agent.py

"""
agent.py  –  LangGraph-Agent mit
 • Gemini 2.0 Flash
 • Datei-Tools (CSV, Excel, Audio, Bild-Describe, OCR)
 • Fehler-Retry-Logik
"""
import os, base64, mimetypes, subprocess, json, tempfile
from typing import Any

from langgraph.graph import START, StateGraph, MessagesState
from langgraph.prebuilt import tools_condition, ToolNode
from langchain_core.tools import tool
from langchain_core.messages import SystemMessage, HumanMessage
from langchain_google_genai import ChatGoogleGenerativeAI
from langchain_community.tools.tavily_search import TavilySearchResults

# ----------------------------------------------------------------------
# 1 ── ENV / LLM
# ----------------------------------------------------------------------
GOOGLE_API_KEY = os.getenv("GOOGLE_API_KEY")

llm = ChatGoogleGenerativeAI(
    model="gemini-2.0-flash",
    google_api_key=GOOGLE_API_KEY,
    temperature=0,
    max_output_tokens=2048,
)

# ----------------------------------------------------------------------
# 2 ── ERROR-WRAPPER  (garantiert "ERROR:"-String statt Exception)
# ----------------------------------------------------------------------
def error_guard(fn):
    def wrapper(*args, **kwargs):
        try:
            return fn(*args, **kwargs)
        except Exception as e:
            return f"ERROR: {e}"
    return wrapper

# ----------------------------------------------------------------------
# 3 ── BASIS-TOOLS
# ----------------------------------------------------------------------
@tool
@error_guard
def simple_calculator(operation: str, a: float, b: float) -> float:
    """Basic maths: add, subtract, multiply, divide."""
    ops = {"add": a + b, "subtract": a - b, "multiply": a * b,
           "divide": a / b if b else float("inf")}
    return ops.get(operation, "ERROR: unknown operation")

@tool
@error_guard
def fetch_gaia_file(task_id: str) -> str:
    """Download attachment for current GAIA task_id; returns local file path."""
    import requests, pathlib, uuid
    url = f"https://agents-course-unit4-scoring.hf.space/file/{task_id}"
    r = requests.get(url, timeout=15)
    r.raise_for_status()
    suffix = pathlib.Path(url).suffix or ""
    fp = pathlib.Path(tempfile.gettempdir())/f"{uuid.uuid4().hex}{suffix}"
    fp.write_bytes(r.content)
    return str(fp)

@tool
@error_guard
def parse_csv(file_path: str, query: str = "") -> str:
    """Load CSV & answer query using pandas.eval."""
    import pandas as pd
    df = pd.read_csv(file_path)
    if not query:
        return df.head().to_markdown()
    return str(pd.eval(query, local_dict={"df": df}))

@tool
@error_guard
def parse_excel(file_path: str, query: str = "") -> str:
    """Load first sheet of Excel & answer query using pandas.eval."""
    import pandas as pd
    df = pd.read_excel(file_path)
    if not query:
        return df.head().to_markdown()
    return str(pd.eval(query, local_dict={"df": df}))

# ----------------------------------------------------------------------
# 4 ── GEMINI MULTIMODAL-TOOLS
# ----------------------------------------------------------------------
@tool
@error_guard
def describe_image(file_path: str, prompt: str = "Describe the image.") -> str:
    """Send a local image (base64) to Gemini Vision and return description."""
    mime, _ = mimetypes.guess_type(file_path)
    if not (mime and mime.startswith("image/")):
        return "ERROR: not an image."
    with open(file_path, "rb") as f:
        b64 = base64.b64encode(f.read()).decode()
    content = [
        {"type": "text", "text": prompt},
        {"type": "image_url", "image_url": f"data:{mime};base64,{b64}"},
    ]
    resp = llm.invoke([HumanMessage(content=content)])
    return resp.content

@tool
@error_guard
def gemini_transcribe_audio(file_path: str,
                            prompt: str = "Transcribe the audio.") -> str:
    """Transcribe audio via Gemini multimodal."""
    mime, _ = mimetypes.guess_type(file_path)
    if not (mime and mime.startswith("audio/")):
        return "ERROR: not audio."
    with open(file_path, "rb") as f:
        b64 = base64.b64encode(f.read()).decode()
    content = [
        {"type": "text", "text": prompt},
        {"type": "media", "data": b64, "mime_type": mime},
    ]
    resp = llm.invoke([HumanMessage(content=content)])
    return resp.content

# ----------------------------------------------------------------------
# 5 ── OFFLINE OCR-TOOL  (pytesseract)
# ----------------------------------------------------------------------
@tool
@error_guard
def ocr_image(file_path: str, lang: str = "eng") -> str:
    """Extract text from image using pytesseract."""
    from PIL import Image
    import pytesseract
    img = Image.open(file_path)
    return pytesseract.image_to_string(img, lang=lang).strip()

# ----------------------------------------------------------------------
# 6 ── WEB / WIKI SEARCH
# ----------------------------------------------------------------------
@tool
@error_guard
def web_search(query: str, max_results: int = 5) -> str:
    """Tavily web search – returns markdown list of results."""
    search = TavilySearchResults(max_results=max_results)
    hits = search.invoke(query)
    if not hits:
        return "ERROR: no results."
    return "\n\n".join(f"{hit['title']} – {hit['url']}" for hit in hits)


# ----------------------------------------------------------------------
# 7 ── SYSTEM-PROMPT
# ----------------------------------------------------------------------
system_prompt = SystemMessage(content=(
    "You are a precise GAIA challenge agent.\n"
    "Always attempt a TOOL call before giving up. "
    "If a tool returns 'ERROR', think of an alternative tool or parameters.\n"
    "Use fetch_gaia_file(task_id) for any attachment."
))

# ----------------------------------------------------------------------
# 8 ── LangGraph Nodes
# ----------------------------------------------------------------------
tools = [
    fetch_gaia_file,
    parse_csv,
    parse_excel,
    gemini_transcribe_audio,
    ocr_image,
    describe_image,
    web_search,
    simple_calculator,
]

llm_with_tools = llm.bind_tools(tools)


def safe_llm_invoke(msgs):
    for attempt in range(2):
        resp = llm_with_tools.invoke(msgs)
        content = resp.content or ""
        if not content.startswith("ERROR"):
            return resp
        msgs.append(
            SystemMessage(content="Previous tool call returned ERROR. Try another approach.")
        )
    return resp


def assistant(state: MessagesState):
    msgs = state["messages"]
    if not msgs or msgs[0].type != "system":
        msgs = [system_prompt] + msgs
    return {"messages": [safe_llm_invoke(msgs)]}

# ----------------------------------------------------------------------
# 9 ── Graph
# ----------------------------------------------------------------------
builder = StateGraph(MessagesState)
builder.add_node("assistant", assistant)
builder.add_node("tools", ToolNode(tools))
builder.add_edge(START, "assistant")
builder.add_conditional_edges("assistant", tools_condition)
builder.add_edge("tools", "assistant")

agent_executor = builder.compile()