bundesmessenger-ios/Riot/Model/HomeserverConfiguration/HomeserverConfigurationBuilder.swift

// 
// Copyright 2020 New Vector Ltd
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

import Foundation

/// `HomeserverConfigurationBuilder` build `HomeserverConfiguration` objects according to injected inputs
@objcMembers
final class HomeserverConfigurationBuilder: NSObject {

    // MARK: - Properties
    
    private let vectorWellKnownParser = VectorWellKnownParser()
    
    // MARK: - Public
    
    /// Create an `HomeserverConfiguration` from an HS Well-Known when possible otherwise it takes hardcoded values from BuildSettings by default.
    func build(from wellKnown: MXWellKnown?) -> HomeserverConfiguration {
        var vectorWellKnownEncryptionConfiguration: VectorWellKnownEncryptionConfiguration?
        var vectorWellKnownJitsiConfiguration: VectorWellKnownJitsiConfiguration?
        
        if let wellKnown = wellKnown, let vectorWellKnown = self.vectorWellKnownParser.parse(jsonDictionary: wellKnown.jsonDictionary()) {
            vectorWellKnownEncryptionConfiguration = self.getEncryptionConfiguration(from: vectorWellKnown)
            vectorWellKnownJitsiConfiguration = self.getJitsiConfiguration(from: vectorWellKnown)
        }

        // bwi: (#4218) the well-known defaults for bwi are different than the element defaults. E2EE decryption is true instead of false, presharingmode is .whenEnteringRoom instead of .whenTyping and our backup method is only .passphrase instead of all
        
        // Encryption configuration
        // Enable E2EE by default when there is no value
        let isE2EEByDefaultEnabled = vectorWellKnownEncryptionConfiguration?.isE2EEByDefaultEnabled ?? true
        // Disable mandatory secure backup when there is no value
        let isSecureBackupRequired = vectorWellKnownEncryptionConfiguration?.isSecureBackupRequired ?? true
        // Default to `MXKKeyPreSharingWhenTyping` when there is no value
        let outboundKeysPreSharingMode = vectorWellKnownEncryptionConfiguration?.outboundKeysPreSharingMode ?? .whenEnteringRoom
        // Defaults to all secure backup methods available when there is no value
        let secureBackupSetupMethods: [VectorWellKnownBackupSetupMethod]
        if let backupSetupMethods = vectorWellKnownEncryptionConfiguration?.secureBackupSetupMethods {
            secureBackupSetupMethods = backupSetupMethods.isEmpty ? [.passphrase] : backupSetupMethods
        } else {
            secureBackupSetupMethods = [.passphrase]
        }

        let encryptionConfiguration = HomeserverEncryptionConfiguration(isE2EEByDefaultEnabled: isE2EEByDefaultEnabled,
                                                                        isSecureBackupRequired: isSecureBackupRequired,
                                                                        secureBackupSetupMethods: secureBackupSetupMethods,
                                                                        outboundKeysPreSharingMode: outboundKeysPreSharingMode)
        
        // Jitsi configuration
        let jitsiPreferredDomain: String?
        let jitsiServerURL: URL?
        let hardcodedJitsiServerURL: URL? = BWIBuildSettings.shared.jitsiServerUrl
        
        if let preferredDomain = vectorWellKnownJitsiConfiguration?.preferredDomain {
            jitsiPreferredDomain = preferredDomain
            jitsiServerURL = self.jitsiServerURL(from: preferredDomain) ?? hardcodedJitsiServerURL
        } else {
            jitsiPreferredDomain = hardcodedJitsiServerURL?.host
            jitsiServerURL = hardcodedJitsiServerURL
        }
        
        // Tile server configuration
        
        let tileServerMapStyleURL: URL
        if let mapStyleURLString = wellKnown?.tileServer?.mapStyleURLString,
           let mapStyleURL = URL(string: mapStyleURLString) {
            tileServerMapStyleURL = mapStyleURL
        } else {
            tileServerMapStyleURL = URL(string: BWIBuildSettings.shared.serverConfigDefaultMapstyleURLString)!
        }
                
        
        let tileServerConfiguration = HomeserverTileServerConfiguration(mapStyleURL: tileServerMapStyleURL)
        
        // Create HomeserverConfiguration
        
        let jitsiConfiguration = HomeserverJitsiConfiguration(serverDomain: jitsiPreferredDomain,
                                                              serverURL: jitsiServerURL)
                
        return HomeserverConfiguration(jitsi: jitsiConfiguration,
                                       encryption: encryptionConfiguration,
                                       tileServer: tileServerConfiguration)
    }
    
    // MARK: - Private
    
    private func getJitsiConfiguration(from vectorWellKnown: VectorWellKnown) -> VectorWellKnownJitsiConfiguration? {
                
        let jitsiConfiguration: VectorWellKnownJitsiConfiguration?
        
        if let lastJitsiConfiguration = vectorWellKnown.jitsi {
            jitsiConfiguration = lastJitsiConfiguration
        } else if let deprecatedJitsiConfiguration = vectorWellKnown.deprecatedJitsi {
            MXLog.debug("[HomeserverConfigurationBuilder] getJitsiConfiguration - Use deprecated configuration")
            jitsiConfiguration = deprecatedJitsiConfiguration
        } else {
            MXLog.debug("[HomeserverConfigurationBuilder] getJitsiConfiguration - No configuration found")
            jitsiConfiguration = nil
        }
        
        return jitsiConfiguration
    }
    
    private func getEncryptionConfiguration(from vectorWellKnown: VectorWellKnown) -> VectorWellKnownEncryptionConfiguration? {
        
        let encryptionConfiguration: VectorWellKnownEncryptionConfiguration?
        
        if let lastEncryptionConfiguration = vectorWellKnown.encryption {
            encryptionConfiguration = lastEncryptionConfiguration
        } else if let deprecatedEncryptionConfiguration = vectorWellKnown.deprecatedEncryption {
            MXLog.debug("[HomeserverConfigurationBuilder] getEncryptionConfiguration - Use deprecated configuration")
            encryptionConfiguration = deprecatedEncryptionConfiguration
        } else {
            MXLog.debug("[HomeserverConfigurationBuilder] getEncryptionConfiguration - No configuration found")
            encryptionConfiguration = nil
        }
        
        return encryptionConfiguration
    }
    
    private func jitsiServerURL(from jitsiServerDomain: String) -> URL? {
        let jitsiStringURL: String
        if jitsiServerDomain.starts(with: "http") {
            jitsiStringURL = jitsiServerDomain
        } else {
            jitsiStringURL = "https://\(jitsiServerDomain)"
        }
        
        guard let jitsiServerURL = URL(string: jitsiStringURL) else {
            MXLog.debug("[HomeserverConfigurationBuilder] Jitsi server URL is not valid")
            return nil
        }
        
        return jitsiServerURL
    }
}