from typing import Any, Dict, Literal, Optional
from uuid import uuid4
from langchain_core.messages import BaseMessage
from langgraph.types import StreamWriter
from langgraph_agent_toolkit.agents.blueprints.bg_task_agent.utils import CustomData
from langgraph_agent_toolkit.schema.task_data import TaskData
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class Task:
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def __init__(self, task_name: str, writer: StreamWriter | None = None) -> None:
self.name = task_name
self.id = str(uuid4())
self.state: Literal["new", "running", "complete"] = "new"
self.result: Literal["success", "error"] | None = None
self.writer = writer
def _generate_and_dispatch_message(self, writer: StreamWriter | None, data: dict):
writer = writer or self.writer
task_data = TaskData(name=self.name, run_id=self.id, state=self.state, data=data)
if self.result:
task_data.result = self.result
task_custom_data = CustomData(
type=self.name,
data=task_data.model_dump(),
)
if writer:
task_custom_data.dispatch(writer)
return task_custom_data.to_langchain()
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def start(self, writer: StreamWriter | None = None, data: dict = {}) -> BaseMessage:
self.state = "new"
task_message = self._generate_and_dispatch_message(writer, data)
return task_message
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def write_data(self, writer: StreamWriter | None = None, data: dict = {}) -> BaseMessage:
if self.state == "complete":
raise ValueError("Only incomplete tasks can output data.")
self.state = "running"
task_message = self._generate_and_dispatch_message(writer, data)
return task_message
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def finish(
self,
result: Literal["success", "error"],
writer: StreamWriter | None = None,
data: Optional[Dict[str, Any]] = None,
) -> BaseMessage:
self.state = "complete"
self.result = result
task_message = self._generate_and_dispatch_message(writer, data or {})
return task_message