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//
// MigrationManager.swift
// MullvadVPN
//
// Created by Marco Nikic on 2023-08-08.
// Copyright © 2023 Mullvad VPN AB. All rights reserved.
//
import Foundation
import MullvadLogging
import MullvadREST
import MullvadTypes
enum SettingsMigrationResult {
/// Nothing to migrate.
case nothing
/// Successfully performed migration.
case success
/// Failure when migrating store.
case failure(Error)
}
struct MigrationManager {
private let logger = Logger(label: "MigrationManager")
/// Migrate settings store if needed.
///
/// The following types of error are expected to be returned by this method:
/// `SettingsMigrationError`, `UnsupportedSettingsVersionError`, `ReadSettingsVersionError`.
func migrateSettings(
store: SettingsStore,
proxyFactory: REST.ProxyFactory,
migrationCompleted: @escaping (SettingsMigrationResult) -> Void
) {
let handleCompletion = { (result: SettingsMigrationResult) in
// Reset store upon failure to migrate settings.
if case .failure = result {
SettingsManager.resetStore()
}
migrationCompleted(result)
}
do {
try checkLatestSettingsVersion(in: store)
handleCompletion(.nothing)
} catch {
handleCompletion(.failure(error))
}
}
private func checkLatestSettingsVersion(in store: SettingsStore) throws {
let settingsVersion: Int
do {
let parser = SettingsParser(decoder: JSONDecoder(), encoder: JSONEncoder())
let settingsData = try store.read(key: SettingsKey.settings)
settingsVersion = try parser.parseVersion(data: settingsData)
} catch .itemNotFound as KeychainError {
return
} catch {
throw ReadSettingsVersionError(underlyingError: error)
}
guard settingsVersion != SchemaVersion.current.rawValue else {
return
}
let error = UnsupportedSettingsVersionError(
storedVersion: settingsVersion,
currentVersion: SchemaVersion.current
)
logger.error(error: error, message: "Encountered an unknown version.")
throw error
}
}
/// A wrapper type for errors returned by concrete migrations.
struct SettingsMigrationError: LocalizedError, WrappingError {
private let inner: Error
let sourceVersion, targetVersion: SchemaVersion
var underlyingError: Error? {
inner
}
var errorDescription: String? {
"Failed to migrate settings from \(sourceVersion) to \(targetVersion)."
}
init(sourceVersion: SchemaVersion, targetVersion: SchemaVersion, underlyingError: Error) {
self.sourceVersion = sourceVersion
self.targetVersion = targetVersion
inner = underlyingError
}
}
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