1 files changed, 119 insertions, 0 deletions
diff --git a/app/src/main/kotlin/xyz/brysonsteck/serverfordummies/server/Download.kt b/app/src/main/kotlin/xyz/brysonsteck/serverfordummies/server/Download.kt
new file mode 100644
index 0000000..d7e5aed
--- /dev/null
+++ b/app/src/main/kotlin/xyz/brysonsteck/serverfordummies/server/Download.kt
@@ -0,0 +1,119 @@
+package xyz.brysonsteck.serverfordummies.server
+
+import java.io.*;
+import java.net.*;
+import java.util.*;
+
+class Download: Runnable {
+  public enum class Status {
+    DOWNLOADING, PAUSED, COMPLETE, CANCELLED, ERROR
+  }
+  public var size: Int
+  public var downloaded: Int
+  public var contentLength: Int
+  public var status: Status
+
+  private final val MAX_BUFFER_SIZE: Number = 1024
+
+  private var url: URL
+  private var dir: String
+
+  constructor (url: URL, dir: String) {
+    this.url = url
+    this.dir = dir
+    size = -1
+    downloaded = 0
+    status = Status.DOWNLOADING
+    contentLength = 1
+  }
+
+  public fun start() {
+    val thread = Thread(this)
+    thread.start()
+  }
+
+  private fun getFilename(url: URL): String {
+    val filename = url.getFile()
+    return filename.substring(filename.lastIndexOf('/') + 1)
+  }
+
+  override fun run() { 
+    var stream: InputStream? = null
+    var file: RandomAccessFile? = null
+
+    try {
+      // Open connection to URL.
+      var connection = url.openConnection() as HttpURLConnection;
+
+      // Specify what portion of file to download.
+      connection.setRequestProperty("Range", "bytes=" + downloaded + "-");
+
+      // Connect to server.
+      connection.connect();
+
+      // Make sure response code is in the 200 range.
+      if (connection.responseCode / 100 != 2) {
+        status = Status.ERROR
+      }
+
+      // Check for valid content length.
+      contentLength = connection.getContentLength();
+      if (contentLength < 1) {
+        status = Status.ERROR
+      }
+
+      /* Set the size for this download if it
+        hasn't been already set. */
+      if (size == -1) {
+        size = contentLength;
+      }
+
+      // Open file and seek to the end of it.
+      file = RandomAccessFile(dir + getFilename(url), "rw");
+      file.seek(downloaded.toLong());
+
+      stream = connection.getInputStream();
+      while (status == Status.DOWNLOADING) {
+        /* Size buffer according to how much of the
+          file is left to download. */
+        val buffer: ByteArray;
+        if (size - downloaded > MAX_BUFFER_SIZE as Int) {
+          buffer = ByteArray(MAX_BUFFER_SIZE)
+        } else {
+          buffer = ByteArray(size - downloaded);
+        }
+
+        // Read from server into buffer.
+        val read = stream.read(buffer);
+        if (read == -1)
+          break;
+
+        // Write buffer to file.
+        file.write(buffer, 0, read);
+        downloaded += read;
+      }
+
+      /* Change status to complete if this point was
+          reached because downloading has finished. */
+      if (status == Status.DOWNLOADING) {
+          status = Status.COMPLETE;
+      }
+    } catch (e: Exception) {
+      status = Status.ERROR
+    } finally {
+        // Close file.
+        if (file != null) {
+            try {
+                file.close();
+            } catch (e: Exception) {}
+        }
+
+        // Close connection to server.
+        if (stream != null) {
+            try {
+                stream.close();
+            } catch (e: Exception) {}
+        }
+    }
+  }
+}