Cleanup some nullability

app/src/main/java/com/hippo/ehviewer/EhDB.kt

@@ -49,16 +49,10 @@ object EhDB {
     // Fix state
     @get:Synchronized
     val allDownloadInfo: List<DownloadInfo>
-        get() {
-            val dao = db.downloadsDao()
-            val list = dao.list()
-            // Fix state
-            for (info in list) {
-                if (info.state == DownloadInfo.STATE_WAIT || info.state == DownloadInfo.STATE_DOWNLOAD) {
-                    info.state = DownloadInfo.STATE_NONE
-                }
+        get() = db.downloadsDao().list().onEach {
+            if (it.state == DownloadInfo.STATE_WAIT || it.state == DownloadInfo.STATE_DOWNLOAD) {
+                it.state = DownloadInfo.STATE_NONE
             }
-            return list
         }
 
     @Synchronized
@@ -67,16 +61,14 @@ object EhDB {
         dao.update(downloadInfos)
     }
 
-    // Insert or update
     @Synchronized
     fun putDownloadInfo(downloadInfo: DownloadInfo) {
-        val dao = db.downloadsDao()
-        if (null != dao.load(downloadInfo.gid)) {
-            // Update
-            dao.update(downloadInfo)
-        } else {
-            // Insert
-            dao.insert(downloadInfo)
+        db.downloadsDao().run {
+            if (load(downloadInfo.gid) != null) {
+                update(downloadInfo)
+            } else {
+                insert(downloadInfo)
+            }
         }
     }
 
@@ -92,20 +84,15 @@ object EhDB {
         return raw?.dirname
     }
 
-    /**
-     * Insert or update
-     */
     @Synchronized
     fun putDownloadDirname(gid: Long, dirname: String?) {
         val dao = db.downloadDirnameDao()
         var raw = dao.load(gid)
-        if (raw != null) { // Update
+        if (raw != null) {
             raw.dirname = dirname
             dao.update(raw)
-        } else { // Insert
-            raw = DownloadDirname()
-            raw.gid = gid
-            raw.dirname = dirname
+        } else {
+            raw = DownloadDirname(gid, dirname)
             dao.insert(raw)
         }
     }
@@ -124,13 +111,10 @@ object EhDB {
 
     @get:Synchronized
     val allDownloadLabelList: List<DownloadLabel>
-        get() {
-            val dao = db.downloadLabelDao()
-            return dao.list()
-        }
+        get() = db.downloadLabelDao().list()
 
     @Synchronized
-    fun addDownloadLabel(label: String?): DownloadLabel {
+    fun addDownloadLabel(label: String): DownloadLabel {
         val dao = db.downloadLabelDao()
         val raw = DownloadLabel()
         raw.label = label

app/src/main/java/com/hippo/ehviewer/download/DownloadManager.kt

@@ -37,6 +37,8 @@ import com.hippo.yorozuya.collect.LongList
 import kotlinx.coroutines.coroutineScope
 import kotlinx.coroutines.launch
 import java.util.LinkedList
+import kotlin.contracts.ExperimentalContracts
+import kotlin.contracts.contract
 
 object DownloadManager : OnSpiderListener {
     // All download info list
@@ -92,14 +94,20 @@ object DownloadManager : OnSpiderListener {
             allInfoMap.put(info.gid, info)
 
             // Add to each label list
-            var list = getInfoListForLabel(info.label)
-            if (list == null) {
-                // Can't find the label in label list
-                list = LinkedList()
-                map[info.label] = list
-                if (!containLabel(info.label)) {
+            val label = info.label
+
+            val list = getInfoListForLabel(label) ?: LinkedList<DownloadInfo>().also {
+                /* Contracts says if [getInfoListForLabel] return null, the param [label] is not null
+                 * [label] is local immutable
+                 * Why [label] is not smart casted to [String!] here ???
+                 *
+                 * TODO: Report it to kotlin compiler team
+                 */
+                label!!
+                map[info.label] = it
+                if (!containLabel(label)) {
                     // Add label to DB and list
-                    labels.add(EhDB.addDownloadLabel(info.label))
+                    labels.add(EhDB.addDownloadLabel(label))
                 }
             }
             list.add(info)
@@ -109,7 +117,11 @@ object DownloadManager : OnSpiderListener {
         mDownloadInfoListeners = ArrayList()
     }
 
+    @OptIn(ExperimentalContracts::class)
     private fun getInfoListForLabel(label: String?): LinkedList<DownloadInfo>? {
+        contract {
+            returns(null) implies (label != null)
+        }
         return if (label == null) {
             mDefaultInfoList
         } else {
@@ -342,7 +354,7 @@ object DownloadManager : OnSpiderListener {
                 mMap[info.label] = list
                 if (!containLabel(info.label)) {
                     // Add label to DB and list
-                    mLabelList.add(EhDB.addDownloadLabel(info.label))
+                    mLabelList.add(EhDB.addDownloadLabel(info.label!!))
                 }
             }
             list.add(info)