add deferred to timestamp type, other types WIP

CodableFirebase/DecodeStrategy.swift

@@ -13,6 +13,8 @@ public enum DateDecodingStrategy {
     /// Defer to `Date` for decoding. This is the default strategy.
     case deferredToDate
 
+    case deferredToTimestamp
+    
     /// Decode the `Date` as a UNIX timestamp from a JSON number.
     case secondsSince1970
 
@@ -43,13 +45,17 @@ public enum DataDecodingStrategy {
 }
 
 public enum FirestoreTypeDecodingStrategy {
-    case byProtocol
+    case deferredToPtotocol
+    case custom((_ value: Any) throws -> Any)
 }
 
 
 extension CodingUserInfoKey {
     public static let dateDecodingStrategy: CodingUserInfoKey = CodingUserInfoKey(rawValue: "dateDecodingStrategy")!
+    
     public static let dataDecodingStrategy: CodingUserInfoKey = CodingUserInfoKey(rawValue: "dataDecodingStrategy")!
+
+    public static let firestoreTypeDecodingStrategy: CodingUserInfoKey = CodingUserInfoKey(rawValue: "firestoreTypeDecodingStrategy")!
 }
 
 extension Dictionary where Key == CodingUserInfoKey, Value == Any {
@@ -60,4 +66,12 @@ extension Dictionary where Key == CodingUserInfoKey, Value == Any {
     var dataDecodingStrategy: DataDecodingStrategy? {
         return self[.dataDecodingStrategy] as? DataDecodingStrategy
     }
+
+    var firestoreTypeDecodingStrategy: FirestoreTypeDecodingStrategy {
+        if let strategy = self[.firestoreTypeDecodingStrategy] as? FirestoreTypeDecodingStrategy {
+            return strategy
+        }
+
+        return FirestoreTypeDecodingStrategy.deferredToPtotocol
+    }
 }

CodableFirebase/Decoder.swift

@@ -1104,6 +1104,9 @@ extension _FirebaseDecoder {
         }
         
         switch options {
+        case .deferredToTimestamp:
+            let timestamp = value as! TimestampType
+            return timestamp.dateValue()
         case .deferredToDate:
             self.storage.push(container: value)
             let date = try Date(from: self)
@@ -1219,7 +1222,13 @@ extension _FirebaseDecoder {
             decoded = decimal as! T
         }
         else if userInfo.skipFirestoreTypes && (T.self is FirestoreDecodable.Type) {
-            decoded = value as! T
+            let strategy = userInfo.firestoreTypeDecodingStrategy
+            switch strategy {
+            case .deferredToPtotocol:
+                decoded = value as! T
+            case .custom(let decodeFunc):
+                decoded = try decodeFunc(value) as! T
+            }
         }
         else {
             self.storage.push(container: value)

CodableFirebase/EncodeStrategy.swift

@@ -13,6 +13,8 @@ public enum DateEncodingStrategy {
     /// Defer to `Date` for choosing an encoding. This is the default strategy.
     case deferredToDate
 
+    case deferredToTimestamp((Date) -> TimestampType)
+
     /// Encode the `Date` as a UNIX timestamp (as a JSON number).
     case secondsSince1970
 
@@ -46,11 +48,19 @@ public enum DataEncodingStrategy {
     case custom((Data, Encoder) throws -> Void)
 }
 
+public enum FirestoreTypeEncodingStrategy {
+    case deferredToPtotocol
+    case custom((_ value: Any) throws -> Any)
+}
+
 extension CodingUserInfoKey {
     public static let dateEncodingStrategy: CodingUserInfoKey = CodingUserInfoKey(rawValue: "dateEncodingStrategy")!
+
     public static let dataEncodingStrategy: CodingUserInfoKey = CodingUserInfoKey(rawValue: "dataEncodingStrategy")!
 
     public static let skipFirestoreTypes: CodingUserInfoKey = CodingUserInfoKey(rawValue: "skipFirestoreTypes")!
+
+    public static let firestoreTypeEncodingStrategy: CodingUserInfoKey = CodingUserInfoKey(rawValue: "firestoreTypeEncodingStrategy")!
 }
 
 extension Dictionary where Key == CodingUserInfoKey, Value == Any {
@@ -68,4 +78,12 @@ extension Dictionary where Key == CodingUserInfoKey, Value == Any {
         }
         return false
     }
+
+    var firestoreTypeEncodingStrategy: FirestoreTypeEncodingStrategy {
+        if let strategy = self[.firestoreTypeEncodingStrategy] as? FirestoreTypeEncodingStrategy {
+            return strategy
+        }
+
+        return FirestoreTypeEncodingStrategy.deferredToPtotocol
+    }
 }

CodableFirebase/Encoder.swift

@@ -306,6 +306,8 @@ extension _FirebaseEncoder {
         guard let options = userInfo.dateEncodingStrategy else { return date as NSDate }
         
         switch options {
+        case .deferredToTimestamp(let converter):
+            return converter(date) as! NSObject
         case .deferredToDate:
             // Must be called with a surrounding with(pushedKey:) call.
             try date.encode(to: self)
@@ -377,10 +379,18 @@ extension _FirebaseEncoder {
         } else if T.self == Decimal.self || T.self == NSDecimalNumber.self {
             return (value as! NSDecimalNumber)
         } else if userInfo.skipFirestoreTypes && (value is FirestoreEncodable) {
-            guard let value = value as? NSObject else {
+            let target: Any
+            switch userInfo.firestoreTypeDecodingStrategy {
+            case .deferredToPtotocol:
+                target = value
+            case .custom(let encodeFunc):
+                target = try encodeFunc(value)
+            }
+
+            guard let result = target as? NSObject else {
                 throw DocumentReferenceError.typeIsNotNSObject
             }
-            return value
+            return result
         }
         
         // The value should request a container from the _FirebaseEncoder.

CodableFirebase/FirestoreDecoder.swift

@@ -26,9 +26,11 @@ public protocol TimestampType: FirestoreDecodable, FirestoreEncodable {
 }
 
 open class FirestoreDecoder {
-    public init() {}
+    public init(userInfo: [CodingUserInfoKey: Any] = [.skipFirestoreTypes: true]) {
+        self.userInfo = userInfo
+    }
     
-    open var userInfo: [CodingUserInfoKey : Any] = [.skipFirestoreTypes: true]
+    public let userInfo: [CodingUserInfoKey: Any]
     
     open func decode<T : Decodable>(_ type: T.Type, from container: [String: Any]) throws -> T {
         let decoder = _FirebaseDecoder(referencing: container,

CodableFirebase/FirestoreEncoder.swift

@@ -9,10 +9,12 @@
 import Foundation
 
 open class FirestoreEncoder {
-    public init() {}
-    
-    open var userInfo: [CodingUserInfoKey : Any] = [.skipFirestoreTypes: true]
+    public init(userInfo: [CodingUserInfoKey: Any] =  [.skipFirestoreTypes: true]) {
+        self.userInfo = userInfo
+    }
     
+    public let userInfo: [CodingUserInfoKey: Any]
+
     open func encode<Value : Encodable>(_ value: Value) throws -> [String: Any] {
         let topLevel = try encodeToTopLevelContainer(value)
         switch topLevel {

CodableFirebaseTests/TestCodableFirestore.swift

@@ -128,14 +128,36 @@ class TestCodableFirestore: XCTestCase {
         XCTAssertEqual((try? FirestoreEncoder().encode(val)) as NSDictionary?, ["value": val.value])
         XCTAssertEqual(try? FirestoreDecoder().decode(TopLevelWrapper<DocumentReference>.self, from: ["value": val.value]), val)
     }
-  
+
     func testEncodingTimestamp() {
         let timestamp = Timestamp(date: Date())
         let wrapper = TopLevelWrapper(timestamp)
         XCTAssertEqual((try? FirestoreEncoder().encode(wrapper)) as NSDictionary?, ["value": timestamp])
         XCTAssertEqual(try? FirestoreDecoder().decode(TopLevelWrapper<Timestamp>.self, from: ["value": timestamp]), wrapper)
     }
-  
+
+    func testCustomEncodingTimestamp() {
+        let date = Date()
+        let timestamp = Timestamp(date: date)
+
+        // encode date to Timestamp
+        let encodeWrapper = TopLevelWrapper(date)
+        let encodeResult = (try? FirestoreEncoder(userInfo: [CodingUserInfoKey.dateEncodingStrategy: DateEncodingStrategy.deferredToTimestamp({ date in
+            return Timestamp(date: date)
+        })])
+            .encode(encodeWrapper)) as NSDictionary?
+        XCTAssertEqual(encodeResult, ["value": timestamp])
+
+        // decode timestamp to date
+        let decodeWrapper = TopLevelWrapper(timestamp)
+        let decoder = FirestoreDecoder(userInfo: [
+            CodingUserInfoKey.dateDecodingStrategy: DateDecodingStrategy.deferredToTimestamp
+            ])
+
+        let decodeResult = (try? decoder.decode(TopLevelWrapper<Timestamp>.self, from: ["value": timestamp]))
+        XCTAssertEqual(decodeResult, decodeWrapper)
+    }
+
     private func _testEncodeFailure<T : Encodable>(of value: T) {
         do {
             let _ = try FirestoreEncoder().encode(value)
@@ -214,17 +236,21 @@ fileprivate class DocumentReference: NSObject, DocumentReferenceType {}
 // MARK: - Timestamp
 fileprivate class Timestamp: NSObject, TimestampType {
     let date: Date
-  
+
     required init(date: Date) {
         self.date = date
     }
-  
+
     func dateValue() -> Date {
         return date
     }
-  
+
     override func isEqual(_ object: Any?) -> Bool {
         guard let other = object.flatMap({ $0 as? Timestamp }) else { return false }
         return date == other.date
     }
 }
+
+extension Date: FirestoreEncodable {
+
+}