Feat/assistant app (#2086)

Co-authored-by: chenhe <guchenhe@gmail.com>
Co-authored-by: Pascal M <11357019+perzeuss@users.noreply.github.com>

api/core/callback_handler/agent_tool_callback_handler.py

@@ -0,0 +1,74 @@
+import os
+from typing import Any, Dict, Optional, Union
+from pydantic import BaseModel
+
+from langchain.callbacks.base import BaseCallbackHandler
+from langchain.input import print_text
+
+class DifyAgentCallbackHandler(BaseCallbackHandler, BaseModel):
+    """Callback Handler that prints to std out."""
+    color: Optional[str] = ''
+    current_loop = 1
+
+    def __init__(self, color: Optional[str] = None) -> None:
+        super().__init__()
+        """Initialize callback handler."""
+        # use a specific color is not specified
+        self.color = color or 'green'
+        self.current_loop = 1
+
+    def on_tool_start(
+        self,
+        tool_name: str,
+        tool_inputs: Dict[str, Any],
+    ) -> None:
+        """Do nothing."""
+        print_text("\n[on_tool_start] ToolCall:" + tool_name + "\n" + str(tool_inputs) + "\n", color=self.color)
+
+    def on_tool_end(
+        self,
+        tool_name: str,
+        tool_inputs: Dict[str, Any],
+        tool_outputs: str,
+    ) -> None:
+        """If not the final action, print out observation."""
+        print_text("\n[on_tool_end]\n", color=self.color)
+        print_text("Tool: " + tool_name + "\n", color=self.color)
+        print_text("Inputs: " + str(tool_inputs) + "\n", color=self.color)
+        print_text("Outputs: " + str(tool_outputs) + "\n", color=self.color)
+        print_text("\n")
+
+    def on_tool_error(
+        self, error: Union[Exception, KeyboardInterrupt], **kwargs: Any
+    ) -> None:
+        """Do nothing."""
+        print_text("\n[on_tool_error] Error: " + str(error) + "\n", color='red')
+
+    def on_agent_start(
+        self, thought: str
+    ) -> None:
+        """Run on agent start."""
+        if thought:
+            print_text("\n[on_agent_start] \nCurrent Loop: " + \
+                        str(self.current_loop) + \
+                        "\nThought: " + thought + "\n", color=self.color)
+        else:
+            print_text("\n[on_agent_start] \nCurrent Loop: " + str(self.current_loop) + "\n", color=self.color)
+
+    def on_agent_finish(
+        self, color: Optional[str] = None, **kwargs: Any
+    ) -> None:
+        """Run on agent end."""
+        print_text("\n[on_agent_finish]\n Loop: " + str(self.current_loop) + "\n", color=self.color)
+
+        self.current_loop += 1
+
+    @property
+    def ignore_agent(self) -> bool:
+        """Whether to ignore agent callbacks."""
+        return not os.environ.get("DEBUG") or os.environ.get("DEBUG").lower() != 'true'
+
+    @property
+    def ignore_chat_model(self) -> bool:
+        """Whether to ignore chat model callbacks."""
+        return not os.environ.get("DEBUG") or os.environ.get("DEBUG").lower() != 'true'