✨ Remove unused default headers & allow request specific headers

Sources/Hermes/Hermes.swift

@@ -14,6 +14,11 @@ public enum NetworkError: Error {
     case notFound
 }
 
+public protocol HermesMiddleware {
+    func processRequest(_ request: inout URLRequest)
+    func processResponse(_ data: Data?, _ response: URLResponse?, error: Error?)
+}
+
 extension NetworkError: LocalizedError {
     public var errorDescription: String? {
         switch self {
@@ -71,6 +76,7 @@ public struct Resource<T: Codable> {
 public final class Hermes {
     public static let shared = Hermes()
     private var config: HermesConfiguration
+    private var middlewares: [HermesMiddleware] = []
 
     private init(config: HermesConfiguration = HermesConfiguration()) {
         self.config = config
@@ -80,14 +86,29 @@ public final class Hermes {
         self.config = config
     }
 
+    public func addMiddleware(_ middleware: HermesMiddleware) {
+        middlewares.append(middleware)
+    }
+
     private var defaultHeaders: [String: String] {
-        return config.defaultHeaders
+        var headers = [
+            "Content-Type": "application/json",
+            "Accept": "application/json"
+        ]
+        
+        headers.merge(config.defaultHeaders) { _, new in new }
+        
+        return headers
     }
     
     public func load<T: Codable>(_ resource: Resource<T>) async throws -> T {
         var request = URLRequest(url: resource.url)
         request.httpMethod = resource.method.name
 
+        for middleware in middlewares {
+            middleware.processRequest(&request)
+        }
+
         switch resource.method {
             case .get(let queryItems):
                 if let queryItems = queryItems {
@@ -113,21 +134,32 @@ public final class Hermes {
         
         let session = URLSession(configuration: URLSessionConfiguration.default)
         
-        let (data, response) = try await session.data(for: request)
-        
-        guard let httpResponse = response as? HTTPURLResponse else {
-            throw NetworkError.invalidResponse
-        }
-        
-        try validate(response: httpResponse)
-        
-        let decoder = JSONDecoder()
-        decoder.keyDecodingStrategy = config.decodingStrategy
-        
         do {
-            return try decoder.decode(resource.modelType, from: data)
+            let (data, response) = try await session.data(for: request)
+
+            for middleware in middlewares {
+                middleware.processResponse(data, response, error: nil)
+            }
+
+            guard let httpResponse = response as? HTTPURLResponse else {
+                throw NetworkError.invalidResponse
+            }
+
+            try validate(response: httpResponse)
+
+            let decoder = JSONDecoder()
+            decoder.keyDecodingStrategy = config.decodingStrategy
+
+            do {
+                return try decoder.decode(resource.modelType, from: data)
+            } catch {
+                throw NetworkError.decodingError
+            }
         } catch {
-            throw NetworkError.decodingError
+            for middleware in middlewares {
+                middleware.processResponse(nil, nil, error: error)
+            }
+            throw error
         }
     }
     

Tests/HermesTests/HermesTests.swift

@@ -8,7 +8,7 @@ final class HermesTests: XCTestCase {
     }
     
     private func configureHermes() {
-        let defaultHeaders = ["Content-Type": "application/json"]
+        let defaultHeaders = ["Custom-Header": "HeaderValue"]
         let decodingStrategy = JSONDecoder.KeyDecodingStrategy.convertFromSnakeCase
         let config = HermesConfiguration(defaultHeaders: defaultHeaders, decodingStrategy: decodingStrategy)
         Hermes.shared.configure(config)