add workflow logics

api/core/workflow/entities/NodeEntities.py

@@ -0,0 +1,32 @@
+from enum import Enum
+
+
+class NodeType(Enum):
+    """
+    Node Types.
+    """
+    START = 'start'
+    END = 'end'
+    DIRECT_ANSWER = 'direct-answer'
+    LLM = 'llm'
+    KNOWLEDGE_RETRIEVAL = 'knowledge-retrieval'
+    IF_ELSE = 'if-else'
+    CODE = 'code'
+    TEMPLATE_TRANSFORM = 'template-transform'
+    QUESTION_CLASSIFIER = 'question-classifier'
+    HTTP_REQUEST = 'http-request'
+    TOOL = 'tool'
+    VARIABLE_ASSIGNER = 'variable-assigner'
+
+    @classmethod
+    def value_of(cls, value: str) -> 'BlockType':
+        """
+        Get value of given block type.
+
+        :param value: block type value
+        :return: block type
+        """
+        for block_type in cls:
+            if block_type.value == value:
+                return block_type
+        raise ValueError(f'invalid block type value {value}')