nextcloud-desktop/shell_integration/MacOSX/NextcloudIntegration/FileProviderExt/FileProviderExtension.swift

/*
 * Copyright (C) 2022 by Claudio Cambra <claudio.cambra@nextcloud.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
 * for more details.
 */

import FileProvider
import OSLog
import NCDesktopClientSocketKit
import NextcloudKit

class FileProviderExtension: NSObject, NSFileProviderReplicatedExtension, NKCommonDelegate {
    let domain: NSFileProviderDomain
    let ncKit = NextcloudKit()
    lazy var ncKitBackground: NKBackground = {
        let nckb = NKBackground(nkCommonInstance: ncKit.nkCommonInstance)
        return nckb
    }()

    let appGroupIdentifier: String? = Bundle.main.object(forInfoDictionaryKey: "SocketApiPrefix") as? String
    var ncAccount: NextcloudAccount?
    lazy var socketClient: LocalSocketClient? = {
        guard let containerUrl = pathForAppGroupContainer() else {
            NSLog("Could not start file provider socket client properly as could not get container url")
            return nil;
        }

        let socketPath = containerUrl.appendingPathComponent(".fileprovidersocket", conformingTo: .archive)
        let lineProcessor = FileProviderSocketLineProcessor(delegate: self)

        return LocalSocketClient(socketPath: socketPath.path, lineProcessor: lineProcessor)
    }()

    let urlSessionIdentifier: String = "com.nextcloud.session.upload.fileproviderext"
    let urlSessionMaximumConnectionsPerHost = 5
    lazy var urlSession: URLSession = {
        let configuration = URLSessionConfiguration.background(withIdentifier: urlSessionIdentifier)
        configuration.allowsCellularAccess = true
        configuration.sessionSendsLaunchEvents = true
        configuration.isDiscretionary = false
        configuration.httpMaximumConnectionsPerHost = urlSessionMaximumConnectionsPerHost
        configuration.requestCachePolicy = NSURLRequest.CachePolicy.reloadIgnoringLocalCacheData
        configuration.sharedContainerIdentifier = appGroupIdentifier

        let session = URLSession(configuration: configuration, delegate: ncKitBackground, delegateQueue: OperationQueue.main)
        return session
    }()
    var outstandingSessionTasks: [String: URLSessionTask] = [:]
    var outstandingOcIdTemp: [String: String] = [:]

    private var itemIdsForEnumeratorsNeedingSignalling: NSMutableSet = NSMutableSet()

    required init(domain: NSFileProviderDomain) {
        self.domain = domain
        // The containing application must create a domain using `NSFileProviderManager.add(_:, completionHandler:)`. The system will then launch the application extension process, call `FileProviderExtension.init(domain:)` to instantiate the extension for that domain, and call methods on the instance.

        super.init()
        self.socketClient?.start()
    }
    
    func invalidate() {
        // TODO: cleanup any resources
    }

    // MARK: NSFileProviderReplicatedExtension protocol methods
    
    func item(for identifier: NSFileProviderItemIdentifier, request: NSFileProviderRequest, completionHandler: @escaping (NSFileProviderItem?, Error?) -> Void) -> Progress {
        // resolve the given identifier to a record in the model

        NSLog("Received item request for item with identifier: %@", identifier.rawValue)
        if identifier == .rootContainer {
            guard let ncAccount = ncAccount else {
                NSLog("Not providing item: %@ as account not set up yet", identifier.rawValue)
                completionHandler(nil, NSFileProviderError(.notAuthenticated))
                return Progress()
            }

            let metadata = NextcloudItemMetadataTable()

            metadata.account = ncAccount.ncKitAccount
            metadata.directory = true
            metadata.ocId = NSFileProviderItemIdentifier.rootContainer.rawValue
            metadata.fileName = "root"
            metadata.fileNameView = "root"
            metadata.serverUrl = ncAccount.serverUrl
            metadata.classFile = NKCommon.typeClassFile.directory.rawValue

            completionHandler(FileProviderItem(metadata: metadata, parentItemIdentifier: NSFileProviderItemIdentifier.rootContainer, ncKit: ncKit), nil)
            return Progress()
        }

        let dbManager = NextcloudFilesDatabaseManager.shared
        guard let metadata = dbManager.itemMetadataFromFileProviderItemIdentifier(identifier),
              let parentItemIdentifier = parentItemIdentifierFromMetadata(metadata) else {
            completionHandler(nil, NSFileProviderError(.noSuchItem))
            return Progress()
        }

        completionHandler(FileProviderItem(metadata: metadata, parentItemIdentifier: parentItemIdentifier, ncKit: ncKit), nil)
        return Progress()
    }
    
    func fetchContents(for itemIdentifier: NSFileProviderItemIdentifier, version requestedVersion: NSFileProviderItemVersion?, request: NSFileProviderRequest, completionHandler: @escaping (URL?, NSFileProviderItem?, Error?) -> Void) -> Progress {

        NSLog("Received request to fetch contents of item with identifier: %@", itemIdentifier.rawValue)

        let dbManager = NextcloudFilesDatabaseManager.shared
        let ocId = itemIdentifier.rawValue
        guard let metadata = dbManager.itemMetadataFromOcId(ocId) else {
            NSLog("Could not acquire metadata of item with identifier: %@", itemIdentifier.rawValue)
            completionHandler(nil, nil, NSFileProviderError(.noSuchItem))
            return Progress()
        }

        guard !metadata.isDocumentViewableOnly else {
            NSLog("Could not get contents of item as is readonly: %@ %@", itemIdentifier.rawValue, metadata.fileName)
            completionHandler(nil, nil, NSFileProviderError(.cannotSynchronize))
            return Progress()
        }

        let serverUrlFileName = metadata.serverUrl + "/" + metadata.fileName

        NSLog("Fetching file with name %@ at URL: %@", metadata.fileName, serverUrlFileName)

        do {
            let fileNameLocalPath = try localPathForNCFile(ocId: metadata.ocId, fileNameView: metadata.fileNameView)

            guard let updatedMetadata = dbManager.setStatusForItemMetadata(metadata, status: NextcloudItemMetadataTable.Status.downloading) else {
                NSLog("Could not acquire updated metadata of item with identifier: %@", itemIdentifier.rawValue)
                completionHandler(nil, nil, NSFileProviderError(.noSuchItem))
                return Progress()
            }

            self.ncKit.download(serverUrlFileName: serverUrlFileName,
                                fileNameLocalPath: fileNameLocalPath.path,
                                requestHandler: { _ in

            }, taskHandler: { task in
                self.outstandingSessionTasks[serverUrlFileName] = task
                NSFileProviderManager(for: self.domain)?.register(task, forItemWithIdentifier: itemIdentifier, completionHandler: { _ in })
            }, progressHandler: { _ in

            }) { _, etag, date, _, _, _, error in
                self.outstandingSessionTasks.removeValue(forKey: serverUrlFileName)

                if error == .success {
                    NSLog("Acquired contents of item with identifier: %@ and filename: %@", itemIdentifier.rawValue, updatedMetadata.fileName)
                    updatedMetadata.status = NextcloudItemMetadataTable.Status.normal.rawValue
                    updatedMetadata.date = (date ?? NSDate()) as Date
                    updatedMetadata.etag = etag ?? ""

                    dbManager.addLocalFileMetadataFromItemMetadata(updatedMetadata)
                    dbManager.addItemMetadata(updatedMetadata)

                    guard let parentItemIdentifier = parentItemIdentifierFromMetadata(updatedMetadata) else {
                        completionHandler(nil, nil, NSFileProviderError(.noSuchItem))
                        return
                    }
                    let fpItem = FileProviderItem(metadata: updatedMetadata, parentItemIdentifier: parentItemIdentifier, ncKit: self.ncKit)

                    completionHandler(fileNameLocalPath, fpItem, nil)
                } else {
                    NSLog("Could not acquire contents of item with identifier: %@ and fileName: %@", itemIdentifier.rawValue, updatedMetadata.fileName)

                    updatedMetadata.status = NextcloudItemMetadataTable.Status.downloadError.rawValue
                    updatedMetadata.sessionError = error.errorDescription

                    dbManager.addItemMetadata(updatedMetadata)

                    completionHandler(nil, nil, NSFileProviderError(.cannotSynchronize))
                }
            }
        } catch let error {
            NSLog("Could not find local path for file %@, received error: %@", metadata.fileNameView, error.localizedDescription)
        }

        return Progress()
    }
    
    func createItem(basedOn itemTemplate: NSFileProviderItem, fields: NSFileProviderItemFields, contents url: URL?, options: NSFileProviderCreateItemOptions = [], request: NSFileProviderRequest, completionHandler: @escaping (NSFileProviderItem?, NSFileProviderItemFields, Bool, Error?) -> Void) -> Progress {
        // TODO: a new item was created on disk, process the item's creation

        completionHandler(itemTemplate, [], false, nil)
        return Progress()
    }
    
    func modifyItem(_ item: NSFileProviderItem, baseVersion version: NSFileProviderItemVersion, changedFields: NSFileProviderItemFields, contents newContents: URL?, options: NSFileProviderModifyItemOptions = [], request: NSFileProviderRequest, completionHandler: @escaping (NSFileProviderItem?, NSFileProviderItemFields, Bool, Error?) -> Void) -> Progress {
        // TODO: an item was modified on disk, process the item's modification
        
        completionHandler(nil, [], false, NSError(domain: NSCocoaErrorDomain, code: NSFeatureUnsupportedError, userInfo:[:]))
        return Progress()
    }
    
    func deleteItem(identifier: NSFileProviderItemIdentifier, baseVersion version: NSFileProviderItemVersion, options: NSFileProviderDeleteItemOptions = [], request: NSFileProviderRequest, completionHandler: @escaping (Error?) -> Void) -> Progress {
        // TODO: an item was deleted on disk, process the item's deletion
        
        completionHandler(NSError(domain: NSCocoaErrorDomain, code: NSFeatureUnsupportedError, userInfo:[:]))
        return Progress()
    }
    
    func enumerator(for containerItemIdentifier: NSFileProviderItemIdentifier, request: NSFileProviderRequest) throws -> NSFileProviderEnumerator {

        guard let ncAccount = ncAccount else {
            NSLog("Not providing enumerator for container with identifier %@ yet as account not set up")
            itemIdsForEnumeratorsNeedingSignalling.add(containerItemIdentifier)
            throw NSFileProviderError(.notAuthenticated)
        }

        return FileProviderEnumerator(enumeratedItemIdentifier: containerItemIdentifier, ncAccount: ncAccount, ncKit: ncKit)
    }

    // MARK: Nextcloud desktop client communication
    func sendFileProviderDomainIdentifier() {
        let command = "FILE_PROVIDER_DOMAIN_IDENTIFIER_REQUEST_REPLY"
        let argument = domain.identifier.rawValue
        let message = command + ":" + argument + "\n"
        socketClient?.sendMessage(message)
    }

    private func signalEnumeratorAfterAccountSetup() {
        guard let fpManager = NSFileProviderManager(for: domain) else {
            NSLog("Could not get file provider manager for domain %@, cannot notify after account setup", domain)
            return
        }

        assert(ncAccount != nil)

        if !NextcloudFilesDatabaseManager.shared.anyItemMetadatasForAccount(ncAccount!.ncKitAccount) {
            // This refreshes the entire structure of the FileProvider and calls
            // enumerateItems rather than enumerateChanges in the enumerator
            NSLog("Signalling manager for user %@ at server %@ to reimport everything", ncAccount!.username, ncAccount!.serverUrl)
            fpManager.reimportItems(below: .rootContainer, completionHandler: {_ in })
            return
        }

        NSLog("Signalling enumerator for user %@ at server %@", ncAccount!.username, ncAccount!.serverUrl)
        // System will only respond to workingSet when using and NSFileProviderReplicatedExtension
        // https://developer.apple.com/documentation/fileprovider/nonreplicated_file_provider_extension/content_and_change_tracking/tracking_your_file_provider_s_changes/using_push_notifications_to_signal_changes
        fpManager.signalEnumerator(for: .workingSet) { error in
            if error != nil {
                NSLog("Error signalling enumerator for workingSet, received error: %@", error!.localizedDescription)
            }
        }
    }

    func setupDomainAccount(user: String, serverUrl: String, password: String) {
        ncAccount = NextcloudAccount(user: user, serverUrl: serverUrl, password: password)
        ncKit.setup(user: ncAccount!.username,
                     userId: ncAccount!.username,
                     password: ncAccount!.password,
                     urlBase: ncAccount!.serverUrl,
                     userAgent: "Nextcloud-macOS/FileProviderExt",
                     nextcloudVersion: 25,
                     delegate: nil) // TODO: add delegate methods for self

        NSLog("Nextcloud account set up in File Provider extension for user: %@ at server: %@", user, serverUrl)

        if itemIdsForEnumeratorsNeedingSignalling.count > 0 {
            signalEnumeratorAfterAccountSetup()
            itemIdsForEnumeratorsNeedingSignalling = NSMutableSet()
        }
    }
}