created singleton to just fetch data for a decodable. this doesn't handle any customization for a URLRequest, just dealing with a public url for now.

Signed-off-by: Matt Bruce <mbrucedogs@gmail.com>

EmployeeDirectory/Services/NetworkService.swift

@@ -0,0 +1,72 @@
+//
+//  NetworkService.swift
+//  EmployeeDirectory
+//
+//  Created by Matt Bruce on 1/20/25.
+//
+
+import Foundation
+
+public enum NetworkServiceError: Error {
+    /// The response from the server was invalid (e.g., non-200 status code or malformed URL).
+    case invalidResponse
+
+    /// The url giving is invalid or malformed
+    case invalidURL
+    
+    /// The data received was invalid or could not be decoded.
+    case decodingError(DecodingError)
+    
+    /// A network-related error occurred.
+    case networkError(URLError)
+    
+    /// An unexpected, uncategorized error occurred.
+    case unknownError(Error)
+}
+
+public class NetworkService {
+    
+    public static let shared = NetworkService() // Default shared instance
+
+    private let session: URLSession
+
+    /// Public initializer to allow customization
+    public init(session: URLSession = .shared) {
+        self.session = session
+    }
+
+    /// Fetches data from a URL and decodes it into a generic Decodable type.
+    /// - Parameters:
+    ///   - endpoint: The url to fetch data from.
+    ///   - type: The type to decode the data into.
+    /// - Throws: A `ServiceError` for network, decoding, or unexpected errors.
+    /// - Returns: The decoded object of the specified type.
+    public func fetchData<T: Decodable>(from endpoint: String, as type: T.Type) async throws -> T {
+        do {
+            //ensure a valid URL
+            guard let url = URL(string: endpoint) else {
+                throw NetworkServiceError.invalidURL
+            }
+
+            // Perform network request
+            let (data, response) = try await URLSession.shared.data(for: URLRequest(url: url))
+            
+            // Validate HTTP response
+            guard let httpResponse = response as? HTTPURLResponse, httpResponse.statusCode == 200 else {
+                throw NetworkServiceError.invalidResponse
+            }
+            
+            // Decode the response into the specified type
+            return try JSONDecoder().decode(T.self, from: data)
+            
+        } catch let urlError as URLError {
+            throw NetworkServiceError.networkError(urlError)
+            
+        } catch let decodingError as DecodingError {
+            throw NetworkServiceError.decodingError(decodingError)
+            
+        } catch {
+            throw NetworkServiceError.unknownError(error)
+        }
+    }
+}