refactor: remove unused download in DotNetAPI.kt and add todo for upload migration

libsession/src/main/java/org/session/libsession/messaging/utilities/DotNetAPI.kt

@@ -178,80 +178,9 @@ open class DotNetAPI {
         return execute(HTTPVerb.PATCH, server, "users/me", parameters = parameters)
     }
 
-    // DOWNLOAD
-
-    /**
-     * Blocks the calling thread.
-     */
-    fun downloadFile(destination: File, url: String, listener: SignalServiceAttachment.ProgressListener?) {
-        val outputStream = FileOutputStream(destination) // Throws
-        var remainingAttempts = 4
-        var exception: Exception? = null
-        while (remainingAttempts > 0) {
-            remainingAttempts -= 1
-            try {
-                downloadFile(outputStream, url, listener)
-                exception = null
-                break
-            } catch (e: Exception) {
-                exception = e
-            }
-        }
-        if (exception != null) { throw exception }
-    }
-
-    /**
-     * Blocks the calling thread.
-     */
-    private fun downloadFile(outputStream: OutputStream, url: String, listener: SignalServiceAttachment.ProgressListener?) {
-        // We need to throw a PushNetworkException or NonSuccessfulResponseCodeException
-        // because the underlying Signal logic requires these to work correctly
-        val oldPrefixedHost = "https://" + HttpUrl.get(url).host()
-        var newPrefixedHost = oldPrefixedHost
-        if (oldPrefixedHost.contains(FileServerAPI.fileStorageBucketURL)) {
-            newPrefixedHost = FileServerAPI.shared.server
-        }
-        // Edge case that needs to work: https://file-static.lokinet.org/i1pNmpInq3w9gF3TP8TFCa1rSo38J6UM
-        // → https://file.getsession.org/loki/v1/f/XLxogNXVEIWHk14NVCDeppzTujPHxu35
-        val fileID = url.substringAfter(oldPrefixedHost).substringAfter("/f/")
-        val sanitizedURL = "$newPrefixedHost/loki/v1/f/$fileID"
-        val request = Request.Builder().url(sanitizedURL).get()
-        try {
-            val serverPublicKey = if (newPrefixedHost.contains(FileServerAPI.shared.server)) FileServerAPI.fileServerPublicKey
-            else FileServerAPI.shared.getPublicKeyForOpenGroupServer(newPrefixedHost).get()
-            val json = OnionRequestAPI.sendOnionRequest(request.build(), newPrefixedHost, serverPublicKey, isJSONRequired = false).get()
-            val result = json["result"] as? String
-            if (result == null) {
-                Log.d("Loki", "Couldn't parse attachment from: $json.")
-                throw PushNetworkException("Missing response body.")
-            }
-            val body = Base64.decode(result)
-            if (body.size > FileServerAPI.maxFileSize) {
-                Log.d("Loki", "Attachment size limit exceeded.")
-                throw PushNetworkException("Max response size exceeded.")
-            }
-            val input = body.inputStream()
-            val buffer = ByteArray(32768)
-            var count = 0
-            var bytes = input.read(buffer)
-            while (bytes >= 0) {
-                outputStream.write(buffer, 0, bytes)
-                count += bytes
-                if (count > FileServerAPI.maxFileSize) {
-                    Log.d("Loki", "Attachment size limit exceeded.")
-                    throw PushNetworkException("Max response size exceeded.")
-                }
-                listener?.onAttachmentProgress(body.size.toLong(), count.toLong())
-                bytes = input.read(buffer)
-            }
-        } catch (e: Exception) {
-            Log.d("Loki", "Couldn't download attachment due to error: $e.")
-            throw if (e is NonSuccessfulResponseCodeException) e else PushNetworkException(e)
-        }
-    }
-
     // UPLOAD
 
+    // TODO: migrate to v2 file server
     @Throws(PushNetworkException::class, NonSuccessfulResponseCodeException::class)
     fun uploadAttachment(server: String, attachment: PushAttachmentData): UploadResult {
         // This function mimics what Signal does in PushServiceSocket