From 255356ff19bcd550ffbad06681b86bc8df35b07d Mon Sep 17 00:00:00 2001
From: Matt Bruce <mbrucedogs@gmail.com>
Date: Mon, 20 Jan 2025 17:05:20 -0600
Subject: [PATCH] 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>
---
 .../Services/NetworkService.swift             | 47 +++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/EmployeeDirectory/Services/NetworkService.swift b/EmployeeDirectory/Services/NetworkService.swift
index 5fb1366..80582dd 100644
--- a/EmployeeDirectory/Services/NetworkService.swift
+++ b/EmployeeDirectory/Services/NetworkService.swift
@@ -23,3 +23,50 @@ public enum NetworkServiceError: Error {
     /// 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)
+        }
+    }
+}