//
//  NCNetworking.swift
//  Nextcloud
//
//  Created by Marino Faggiana on 23/10/19.
//  Copyright © 2019 Marino Faggiana. All rights reserved.
//
//  Author Marino Faggiana <marino.faggiana@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 3 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.
//
//  You should have received a copy of the GNU General Public License
//  along with this program.  If not, see <http://www.gnu.org/licenses/>.
//

import UIKit
import OpenSSL
import NextcloudKit
import Alamofire
import Queuer

@objc public protocol NCNetworkingDelegate {
    @objc optional func downloadProgress(_ progress: Float, totalBytes: Int64, totalBytesExpected: Int64, fileName: String, serverUrl: String, session: URLSession, task: URLSessionTask)
    @objc optional func uploadProgress(_ progress: Float, totalBytes: Int64, totalBytesExpected: Int64, fileName: String, serverUrl: String, session: URLSession, task: URLSessionTask)
    @objc optional func downloadComplete(fileName: String, serverUrl: String, etag: String?, date: NSDate?, dateLastModified: NSDate?, length: Int64, fileNameLocalPath: String?, task: URLSessionTask, error: NKError)
    @objc optional func uploadComplete(fileName: String, serverUrl: String, ocId: String?, etag: String?, date: NSDate?, size: Int64, fileNameLocalPath: String?, task: URLSessionTask, error: NKError)
}

#if EXTENSION_FILE_PROVIDER_EXTENSION || EXTENSION_WIDGET
@objc protocol uploadE2EEDelegate: AnyObject { }
#endif

@objcMembers
class NCNetworking: NSObject, NKCommonDelegate {
    public static let shared: NCNetworking = {
        let instance = NCNetworking()
        return instance
    }()

    public struct TransferInForegorund {
        var ocId: String
        var progress: Float
    }

    struct FileNameServerUrl: Hashable {
        var fileName: String
        var serverUrl: String

    }

    weak var delegate: NCNetworkingDelegate?
    let utilityFileSystem = NCUtilityFileSystem()
    let utility = NCUtility()
    var lastReachability: Bool = true
    var networkReachability: NKCommon.TypeReachability?
    let downloadRequest = ThreadSafeDictionary<String, DownloadRequest>()
    let uploadRequest = ThreadSafeDictionary<String, UploadRequest>()
    let uploadMetadataInBackground = ThreadSafeDictionary<FileNameServerUrl, tableMetadata>()
    let downloadMetadataInBackground = ThreadSafeDictionary<FileNameServerUrl, tableMetadata>()
    var transferInForegorund: TransferInForegorund?

    lazy var nkBackground: NKBackground = {
        let nckb = NKBackground(nkCommonInstance: NextcloudKit.shared.nkCommonInstance)
        return nckb
    }()

    public let sessionMaximumConnectionsPerHost = 5
    public let sessionDownloadBackground: String = "com.nextcloud.session.download.background"
    public let sessionUploadBackground: String = "com.nextcloud.session.upload.background"
    public let sessionUploadBackgroundWWan: String = "com.nextcloud.session.upload.backgroundWWan"
    public let sessionUploadBackgroundExtension: String = "com.nextcloud.session.upload.extension"

    public lazy var sessionManagerDownloadBackground: URLSession = {
        let configuration = URLSessionConfiguration.background(withIdentifier: sessionDownloadBackground)
        configuration.allowsCellularAccess = true
        configuration.sessionSendsLaunchEvents = true
        configuration.isDiscretionary = false
        configuration.httpMaximumConnectionsPerHost = sessionMaximumConnectionsPerHost
        configuration.requestCachePolicy = NSURLRequest.CachePolicy.reloadIgnoringLocalCacheData
        let session = URLSession(configuration: configuration, delegate: nkBackground, delegateQueue: OperationQueue.main)
        return session
    }()

    public lazy var sessionManagerUploadBackground: URLSession = {
        let configuration = URLSessionConfiguration.background(withIdentifier: sessionUploadBackground)
        configuration.allowsCellularAccess = true
        configuration.sessionSendsLaunchEvents = true
        configuration.isDiscretionary = false
        configuration.httpMaximumConnectionsPerHost = sessionMaximumConnectionsPerHost
        configuration.requestCachePolicy = NSURLRequest.CachePolicy.reloadIgnoringLocalCacheData
        let session = URLSession(configuration: configuration, delegate: nkBackground, delegateQueue: OperationQueue.main)
        return session
    }()

    public lazy var sessionManagerUploadBackgroundWWan: URLSession = {
        let configuration = URLSessionConfiguration.background(withIdentifier: sessionUploadBackgroundWWan)
        configuration.allowsCellularAccess = false
        configuration.sessionSendsLaunchEvents = true
        configuration.isDiscretionary = false
        configuration.httpMaximumConnectionsPerHost = sessionMaximumConnectionsPerHost
        configuration.requestCachePolicy = NSURLRequest.CachePolicy.reloadIgnoringLocalCacheData
        let session = URLSession(configuration: configuration, delegate: nkBackground, delegateQueue: OperationQueue.main)
        return session
    }()

#if EXTENSION
    public lazy var sessionManagerUploadBackgroundExtension: URLSession = {
        let configuration = URLSessionConfiguration.background(withIdentifier: sessionUploadBackgroundExtension)
        configuration.allowsCellularAccess = true
        configuration.sessionSendsLaunchEvents = true
        configuration.isDiscretionary = false
        configuration.httpMaximumConnectionsPerHost = sessionMaximumConnectionsPerHost
        configuration.requestCachePolicy = NSURLRequest.CachePolicy.reloadIgnoringLocalCacheData
        configuration.sharedContainerIdentifier = NCBrandOptions.shared.capabilitiesGroups
        let session = URLSession(configuration: configuration, delegate: nkBackground, delegateQueue: OperationQueue.main)
        return session
    }()
#endif

    // REQUESTS
    var requestsUnifiedSearch: [DataRequest] = []

    // OPERATIONQUEUE
    let downloadThumbnailQueue = Queuer(name: "downloadThumbnailQueue", maxConcurrentOperationCount: 10, qualityOfService: .default)
    let downloadThumbnailActivityQueue = Queuer(name: "downloadThumbnailActivityQueue", maxConcurrentOperationCount: 10, qualityOfService: .default)
    let unifiedSearchQueue = Queuer(name: "unifiedSearchQueue", maxConcurrentOperationCount: 1, qualityOfService: .default)
    let saveLivePhotoQueue = Queuer(name: "saveLivePhotoQueue", maxConcurrentOperationCount: 1, qualityOfService: .default)
    let downloadQueue = Queuer(name: "downloadQueue", maxConcurrentOperationCount: NCBrandOptions.shared.maxConcurrentOperationDownload, qualityOfService: .default)
    let downloadAvatarQueue = Queuer(name: "downloadAvatarQueue", maxConcurrentOperationCount: 10, qualityOfService: .default)
    let convertLivePhotoQueue = Queuer(name: "convertLivePhotoQueue", maxConcurrentOperationCount: 10, qualityOfService: .default)

    // MARK: - init

    override init() {
        super.init()

#if EXTENSION
        print("Start Background Upload Extension: ", sessionUploadBackgroundExtension)
#else
        print("Start Background Download: ", sessionManagerDownloadBackground)
        print("Start Background Upload: ", sessionManagerUploadBackground)
        print("Start Background Upload WWan: ", sessionManagerUploadBackgroundWWan)
#endif
    }

    // MARK: - Communication Delegate

    func networkReachabilityObserver(_ typeReachability: NKCommon.TypeReachability) {

        if typeReachability == NKCommon.TypeReachability.reachableCellular || typeReachability == NKCommon.TypeReachability.reachableEthernetOrWiFi {
            if !lastReachability {
#if !EXTENSION
                NCService().startRequestServicesServer()
#endif
            }
            lastReachability = true
        } else {
            if lastReachability {
                let error = NKError(errorCode: NCGlobal.shared.errorNetworkNotAvailable, errorDescription: "")
                NCContentPresenter().messageNotification("_network_not_available_", error: error, delay: NCGlobal.shared.dismissAfterSecond, type: NCContentPresenter.messageType.info)
            }
            lastReachability = false
        }
        networkReachability = typeReachability
    }

    func authenticationChallenge(_ session: URLSession,
                                 didReceive challenge: URLAuthenticationChallenge,
                                 completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void) {
        DispatchQueue.global().async {
            self.checkTrustedChallenge(session, didReceive: challenge, completionHandler: completionHandler)
        }
    }

    func urlSessionDidFinishEvents(forBackgroundURLSession session: URLSession) {

#if !EXTENSION
        if let appDelegate = UIApplication.shared.delegate as? AppDelegate, let completionHandler = appDelegate.backgroundSessionCompletionHandler {
            NextcloudKit.shared.nkCommonInstance.writeLog("[INFO] Called urlSessionDidFinishEvents for Background URLSession")
            appDelegate.backgroundSessionCompletionHandler = nil
            completionHandler()
        }
#endif
    }

    // MARK: -

    func cancelAllQueue() {
        downloadQueue.cancelAll()
        downloadThumbnailQueue.cancelAll()
        downloadThumbnailActivityQueue.cancelAll()
        downloadAvatarQueue.cancelAll()
        unifiedSearchQueue.cancelAll()
        saveLivePhotoQueue.cancelAll()
        convertLivePhotoQueue.cancelAll()
    }

    func cancelAllTask() {
        cancelAllQueue()
        cancelDataTask()
        cancelDownloadTasks()
        cancelUploadTasks()
        cancelDownloadBackgroundTask()
        cancelUploadBackgroundTask()
    }

    // MARK: - Pinning check

    public func checkTrustedChallenge(_ session: URLSession,
                                      didReceive challenge: URLAuthenticationChallenge,
                                      completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void) {

        let protectionSpace: URLProtectionSpace = challenge.protectionSpace
        let directoryCertificate = utilityFileSystem.directoryCertificates
        let host = challenge.protectionSpace.host
        let certificateSavedPath = directoryCertificate + "/" + host + ".der"
        var isTrusted: Bool

        if let serverTrust: SecTrust = protectionSpace.serverTrust, let certificate = SecTrustGetCertificateAtIndex(serverTrust, 0) {

            // extarct certificate txt
            saveX509Certificate(certificate, host: host, directoryCertificate: directoryCertificate)

            let isServerTrusted = SecTrustEvaluateWithError(serverTrust, nil)
            let certificateCopyData = SecCertificateCopyData(certificate)
            let data = CFDataGetBytePtr(certificateCopyData)
            let size = CFDataGetLength(certificateCopyData)
            let certificateData = NSData(bytes: data, length: size)

            certificateData.write(toFile: directoryCertificate + "/" + host + ".tmp", atomically: true)

            if isServerTrusted {
                isTrusted = true
            } else if let certificateDataSaved = NSData(contentsOfFile: certificateSavedPath), certificateData.isEqual(to: certificateDataSaved as Data) {
                isTrusted = true
            } else {
                isTrusted = false
            }
        } else {
            isTrusted = false
        }

        if isTrusted {
            completionHandler(URLSession.AuthChallengeDisposition.useCredential, URLCredential(trust: challenge.protectionSpace.serverTrust!))
        } else {
#if !EXTENSION
            DispatchQueue.main.async { (UIApplication.shared.delegate as? AppDelegate)?.trustCertificateError(host: host) }
#endif
            completionHandler(URLSession.AuthChallengeDisposition.performDefaultHandling, nil)
        }
    }

    func writeCertificate(host: String) {

        let directoryCertificate = utilityFileSystem.directoryCertificates
        let certificateAtPath = directoryCertificate + "/" + host + ".tmp"
        let certificateToPath = directoryCertificate + "/" + host + ".der"

        if !utilityFileSystem.copyFile(atPath: certificateAtPath, toPath: certificateToPath) {
            NextcloudKit.shared.nkCommonInstance.writeLog("[ERROR] Write certificare error")
        }
    }

    func saveX509Certificate(_ certificate: SecCertificate, host: String, directoryCertificate: String) {

        let certNamePathTXT = directoryCertificate + "/" + host + ".txt"
        let data: CFData = SecCertificateCopyData(certificate)
        let mem = BIO_new_mem_buf(CFDataGetBytePtr(data), Int32(CFDataGetLength(data)))
        let x509cert = d2i_X509_bio(mem, nil)

        if x509cert == nil {
            NextcloudKit.shared.nkCommonInstance.writeLog("[ERROR] OpenSSL couldn't parse X509 Certificate")
        } else {
            // save details
            if FileManager.default.fileExists(atPath: certNamePathTXT) {
                do {
                    try FileManager.default.removeItem(atPath: certNamePathTXT)
                } catch { }
            }
            let fileCertInfo = fopen(certNamePathTXT, "w")
            if fileCertInfo != nil {
                let output = BIO_new_fp(fileCertInfo, BIO_NOCLOSE)
                X509_print_ex(output, x509cert, UInt(XN_FLAG_COMPAT), UInt(X509_FLAG_COMPAT))
                BIO_free(output)
            }
            fclose(fileCertInfo)
            X509_free(x509cert)
        }

        BIO_free(mem)
    }

    func checkPushNotificationServerProxyCertificateUntrusted(viewController: UIViewController?,
                                                              completion: @escaping (_ error: NKError) -> Void) {

        guard let host = URL(string: NCBrandOptions.shared.pushNotificationServerProxy)?.host else { return }

        NextcloudKit.shared.checkServer(serverUrl: NCBrandOptions.shared.pushNotificationServerProxy) { error in
            guard error == .success else {
                completion(.success)
                return
            }

            if error == .success {
                NCNetworking.shared.writeCertificate(host: host)
                completion(error)
            } else if error.errorCode == NSURLErrorServerCertificateUntrusted {
                let alertController = UIAlertController(title: NSLocalizedString("_ssl_certificate_untrusted_", comment: ""), message: NSLocalizedString("_connect_server_anyway_", comment: ""), preferredStyle: .alert)
                alertController.addAction(UIAlertAction(title: NSLocalizedString("_yes_", comment: ""), style: .default, handler: { _ in
                    NCNetworking.shared.writeCertificate(host: host)
                    completion(.success)
                }))
                alertController.addAction(UIAlertAction(title: NSLocalizedString("_no_", comment: ""), style: .default, handler: { _ in
                    completion(error)
                }))
                alertController.addAction(UIAlertAction(title: NSLocalizedString("_certificate_details_", comment: ""), style: .default, handler: { _ in
                    if let navigationController = UIStoryboard(name: "NCViewCertificateDetails", bundle: nil).instantiateInitialViewController() as? UINavigationController,
                       let vcCertificateDetails = navigationController.topViewController as? NCViewCertificateDetails {
                        vcCertificateDetails.host = host
                        viewController?.present(navigationController, animated: true)
                    }
                }))
                viewController?.present(alertController, animated: true)
            }
        }
    }
}