agent.py

# agent.py  –  Gemini 2.0 Flash · LangGraph · Mehrere Tools
# =========================================================
import os, asyncio, base64, mimetypes, tempfile, functools, json
from typing import Dict, Any, List, Optional

from langgraph.graph import START, StateGraph, MessagesState, END
from langgraph.prebuilt import tools_condition, ToolNode

from langchain_core.messages import SystemMessage, HumanMessage
from langchain_core.tools import tool

from langchain_google_genai import ChatGoogleGenerativeAI
from langchain_community.tools.tavily_search import TavilySearchResults

# ---------------------------------------------------------------------
# Konstanten / API-Keys
# ---------------------------------------------------------------------
GOOGLE_API_KEY = os.getenv("GOOGLE_API_KEY")
TAVILY_KEY     = os.getenv("TAVILY_API_KEY")

# ---------------------------------------------------------------------
# Fehler-Wrapper – behält Doc-String dank wraps
# ---------------------------------------------------------------------
import functools
def error_guard(fn):
    @functools.wraps(fn)
    def wrapper(*args, **kwargs):
        try:
            return fn(*args, **kwargs)
        except Exception as e:
            return f"ERROR: {e}"
    return wrapper


# ---------------------------------------------------------------------
# 1) fetch_gaia_file   – Datei vom GAIA-Server holen
# ---------------------------------------------------------------------
GAIA_FILE_ENDPOINT = "https://agents-course-unit4-scoring.hf.space/file"

@tool
@error_guard
def fetch_gaia_file(task_id: str) -> str:
    """Download the attachment for the given GAIA task_id and return local path."""
    url = f"{GAIA_FILE_ENDPOINT}/{task_id}"
    try:
        response = requests.get(url, timeout=30)
        response.raise_for_status()
        file_name = response.headers.get("x-gaia-filename", f"{task_id}")
        tmp_path = tempfile.gettempdir() + "/" + file_name
        with open(tmp_path, "wb") as f:
            f.write(response.content)
        return tmp_path
    except Exception as e:
        return f"ERROR: could not fetch file – {e}"

# ---------------------------------------------------------------------
# 2) CSV-Parser
# ---------------------------------------------------------------------
import pandas as pd

@tool
@error_guard
def parse_csv(file_path: str, query: str = "") -> str:
    """Load a CSV file and answer a quick pandas query (optional)."""
    df = pd.read_csv(file_path)
    if not query:
        return f"Loaded CSV with {len(df)} rows and {len(df.columns)} cols.\nColumns: {list(df.columns)}"
    try:
        result = df.query(query)
        return result.to_markdown()
    except Exception as e:
        return f"ERROR in pandas query: {e}"

# ---------------------------------------------------------------------
# 3) Excel-Parser
# ---------------------------------------------------------------------
@tool
@error_guard
def parse_excel(file_path: str, query: str = "") -> str:
    """Load an Excel file (first sheet) and answer a pandas query (optional)."""
    df = pd.read_excel(file_path)
    if not query:
        return f"Loaded Excel with {len(df)} rows and {len(df.columns)} cols.\nColumns: {list(df.columns)}"
    try:
        result = df.query(query)
        return result.to_markdown()
    except Exception as e:
        return f"ERROR in pandas query: {e}"

# ---------------------------------------------------------------------
# 4) Gemini-Audio-Transkription
# ---------------------------------------------------------------------
@tool
@error_guard
def gemini_transcribe_audio(file_path: str, prompt: str = "Transcribe the audio.") -> str:
    """Use Gemini to transcribe an audio file."""
    with open(file_path, "rb") as f:
        b64 = base64.b64encode(f.read()).decode()
    mime = mimetypes.guess_type(file_path)[0] or "audio/mpeg"
    message = HumanMessage(
        content=[
            {"type": "text", "text": prompt},
            {"type": "media", "data": b64, "mime_type": mime},
        ]
    )
    resp = asyncio.run(safe_invoke([message]))
    return resp.content if hasattr(resp, "content") else str(resp)

# ---------------------------------------------------------------------
# 5) Bild-Beschreibung
# ---------------------------------------------------------------------
@tool
@error_guard
def describe_image(file_path: str, prompt: str = "Describe this image.") -> str:
    """Gemini vision – Bild beschreiben."""
    from PIL import Image
    img = Image.open(file_path)
    message = HumanMessage(
        content=[
            {"type": "text", "text": prompt},
            img,  # langchain übernimmt Encoding
        ]
    )
    resp = asyncio.run(safe_invoke([message]))
    return resp.content

# ---------------------------------------------------------------------
# 6) OCR-Tool
# ---------------------------------------------------------------------
@tool
@error_guard
def ocr_image(file_path: str, lang: str = "eng") -> str:
    """Extract text from an image via pytesseract."""
    try:
        import pytesseract
        from PIL import Image
        text = pytesseract.image_to_string(Image.open(file_path), lang=lang)
        return text.strip() or "No text found."
    except Exception as e:
        return f"ERROR: {e}"

# ---------------------------------------------------------------------
# 7) Tavily-Web-Suche
# ---------------------------------------------------------------------
@tool
@error_guard
def web_search(query: str, max_results: int = 5) -> str:
    """Search the web via Tavily and return a markdown list of results."""
    hits = TavilySearchResults(max_results=max_results, api_key=TAVILY_KEY).invoke(query)
    if not hits:
        return "No results."
    return "\n\n".join(f"{h['title']} – {h['url']}" for h in hits)

# ---------------------------------------------------------------------
# 8) Kleiner Rechner
# ---------------------------------------------------------------------
@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, f"ERROR: unknown op '{operation}'")

# ---------------------------------------------------------------------
# LLM + Semaphore-Throttle  (Gemini 2.0 Flash)
# ---------------------------------------------------------------------
gemini_llm = ChatGoogleGenerativeAI(
    model="gemini-2.0-flash",
    google_api_key=GOOGLE_API_KEY,
    temperature=0,
    max_output_tokens=2048,
).bind_tools([
    fetch_gaia_file, parse_csv, parse_excel,
    gemini_transcribe_audio, describe_image, ocr_image,
    web_search, simple_calculator,] ,return_named_tools=True)

LLM_SEMA = asyncio.Semaphore(2)           # 3 gleichz. Anfragen ≈ < 15/min

# safe_invoke neu (ersetzt die alte Funktion)
async def safe_invoke(msgs, tries: int = 4):
    """Gemini-Aufruf mit Semaphor + Exponential-Back-off bei 429 / Netzfehlern."""
    delay = 4
    for t in range(tries):
        async with LLM_SEMA:
            try:
                return await gemini_llm.ainvoke(msgs)
            except Exception as e:
                # nur bei Rate-Limit oder Netzwerk erneut versuchen
                if ("429" in str(e) or "RateLimit" in str(e)) and t < tries - 1:
                    await asyncio.sleep(delay)
                    delay *= 2          # 4 s, 8 s, 16 s …
                    continue
                raise

# ---------------------------------------------------------------------
# System-Prompt
# ---------------------------------------------------------------------
system_prompt = SystemMessage(content="""
You are a helpful assistant tasked with answering questions using a set of tools. 
Now, I will ask you a question. Report your thoughts, and finish your answer with the following template: 
FINAL ANSWER: [YOUR FINAL ANSWER]. 
YOUR FINAL ANSWER should be a number OR as few words as possible OR a comma separated list of numbers and/or strings. If you are asked for a number, don't use comma to write your number neither use units such as $ or percent sign unless specified otherwise. If you are asked for a string, don't use articles, neither abbreviations (e.g. for cities), and write the digits in plain text unless specified otherwise. If you are asked for a comma separated list, apply the above rules depending of whether the element to be put in the list is a number or a string.
Your answer should only start with "FINAL ANSWER: ", then follows with the answer. 
""")

# ---------------------------------------------------------------------
# LangGraph – Assistant-Node
# ---------------------------------------------------------------------
def assistant(state: MessagesState):
    msgs = state["messages"]
    if msgs[0].type != "system":
        msgs = [system_prompt] + msgs
    resp = asyncio.run(safe_invoke(msgs))
    finished = resp.content.lower().lstrip().startswith("final answer") or not resp.tool_calls
    return {"messages": [resp], "should_end": finished}

def route(state):
    return "END" if state["should_end"] else "tools"

# ---------------------------------------------------------------------
# Tools-Liste & Graph
# ---------------------------------------------------------------------
tools = [
    fetch_gaia_file, parse_csv, parse_excel,
    gemini_transcribe_audio, describe_image, ocr_image,
    web_search, simple_calculator,
]

builder = StateGraph(MessagesState)
builder.add_node("assistant", assistant)
builder.add_node("tools", ToolNode(tools))
builder.add_edge(START, "assistant")
builder.add_conditional_edges("assistant", route, {"tools": "tools", "END": END})

# Compile
agent_executor = builder.compile()