implement DownloadWorker class

src/main/java/DownloadWorker.java

@@ -1,12 +1,5 @@
 import java.util.Random;
 
-/**
- * Simulates downloading a single chunk of a file.
- *
- * <p>This class is intentionally provided as a skeleton for students.
- * The main multithreading and simulation logic should be completed
- * in the run() method.</p>
- */
 public class DownloadWorker implements Runnable {
 
     private final ChunkStatus chunkStatus;
@@ -21,23 +14,31 @@ public class DownloadWorker implements Runnable {
 
     @Override
     public void run() {
-        // TODO: Record the chunk start time in chunkStatus.
+
         double downloaded = 0.0;
-
-        // TODO: Print a message that this chunk has started downloading.
-
+        long startTime = System.currentTimeMillis();
+        chunkStatus.setStartTimeMs(startTime);
+        System.out.println("Chunk: " + chunkStatus.getChunkId() + " has started downloading.");
         while (downloaded < chunkStatus.getChunkSizeMB()) {
-            // TODO: Generate a random sleep delay between min and max delay.
-            // TODO: Sleep for that delay.
-            // TODO: Generate a random download amount for this step.
-            // TODO: Increase downloaded, but do not go beyond chunk size.
-            // TODO: Save the updated downloaded value into chunkStatus.
-            // TODO: Optionally print step-by-step progress.
+
+            long randomSleep = random.nextLong(config.getMinStepDelayMs(), config.getMaxStepDelayMs());
+
+            try {
+                Thread.sleep(randomSleep);
+            }
+            catch (InterruptedException e) {
+                System.out.println(e.getMessage());
+            }
+
+            double down = random.nextDouble();
+            downloaded = Math.min(downloaded + down, chunkStatus.getChunkSizeMB());
+            chunkStatus.setDownloadedMB(chunkStatus.getDownloadedMB() + downloaded);
         }
 
-        // TODO: Mark the chunk as completed.
-        // TODO: Record the chunk end time in chunkStatus.
-        // TODO: Print a message that this chunk has finished downloading.
+        chunkStatus.setCompleted(true);
+        Long endTime = System.currentTimeMillis();
+        chunkStatus.setEndTimeMs(endTime);
+        System.out.println("Chunk: " + chunkStatus.getChunkId() + " has completed downloading.");
     }
 
 }