/*****************************************************************************
 * VLCDragAndDropManager.swift
 * VLC for iOS
 *****************************************************************************
 * Copyright (c) 2017 VideoLAN. All rights reserved.
 * $Id$
 *
 * Authors: Carola Nitz <caro # videolan.org>
 *
 * Refer to the COPYING file of the official project for license.
 *****************************************************************************/

import MobileCoreServices
import UIKit

@available(iOS 11.0, *)
struct DropError: Error {
    enum ErrorKind {
        case moveFileToDocuments
        case loadFileRepresentationFailed
    }

    let kind: ErrorKind
}

@available(iOS 11.0, *)
protocol VLCDragAndDropManagerDelegate: NSObjectProtocol {
    func dragAndDropManagerRequestsFile(manager: NSObject, atIndexPath indexPath: IndexPath) -> Any?
    func dragAndDropManagerInsertItem(manager: NSObject, item: NSManagedObject, atIndexPath indexPath: IndexPath)
    func dragAndDropManagerDeleteItem(manager: NSObject, atIndexPath indexPath: IndexPath)
    func dragAndDropManagerRemoveFileFromFolder(manager: NSObject, file: NSManagedObject)
    func dragAndDropManagerCurrentSelection(manager: NSObject) -> AnyObject?
}

@available(iOS 11.0, *)
class VLCDragAndDropManager<ModelType>: NSObject {
//, UICollectionViewDragDelegate, UITableViewDragDelegate, UICollectionViewDropDelegate, UITableViewDropDelegate, UIDropInteractionDelegate {

//    let utiTypeIdentifiers: [String] = VLCDragAndDropManager.supportedTypeIdentifiers()
//    var cateory: ModelType
//    /// Returns the supported type identifiers that VLC can process.
//    /// It fetches the identifiers in LSItemContentTypes from all the CFBundleDocumentTypes in the info.plist.
//    /// Video, Audio and Subtitle formats
//    ///
//    /// - Returns: Array of UTITypeIdentifiers
//    private class func supportedTypeIdentifiers() -> [String] {
//        var typeIdentifiers: [String] = []
//        if let documents = Bundle.main.infoDictionary?["CFBundleDocumentTypes"] as? [[String: Any]] {
//            for item in documents {
//                if let value = item["LSItemContentTypes"] as? [String] {
//                    typeIdentifiers.append(contentsOf: value)
//                }
//            }
//        }
//        return typeIdentifiers
//    }
//
//    @available(*, unavailable, message: "use init(category:)")
//    override init() {
//        fatalError()
//    }
//
//    init(cateory: ModelType) {
//        self.cateory = cateory
//        super.init()
//    }
//
//    // MARK: - TableView
//
//    func tableView(_ tableView: UITableView, canHandle session: UIDropSession) -> Bool {
//        return canHandleDropSession(session: session)
//    }
//
//    func tableView(_ tableView: UITableView, itemsForAddingTo session: UIDragSession, at indexPath: IndexPath, point: CGPoint) -> [UIDragItem] {
//        return dragItems(forIndexPath: indexPath)
//    }
//
//    func tableView(_ tableView: UITableView, itemsForBeginning session: UIDragSession, at indexPath: IndexPath) -> [UIDragItem] {
//        return dragItems(forIndexPath: indexPath)
//    }
//
//    func tableView(_ tableView: UITableView, dropSessionDidUpdate session: UIDropSession, withDestinationIndexPath destinationIndexPath: IndexPath?) -> UITableViewDropProposal {
//        let operation = dropOperation(hasActiveDrag: tableView.hasActiveDrag, firstSessionItem: session.items.first, withDestinationIndexPath: destinationIndexPath)
//        return UITableViewDropProposal(operation: operation, intent: .insertIntoDestinationIndexPath)
//    }
//
//    func tableView(_ tableView: UITableView, performDropWith coordinator: UITableViewDropCoordinator) {
//        let section = tableView.numberOfSections - 1
//        let row = tableView.numberOfRows(inSection: section)
//        let destinationPath = coordinator.destinationIndexPath ?? IndexPath(row: row, section: section)
//
//        for item in coordinator.items {
//            let itemProvider = item.dragItem.itemProvider
//            // we're not gonna handle moving of folders
//            if let sourceItem = item.dragItem.localObject, fileIsCollection(file: sourceItem as AnyObject) {
//                continue
//            }
//
//            if fileIsFolder(atIndexPath: destinationPath) { // handle dropping onto a folder
//                addDragItem(tableView: tableView, dragItem: item, toFolderAt: destinationPath)
//                continue
//            }
//
//            if item.sourceIndexPath != nil { // element within VLC
//                moveItem(tableView: tableView, item: item, toIndexPath: destinationPath)
//                continue
//            }
//            // Element dragging from another App
//            let placeholder = UITableViewDropPlaceholder(insertionIndexPath: destinationPath, reuseIdentifier: VLCPlaylistTableViewCell.cellIdentifier(), rowHeight: VLCPlaylistTableViewCell.heightOfCell())
//            let placeholderContext = coordinator.drop(item.dragItem, to: placeholder)
//            createFileWith(itemProvider: itemProvider) {
//                [weak self] file, error in
//
//                guard let strongSelf = self else { return }
//
//                if let file = file {
//                    placeholderContext.commitInsertion() {
//                        insertionIndexPath in
//                        strongSelf.cateory.dragAndDropManagerInsertItem(manager: strongSelf, item: file, atIndexPath: insertionIndexPath)
//                    }
//                }
//                if let error = error as? DropError {
//                    strongSelf.handleError(error: error, itemProvider: item.dragItem.itemProvider)
//                    placeholderContext.deletePlaceholder()
//                }
//            }
//        }
//    }
//
//    private func inFolder() -> Bool {
//        return cateory.dragAndDropManagerCurrentSelection(manager: self) as? MLLabel != nil
//    }
//
//    private func moveItem(tableView: UITableView, item: UITableViewDropItem, toIndexPath destinationPath: IndexPath) {
//        if let mlFile = item.dragItem.localObject as? MLFile, !mlFile.labels.isEmpty && !inFolder() {
//            tableView.performBatchUpdates({
//                tableView.insertRows(at: [destinationPath], with: .automatic)
//                cateory.dragAndDropManagerInsertItem(manager: self, item: mlFile, atIndexPath: destinationPath)
//                cateory.dragAndDropManagerRemoveFileFromFolder(manager: self, file: mlFile)
//            }, completion: nil)
//        }
//    }
//
//    private func addDragItem(tableView: UITableView, dragItem item: UITableViewDropItem, toFolderAt index: IndexPath) {
//        if let sourcepath = item.sourceIndexPath { // local file that just needs to be moved
//            tableView.performBatchUpdates({
//                if let file = cateory.dragAndDropManagerRequestsFile(manager: self, atIndexPath: sourcepath) as? MLFile {
//                    tableView.deleteRows(at: [sourcepath], with: .automatic)
//                    addFile(file: file, toFolderAt: index)
//                    cateory.dragAndDropManagerDeleteItem(manager: self, atIndexPath: sourcepath)
//                }
//            }, completion: nil)
//            return
//        }
//        // file from other app
//        createFileWith(itemProvider: item.dragItem.itemProvider) {
//            [weak self] file, error in
//
//            if let strongSelf = self, let file = file {
//                strongSelf.addFile(file: file, toFolderAt: index)
//            }
//        }
//    }
//
//    // MARK: - Collectionview
//
//    func collectionView(_ collectionView: UICollectionView, canHandle session: UIDropSession) -> Bool {
//        return canHandleDropSession(session: session)
//    }
//
//    func collectionView(_ collectionView: UICollectionView, itemsForBeginning session: UIDragSession, at indexPath: IndexPath) -> [UIDragItem] {
//        return dragItems(forIndexPath: indexPath)
//    }
//
//    func collectionView(_ collectionView: UICollectionView, itemsForAddingTo session: UIDragSession, at indexPath: IndexPath, point: CGPoint) -> [UIDragItem] {
//        return dragItems(forIndexPath: indexPath)
//    }
//
//    func collectionView(_ collectionView: UICollectionView, dropSessionDidUpdate session: UIDropSession, withDestinationIndexPath destinationIndexPath: IndexPath?) -> UICollectionViewDropProposal {
//        let operation = dropOperation(hasActiveDrag: collectionView.hasActiveDrag, firstSessionItem: session.items.first, withDestinationIndexPath: destinationIndexPath)
//        return UICollectionViewDropProposal(operation: operation, intent: .insertIntoDestinationIndexPath)
//    }
//
//    func collectionView(_ collectionView: UICollectionView, performDropWith coordinator: UICollectionViewDropCoordinator) {
//        let section = collectionView.numberOfSections - 1
//        let row = collectionView.numberOfItems(inSection: section)
//        let destinationPath = coordinator.destinationIndexPath ?? IndexPath(row: row, section: section)
//
//        for item in coordinator.items {
//            if let sourceItem = item.dragItem.localObject, fileIsCollection(file: sourceItem as AnyObject) { // We're not handling moving of Collection
//                continue
//            }
//            if fileIsFolder(atIndexPath: destinationPath) { // handle dropping onto a folder
//                addDragItem(collectionView: collectionView, dragItem: item, toFolderAt: destinationPath)
//                continue
//            }
//            if item.sourceIndexPath != nil { // element within VLC
//                moveItem(collectionView: collectionView, item: item, toIndexPath: destinationPath)
//                continue
//            }
//            // Element from another App
//            let placeholder = UICollectionViewDropPlaceholder(insertionIndexPath: destinationPath, reuseIdentifier: VLCPlaylistCollectionViewCell.cellIdentifier())
//            let placeholderContext = coordinator.drop(item.dragItem, to: placeholder)
//            createFileWith(itemProvider: item.dragItem.itemProvider) {
//                [weak self] file, error in
//
//                guard let strongSelf = self else { return }
//
//                if let file = file {
//                    placeholderContext.commitInsertion() {
//                        insertionIndexPath in
//                        strongSelf.cateory.dragAndDropManagerInsertItem(manager: strongSelf, item: file, atIndexPath: insertionIndexPath)
//                    }
//                }
//                if let error = error as? DropError {
//                    strongSelf.handleError(error: error, itemProvider: item.dragItem.itemProvider)
//                    placeholderContext.deletePlaceholder()
//                }
//            }
//        }
//    }
//
//    private func moveItem(collectionView: UICollectionView, item: UICollectionViewDropItem, toIndexPath destinationPath: IndexPath) {
//        if let mlFile = item.dragItem.localObject as? MLFile, !mlFile.labels.isEmpty && !inFolder() {
//            collectionView.performBatchUpdates({
//                collectionView.insertItems(at: [destinationPath])
//                cateory.dragAndDropManagerInsertItem(manager: self, item: mlFile, atIndexPath: destinationPath)
//                cateory.dragAndDropManagerRemoveFileFromFolder(manager: self, file: mlFile)
//            }, completion: nil)
//        }
//    }
//
//    private func addDragItem(collectionView: UICollectionView, dragItem item: UICollectionViewDropItem, toFolderAt index: IndexPath) {
//        if let sourcepath = item.sourceIndexPath {
//            // local file that just needs to be moved
//            collectionView.performBatchUpdates({
//                if let file = cateory.dragAndDropManagerRequestsFile(manager: self, atIndexPath: sourcepath) as? MLFile {
//                    collectionView.deleteItems(at: [sourcepath])
//                    addFile(file: file, toFolderAt: index)
//                    cateory.dragAndDropManagerDeleteItem(manager: self, atIndexPath: sourcepath)
//                }
//            }, completion: nil)
//        } else {
//            // file from other app
//            createFileWith(itemProvider: item.dragItem.itemProvider) {
//                [weak self] file, error in
//                if let strongSelf = self, let file = file {
//                    strongSelf.addFile(file: file, toFolderAt: index)
//                }
//            }
//        }
//    }
//
//    // MARK: - DropInteractionDelegate for EmptyView
//
//    func dropInteraction(_ interaction: UIDropInteraction, canHandle session: UIDropSession) -> Bool {
//        return canHandleDropSession(session: session)
//    }
//
//    func dropInteraction(_ interaction: UIDropInteraction, sessionDidUpdate session: UIDropSession) -> UIDropProposal {
//        return UIDropProposal(operation: .copy)
//    }
//
//    func dropInteraction(_ interaction: UIDropInteraction, performDrop session: UIDropSession) {
//        for item in session.items {
//            createFileWith(itemProvider: item.itemProvider) {
//                [weak self] _, error in
//                if let error = error as? DropError {
//                    self?.handleError(error: error, itemProvider: item.itemProvider)
//                }
//                // no need to handle the file case since the libraryVC updates itself after getting a file
//            }
//        }
//    }
//
//    // MARK: - Shared Methods
//
//    // Checks if the session has items conforming to typeidentifiers
//    private func canHandleDropSession(session: UIDropSession) -> Bool {
//        if session.localDragSession != nil {
//            return true
//        }
//        return session.hasItemsConforming(toTypeIdentifiers: utiTypeIdentifiers)
//    }
//
//    /// Returns a drop operation type
//    ///
//    /// - Parameters:
//    ///   - hasActiveDrag: State if the drag started within the app
//    ///   - item: UIDragItem from session
//    /// - Returns: UIDropOperation
//    private func dropOperation(hasActiveDrag: Bool, firstSessionItem item: AnyObject?, withDestinationIndexPath destinationIndexPath: IndexPath?) -> UIDropOperation {
//        let inAlbum = cateory.dragAndDropManagerCurrentSelection(manager: self) as? MLAlbum != nil
//        let inShow = cateory.dragAndDropManagerCurrentSelection(manager: self) as? MLShow != nil
//        // you can move files into a folder or copy from anothr app into a folder
//        if fileIsFolder(atIndexPath: destinationIndexPath) {
//            // no dragging entire shows and albums into folders
//            if let dragItem = item, let mlFile = dragItem.localObject as? MLFile, mlFile.isAlbumTrack() || mlFile.isShowEpisode() {
//                return .forbidden
//            }
//            return hasActiveDrag ? .move : .copy
//        }
//        // you can't reorder
//        if inFolder() {
//            return hasActiveDrag ? .forbidden : .copy
//        }
//        // you can't reorder in or drag into an Album or Show
//        if inAlbum || inShow {
//            return .cancel
//        }
//        // we're dragging a file out of a folder
//        if let dragItem = item, let mlFile = dragItem.localObject as? MLFile, !mlFile.labels.isEmpty {
//            return .copy
//        }
//        // no reorder from another app into the top layer
//        return hasActiveDrag ? .forbidden : .copy
//    }
//
//    /// show an Alert when dropping failed
//    ///
//    /// - Parameters:
//    ///   - error: the type of error that happend
//    ///   - itemProvider: the itemProvider to retrieve the suggestedName
//    private func handleError(error: DropError, itemProvider: NSItemProvider) {
//        let message: String
//        let filename = itemProvider.suggestedName ?? NSLocalizedString("THIS_FILE", comment: "")
//        switch error.kind {
//        case .loadFileRepresentationFailed:
//            message = String(format: NSLocalizedString("NOT_SUPPORTED_FILETYPE", comment: ""), filename)
//        case .moveFileToDocuments:
//            message = String(format: NSLocalizedString("FILE_EXISTS", comment: ""), filename)
//        }
//        let alert = UIAlertController(title: NSLocalizedString("ERROR", comment: ""), message: message, preferredStyle: .alert)
//        alert.addAction(UIAlertAction(title: NSLocalizedString("OK", comment: ""), style: .default, handler: nil))
//        UIApplication.shared.keyWindow?.rootViewController?.present(alert, animated: true, completion: nil)
//    }
//
//    private func fileIsFolder(atIndexPath indexPath: IndexPath?) -> Bool {
//        if let indexPath = indexPath {
//            let file = cateory.dragAndDropManagerRequestsFile(manager: self, atIndexPath: indexPath)
//            return file as? MLLabel != nil
//        }
//        return false
//    }
//
//    private func fileIsCollection(file: Any?) -> Bool {
//        let isFolder = file as? MLLabel != nil
//        let isAlbum = file as? MLAlbum != nil
//        let isShow = file as? MLShow != nil
//        return isFolder || isAlbum || isShow
//    }
//
//    private func fileIsCollection(atIndexPath indexPath: IndexPath?) -> Bool {
//        if let indexPath = indexPath {
//            if let file = cateory.dragAndDropManagerRequestsFile(manager: self, atIndexPath: indexPath) {
//                return fileIsCollection(file:file)
//            }
//        }
//        return false
//    }
//
//    // creating dragItems for the file at indexpath
//    private func dragItems(forIndexPath indexPath: IndexPath) -> [UIDragItem] {
//        if let file = cateory.dragAndDropManagerRequestsFile(manager: self, atIndexPath: indexPath) {
//            if fileIsCollection(atIndexPath: indexPath) {
//                return dragItemsforCollection(file: file)
//            }
//            return dragItem(fromFile: file)
//        }
//        assert(false, "we can't generate a dragfile if the delegate can't return a file ")
//        return []
//    }
//
//    /// Iterates over the items of a collection to create dragitems.
//    /// Since we're not storing collections as folders we have to provide single files
//    ///
//    /// - Parameter file: Can be of type MLAlbum, MLLabel or MLShow
//    /// - Returns: An array of UIDragItems
//    private func dragItemsforCollection(file: Any) -> [UIDragItem] {
//        var dragItems = [UIDragItem]()
//        var set = Set<AnyHashable>()
//        if let folder = file as? MLLabel {
//            set = folder.files
//        } else if let album = file as? MLAlbum {
//            for track in album.tracks {
//                if let mlfile = (track as? MLAlbumTrack)?.files.first {
//                    _ = set.insert(mlfile)
//                }
//            }
//        } else if let show = file as? MLShow {
//            for episode in show.episodes {
//                if let mlfile = (episode as? MLShowEpisode)?.files {
//                    set = set.union(mlfile)
//                }
//            }
//        } else {
//            assert(false, "can't get dragitems from a file that is not a collection")
//        }
//        for convertibleFile in set {
//            if let mlfile = convertibleFile as? MLFile, let item = dragItem(fromFile: mlfile).first {
//                dragItems.append(item)
//            }
//        }
//        return dragItems
//    }
//
//    //Provides an item for other applications
//    private func dragItem(fromFile file: Any) -> [UIDragItem] {
//        guard let file = mlFile(from: file as AnyObject), let path = file.url else {
//            assert(false, "can't create a dragitem if there is no file or the file has no url")
//            return []
//        }
//
//        let data = try? Data(contentsOf: path, options: .mappedIfSafe)
//        let itemProvider = NSItemProvider()
//        itemProvider.suggestedName = path.lastPathComponent
//        // maybe use UTTypeForFileURL
//        if let identifiers = try? path.resourceValues(forKeys: [.typeIdentifierKey]), let identifier = identifiers.typeIdentifier {
//            // here we can show progress
//            itemProvider.registerDataRepresentation(forTypeIdentifier: identifier, visibility: .all) { completion -> Progress? in
//                completion(data, nil)
//                return nil
//            }
//            let dragitem = UIDragItem(itemProvider: itemProvider)
//            dragitem.localObject = file
//            return [dragitem]
//        }
//        assert(false, "we can't provide a typeidentifier")
//        return []
//    }
//
//    private func mlFile(from file: AnyObject) -> MLFile? {
//        if let episode = file as? MLShowEpisode, let convertedfile = episode.files.first as? MLFile {
//            return convertedfile
//        }
//
//        if let track = file as? MLAlbumTrack, let convertedfile = track.files.first as? MLFile {
//            return convertedfile
//        }
//
//        if let convertedfile = file as? MLFile {
//            return convertedfile
//        }
//        return nil
//    }
//
//    private func addFile(file: MLFile, toFolderAt folderIndex: IndexPath) {
//        let label = cateory.dragAndDropManagerRequestsFile(manager: self, atIndexPath: folderIndex) as! MLLabel
//        DispatchQueue.main.async {
//            _ = label.files.insert(file)
//            file.labels = [label]
//            file.folderTrackNumber = NSNumber(integerLiteral: label.files.count - 1)
//        }
//    }
//
//    /// try to create a file from the dropped item
//    ///
//    /// - Parameters:
//    ///   - itemProvider: itemprovider which is used to load the files from
//    ///   - completion: callback with the successfully created file or error if it failed
//    private func createFileWith(itemProvider: NSItemProvider, completion: @escaping ((MLFile?, Error?) -> Void)) {
//        itemProvider.loadFileRepresentation(forTypeIdentifier: kUTTypeData as String) {
//            [weak self] (url, error) in
//            guard let strongSelf = self else { return }
//
//            guard let url = url else {
//                DispatchQueue.main.async {
//                    completion(nil, DropError(kind: .loadFileRepresentationFailed))
//                }
//                return
//            }
//            // returns nil for local session but this should also not be called for a local session
//            guard let destinationURL = strongSelf.moveFileToDocuments(fromURL: url) else {
//                DispatchQueue.main.async {
//                    completion(nil, DropError(kind: .moveFileToDocuments))
//                }
//                return
//            }
//            DispatchQueue.global(qos: .background).async {
//                let sharedlib = MLMediaLibrary.sharedMediaLibrary() as? MLMediaLibrary
//                sharedlib?.addFilePaths([destinationURL.path])
//
//                if let file = MLFile.file(for: destinationURL).first as? MLFile {
//                    DispatchQueue.main.async {
//                        // we dragged into a folder
//                        if let selection = strongSelf.cateory.dragAndDropManagerCurrentSelection(manager: strongSelf) as? MLLabel {
//                            file.labels = [selection]
//                        }
//                        completion(file, nil)
//                    }
//                }
//            }
//        }
//    }
//
//    private func moveFileToDocuments(fromURL filepath: URL?) -> URL? {
//        let searchPaths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)
//        let newDirectoryPath = searchPaths.first
//        guard let directoryPath = newDirectoryPath, let url = filepath else {
//            return nil
//        }
//        let destinationURL = URL(fileURLWithPath: "\(directoryPath)" + "/" + "\(url.lastPathComponent)")
//        do {
//            try FileManager.default.moveItem(at: url, to: destinationURL)
//        } catch let error {
//            print(error.localizedDescription)
//            return nil
//        }
//        return destinationURL
//    }
}