Improve network handling in API wrapper

Sources/SnapAuth/ApiClient.swift

@@ -22,33 +22,46 @@ struct SnapAuthClient {
         path: String,
         body: Encodable,
         type: T.Type
-    ) async -> SAWrappedResponse<T>? {
+    ) async -> Result<T, SnapAuthError> where T: Decodable {
         let url = urlBase.appendingPathComponent(path)
         var request = URLRequest(url: url)
         request.httpMethod = "POST"
         request.setValue("application/json", forHTTPHeaderField: "content-type")
         request.setValue(basic, forHTTPHeaderField: "Authorization")
-        let json = try! JSONEncoder().encode(body)
-        request.httpBody = json
-        logger?.debug("--> \(String(decoding: json, as: UTF8.self))")
 
-        let (data, response) = try! await URLSession.shared.data(for: request)
+        do {
+            let json = try JSONEncoder().encode(body)
+            request.httpBody = json
+            logger?.debug("--> \(String(decoding: json, as: UTF8.self))")
+        } catch {
+            return .failure(.sdkEncodingError)
+        }
+
+        let data: Data
+        let response: URLResponse
+        do {
+            (data, response) = try await URLSession.shared.data(for: request)
+        } catch {
+            return .failure(.networkInterruption)
+        }
+
         let jsonString = String(data: data, encoding: .utf8)
         logger?.debug("<-- \(jsonString ?? "not a string")")
 
         // This allows skipping custom decodable implementations
         let decoder = JSONDecoder()
         decoder.dateDecodingStrategy = .secondsSince1970
-        guard let parsed = try? decoder.decode(
-            SAWrappedResponse<T>.self,
-            from: data)
+        guard let parsed = try? decoder.decode(SAWrappedResponse<T>.self, from: data)
         else {
-            logger?.error("Decoding request failed")
-            // TODO: return some sort of failure SAResponse
-            return nil
+            logger?.error("Decoding response failed")
+            return .failure(.malformedResposne)
         }
 
-        return parsed
+        guard let wrapped = parsed.result else {
+            // TODO: match all of the docuemented error types
+            return .failure(.badRequest)
+        }
+        return .success(wrapped)
     }
 
 }

Sources/SnapAuth/Errors.swift

@@ -7,3 +7,18 @@ public enum AuthenticationError: Error {
 
     case asAuthorizationError
 }
+
+
+public enum SnapAuthError: Error {
+    /// The network request was disrupted.
+    case networkInterruption
+
+    /// The SDK received a response from SnapAuth, but it arrived in an unexpected format. If you encounter this, please reach out to us.
+    case malformedResposne
+
+    /// The SDK was unable to encode data to send to SnapAuth. If you ever encounter this, please reach out to us.
+    case sdkEncodingError
+
+    /// The request was valid and understood, but processing was refused.
+    case badRequest
+}

Sources/SnapAuth/SnapAuth+ASACD.swift

@@ -112,23 +112,19 @@ extension SnapAuth: ASAuthorizationControllerDelegate {
         let body = SAProcessRegisterRequest(credential: credential)
 
         Task {
-            let tokenResponse = await api.makeRequest(
+            let response = await api.makeRequest(
                 path: "/registration/process",
                 body: body,
                 type: SAProcessAuthResponse.self)
-            guard tokenResponse != nil else {
+            guard case let .success(processAuth) = response else {
                 logger.debug("no/invalid process response")
-                // TODO: delegate failure (network error?)
-                return
-            }
-            guard tokenResponse!.result != nil else {
-                // TODO: bubble this up
+                // TODO: bubble this up via delegate failure (network error?)
                 return
             }
             logger.debug("got token response")
             let rewrapped = SnapAuthTokenInfo(
-                token: tokenResponse!.result!.token,
-                expiresAt: tokenResponse!.result!.expiresAt)
+                token: processAuth.token,
+                expiresAt: processAuth.expiresAt)
 
             await delegate?.snapAuth(didFinishRegistration: .success(rewrapped))
         }
@@ -162,23 +158,19 @@ extension SnapAuth: ASAuthorizationControllerDelegate {
         logger.debug("made a body")
 //        logger.debug("user id \(assertion.userID.base64EncodedString())")
         Task {
-            let tokenResponse = await api.makeRequest(
+            let response = await api.makeRequest(
                 path: "/auth/process",
                 body: body,
                 type: SAProcessAuthResponse.self)
-            guard tokenResponse != nil else {
+            guard case let .success(authResponse) = response else {
                 logger.debug("no/invalid process response")
-                // TODO: delegate failure (network error?)
-                return
-            }
-            guard tokenResponse!.result != nil else {
-                // TODO: bubble this up
+                // TODO: bubble this up via delegate failure (network error?)
                 return
             }
             logger.debug("got token response")
             let rewrapped = SnapAuthTokenInfo(
-                token: tokenResponse!.result!.token,
-                expiresAt: tokenResponse!.result!.expiresAt)
+                token: authResponse.token,
+                expiresAt: authResponse.expiresAt)
 
             await delegate?.snapAuth(didFinishAuthentication: .success(rewrapped))
         }

Sources/SnapAuth/SnapAuth.swift

@@ -104,18 +104,18 @@ public class SnapAuth: NSObject { // NSObject for ASAuthorizationControllerDeleg
         state = .registering
 
         let body = SACreateRegisterOptionsRequest(user: nil)
-        let options = await api.makeRequest(
+        let response = await api.makeRequest(
             path: "/registration/createOptions",
             body: body,
-            type: SACreateRegisterOptionsResponse.self)!
+            type: SACreateRegisterOptionsResponse.self)
 
-        guard options.result != nil else {
+        guard case let .success(options) = response else {
             // TODO: bubble error
             return
         }
 
         let authRequests = buildRegisterRequests(
-            from: options.result!,
+            from: options,
             name: name,
             displayName: displayName,
             authenticators: authenticators)
@@ -159,20 +159,20 @@ public class SnapAuth: NSObject { // NSObject for ASAuthorizationControllerDeleg
 
         let body = ["user": user]
 
-        let parsed = await api.makeRequest(
+        let response = await api.makeRequest(
             path: "/auth/createOptions",
             body: body,
-            type: SACreateAuthOptionsResponse.self)!
+            type: SACreateAuthOptionsResponse.self)
 
 
-        guard parsed.result != nil else {
+        guard case let .success(options) = response else {
             // TODO: bubble error
             return
         }
 
         logger.debug("before controller")
         let authRequests = buildAuthRequests(
-            from: parsed.result!,
+            from: options,
             authenticators: authenticators)
 
         // Set up the native controller and start the request(s).