✨ 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 {
@@ -58,17 +63,20 @@ public struct Resource<T: Codable> {
     let url: URL
     var method: HTTPMethod = .get([])
     var modelType: T.Type
+    var headers: [String: String]
     
-    public init(url: URL, method: HTTPMethod, modelType: T.Type) {
+    public init(url: URL, method: HTTPMethod, modelType: T.Type, headers: [String: String] = [:]) {
         self.url = url
         self.method = method
         self.modelType = modelType
+        self.headers = headers
     }
 }
 
 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
@@ -78,20 +86,29 @@ public final class Hermes {
         self.config = config
     }
 
-    private var defaultHeaders: [String: String] {
+    public func addMiddleware(_ middleware: HermesMiddleware) {
-        var headers = ["Content-Type": "application/json"]
+        middlewares.append(middleware)
-        if let token = UserDefaults.standard.string(forKey: "authToken") {
-            headers["Authorization"] = "Bearer \(token)"
     }
-        headers.merge(config.defaultHeaders) { (_, new) in new }
+
+    private var defaultHeaders: [String: String] {
+        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 {
@@ -107,14 +124,23 @@ public final class Hermes {
                 break
         }
         
-        request.allHTTPHeaderFields = defaultHeaders
+        var headers = defaultHeaders
         
-        let configuration = URLSessionConfiguration.default
+        if !resource.headers.isEmpty {
-        configuration.httpAdditionalHeaders = defaultHeaders
+            headers.merge(resource.headers) { _, new in new }
-        let session = URLSession(configuration: configuration)
+        }
         
+        request.allHTTPHeaderFields = headers
+        
+        let session = URLSession(configuration: URLSessionConfiguration.default)
+        
+        do {
             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
             }
@@ -129,11 +155,17 @@ public final class Hermes {
             } catch {
                 throw NetworkError.decodingError
             }
+        } catch {
+            for middleware in middlewares {
+                middleware.processResponse(nil, nil, error: error)
+            }
+            throw error
+        }
     }
     
     private func validate(response: HTTPURLResponse) throws {
         switch response.statusCode {
-            case 200...299:
+            case 200 ... 299:
                 return
             case 400:
                 throw NetworkError.badRequest