feat: partial download support and cleanup for incomplete files

composeApp/src/androidMain/kotlin/com/nuvio/app/features/downloads/DownloadsPlatformDownloader.android.kt

@@ -51,26 +51,61 @@ internal actual object DownloadsPlatformDownloader {
             val downloadsDir = File(context.filesDir, "downloads").apply { mkdirs() }
             val destination = File(downloadsDir, request.destinationFileName)
             val tempFile = File(downloadsDir, "${request.destinationFileName}.part")
-            if (tempFile.exists()) tempFile.delete()
-
-            val requestBuilder = Request.Builder().url(request.sourceUrl)
-            request.sourceHeaders.forEach { (key, value) ->
-                requestBuilder.header(key, value)
-            }
-            val httpRequest = requestBuilder.get().build()
-            call = downloadHttpClient.newCall(httpRequest)
 
             try {
-                call?.execute()?.use { response ->
+                var resumeFromBytes = tempFile.takeIf { it.exists() }?.length()?.coerceAtLeast(0L) ?: 0L
+
+                fun buildRequest(rangeStart: Long?): Request {
+                    val requestBuilder = Request.Builder().url(request.sourceUrl)
+                    request.sourceHeaders.forEach { (key, value) ->
+                        requestBuilder.header(key, value)
+                    }
+                    if (rangeStart != null && rangeStart > 0L) {
+                        requestBuilder.header("Range", "bytes=$rangeStart-")
+                    }
+                    return requestBuilder.get().build()
+                }
+
+                var attemptedRangeRequest = resumeFromBytes > 0L
+                var httpRequest = buildRequest(if (attemptedRangeRequest) resumeFromBytes else null)
+                call = downloadHttpClient.newCall(httpRequest)
+                var response = call?.execute() ?: error("Download request failed")
+
+                if (attemptedRangeRequest && response.code == 416) {
+                    response.close()
+                    tempFile.delete()
+                    resumeFromBytes = 0L
+                    attemptedRangeRequest = false
+                    httpRequest = buildRequest(null)
+                    call = downloadHttpClient.newCall(httpRequest)
+                    response = call?.execute() ?: error("Download request failed")
+                }
+
+                response.use { response ->
                     if (!response.isSuccessful) {
                         error("Request failed with HTTP ${response.code}")
                     }
+
+                    val isPartialResume = attemptedRangeRequest && response.code == 206 && resumeFromBytes > 0L
+                    val appendToTemp = isPartialResume
+                    val startingBytes = if (appendToTemp) resumeFromBytes else 0L
+
+                    if (!appendToTemp && tempFile.exists()) {
+                        tempFile.delete()
+                    }
+
                     val body = response.body ?: error("Empty response body")
-                    val totalBytes = body.contentLength().takeIf { it > 0L }
-                    var downloadedBytes = 0L
+                    val totalBytes = resolveTotalBytes(
+                        startingBytes = startingBytes,
+                        isPartialResume = isPartialResume,
+                        contentRangeHeader = response.header("Content-Range"),
+                        contentLength = body.contentLength().takeIf { it > 0L },
+                    )
+                    var downloadedBytes = startingBytes
+                    onProgress(downloadedBytes, totalBytes)
 
                     body.byteStream().use { input ->
-                        FileOutputStream(tempFile, false).use { output ->
+                        FileOutputStream(tempFile, appendToTemp).use { output ->
                             val buffer = ByteArray(16 * 1024)
                             while (true) {
                                 ensureActive()
@@ -95,10 +130,7 @@ internal actual object DownloadsPlatformDownloader {
                     val finalSize = destination.length()
                     onSuccess(destination.toURI().toString(), totalBytes ?: finalSize)
                 }
-            } catch (_: CancellationException) {
-                tempFile.delete()
             } catch (error: Throwable) {
-                tempFile.delete()
                 onFailure(error.message ?: "Download failed")
             }
         }
@@ -115,6 +147,14 @@ internal actual object DownloadsPlatformDownloader {
         val file = localFileUri.toLocalFileOrNull() ?: return false
         return runCatching { file.delete() }.getOrDefault(false)
     }
+
+    actual fun removePartialFile(destinationFileName: String): Boolean {
+        val context = appContext ?: return false
+        val downloadsDir = File(context.filesDir, "downloads")
+        val tempFile = File(downloadsDir, "$destinationFileName.part")
+        if (!tempFile.exists()) return true
+        return runCatching { tempFile.delete() }.getOrDefault(false)
+    }
 }
 
 private class AndroidDownloadsTaskHandle(
@@ -134,3 +174,28 @@ private fun String.toLocalFileOrNull(): File? {
         }
     }.getOrNull()
 }
+
+private fun resolveTotalBytes(
+    startingBytes: Long,
+    isPartialResume: Boolean,
+    contentRangeHeader: String?,
+    contentLength: Long?,
+): Long? {
+    parseContentRangeTotal(contentRangeHeader)?.let { return it }
+    val normalizedLength = contentLength?.takeIf { it > 0L } ?: return null
+    return if (isPartialResume && startingBytes > 0L) {
+        startingBytes + normalizedLength
+    } else {
+        normalizedLength
+    }
+}
+
+private fun parseContentRangeTotal(headerValue: String?): Long? {
+    val value = headerValue?.trim().orEmpty()
+    if (value.isBlank()) return null
+    val slashIndex = value.lastIndexOf('/')
+    if (slashIndex == -1 || slashIndex == value.lastIndex) return null
+    val totalPart = value.substring(slashIndex + 1).trim()
+    if (totalPart == "*") return null
+    return totalPart.toLongOrNull()?.takeIf { it > 0L }
+}

composeApp/src/commonMain/kotlin/com/nuvio/app/features/downloads/DownloadsPlatformDownloader.kt

@@ -19,4 +19,6 @@ internal expect object DownloadsPlatformDownloader {
     ): DownloadsTaskHandle
 
     fun removeFile(localFileUri: String?): Boolean
+
+    fun removePartialFile(destinationFileName: String): Boolean
 }

composeApp/src/commonMain/kotlin/com/nuvio/app/features/downloads/DownloadsRepository.kt

@@ -115,6 +115,7 @@ object DownloadsRepository {
             replacedExisting = true
             activeHandles.remove(existing.id)?.cancel()
             DownloadsPlatformDownloader.removeFile(existing.localFileUri)
+            DownloadsPlatformDownloader.removePartialFile(existing.fileName)
             currentItems.removeAll { it.id == existing.id }
         }
 
@@ -194,8 +195,6 @@ object DownloadsRepository {
 
         val reset = item.copy(
             status = DownloadStatus.Downloading,
-            downloadedBytes = 0L,
-            totalBytes = null,
             errorMessage = null,
             localFileUri = null,
             updatedAtEpochMs = DownloadsClock.nowEpochMs(),
@@ -216,6 +215,7 @@ object DownloadsRepository {
 
         activeHandles.remove(downloadId)?.cancel()
         DownloadsPlatformDownloader.removeFile(item.localFileUri)
+        DownloadsPlatformDownloader.removePartialFile(item.fileName)
 
         publish(_uiState.value.items.filterNot { it.id == downloadId })
         persist()
@@ -241,7 +241,6 @@ object DownloadsRepository {
                     item
                 }
             }
-            .sortedByDescending { it.updatedAtEpochMs }
 
         _uiState.value = DownloadsUiState(normalized)
         notifyLiveStatusPlatform()
@@ -332,7 +331,7 @@ object DownloadsRepository {
 
     private fun publish(items: List<DownloadItem>) {
         _uiState.value = DownloadsUiState(
-            items = items.sortedByDescending { it.updatedAtEpochMs },
+            items = items,
         )
         notifyLiveStatusPlatform()
     }
@@ -378,7 +377,7 @@ private object DownloadsCodec {
     fun encodeItems(items: Collection<DownloadItem>): String =
         json.encodeToString(
             StoredDownloadsPayload(
-                items = items.toList().sortedByDescending { it.updatedAtEpochMs },
+                items = items.toList(),
             ),
         )
 }

composeApp/src/commonMain/kotlin/com/nuvio/app/features/downloads/DownloadsScreen.kt

@@ -11,6 +11,7 @@ import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.lazy.LazyListScope
+import androidx.compose.foundation.lazy.items
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.rounded.Delete
 import androidx.compose.material.icons.rounded.Pause
@@ -116,8 +117,10 @@ private fun LazyListScope.downloadsRootContent(
         item {
             SectionTitle("ACTIVE")
         }
-        items(activeItems.size) { index ->
-            val item = activeItems[index]
+        items(
+            items = activeItems,
+            key = { it.id },
+        ) { item ->
             DownloadRow(
                 item = item,
                 onOpen = { onOpenDownload(item) },
@@ -133,8 +136,10 @@ private fun LazyListScope.downloadsRootContent(
         item {
             SectionTitle("MOVIES")
         }
-        items(completedMovies.size) { index ->
-            val item = completedMovies[index]
+        items(
+            items = completedMovies,
+            key = { it.id },
+        ) { item ->
             DownloadRow(
                 item = item,
                 onOpen = { onOpenDownload(item) },
@@ -150,8 +155,10 @@ private fun LazyListScope.downloadsRootContent(
         item {
             SectionTitle("SHOWS")
         }
-        items(completedShows.size) { index ->
-            val (item, episodes) = completedShows[index]
+        items(
+            items = completedShows,
+            key = { (item, _) -> item.parentMetaId },
+        ) { (item, episodes) ->
             Surface(
                 modifier = Modifier
                     .fillMaxWidth()
@@ -262,8 +269,10 @@ private fun LazyListScope.downloadsShowContent(
                 .thenByDescending { it.updatedAtEpochMs },
         )
 
-        items(sortedEpisodes.size) { index ->
-            val item = sortedEpisodes[index]
+        items(
+            items = sortedEpisodes,
+            key = { it.id },
+        ) { item ->
             DownloadRow(
                 item = item,
                 onOpen = { onOpenDownload(item) },

composeApp/src/iosMain/kotlin/com/nuvio/app/features/downloads/DownloadsPlatformDownloader.ios.kt

@@ -52,24 +52,52 @@ internal actual object DownloadsPlatformDownloader {
             val destinationPath = "$downloadsDirectory/${request.destinationFileName}"
             val tempPath = "$downloadsDirectory/${request.destinationFileName}.part"
 
-            removePathIfExists(tempPath)
-
             try {
-                val response = downloadHttpClient.get(request.sourceUrl) {
+                var resumeFromBytes = fileSizeOrNull(tempPath)?.coerceAtLeast(0L) ?: 0L
+
+                suspend fun performRequest(rangeStart: Long?) = downloadHttpClient.get(request.sourceUrl) {
                     request.sourceHeaders.forEach { (key, value) ->
                         header(key, value)
                     }
+                    if (rangeStart != null && rangeStart > 0L) {
+                        header("Range", "bytes=$rangeStart-")
+                    }
+                }
+
+                var attemptedRangeRequest = resumeFromBytes > 0L
+                var response = performRequest(if (attemptedRangeRequest) resumeFromBytes else null)
+
+                if (attemptedRangeRequest && response.status.value == 416) {
+                    removePathIfExists(tempPath)
+                    resumeFromBytes = 0L
+                    attemptedRangeRequest = false
+                    response = performRequest(null)
                 }
 
                 if (!response.status.isSuccess()) {
                     error("Request failed with HTTP ${response.status.value}")
                 }
 
-                val totalBytes = response.headers["Content-Length"]?.toLongOrNull()?.takeIf { it > 0L }
+                val isPartialResume = attemptedRangeRequest && response.status.value == 206 && resumeFromBytes > 0L
+                val appendToTemp = isPartialResume
+                val startingBytes = if (appendToTemp) resumeFromBytes else 0L
+
+                if (!appendToTemp) {
+                    removePathIfExists(tempPath)
+                }
+
+                val totalBytes = resolveTotalBytes(
+                    startingBytes = startingBytes,
+                    isPartialResume = isPartialResume,
+                    contentRangeHeader = response.headers["Content-Range"],
+                    contentLength = response.headers["Content-Length"]?.toLongOrNull()?.takeIf { it > 0L },
+                )
                 val channel = response.bodyAsChannel()
                 val wrote = writeChannelToFile(
                     channel = channel,
                     path = tempPath,
+                    append = appendToTemp,
+                    initialDownloadedBytes = startingBytes,
                     totalBytes = totalBytes,
                     onProgress = onProgress,
                 )
@@ -90,10 +118,7 @@ internal actual object DownloadsPlatformDownloader {
                 val localFileUri = NSURL.fileURLWithPath(destinationPath).absoluteString ?: "file://$destinationPath"
                 val finalSize = fileSizeOrNull(destinationPath)
                 onSuccess(localFileUri, totalBytes ?: finalSize)
-            } catch (_: CancellationException) {
-                removePathIfExists(tempPath)
             } catch (error: Throwable) {
-                removePathIfExists(tempPath)
                 onFailure(error.message ?: "Download failed")
             }
         }
@@ -106,6 +131,11 @@ internal actual object DownloadsPlatformDownloader {
         val path = localFileUri.toLocalPath() ?: return false
         return removePathIfExists(path)
     }
+
+    actual fun removePartialFile(destinationFileName: String): Boolean {
+        val tempPath = "${downloadsDirectoryPath()}/$destinationFileName.part"
+        return removePathIfExists(tempPath)
+    }
 }
 
 private class IosDownloadsTaskHandle(
@@ -139,12 +169,15 @@ private fun removePathIfExists(path: String): Boolean {
 private suspend fun writeChannelToFile(
     channel: ByteReadChannel,
     path: String,
+    append: Boolean,
+    initialDownloadedBytes: Long,
     totalBytes: Long?,
     onProgress: (downloadedBytes: Long, totalBytes: Long?) -> Unit,
 ): Boolean {
-    val file = fopen(path, "wb") ?: return false
+    val file = fopen(path, if (append) "ab" else "wb") ?: return false
     val buffer = ByteArray(16 * 1024)
-    var downloadedBytes = 0L
+    var downloadedBytes = initialDownloadedBytes
+    onProgress(downloadedBytes, totalBytes)
 
     return try {
         while (true) {
@@ -192,3 +225,28 @@ private fun String.toLocalPath(): String? {
     }
     return takeIf { it.isNotBlank() }
 }
+
+private fun resolveTotalBytes(
+    startingBytes: Long,
+    isPartialResume: Boolean,
+    contentRangeHeader: String?,
+    contentLength: Long?,
+): Long? {
+    parseContentRangeTotal(contentRangeHeader)?.let { return it }
+    val normalizedLength = contentLength?.takeIf { it > 0L } ?: return null
+    return if (isPartialResume && startingBytes > 0L) {
+        startingBytes + normalizedLength
+    } else {
+        normalizedLength
+    }
+}
+
+private fun parseContentRangeTotal(headerValue: String?): Long? {
+    val value = headerValue?.trim().orEmpty()
+    if (value.isBlank()) return null
+    val slashIndex = value.lastIndexOf('/')
+    if (slashIndex == -1 || slashIndex == value.lastIndex) return null
+    val totalPart = value.substring(slashIndex + 1).trim()
+    if (totalPart == "*") return null
+    return totalPart.toLongOrNull()?.takeIf { it > 0L }
+}