Initial implementation of APKINDEX, fetching, reading, parsing, & merging

Sources/apk/Index/ApkIndexDownloader.swift

@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: Apache-2.0
+
+import Foundation
+
+struct ApkIndexDownloader {
+  func downloadFile(remote remoteURL: URL, destination destLocalURL: URL) {
+    let sem = DispatchSemaphore.init(value: 0)
+    let downloadTask = URLSession.shared.downloadTask(with: remoteURL) { url, response, error in
+      if let localURL = url {
+        do {
+          // Replace existing APKINDEX.tar.gz files
+          if FileManager.default.fileExists(atPath: destLocalURL.path()) {
+            try FileManager.default.removeItem(at: destLocalURL)
+          }
+          // Move temporary to the new location
+          try FileManager.default.moveItem(at: localURL, to: destLocalURL)
+        } catch {
+          print("Download error: \(error.localizedDescription)")
+        }
+      }
+      sem.signal()
+    }
+    downloadTask.resume()
+    sem.wait()
+  }
+}