/*
 * 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 {
    let domain: NSFileProviderDomain

    let appGroupIdentifier: String? = Bundle.main.object(forInfoDictionaryKey: "SocketApiPrefix") as? String
    var ncAccount: FileProviderDomainNextcloudAccountData = FileProviderDomainNextcloudAccountData()
    lazy var socketClient: LocalSocketClient? = {
        guard let fileProviderSocketApiPrefix = appGroupIdentifier else {
            NSLog("Could not start file provider socket client properly as SocketApiPrefix is missing")
            return nil;
        }

        let containerUrl = FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: fileProviderSocketApiPrefix)
        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: NKBackground.shared, delegateQueue: OperationQueue.main)
        return session
    }()

    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
        
        // TODO: implement the actual lookup

        completionHandler(FileProviderItem(identifier: identifier), nil)
        return Progress()
    }
    
    func fetchContents(for itemIdentifier: NSFileProviderItemIdentifier, version requestedVersion: NSFileProviderItemVersion?, request: NSFileProviderRequest, completionHandler: @escaping (URL?, NSFileProviderItem?, Error?) -> Void) -> Progress {
        // TODO: implement fetching of the contents for the itemIdentifier at the specified version
        
        completionHandler(nil, nil, NSError(domain: NSCocoaErrorDomain, code: NSFeatureUnsupportedError, userInfo:[:]))
        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 {
        return FileProviderEnumerator(enumeratedItemIdentifier: containerItemIdentifier)
    }

    // 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)
    }

    func setupDomainAccount(keychainAccount:String) {
        ncAccount = FileProviderDomainNextcloudAccountData(withKeychainAccount:keychainAccount)
    }
}