[ECO-5035] Remove usage of Decodable for decoding data recieved from Realtime

Sources/AblyChat/ChatAPI.swift

@@ -15,9 +15,14 @@ internal final class ChatAPI: Sendable {
         return try await makePaginatedRequest(endpoint, params: params.asQueryItems())
     }
 
-    internal struct SendMessageResponse: Codable {
+    internal struct SendMessageResponse: JSONObjectDecodable {
         internal let serial: String
         internal let createdAt: Int64
+
+        internal init(jsonObject: [String: JSONValue]) throws {
+            serial = try jsonObject.stringValueForKey("serial")
+            createdAt = try Int64(jsonObject.numberValueForKey("createdAt"))
+        }
     }
 
     // (CHA-M3) Messages are sent to Ably via the Chat REST API, using the send method.
@@ -62,8 +67,7 @@ internal final class ChatAPI: Sendable {
         return try await makeRequest(endpoint, method: "GET")
     }
 
-    // TODO: https://github.com/ably-labs/ably-chat-swift/issues/84 - Improve how we're decoding via `JSONSerialization` within the `DictionaryDecoder`
-    private func makeRequest<Response: Codable>(_ url: String, method: String, body: [String: JSONValue]? = nil) async throws -> Response {
+    private func makeRequest<Response: JSONDecodable>(_ url: String, method: String, body: [String: JSONValue]? = nil) async throws -> Response {
         let ablyCocoaBody: Any? = if let body {
             JSONValue.object(body).toAblyCocoaData
         } else {
@@ -85,7 +89,8 @@ internal final class ChatAPI: Sendable {
                     }
 
                     do {
-                        let decodedResponse = try DictionaryDecoder().decode(Response.self, from: firstItem)
+                        let jsonValue = JSONValue(ablyCocoaData: firstItem)
+                        let decodedResponse = try Response(jsonValue: jsonValue)
                         continuation.resume(returning: decodedResponse)
                     } catch {
                         continuation.resume(throwing: error)
@@ -97,7 +102,7 @@ internal final class ChatAPI: Sendable {
         }
     }
 
-    private func makePaginatedRequest<Response: Codable & Sendable & Equatable>(
+    private func makePaginatedRequest<Response: JSONDecodable & Sendable & Equatable>(
         _ url: String,
         params: [String: String]? = nil
     ) async throws -> any PaginatedResult<Response> {
@@ -116,26 +121,3 @@ internal final class ChatAPI: Sendable {
         case noItemInResponse
     }
 }
-
-internal struct DictionaryDecoder {
-    private let decoder = {
-        var decoder = JSONDecoder()
-
-        // Ably’s REST APIs always serialise dates as milliseconds since Unix epoch
-        decoder.dateDecodingStrategy = .millisecondsSince1970
-
-        return decoder
-    }()
-
-    // Function to decode from a dictionary
-    internal func decode<T: Decodable>(_: T.Type, from dictionary: NSDictionary) throws -> T {
-        let data = try JSONSerialization.data(withJSONObject: dictionary)
-        return try decoder.decode(T.self, from: data)
-    }
-
-    // Function to decode from a dictionary array
-    internal func decode<T: Decodable>(_: T.Type, from dictionary: [NSDictionary]) throws -> T {
-        let data = try JSONSerialization.data(withJSONObject: dictionary)
-        return try decoder.decode(T.self, from: data)
-    }
-}

Sources/AblyChat/Events.swift

@@ -3,7 +3,7 @@ import Ably
 /**
  * Chat Message Actions.
  */
-public enum MessageAction: String, Codable, Sendable {
+public enum MessageAction: String, Sendable {
     /**
      * Action applied to a new message.
      */

Sources/AblyChat/Headers.swift

@@ -1,8 +1,8 @@
 // TODO: https://github.com/ably-labs/ably-chat-swift/issues/13 - try to improve this type
 
-public enum HeadersValue: Sendable, Codable, Equatable {
+public enum HeadersValue: Sendable, Equatable {
     case string(String)
-    case number(Double) // Changed from NSNumber to Double to conform to Codable. Address in linked issue above.
+    case number(Double)
     case bool(Bool)
     case null
 }

Sources/AblyChat/JSONCodable.swift

@@ -1,3 +1,5 @@
+import Foundation
+
 internal protocol JSONEncodable {
     var toJSONValue: JSONValue { get }
 }
@@ -27,6 +29,7 @@ internal enum JSONValueDecodingError: Error {
     case valueIsNotObject
     case noValueForKey(String)
     case wrongTypeForKey(String, actualValue: JSONValue)
+    case failedToDecodeFromRawValue(String)
 }
 
 // Default implementation of `JSONDecodable` conformance for `JSONObjectDecodable`
@@ -42,7 +45,7 @@ internal extension JSONObjectDecodable {
 
 internal typealias JSONObjectCodable = JSONObjectDecodable & JSONObjectEncodable
 
-// MARK: - Extracting values from a dictionary
+// MARK: - Extracting primitive values from a dictionary
 
 /// This extension adds some helper methods for extracting values from a dictionary of `JSONValue` values; you may find them helpful when implementing `JSONCodable`.
 internal extension [String: JSONValue] {
@@ -63,7 +66,7 @@ internal extension [String: JSONValue] {
         return objectValue
     }
 
-    /// If this dictionary contains a value for `key`, and this value has case `object`, this returns the associated value. If this dictionary does not contain a value for `key`, or if the value for key has case `null`, it returns `nil`.
+    /// If this dictionary contains a value for `key`, and this value has case `object`, this returns the associated value. If this dictionary does not contain a value for `key`, or if the value for `key` has case `null`, it returns `nil`.
     ///
     /// - Throws: `JSONValueDecodingError.wrongTypeForKey` if the value does not have case `object` or `null`
     func optionalObjectValueForKey(_ key: String) throws -> [String: JSONValue]? {
@@ -99,7 +102,7 @@ internal extension [String: JSONValue] {
         return arrayValue
     }
 
-    /// If this dictionary contains a value for `key`, and this value has case `array`, this returns the associated value. If this dictionary does not contain a value for `key`, or if the value for key has case `null`, it returns `nil`.
+    /// If this dictionary contains a value for `key`, and this value has case `array`, this returns the associated value. If this dictionary does not contain a value for `key`, or if the value for `key` has case `null`, it returns `nil`.
     ///
     /// - Throws: `JSONValueDecodingError.wrongTypeForKey` if the value does not have case `array` or `null`
     func optionalArrayValueForKey(_ key: String) throws -> [JSONValue]? {
@@ -135,7 +138,7 @@ internal extension [String: JSONValue] {
         return stringValue
     }
 
-    /// If this dictionary contains a value for `key`, and this value has case `string`, this returns the associated value. If this dictionary does not contain a value for `key`, or if the value for key has case `null`, it returns `nil`.
+    /// If this dictionary contains a value for `key`, and this value has case `string`, this returns the associated value. If this dictionary does not contain a value for `key`, or if the value for `key` has case `null`, it returns `nil`.
     ///
     /// - Throws: `JSONValueDecodingError.wrongTypeForKey` if the value does not have case `string` or `null`
     func optionalStringValueForKey(_ key: String) throws -> String? {
@@ -171,7 +174,7 @@ internal extension [String: JSONValue] {
         return numberValue
     }
 
-    /// If this dictionary contains a value for `key`, and this value has case `number`, this returns the associated value. If this dictionary does not contain a value for `key`, or if the value for key has case `null`, it returns `nil`.
+    /// If this dictionary contains a value for `key`, and this value has case `number`, this returns the associated value. If this dictionary does not contain a value for `key`, or if the value for `key` has case `null`, it returns `nil`.
     ///
     /// - Throws: `JSONValueDecodingError.wrongTypeForKey` if the value does not have case `number` or `null`
     func optionalNumberValueForKey(_ key: String) throws -> Double? {
@@ -228,3 +231,70 @@ internal extension [String: JSONValue] {
         return boolValue
     }
 }
+
+// MARK: - Extracting dates from a dictionary
+
+internal extension [String: JSONValue] {
+    /// If this dictionary contains a value for `key`, and this value has case `number`, this returns a date created by interpreting this value as the number of milliseconds since the Unix epoch (which is the format used by Ably).
+    ///
+    /// - Throws:
+    ///   - `JSONValueDecodingError.noValueForKey` if the key is absent
+    ///   - `JSONValueDecodingError.wrongTypeForKey` if the value does not have case `number`
+    func ablyProtocolDateValueForKey(_ key: String) throws -> Date {
+        let millisecondsSinceEpoch = try numberValueForKey(key)
+
+        return dateFromMillisecondsSinceEpoch(millisecondsSinceEpoch)
+    }
+
+    /// If this dictionary contains a value for `key`, and this value has case `number`, this returns a date created by interpreting this value as the number of milliseconds since the Unix epoch (which is the format used by Ably). If this dictionary does not contain a value for `key`, or if the value for `key` has case `null`, it returns `nil`.
+    ///
+    /// - Throws: `JSONValueDecodingError.wrongTypeForKey` if the value does not have case `number` or `null`
+    func optionalAblyProtocolDateValueForKey(_ key: String) throws -> Date? {
+        guard let millisecondsSinceEpoch = try optionalNumberValueForKey(key) else {
+            return nil
+        }
+
+        return dateFromMillisecondsSinceEpoch(millisecondsSinceEpoch)
+    }
+
+    private func dateFromMillisecondsSinceEpoch(_ millisecondsSinceEpoch: Double) -> Date {
+        .init(timeIntervalSince1970: millisecondsSinceEpoch / 1000)
+    }
+}
+
+// MARK: - Extracting RawRepresentable values from a dictionary
+
+internal extension [String: JSONValue] {
+    /// If this dictionary contains a value for `key`, and this value has case `string`, this creates an instance of `T` using its `init(rawValue:)` initializer.
+    ///
+    /// - Throws:
+    ///   - `JSONValueDecodingError.noValueForKey` if the key is absent
+    ///   - `JSONValueDecodingError.wrongTypeForKey` if the value does not have case `string`
+    ///   - `JSONValueDecodingError.failedToDecodeFromRawValue` if `init(rawValue:)` returns `nil`
+    func rawRepresentableValueForKey<T: RawRepresentable>(_ key: String, type: T.Type = T.self) throws -> T where T.RawValue == String {
+        let rawValue = try stringValueForKey(key)
+
+        return try rawRepresentableValueFromRawValue(rawValue, type: T.self)
+    }
+
+    /// If this dictionary contains a value for `key`, and this value has case `string`, this creates an instance of `T` using its `init(rawValue:)` initializer. If this dictionary does not contain a value for `key`, or if the value for `key` has case `null`, it returns `nil`.
+    ///
+    /// - Throws:
+    ///   - `JSONValueDecodingError.wrongTypeForKey` if the value does not have case `string` or `null`
+    ///   - `JSONValueDecodingError.failedToDecodeFromRawValue` if `init(rawValue:)` returns `nil`
+    func optionalRawRepresentableValueForKey<T: RawRepresentable>(_ key: String, type: T.Type = T.self) throws -> T? where T.RawValue == String {
+        guard let rawValue = try optionalStringValueForKey(key) else {
+            return nil
+        }
+
+        return try rawRepresentableValueFromRawValue(rawValue, type: T.self)
+    }
+
+    private func rawRepresentableValueFromRawValue<T: RawRepresentable>(_ rawValue: String, type _: T.Type = T.self) throws -> T where T.RawValue == String {
+        guard let value = T(rawValue: rawValue) else {
+            throw JSONValueDecodingError.failedToDecodeFromRawValue(rawValue)
+        }
+
+        return value
+    }
+}

Sources/AblyChat/JSONValue.swift

@@ -136,6 +136,7 @@ internal extension JSONValue {
     /// - a non-`nil` value of `ARTPresenceMessage`’s `data` property
     /// - a non-`nil` value of `ARTMessage`’s `data` property
     /// - the return value of the `toJSON()` method of a non-`nil` value of `ARTMessage`’s `extras` property
+    /// - an element of `ARTHTTPPaginatedResult`’s `items` array
     init(ablyCocoaData: Any) {
         switch ablyCocoaData {
         case let dictionary as [String: Any]:

Sources/AblyChat/Message.swift

@@ -13,7 +13,7 @@ public typealias MessageMetadata = Metadata
 /**
  * Represents a single message in a chat room.
  */
-public struct Message: Sendable, Codable, Identifiable, Equatable {
+public struct Message: Sendable, Identifiable, Equatable {
     // id to meet Identifiable conformance. 2 messages in the same channel cannot have the same serial.
     public var id: String { serial }
 
@@ -87,15 +87,19 @@ public struct Message: Sendable, Codable, Identifiable, Equatable {
         self.metadata = metadata
         self.headers = headers
     }
+}
 
-    internal enum CodingKeys: String, CodingKey {
-        case serial
-        case action
-        case clientID = "clientId"
-        case roomID = "roomId"
-        case text
-        case createdAt
-        case metadata
-        case headers
+extension Message: JSONObjectDecodable {
+    internal init(jsonObject: [String: JSONValue]) throws {
+        try self.init(
+            serial: jsonObject.stringValueForKey("serial"),
+            action: jsonObject.rawRepresentableValueForKey("action"),
+            clientID: jsonObject.stringValueForKey("clientId"),
+            roomID: jsonObject.stringValueForKey("roomId"),
+            text: jsonObject.stringValueForKey("text"),
+            createdAt: jsonObject.optionalAblyProtocolDateValueForKey("createdAt"),
+            metadata: jsonObject.objectValueForKey("metadata").mapValues { try .init(jsonValue: $0) },
+            headers: jsonObject.objectValueForKey("headers").mapValues { try .init(jsonValue: $0) }
+        )
     }
 }

Sources/AblyChat/Metadata.swift

@@ -1,7 +1,6 @@
 // TODO: https://github.com/ably-labs/ably-chat-swift/issues/13 - try to improve this type
-// I attempted to address this issue by making a struct conforming to Codable which would at least give us some safety in knowing items can be encoded and decoded. Gave up on it due to fixing other protocol requirements so gone for the same approach as Headers for now, we can investigate whether we need to be open to more types than this later.
 
-public enum MetadataValue: Sendable, Codable, Equatable {
+public enum MetadataValue: Sendable, Equatable {
     case string(String)
     case number(Double)
     case bool(Bool)

Sources/AblyChat/Occupancy.swift

@@ -48,7 +48,7 @@ public extension Occupancy {
 /**
  * Represents the occupancy of a chat room.
  */
-public struct OccupancyEvent: Sendable, Encodable, Decodable {
+public struct OccupancyEvent: Sendable {
     /**
      * The number of connections to the chat room.
      */
@@ -64,3 +64,12 @@ public struct OccupancyEvent: Sendable, Encodable, Decodable {
         self.presenceMembers = presenceMembers
     }
 }
+
+extension OccupancyEvent: JSONObjectDecodable {
+    internal init(jsonObject: [String: JSONValue]) throws {
+        try self.init(
+            connections: Int(jsonObject.numberValueForKey("connections")),
+            presenceMembers: Int(jsonObject.numberValueForKey("presenceMembers"))
+        )
+    }
+}

Sources/AblyChat/PaginatedResult.swift

@@ -13,7 +13,7 @@ public protocol PaginatedResult<T>: AnyObject, Sendable, Equatable {
 }
 
 /// Used internally to reduce the amount of duplicate code when interacting with `ARTHTTPPaginatedCallback`'s. The wrapper takes in the callback result from the caller e.g. `realtime.request` and either throws the appropriate error, or decodes and returns the response.
-internal struct ARTHTTPPaginatedCallbackWrapper<Response: Codable & Sendable & Equatable> {
+internal struct ARTHTTPPaginatedCallbackWrapper<Response: JSONDecodable & Sendable & Equatable> {
     internal let callbackResult: (ARTHTTPPaginatedResponse?, ARTErrorInfo?)
 
     internal func handleResponse(continuation: CheckedContinuation<PaginatedResultWrapper<Response>, any Error>) {
@@ -32,7 +32,8 @@ internal struct ARTHTTPPaginatedCallbackWrapper<Response: Codable & Sendable & E
         }
 
         do {
-            let decodedResponse = try DictionaryDecoder().decode([Response].self, from: paginatedResponse.items)
+            let jsonValues = paginatedResponse.items.map { JSONValue(ablyCocoaData: $0) }
+            let decodedResponse = try jsonValues.map { try Response(jsonValue: $0) }
             let result = paginatedResponse.toPaginatedResult(items: decodedResponse)
             continuation.resume(returning: result)
         } catch {
@@ -46,7 +47,7 @@ internal struct ARTHTTPPaginatedCallbackWrapper<Response: Codable & Sendable & E
 }
 
 /// `PaginatedResult` protocol implementation allowing access to the underlying items from a lower level paginated response object e.g. `ARTHTTPPaginatedResponse`, whilst succinctly handling errors through the use of `ARTHTTPPaginatedCallbackWrapper`.
-internal final class PaginatedResultWrapper<T: Codable & Sendable & Equatable>: PaginatedResult {
+internal final class PaginatedResultWrapper<T: JSONDecodable & Sendable & Equatable>: PaginatedResult {
     internal let items: [T]
     internal let hasNext: Bool
     internal let isLast: Bool
@@ -96,7 +97,7 @@ internal final class PaginatedResultWrapper<T: Codable & Sendable & Equatable>:
 
 private extension ARTHTTPPaginatedResponse {
     /// Converts an `ARTHTTPPaginatedResponse` to a `PaginatedResultWrapper` allowing for access to operations as per conformance to `PaginatedResult`.
-    func toPaginatedResult<T: Codable & Sendable>(items: [T]) -> PaginatedResultWrapper<T> {
+    func toPaginatedResult<T: JSONDecodable & Sendable>(items: [T]) -> PaginatedResultWrapper<T> {
         PaginatedResultWrapper(paginatedResponse: self, items: items)
     }
 }