Decode folder hierarchy

app/src/main/java/eu/faircode/email/Core.java

@@ -742,6 +742,8 @@ class Core {
             Folder[] ifolders = defaultFolder.list("*");
             Log.i("Remote folder count=" + ifolders.length + " separator=" + separator);
 
+            Map<String, EntityFolder> nameFolder = new HashMap<>();
+            Map<String, List<EntityFolder>> parentFolders = new HashMap<>();
             for (Folder ifolder : ifolders) {
                 String fullName = ifolder.getFullName();
                 String[] attrs = ((IMAPFolder) ifolder).getAttributes();
@@ -803,6 +805,18 @@ class Core {
                                 db.folder().setFolderType(folder.id, type);
                         }
                     }
+
+                    nameFolder.put(folder.name, folder);
+                    String parentName = folder.getParentName(separator);
+                    if (!parentFolders.containsKey(parentName))
+                        parentFolders.put(parentName, new ArrayList<EntityFolder>());
+                    parentFolders.get(parentName).add(folder);
+                }
+
+                for (String parentName : parentFolders.keySet()) {
+                    EntityFolder parent = nameFolder.get(parentName);
+                    for (EntityFolder child : parentFolders.get(parentName))
+                        db.folder().setFolderParent(child.id, parent == null ? null : parent.id);
                 }
             }
 

app/src/main/java/eu/faircode/email/DB.java

@@ -50,7 +50,7 @@ import io.requery.android.database.sqlite.RequerySQLiteOpenHelperFactory;
 // https://developer.android.com/topic/libraries/architecture/room.html
 
 @Database(
-        version = 59,
+        version = 60,
         entities = {
                 EntityIdentity.class,
                 EntityAccount.class,
@@ -655,6 +655,13 @@ public abstract class DB extends RoomDatabase {
                         db.execSQL("CREATE  INDEX `index_contact_avatar` ON `contact` (`avatar`)");
                     }
                 })
+                .addMigrations(new Migration(59, 60) {
+                    @Override
+                    public void migrate(SupportSQLiteDatabase db) {
+                        Log.i("DB migration from version " + startVersion + " to " + endVersion);
+                        db.execSQL("ALTER TABLE `folder` ADD COLUMN `parent` INTEGER");
+                    }
+                })
                 .build();
     }
 

app/src/main/java/eu/faircode/email/DaoFolder.java

@@ -155,6 +155,9 @@ public interface DaoFolder {
     @Query("UPDATE folder SET level = :level WHERE id = :id")
     int setFolderLevel(long id, int level);
 
+    @Query("UPDATE folder SET parent = :parent WHERE id = :id")
+    int setFolderParent(long id, Long parent);
+
     @Query("UPDATE folder" +
             " SET type = '" + EntityFolder.USER + "'" +
             " WHERE account = :account" +

app/src/main/java/eu/faircode/email/EntityFolder.java

@@ -63,6 +63,7 @@ public class EntityFolder implements Serializable {
     @PrimaryKey(autoGenerate = true)
     public Long id;
     public Long account; // Outbox = null
+    public Long parent;
     @NonNull
     public String name;
     @NonNull
@@ -239,6 +240,19 @@ public class EntityFolder implements Serializable {
         return level;
     }
 
+    String getParentName(Character separator) {
+        if (separator == null)
+            return null;
+        else {
+            int p = name.lastIndexOf(separator);
+            if (p < 0)
+                return null;
+            else
+                return name.substring(0, p);
+        }
+
+    }
+
     @Override
     public boolean equals(Object obj) {
         if (obj instanceof EntityFolder) {