Keep bounded Epic downloads in a stable UI stage

app/src/main/java/com/droiddeck/launcher/stores/epic/EpicBackend.kt

@@ -146,6 +146,8 @@ object EpicBackend : StoreBackend, EpicLaunchSupport {
                     EpicLibrary.rememberSize(app, item.id, diskBytes)
                 }
                 override fun onStage(stage: String, done: Long, total: Long, items: Int, itemsTotal: Int) {
+                    // Assembly overlaps chunk fetching; only the final install event advances the UI.
+                    if (stage == "stream") return
                     handle.stage(when (stage) { "check" -> DownloadStage.MANIFEST; "verify" -> DownloadStage.VERIFY; else -> DownloadStage.INSTALL })
                     handle.stageProgress(done, total, items, itemsTotal, bytes = stage == "install")
                 }

app/src/main/java/com/droiddeck/launcher/stores/epic/EpicDownloadManager.java

@@ -55,6 +55,7 @@ public final class EpicDownloadManager {
         /**
          * The active stage's own count: {@code stage} is "check" (the files already there, before
          * anything is fetched), "verify" or "install" (bytes written), {@code done} of
+         * "stream" reports assembly during a bounded download without completing the install stage.
          * {@code total} an amount (bytes, or items when there are no bytes), {@code items} of
          * {@code itemsTotal} the files, when it counts files.
          */
@@ -247,7 +248,7 @@ public final class EpicDownloadManager {
                 if (cancel.get()) return null;
                 String relPath = file.filename.replace("\\", "/");
                 File outFile = new File(installDir, relPath);
-                cb.onProgress("Writing: " + (relPath.contains("/") ? relPath.substring(relPath.lastIndexOf('/') + 1) : relPath), 80 + (int) (doneFiles * 20L / totalFiles));
+                cb.onProgress("Downloading chunks: " + (relPath.contains("/") ? relPath.substring(relPath.lastIndexOf('/') + 1) : relPath), (int) (completedBytes * 80L / Math.max(1, fTotalBytes)));
                 // Like the native assembler, write to the final path and remove it on failure.
                 // A sibling "<name>.part" can itself be a legitimate file in the manifest.
                 File partFile = outFile;
@@ -308,9 +309,10 @@ public final class EpicDownloadManager {
                 }
                 doneFiles++;
                 writtenBytes += file.fileSize();
-                cb.onStage("install", writtenBytes, pendingBytes, doneFiles, totalFiles);
+                cb.onStage("stream", writtenBytes, pendingBytes, doneFiles, totalFiles);
             }
             deleteDir(chunkCacheDir);
+            cb.onStage("install", writtenBytes, pendingBytes, doneFiles, totalFiles);
             cb.onProgress("Complete", 100);
             return new Result(manifest.launchExe, manifest.buildVersion, planned).withPrereq(manifest);
         } catch (InstallException e) {

app/src/test/java/com/droiddeck/launcher/stores/epic/EpicBoundedInstallTest.kt

@@ -106,7 +106,7 @@ class EpicBoundedInstallTest {
         val callback = object : EpicDownloadManager.Callback {
             override fun onProgress(message: String, pct: Int) {}
             override fun onStage(stage: String, done: Long, total: Long, items: Int, itemsTotal: Int) {
-                if (stage == "install" && items == 1) cancel.set(true)
+                if (stage == "stream" && items == 1) cancel.set(true)
             }
         }
         assertNull(install(cancel, callback))
@@ -121,7 +121,7 @@ class EpicBoundedInstallTest {
         val cancel = AtomicBoolean()
         val callback = object : EpicDownloadManager.Callback {
             override fun onProgress(message: String, pct: Int) {
-                if (message.startsWith("Downloading chunks")) cancel.set(true)
+                if (message.startsWith("Downloading chunks (")) cancel.set(true)
             }
         }
         assertNull(install(cancel, callback))
@@ -156,6 +156,28 @@ class EpicBoundedInstallTest {
         assertNotNull(install())
     }
 
+    @Test fun boundedProgressNeverReentersDownloadAfterEnteringInstall() {
+        val events = mutableListOf<String>()
+        val callback = object : EpicDownloadManager.Callback {
+            override fun onProgress(message: String, pct: Int) {
+                if (message.startsWith("Downloading chunks")) events.add("download")
+                if (message.startsWith("Writing")) events.add("install")
+            }
+            override fun onBytes(done: Long, total: Long, speedBps: Long) { events.add("download") }
+            override fun onStage(stage: String, done: Long, total: Long, items: Int, itemsTotal: Int) {
+                if (stage == "install") {
+                    assertEquals(total, done)
+                    assertEquals(itemsTotal, items)
+                    events.add("install")
+                }
+            }
+        }
+        assertNotNull(install(callback = callback))
+        val firstInstall = events.indexOf("install")
+        assertTrue(firstInstall > 0)
+        assertFalse(events.drop(firstInstall).contains("download"))
+    }
+
     @Test fun hogwartsSizedSequentialPlanFitsAvailableSpaceWithoutFullChunkCache() {
         val gib = 1024L * 1024 * 1024
         val file = EpicDownloadManager.FileInfo()