//
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// SingleUserDefaultsStore
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//
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// Copyright (c) 2018-Present Omar Albeik - https://github.com/omaralbeik
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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import Foundation
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/// `SingleUserDefaultsStore` offers a convenient way to store a single `Codable` object in `UserDefaults`.
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open class SingleUserDefaultsStore<T: Codable> {
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/// Store's unique identifier.
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///
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/// **Warning**: Never use the same identifier for two -or more- different stores.
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public let uniqueIdentifier: String
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/// JSON encoder to be used for encoding object to be stored.
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open var encoder: JSONEncoder
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/// JSON decoder to be used to decode the stored object.
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open var decoder: JSONDecoder
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/// UserDefaults store.
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private var store: UserDefaults
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/// Initialize store with given identifier.
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///
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/// **Warning**: Never use the same identifier for two -or more- different stores.
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///
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/// - Parameter uniqueIdentifier: store's unique identifier.
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/// - Parameter encoder: JSON encoder to be used for encoding object to be stored. _default is `JSONEncoder()`_
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/// - Parameter decoder: JSON decoder to be used to decode the stored object. _default is `JSONDecoder()`_
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required public init?(
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uniqueIdentifier: String,
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encoder: JSONEncoder = .init(),
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decoder: JSONDecoder = .init()
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) {
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guard let store = UserDefaults(suiteName: uniqueIdentifier) else { return nil }
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self.uniqueIdentifier = uniqueIdentifier
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self.encoder = encoder
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self.decoder = decoder
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self.store = store
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}
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/// Save object to store. _O(1)_
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///
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/// - Parameter object: object to save.
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/// - Throws: JSON encoding error.
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public func save(_ object: T) throws {
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let data = try encoder.encode(generateDict(for: object))
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store.set(data, forKey: key)
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}
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/// Get object from store. _O(1)_
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public var object: T? {
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guard let data = store.data(forKey: key) else { return nil }
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guard let dict = try? decoder.decode([String: T].self, from: data) else { return nil }
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return extractObject(from: dict)
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}
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/// Delete object from store. _O(1)_
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public func delete() {
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store.set(nil, forKey: key)
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store.removeSuite(named: uniqueIdentifier)
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}
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}
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// MARK: - Helpers
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private extension SingleUserDefaultsStore {
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/// Enclose the object in a dictionary to enable single object storing.
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///
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/// - Parameter object: object.
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/// - Returns: dictionary enclosing object.
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func generateDict(for object: T) -> [String: T] {
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return ["object": object]
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}
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/// Extract object from dictionary.
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///
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/// - Parameter dict: dictionary.
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/// - Returns: object.
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func extractObject(from dict: [String: T]) -> T? {
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return dict["object"]
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}
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/// Store key for object.
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var key: String {
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return "\(uniqueIdentifier)-single-object"
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}
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}
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