Rework many parts and move some components into the core module

core/src/main/java/io/xpipe/core/data/node/SimpleTupleNode.java

@@ -64,7 +64,12 @@ public class SimpleTupleNode extends TupleNode {
 
     @Override
     public DataStructureNode forKey(String name) {
-        return nodes.get(names.indexOf(name));
+        var index = names.indexOf(name);
+        if (index == -1) {
+            throw new IllegalArgumentException("Key " + name + " not found");
+        }
+
+        return nodes.get(index);
     }
 
     @Override

core/src/main/java/io/xpipe/core/source/DataSourceDescriptor.java

@@ -10,5 +10,7 @@ public interface DataSourceDescriptor<DS extends DataStore> {
         return Optional.empty();
     }
 
+    DataSourceInfo determineInfo(DS store) throws Exception;
+
     DataSourceType getType();
 }

core/src/main/java/io/xpipe/core/source/DataSourceId.java

@@ -87,6 +87,6 @@ public class DataSourceId {
 
     @Override
     public String toString() {
-        return collectionName + SEPARATOR + entryName;
+        return (collectionName != null ? collectionName : "") + SEPARATOR + entryName;
     }
 }

core/src/main/java/io/xpipe/core/source/DataSourceInfo.java

@@ -0,0 +1,41 @@
+package io.xpipe.core.source;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonTypeInfo;
+import com.fasterxml.jackson.annotation.JsonTypeName;
+import io.xpipe.core.data.type.TupleType;
+import lombok.EqualsAndHashCode;
+import lombok.Value;
+
+@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property = "type")
+public abstract class DataSourceInfo {
+
+    public abstract DataSourceType getType();
+
+    @EqualsAndHashCode(callSuper = false)
+    @Value
+    @JsonTypeName("table")
+    public static class Table extends DataSourceInfo {
+        TupleType dataType;
+        int rowCount;
+
+        @JsonCreator
+        public Table(TupleType dataType, int rowCount) {
+            this.dataType = dataType;
+            this.rowCount = rowCount;
+        }
+
+        @Override
+        public DataSourceType getType() {
+            return DataSourceType.TABLE;
+        }
+    }
+
+    public Table asTable() {
+        if (!getType().equals(DataSourceType.TABLE)) {
+            throw new IllegalStateException("Not a table");
+        }
+
+        return (Table) this;
+    }
+}

core/src/main/java/io/xpipe/core/store/DataStore.java

@@ -8,6 +8,11 @@ import java.util.Optional;
 @JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property = "type")
 public interface DataStore {
 
+    @SuppressWarnings("unchecked")
+    default <DS extends DataStore> DS asNeeded() {
+        return (DS) this;
+    }
+
     default Optional<String> determineDefaultName() {
         return Optional.empty();
     }

core/src/main/java/io/xpipe/core/util/CoreJacksonModule.java

@@ -2,7 +2,6 @@ package io.xpipe.core.util;
 
 import com.fasterxml.jackson.core.JsonGenerator;
 import com.fasterxml.jackson.core.JsonParser;
-import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.DeserializationContext;
 import com.fasterxml.jackson.databind.JsonDeserializer;
 import com.fasterxml.jackson.databind.JsonSerializer;
@@ -12,6 +11,7 @@ import com.fasterxml.jackson.databind.module.SimpleModule;
 import io.xpipe.core.data.type.ArrayType;
 import io.xpipe.core.data.type.TupleType;
 import io.xpipe.core.data.type.ValueType;
+import io.xpipe.core.source.DataSourceInfo;
 import io.xpipe.core.store.LocalFileDataStore;
 
 import java.io.IOException;
@@ -26,7 +26,8 @@ public class CoreJacksonModule extends SimpleModule {
                 new NamedType(LocalFileDataStore.class),
                 new NamedType(ValueType.class),
                 new NamedType(TupleType.class),
-                new NamedType(ArrayType.class)
+                new NamedType(ArrayType.class),
+                new NamedType(DataSourceInfo.Table.class)
         );
 
         addSerializer(Charset.class, new CharsetSerializer());