//
//  NCManageDatabase.swift
//  Nextcloud
//
//  Created by Marino Faggiana on 06/05/17.
//  Copyright © 2017 Marino Faggiana. All rights reserved.
//
//  Author Marino Faggiana <marino.faggiana@nextcloud.com>
//  Author Henrik Storch <henrik.storch@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 RealmSwift
import NextcloudKit
import CoreMedia
import Photos

protocol DateCompareable {
    var dateKey: Date { get }
}

class NCManageDatabase: NSObject {
    @objc static let shared: NCManageDatabase = {
        let instance = NCManageDatabase()
        return instance
    }()

    let utilityFileSystem = NCUtilityFileSystem()

    override init() {

        let dirGroup = FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: NCBrandOptions.shared.capabilitiesGroups)
        let databaseFileUrlPath = dirGroup?.appendingPathComponent(NCGlobal.shared.appDatabaseNextcloud + "/" + databaseName)

        let bundleUrl: URL = Bundle.main.bundleURL
        let bundlePathExtension: String = bundleUrl.pathExtension
        let isAppex: Bool = bundlePathExtension == "appex"

        if let databaseFilePath = databaseFileUrlPath?.path {
            if FileManager.default.fileExists(atPath: databaseFilePath) {
                NextcloudKit.shared.nkCommonInstance.writeLog("DATABASE FOUND in " + databaseFilePath)
            } else {
                NextcloudKit.shared.nkCommonInstance.writeLog("DATABASE NOT FOUND in " + databaseFilePath)
            }
        }

        // Disable file protection for directory DB
        // https://docs.mongodb.com/realm/sdk/ios/examples/configure-and-open-a-realm/#std-label-ios-open-a-local-realm
        if let folderPathURL = dirGroup?.appendingPathComponent(NCGlobal.shared.appDatabaseNextcloud) {
            let folderPath = folderPathURL.path
            do {
                try FileManager.default.setAttributes([FileAttributeKey.protectionKey: FileProtectionType.completeUntilFirstUserAuthentication], ofItemAtPath: folderPath)
            } catch {
                print("Dangerous error")
            }
        }

        if isAppex {

            Realm.Configuration.defaultConfiguration = Realm.Configuration(
                fileURL: dirGroup?.appendingPathComponent(NCGlobal.shared.appDatabaseNextcloud + "/" + databaseName),
                schemaVersion: databaseSchemaVersion,
                objectTypes: [tableMetadata.self,
                              tableLocalFile.self,
                              tableDirectory.self,
                              tableTag.self,
                              tableAccount.self,
                              tableCapabilities.self,
                              tablePhotoLibrary.self,
                              tableE2eEncryption.self,
                              tableE2eEncryptionLock.self,
                              tableE2eMetadata12.self,
                              tableE2eMetadata.self,
                              tableE2eUsers.self,
                              tableE2eCounter.self,
                              tableShare.self,
                              tableChunk.self,
                              tableAvatar.self,
                              tableDashboardWidget.self,
                              tableDashboardWidgetButton.self,
                              NCDBLayoutForView.self,
                              TableSecurityGuardDiagnostics.self]
            )

        } else {

            do {
                _ = try Realm(configuration: Realm.Configuration(

                    fileURL: databaseFileUrlPath,
                    schemaVersion: databaseSchemaVersion,

                    migrationBlock: { migration, oldSchemaVersion in

                        if oldSchemaVersion < 255 {
                            migration.deleteData(forType: tableActivity.className())
                            migration.deleteData(forType: tableActivityLatestId.className())
                            migration.deleteData(forType: tableActivityPreview.className())
                            migration.deleteData(forType: tableActivitySubjectRich.className())
                        }

                        if oldSchemaVersion < 292 {
                            migration.deleteData(forType: tableVideo.className())
                        }

                        if oldSchemaVersion < 319 {
                            migration.deleteData(forType: tableChunk.className())
                            migration.deleteData(forType: tableDirectory.className())
                            migration.deleteData(forType: tableE2eEncryptionLock.className())
                            migration.deleteData(forType: tableGPS.className())
                        }

                        if oldSchemaVersion < 333 {
                            migration.deleteData(forType: tableMetadata.className())
                            migration.enumerateObjects(ofType: tableDirectory.className()) { _, newObject in
                                newObject?["etag"] = ""
                            }
                        }

                    }, shouldCompactOnLaunch: { totalBytes, usedBytes in

                        // totalBytes refers to the size of the file on disk in bytes (data + free space)
                        // usedBytes refers to the number of bytes used by data in the file

                        // Compact if the file is over 100MB in size and less than 50% 'used'
                        let oneHundredMB = 100 * 1024 * 1024
                        return (totalBytes > oneHundredMB) && (Double(usedBytes) / Double(totalBytes)) < 0.5
                    }
                ))

            } catch let error {
                if let databaseFileUrlPath = databaseFileUrlPath {
                    do {
#if !EXTENSION
                        let nkError = NKError(errorCode: NCGlobal.shared.errorInternalError, errorDescription: error.localizedDescription)
                        NCContentPresenter().showError(error: nkError, priority: .max)
#endif
                        NextcloudKit.shared.nkCommonInstance.writeLog("DATABASE ERROR: \(error.localizedDescription)")
                        try FileManager.default.removeItem(at: databaseFileUrlPath)
                    } catch {}
                }
            }

            Realm.Configuration.defaultConfiguration = Realm.Configuration(
                fileURL: dirGroup?.appendingPathComponent(NCGlobal.shared.appDatabaseNextcloud + "/" + databaseName),
                schemaVersion: databaseSchemaVersion
            )
        }

        // Verify Database, if corrupt remove it
        do {
            _ = try Realm()
        } catch let error {
            if let databaseFileUrlPath = databaseFileUrlPath {
                do {
#if !EXTENSION
                    let nkError = NKError(errorCode: NCGlobal.shared.errorInternalError, errorDescription: error.localizedDescription)
                    NCContentPresenter().showError(error: nkError, priority: .max)
#endif
                    NextcloudKit.shared.nkCommonInstance.writeLog("DATABASE ERROR: \(error.localizedDescription)")
                    try FileManager.default.removeItem(at: databaseFileUrlPath)
                } catch { }
            }
        }

        do {
            _ = try Realm()
        } catch let error as NSError {
            NextcloudKit.shared.nkCommonInstance.writeLog("Could not open database: \(error)")
        }
    }

    // MARK: -
    // MARK: Utility Database

    @objc func clearTable(_ table: Object.Type, account: String? = nil) {

        do {
            let realm = try Realm()
            try realm.write {
                var results: Results<Object>

                if let account = account {
                    results = realm.objects(table).filter("account == %@", account)
                } else {
                    results = realm.objects(table)
                }

                realm.delete(results)
            }
        } catch let error {
            NextcloudKit.shared.nkCommonInstance.writeLog("Could not write to database: \(error)")
        }
    }

    @objc func clearDatabase(account: String?, removeAccount: Bool) {

        if removeAccount {
            self.clearTable(tableAccount.self, account: account)
        }

        self.clearTable(tableActivity.self, account: account)
        self.clearTable(tableActivityLatestId.self, account: account)
        self.clearTable(tableActivityPreview.self, account: account)
        self.clearTable(tableActivitySubjectRich.self, account: account)
        self.clearTable(tableAvatar.self)
        self.clearTable(tableCapabilities.self, account: account)
        self.clearTable(tableChunk.self, account: account)
        self.clearTable(tableComments.self, account: account)
        self.clearTable(tableDashboardWidget.self, account: account)
        self.clearTable(tableDashboardWidgetButton.self, account: account)
        self.clearTable(tableDirectEditingCreators.self, account: account)
        self.clearTable(tableDirectEditingEditors.self, account: account)
        self.clearTable(tableDirectory.self, account: account)
        self.clearTablesE2EE(account: account)
        self.clearTable(tableExternalSites.self, account: account)
        self.clearTable(tableGPS.self, account: nil)
        self.clearTable(TableGroupfolders.self, account: account)
        self.clearTable(TableGroupfoldersGroups.self, account: account)
        self.clearTable(NCDBLayoutForView.self, account: account)
        self.clearTable(tableLocalFile.self, account: account)
        self.clearTable(tableMetadata.self, account: account)
        self.clearTable(tablePhotoLibrary.self, account: account)
        self.clearTable(tableShare.self, account: account)
        self.clearTable(TableSecurityGuardDiagnostics.self, account: account)
        self.clearTable(tableTag.self, account: account)
        self.clearTable(tableTip.self)
        self.clearTable(tableTrash.self, account: account)
        self.clearTable(tableUserStatus.self, account: account)
        self.clearTable(tableVideo.self, account: account)
    }

    func clearTablesE2EE(account: String?) {

        self.clearTable(tableE2eEncryption.self, account: account)
        self.clearTable(tableE2eEncryptionLock.self, account: account)
        self.clearTable(tableE2eMetadata12.self, account: account)
        self.clearTable(tableE2eMetadata.self, account: account)
        self.clearTable(tableE2eUsers.self, account: account)
        self.clearTable(tableE2eCounter.self, account: account)
    }

    @objc func removeDB() {

        let realmURL = Realm.Configuration.defaultConfiguration.fileURL!
        let realmURLs = [
            realmURL,
            realmURL.appendingPathExtension("lock"),
            realmURL.appendingPathExtension("note"),
            realmURL.appendingPathExtension("management")
        ]
        for URL in realmURLs {
            do {
                try FileManager.default.removeItem(at: URL)
            } catch let error {
                NextcloudKit.shared.nkCommonInstance.writeLog("Could not write to database: \(error)")
            }
        }
    }

    func getThreadConfined(_ object: Object) -> Any {

        return ThreadSafeReference(to: object)
    }

    func putThreadConfined(_ tableRef: ThreadSafeReference<Object>) -> Object? {

        do {
            let realm = try Realm()
            return realm.resolve(tableRef)
        } catch let error as NSError {
            NextcloudKit.shared.nkCommonInstance.writeLog("Could not write to database: \(error)")
        }

        return nil
    }
}