agent.py

from typing import TypedDict, Annotated, Sequence
import operator
from langgraph.graph import StateGraph, END
from transformers import AutoTokenizer, AutoModelForCausalLM, pipeline
from ai_tools import Calculator, DocRetriever, WebSearcher

# Configuration
MODEL_NAME = "HuggingFaceH4/zephyr-7b-beta"
tokenizer = AutoTokenizer.from_pretrained(MODEL_NAME)
model = AutoModelForCausalLM.from_pretrained(MODEL_NAME)
llm_pipeline = pipeline("text-generation", model=model, tokenizer=tokenizer)

# Define tools
tools = [Calculator(), WebSearcher()]
doc_retriever = DocRetriever()
tool_map = {tool.name: tool for tool in tools}
tool_map["DocRetriever"] = doc_retriever

# Agent State
class AgentState(TypedDict):
    input: str
    context: Annotated[Sequence[str], operator.add]
    last_tool: str

# Tool calling prompt template
TOOL_PROMPT = """<|system|>
You're an expert problem solver. Use these tools:
{tool_descriptions}

Respond ONLY in this format:
Thought: <strategy>
Action: <tool_name>
Action Input: <input>
</s>
<|user|>
{input}
Context: {context}
</s>
<|assistant|>
"""

# Initialize graph
graph = StateGraph(AgentState)

# Node: Generate tool calls
def agent_node(state):
    tool_list = "\n".join([f"- {t.name}: {t.description}" for t in tools])
    prompt = TOOL_PROMPT.format(
        tool_descriptions=tool_list,
        input=state["input"],
        context=state["context"]
    )
    
    response = llm_pipeline(
        prompt,
        max_new_tokens=150,
        do_sample=True,
        temperature=0.2,
        pad_token_id=tokenizer.eos_token_id
    )[0]['generated_text']
    
    # Extract tool call
    action_match = re.search(r"Action: (\w+)", response)
    action_input_match = re.search(r"Action Input: (.+?)\n", response)
    
    if action_match and action_input_match:
        tool_name = action_match.group(1)
        tool_input = action_input_match.group(1).strip()
        return {
            "last_tool": tool_name,
            "tool_input": tool_input,
            "thought": response
        }
    else:
        return {"last_tool": "FINISH", "output": response}

# Node: Execute tools
def tool_node(state):
    tool = tool_map.get(state["last_tool"])
    if not tool:
        return {"context": f"Error: Unknown tool {state['last_tool']}"}
    
    result = tool.run(state["tool_input"])
    return {"context": f"Tool {tool.name} returned: {result}"}

# Define graph structure
graph.add_node("agent", agent_node)
graph.add_node("tool", tool_node)
graph.set_entry_point("agent")

# Conditional edges
def route_action(state):
    if state["last_tool"] == "FINISH":
        return END
    return "tool"

graph.add_edge("agent", "tool")
graph.add_conditional_edges("tool", route_action, {"agent": "agent", END: END})
graph.add_edge("tool", "agent")  # Loop back after tool use

# Compile the agent
agent = graph.compile()

# Interface function
def run_agent(query: str, document: str = ""):
    doc_retriever.document = document  # Load document
    state = {"input": query, "context": [], "last_tool": ""}
    
    for step in agent.stream(state):
        for node, value in step.items():
            if node == "agent":
                print(f"THOUGHT: {value['thought']}")
            if node == "tool":
                print(f"TOOL RESULT: {value['context']}")
    
    return state["context"][-1] if state["context"] else "No output"