImage = Database.TileImage(name: "default", width: 40, caps: [])
            log("Showing default tile image")
            vc.load(tileImage: tileImage)
        }
        nav.pushViewController(vc, animated: true)
        nav.allowLandscape = true
    }
    
    private func showOfflineDialog() {
        let offline = app.database.isInOfflineMode
        if offline {
            print("Marking as online")
            app.database.isInOfflineMode = false
            app.database.uploadRemainingData()
            self.showAlert("Offline mode was disabled", title: "Online")
        } else {
            print("Marking as offline")
            app.database.isInOfflineMode = true
            self.showAlert("Offline mode was enabled", title: "Offline")
        }
    }
    
    private func downloadCapNames() {
        app.database.downloadCapNames { success in
            guard success else {
                self.hideProcessingScreen()
                self.showAlert("Failed to download cap names", title: "Sync failed")
                return
            }
            self.downloadImageCounts()
        }
    }
    
    private func downloadImageCounts() {
        app.database.downloadImageCounts { success in
            guard success else {
                self.hideProcessingScreen()
                self.showAlert("Failed to download image counts", title: "Sync failed")
                return
            }
            self.hideProcessingScreen()
            self.checkIfCapImagesNeedDownload()
        }
    }
    
    private func checkIfCapImagesNeedDownload() {
        let count = app.database.capCountWithoutImages
        guard count > 0 else {
            log("No cap images to download")
            self.downloadNewestClassifierIfNeeded()
            return
        }
        DispatchQueue.main.async {
            self.askUserToDownload(capImages: count)
        }
    }
    
    private func downloadNewestClassifierIfNeeded() {
        app.database.hasNewClassifier { version, size in
            guard let version = version else {
                return
            }
            DispatchQueue.main.async {
                self.askUserToDownload(classifier: version, size: size)
            }
        }
    }
    
    private func rename(cap: Cap, at indexPath: IndexPath) {
        let detail =  "Choose a new name for the cap"
        askUserForText("Enter new name", detail: detail, existingText: cap.name, yesText: "Save") { text in
            guard app.database.update(name: text, for: cap.id) else {
                self.showAlert("Name could not be set.", title: "Update failed")
                return
            }
        }
    }
    
    private func saveNewCap(for image: UIImage) {
        let detail = "Choose a name for the image"
        askUserForText("Enter name", detail: detail, existingText: accessory!.searchBar.text, yesText: "Save") { text in
            DispatchQueue.global(qos: .userInitiated).async {
                guard app.database.createCap(image: image, name: text) else {
                    self.showAlert("Cap not added", title: "Database error")
                    return
                }
                self.accessory!.discardImage()
            }
        }
    }

    private func updateShownCaps(_ newList: [Cap], insertedId id: Int) {
        // Main queue
        guard shownCaps.count == newList.count - 1 else {
            log("Cap list refresh mismatch: was \(shownCaps.count), is \(newList.count)")
            show(sortedCaps: newList)
            return
        }
        guard let index = newList.firstIndex(where: { $0.id == id}) else {
            log("Cap list refresh without new cap \(id)")
            show(sortedCaps: newList)
            return
        }
        
        self.tableView.beginUpdates()
        self.shownCaps = newList
        let indexPath = IndexPath(row: index, section: 0)
        self.tableView.insertRows(at: [indexPath], with: .automatic)
        self.tableView.endUpdates()
    }

    
    // MARK: User interaction
    
    private func showProcessingScreen() {
        guard processingScreenHud == nil else {
            log("Already showing processing screen")
            return
        }
        
        let style: JGProgressHUDStyle = traitCollection.userInterfaceStyle == .dark ? .dark : .extraLight
        let hud = JGProgressHUD(style: style)
        hud.indicatorView = JGProgressHUDIndeterminateIndicatorView()
        hud.detailTextLabel.text = "Please wait until the app has finished processing."
        hud.textLabel.text = "Processing..."
        hud.show(in: self.view)
        self.processingScreenHud = hud
    }
    
    private func hideProcessingScreen() {
        processingScreenHud?.dismiss()
        processingScreenHud = nil
    }
    
    @objc private func attemptChangeOfUserPermissions() {
        guard isUnlocked else {
            attemptAppUnlock()
            return
        }
        log("Locking app.")
        app.lock()
        isUnlocked = false
        showAllCapsAndScrollToTop()
        updateNavigationItemTitleView()
        showAlert("The app was locked to prevent modifications.", title: "Locked")
    }
    
    private func attemptAppUnlock() {
        log("Presenting unlock dialog to user")
        askUserForText("Enter pin", detail: "Enter the correct pin to unlock write permissions for the app.", placeholder: "Pin", yesText: "Unlock") { text in
            guard let pin = Int(text), app.checkUnlock(with: pin) else {
                self.unlockFailed()
                return
            }
            self.unlockDidSucceed()
        }
    }
    
    private func unlockFailed() {
        showAlert("The pin you entered is incorrect.", title: "Invalid pin")
    }
    
    private func unlockDidSucceed() {
        showAlert("The app was successfully unlocked.", title: "Unlocked")
        isUnlocked = true
        
        showAllCapsAndScrollToTop()
        updateNavigationItemTitleView()
    }
    
    private func loadClassifier(reload: Bool = false) {
        guard classifier == nil || reload else {
            return
        }
        guard let model = app.storage.recognitionModel else {
            downloadNewestClassifierIfNeeded()
            return
        }
        classifier = Classifier(model: model)
    }

    private func askUserToDownload(capImages: Int) {
        let detail = "\(capImages) caps have no image. Would you like to download them now? (\(ByteCountFormatter.string(fromByteCount: Int64(capImages * 10000), countStyle: .file)))"
        presentUserBinaryChoice("Download images", detail: detail, yesText: "Download", noText: "Later", dismissed: {
            self.downloadNewestClassifierIfNeeded()
        }) {
            self.downloadAllCapImages()
        }
    }
    
    private func askUserToDownload(classifier version: Int, size: Int64?) {
        let oldVersion = app.database.classifierVersion
        let sizeText = size != nil ? " (\(ByteCountFormatter.string(fromByteCount: size!, countStyle: .file)))" : ""
        guard oldVersion > 0 else {
            askUserToDownloadFirst(classifier: version, sizeText: sizeText)
            return
        }
        askUserToDownloadNew(classifier: version, sizeText: sizeText, oldVersion: oldVersion)
    }

    private func askUserToDownloadNew(classifier version: Int, sizeText: String, oldVersion: Int) {
        let detail = "Version \(version) of the classifier is available for download (You have version \(oldVersion)). Would you like to download it now?"
        presentUserBinaryChoice("New classifier", detail: detail + sizeText, yesText: "Download") {
            self.downloadClassifier()
        }
    }
    
    private func askUserToDownloadFirst(classifier version: Int, sizeText: String) {
        let detail = "A classifier to match caps is available for download (version \(version). Would you like to download it now?"
        presentUserBinaryChoice("Download classifier", detail: detail + sizeText, yesText: "Download") {
            self.downloadClassifier()
        }
    }
    
    private func askUserForText(_ title: String, detail: String, existingText: String? = nil, placeholder: String? = "Cap name", yesText: String, noText: String = "Cancel", confirmed: @escaping (_ text: String) -> Void) {
        DispatchQueue.main.async {
            let alertController = UIAlertController(
                title: title,
                message: detail,
                preferredStyle: .alert)
            
            alertController.addTextField { textField in
                textField.placeholder = placeholder
                textField.keyboardType = .default
                textField.text = existingText
            }
            
            let action = UIAlertAction(title: yesText, style: .default) { _ in
                guard let name = alertController.textFields?.first?.text else {
                    return
                }
                confirmed(name)
            }
            
            let cancel = UIAlertAction(title: noText, style: .cancel)
            
            alertController.addAction(action)
            alertController.addAction(cancel)
            self.present(alertController, animated: true)
        }
    }
    
    private func presentUserBinaryChoice(_ title: String, detail: String, yesText: String, noText: String = "Cancel", dismissed: (() -> Void)? = nil, confirmed: @escaping () -> Void) {
        let alert = UIAlertController(title: title, message: detail, preferredStyle: .alert)
        
        let confirm = UIAlertAction(title: yesText, style: .default) { _ in
            confirmed()
        }
        let cancel = UIAlertAction(title: noText, style: .cancel) { _ in
            dismissed?()
        }
        alert.addAction(confirm)
        alert.addAction(cancel)
        self.present(alert, animated: true)
        
    }
    
    // MARK: Starting downloads
    
    private func downloadClassifier() {
        let style: JGProgressHUDStyle = traitCollection.userInterfaceStyle == .dark ? .dark : .light
        let hud = JGProgressHUD(style: style)
        //hud.vibrancyEnabled = true
        hud.indicatorView = JGProgressHUDPieIndicatorView()
        hud.detailTextLabel.text = "0 % complete"
        hud.textLabel.text = "Downloading image classifier"
        hud.show(in: self.view)
        
        app.database.downloadClassifier(progress: { progress, received, total in
            DispatchQueue.main.async {
                hud.progress = progress
                let t = ByteCountFormatter.string(fromByteCount: total, countStyle: .file)
                let r = ByteCountFormatter.string(fromByteCount: received, countStyle: .file)
                hud.detailTextLabel.text = String(format: "%.0f", progress * 100) + " % (\(r) / \(t))"
            }
        }) { success in
            DispatchQueue.main.async {
                hud.dismiss()
                self.didDownloadClassifier(successfully: success)
            }
        }
    }
    
    private func downloadAllCapImages() {
        let style: JGProgressHUDStyle = traitCollection.userInterfaceStyle == .dark ? .dark : .light
        let hud = JGProgressHUD(style: style)
        //hud.vibrancyEnabled = true
        hud.indicatorView = JGProgressHUDPieIndicatorView()
        hud.detailTextLabel.text = "0 % complete"
        hud.textLabel.text = "Downloading cap images"
        hud.show(in: self.view)
        
        app.database.downloadMainCapImages { done, total in
            let progress = Float(done) / Float(total)
            let percent = Int((progress * 100).rounded())
            hud.detailTextLabel.text = "\(percent) % (\(done) / \(total))"
            hud.progress = progress
            
            if done >= total {
                hud.dismiss(afterDelay: 1.0)
                self.downloadNewestClassifierIfNeeded()
            }
        }
    }
    
    // MARK: Classification
    
    /// The similarity of the cap to the currently processed image
    private func match(for cap: Int) -> Float? {
        matches?[cap]
    }
    
    private func clearClassifierMatches() {
        matches = nil
    }
    
    private func classify(image: UIImage) {
        guard let classifier = self.classifier else {
            return
        }
        DispatchQueue.global(qos: .userInitiated).async {
            self.log("Classification starting...")
            classifier.recognize(image: image) { matches in
                guard let matches = matches else {
                    self.log("Failed to classify image")
                    self.matches = nil
                    return
                }
                self.log("Classification finished")
                self.matches = matches
                self.sortType = .match
                self.sortAscending = false
                self.showAllCapsAndScrollToTop()
                DispatchQueue.global(qos: .background).async {
                    app.database.update(recognizedCaps: Set(matches.keys))
                }
            }
        }
    }
    
    private func classifyDummyImage() {
        guard let classifier = self.classifier else {
            return
        }
        DispatchQueue.global(qos: .userInitiated).async {
            classifier.recognize(image: UIImage(named: "launch")!) { matches in
                guard let matches = matches else {
                    self.log("Failed to classify dummy image")
                    self.matches = nil
                    return
                }
                self.log("Dummy classification finished")
                DispatchQueue.global(qos: .background).async {
                    app.database.update(recognizedCaps: Set(matches.keys))
                }
            }
        }
    }
    
    // MARK: Finishing downloads
    
    private func didDownloadClassifier(successfully success: Bool) {
        guard success else {
            self.log("Failed to download classifier")
            return
        }
        loadClassifier(reload: true)
        self.log("Classifier was downloaded.")
        guard let image = accessory!.currentImage else {
            classifyDummyImage()
            return
        }
        classify(image: image)
    }
    
    // MARK: - Showing caps

    private func reloadCapsFromDatabase() {
        caps = app.database?.caps ?? []
        showCaps()
    }

    /**
     Match all cap names against the given string and return matches.
     - note: Each space-separated part of the string is matched individually
     */
    private func showCaps(matching text: String? = nil) {
        DispatchQueue.global(qos: .userInteractive).async {
            self.searchText = text
            guard let t = text else {
                self.show(caps: self.caps)
                return
            }
            let found = self.filter(caps: self.caps, matching: t)
            self.show(caps: found)
        }
    }
    
    private func show(caps: [Cap]) {
        show(sortedCaps: sorted(caps: caps))
    }
    
    private func show(sortedCaps caps: [Cap]) {
        shownCaps = caps
        DispatchQueue.main.async {
            self.tableView.reloadData()
        }
    }
    
    private func filter(caps: [Cap], matching text: String) -> [Cap] {
        let textParts = text.components(separatedBy: " ").filter { $0 != "" }
        return caps.compactMap { cap -> Cap? in
            // For each part of text, check if name contains it
            for textItem in textParts {
                if !cap.cleanName.contains(textItem) {
                    return nil
                }
            }
            return cap
        }
    }
    
    private func sorted(caps: [Cap]) -> [Cap] {
        if sortAscending {
            switch sortType {
            case .id: return caps.sorted { $0.id < $1.id }
            case .count: return caps.sorted { $0.count < $1.count }
            case .name: return caps.sorted { $0.name < $1.name }
            case .match: return caps.sorted { match(for: $0.id) ?? 0 < match(for: $1.id) ?? 0 }
            }
        } else {
            switch sortType {
            case .id: return caps.sorted { $0.id > $1.id }
            case .count: return caps.sorted { $0.count > $1.count }
            case .name: return caps.sorted { $0.name > $1.name }
            case .match: return caps.sorted { match(for: $0.id) ?? 0 > match(for: $1.id) ?? 0 }
            }
        }
    }

    /// Resets the cap list to its original state, discarding any previous sorting.
    private func showAllCapsByDescendingId() {
        sortType = .id
        sortAscending = false
        showAllCapsAndScrollToTop()
    }

    /// Display all caps in the table, and scrolls to the top
    private func showAllCapsAndScrollToTop() {
        showCaps()
        tableViewScrollToTop()
    }
    
    // MARK: - TableView
    
    /**
     Scroll the table view to the top
     */
    private func tableViewScrollToTop() {
        guard shownCaps.count > 0 else { return }
        let path = IndexPath(row: 0, section: 0)
        DispatchQueue.main.async {
            self.tableView.scrollToRow(at: path, at: .top, animated: true)
        }
    }
}

// MARK: - SortControllerDelegate

extension TableView: SortControllerDelegate {
    
    func sortController(didSelect sortType: SortCriteria, ascending: Bool) {
        self.sortType = sortType
        self.sortAscending = ascending
        if sortType != .match {
            clearClassifierMatches()
        }
        showAllCapsAndScrollToTop()
    }
}

// MARK: - CameraControllerDelegate

extension TableView: CameraControllerDelegate {
    
    func didCapture(image: UIImage) {
        guard let cap = capToAddImageTo else {
            accessory!.showImageView(with: image, isUnlocked: isUnlocked)
            classify(image: image)
            return
        }
        
        guard app.database.add(image: image, for: cap) else {
            self.error("Could not save image")
            return
        }
        log("Added image for cap \(cap)")
        self.capToAddImageTo = nil
    }
    
    func didCancel() {
        capToAddImageTo = nil
    }
}

// MARK: - UITableViewDataSource

extension TableView {

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "cap") as! CapCell
        let cap = shownCaps[indexPath.row]
        
        configure(cell: cell, for: cap)
        return cell
    }
    
    private func configure(cell: CapCell, for cap: Cap) {
        let matchText = cap.matchLabelText(match: match(for: cap.id), appIsUnlocked: self.isUnlocked)
        let countText = cap.countLabelText(appIsUnlocked: self.isUnlocked)
        
        cell.id = cap.id
        cell.set(name: cap.name)
        cell.set(matchLabel: matchText)
        cell.set(countLabel: countText)
        
        if let image = app.storage.image(for: cap.id) {
            cell.set(image: image)
        } else {
            cell.set(image: nil)
            app.database.downloadMainImage(for: cap.id) { _ in
                // Delegate call will update image
            }
        }
    }

    override func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return shownCaps.count
    }
}

// MARK: - UITableViewDelegate

extension TableView {
    
    private func takeImage(for cap: Int) {
        self.capToAddImageTo = cap
        showCameraView()
    }
    
    override func tableView(_ tableView: UITableView, willSelectRowAt indexPath: IndexPath) -> IndexPath? {
        // Prevent unauthorized users from selecting caps
        isUnlocked ? indexPath : nil
    }
    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        defer {
            tableView.deselectRow(at: indexPath, animated: true)
        }
        // Prevent unauthorized users from making changes
        guard isUnlocked else {
            return
        }
        let cap = shownCaps[indexPath.row]
        guard let image = accessory?.capImage.image else {
            self.giveFeedback(.medium)
            takeImage(for: cap.id)
            return
        }
        guard app.database.add(image: image, for: cap.id) else {
            self.giveFeedback(.heavy)
            self.error("Could not save image")
            return
        }
        self.giveFeedback(.medium)
        // Delegate call will update cell
        self.accessory?.discardImage()
    }

    private func giveFeedback(_ style: UIImpactFeedbackGenerator.FeedbackStyle) {
        UIImpactFeedbackGenerator(style: style).impactOccurred()
    }
    
    override func tableView(_ tableView: UITableView, trailingSwipeActionsConfigurationForRowAt indexPath: IndexPath) -> UISwipeActionsConfiguration? {
        // Prevent unauthorized users from making changes
        guard isUnlocked else {
            return nil
        }
        
        let cap = shownCaps[indexPath.row]
        
        let rename = UIContextualAction(style: .normal, title: "Rename\ncap") { (_, _, success) in
            success(true)
            self.rename(cap: cap, at: indexPath)
            self.giveFeedback(.medium)
        }
        rename.backgroundColor = .blue

        let image = UIContextualAction(style: .normal, title: "Change\nimage") { (_, _, success) in
            self.giveFeedback(.medium)
            let storyboard = UIStoryboard(name: "Main", bundle: nil)
            let controller = storyboard.instantiateViewController(withIdentifier: "ImageSelector") as! ImageSelector
            controller.cap = cap
            self.navigationController?.pushViewController(controller, animated: true)
            success(true)
        }
        image.backgroundColor = .red
        
        return UISwipeActionsConfiguration(actions: [rename, image])
    }
    
    override func tableView(_ tableView: UITableView, leadingSwipeActionsConfigurationForRowAt indexPath: IndexPath) -> UISwipeActionsConfiguration? {
        let cap = shownCaps[indexPath.row]
        
        var actions = [UIContextualAction]()
        // Prevent unauthorized users from making changes
        if isUnlocked {
            let count = UIContextualAction(style: .normal, title: "Update\ncount") { (_, _, success) in
                self.giveFeedback(.medium)
                success(true)
                DispatchQueue.global(qos: .userInitiated).async {
                    app.database.downloadImageCount(for: cap.id)
                }
            }
            count.backgroundColor = .orange
            actions.append(count)
        }
        
        let similar = UIContextualAction(style: .normal, title: "Similar\ncaps") { (_, _, success) in
            self.giveFeedback(.medium)
            self.accessory?.hideImageView()
            guard let image = app.storage.image(for: cap.id) else {
                success(false)
                return
            }
            self.classify(image: image)
            success(true)
        }
        similar.backgroundColor = .blue
        actions.append(similar)
        
        return UISwipeActionsConfiguration(actions: actions)
    }
}

// MARK: - Logging

extension TableView: Logger { }

// MARK: - Protocol DatabaseDelegate

extension TableView: DatabaseDelegate {
    
    func database(didAddCap cap: Cap) {
        caps.append(cap)
        updateNavigationItemTitleView()
        guard let text = searchText else {
            // All caps are shown
            let newList = sorted(caps: caps)
            updateShownCaps(newList, insertedId: cap.id)
            return
        }
        guard filter(caps: [cap], matching: text) != [] else {
            // Cap is not shown, so don't reload
            return
        }
        let newList = sorted(caps: filter(caps: caps, matching: text))
        updateShownCaps(newList, insertedId: cap.id)
    }
    
    func database(didChangeCap id: Int) {
        updateNavigationItemTitleView()
        guard let cap = app.database.cap(for: id) else {
            log("Changed cap \(id) not found in database")
            return
        }
        if let index = caps.firstIndex(where: { $0.id == id}) {
            caps[index] = cap
        } else {
            log("Cap not found in full list")
        }
        if let index = shownCaps.firstIndex(where: { $0.id == id}) {
            shownCaps[index] = cap
        }
        guard let cell = visibleCell(for: id) else {
            return
        }
        configure(cell: cell, for: cap)
    }
    
    func database(didLoadImageForCap cap: Int) {
        guard let cell = visibleCell(for: cap) else {
            return
        }
        guard let image = app.storage.image(for: cap) else {
            log("No image for cap \(cap), although it should be loaded")
            return
        }
        cell.set(image: image)
    }
    
    func databaseNeedsFullRefresh() {
        reloadCapsFromDatabase()
    }
    
    private func visibleCell(for cap: Int) -> CapCell? {
        tableView.visibleCells
            .map { $0 as! CapCell }
            .first { $0.id == cap }
    }
}

// MARK: - Protocol CapSearchDelegate

extension TableView: CapAccessoryDelegate {
    
    func capSearchWasDismissed() {
        showAllCapsAndScrollToTop()
    }
    
    func capSearch(didChange text: String) {
        let cleaned = text.clean
        guard cleaned != "" else {
            self.showCaps(matching: nil)
            return
        }
        self.showCaps(matching: cleaned)
    }
    
    func capAccessoryDidDiscardImage() {
        matches = nil
        showAllCapsByDescendingId()
    }
    
    func capAccessory(shouldSave image: UIImage) {
        saveNewCap(for: image)
    }
    
    func capAccessoryCameraButtonPressed() {
        showCameraView()
    }
}