# Develop an AI agent with LangGraph and LangChain 
# to answer the questions in the "gaia-benchmark/GAIA" dataset.

from pathlib import Path
import os, re, base64, mimetypes, tempfile, uuid, subprocess, json
from urllib.parse import urlparse, unquote
from PIL import Image
import pytesseract
import whisper
import requests
from typing import TypedDict, List, Optional, Dict, Any, Literal
from langchain_core.tools import tool
from langchain_core.messages import HumanMessage, SystemMessage
from langchain_openai import ChatOpenAI
from langgraph.graph import StateGraph, START, END
from tavily import TavilyClient
import serpapi 
import trafilatura
from readability import Document
import html as _html
import wikipedia
from urllib.parse import parse_qs
from youtube_transcript_api import YouTubeTranscriptApi, TranscriptsDisabled, NoTranscriptFound
import yt_dlp

# ==== NEW: (optional) tiny helpers used by browsing nodes ====
def _has_search_key() -> bool:
    """Return True if any supported search backend is configured."""
    return bool(
        os.getenv("TAVILY_API_KEY")
        or os.getenv("SERPAPI_API_KEY")
        or (os.getenv("GOOGLE_API_KEY") and os.getenv("GOOGLE_CSE_ID"))
    )

# Optional: pdf parsing if GAIA sometimes includes PDFs
try:
    import pdfplumber
    _HAS_PDFPLUMBER = True
except Exception:
    _HAS_PDFPLUMBER = False


# -------------- State -------------
class EvidenceItem(TypedDict):
    # ==== CHANGED: expanded allowed kinds to match actual usage paths ====
    kind: Literal["audio_transcript","image_ocr","image_vqa","doc_text","unknown_file","preprocess_error"]
    text: str
    path: Optional[str]
    meta: Dict[str, Any]

class AgentState(TypedDict):
    task_id: str
    question: str
    attachment_urls: List[str]     # empty list when no files
    local_files: List[str]
    evidence: List[EvidenceItem]
    answer: Optional[str]
    parsed_final_answer: Optional[str]
    emit_final_answer: bool  # <<< add this (default True if you want old behavior)
    # ==== NEW: state used by browse pipeline (optional) ====
    use_browsing: Optional[bool]
    web_hits: Optional[List[Dict[str, str]]]
    # ==== NEW: urls found directly in the question ====
    question_urls: Optional[List[str]]
    question_youtube_urls: Optional[List[str]]

# -------------- helpers ---------------
def _filename_from_cd(cd: str) -> str | None:
    # RFC 6266/5987: filename* takes precedence; fall back to filename
    if not cd:
        return None
    # filename*=
    m = re.search(r"filename\*\s*=\s*([^']*)'[^']*'([^;]+)", cd, flags=re.I)
    if m:
        return unquote(m.group(2)).strip().strip('"')
    # filename=
    m = re.search(r'filename\s*=\s*"?(.*?)(?:"|;|$)', cd, flags=re.I)
    if m:
        return m.group(1).strip().strip('"')
    return None

def _pick_extension(ct: str | None) -> str | None:
    if not ct:
        return None
    ct = ct.split(";", 1)[0].strip()
    ext = mimetypes.guess_extension(ct)
    # Fix common mis-maps
    return {".jpe": ".jpg"}.get(ext, ext)

def _summarize_evidence(evidence: List[Dict[str, Any]], limit_chars: int = 6000) -> str:
    """Compact the evidence text for prompting; keep provenance-style tags."""
    chunks = []
    for i, e in enumerate(evidence, 1):
        t = e.get("text", "") or ""
        if len(t) > 1200:  # keep things small but informative
            t = t[:1200] + " …"
        meta = e.get("meta", {})
        tag = f"{e.get('kind','?')}"
        if meta.get("mime"):
            tag += f"({meta['mime']})"
        if meta.get("title"):
            tag += f"[{meta['title']}]"
        if meta.get("url"):
            tag += f"<{meta['url']}>"
        chunks.append(f"[{i}:{tag}] {t}")
    out = "\n".join(chunks)
    return out if len(out) <= limit_chars else out[:limit_chars] + " …"

def _collect_image_paths(evidence: List[Dict[str, Any]], limit: int = 4) -> List[str]:
    """Find image file paths to attach to a vision model."""
    paths = []
    for e in evidence:
        if e.get("path") and str(e.get("meta", {}).get("mime","")).startswith("image"):
            p = e["path"]
            if os.path.exists(p) and p not in paths:
                paths.append(p)
        if len(paths) >= limit:
            break
    return paths

def _image_to_data_url(path: str) -> str:
    """Encode an image file as a data URL for OpenAI chat image parts."""
    with open(path, "rb") as f:
        b64 = base64.b64encode(f.read()).decode("utf-8")
    mime, _ = mimetypes.guess_type(path)
    mime = mime or "image/png"
    return f"data:{mime};base64,{b64}"

def _ensure_final_answer_line(text: str, *, enabled: bool) -> str:
    """When enabled, ensure a `final_answer:` line. When disabled, strip any such line."""
    if enabled:
        if re.search(r"(?im)^final_answer\s*:", text):
            return text
        # best-effort: take last non-empty line
        lines = [ln.strip() for ln in text.splitlines() if ln.strip() and not ln.strip().startswith("```")]
        candidate = lines[-1] if lines else "[NO_ANSWER]"
        return f"{text.rstrip()}\n\nfinal_answer: {candidate}"
    else:
        # remove any final_answer line(s)
        return re.sub(r"(?im)^final_answer\s*:\s*.*\n?", "", text).strip()

def _parse_final_answer(text: str, *, enabled: bool) -> Optional[str]:
    """Only parse when enabled; otherwise return None."""
    if not enabled:
        return None
    m = re.search(r"(?im)^final_answer\s*:\s*(.+)$", text)
    return m.group(1).strip() if m else None

def _convert_to_wav_mono16k(src_path: str) -> str:
    print("converting to mono16... from: ", src_path)
    out = os.path.join(tempfile.gettempdir(), f"gaia_{uuid.uuid4().hex}.wav")
    cmd = ["ffmpeg", "-y", "-i", src_path, "-ac", "1", "-ar", "16000", out]
    # Capture stderr for debugging
    p = subprocess.run(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)
    if p.returncode != 0 or not os.path.exists(out):
        raise RuntimeError(f"ffmpeg failed: {p.stderr[-500:]}")
    return out

# ==== NEW: URL helpers ====
_URL_RE = re.compile(r'https?://\S+')

def _extract_urls(text: str) -> List[str]:
    return _URL_RE.findall(text or "")


# ----------------------Tools ----------------------
@tool
def download_file(url: str, headers: dict | None = None, auth_token: str | None = None) -> str:
    """Download a file following redirects and honoring Content-Disposition. Returns local path."""
    sess = requests.Session()
    hdrs = {"User-Agent": "gaia-agent/1.0"}
    if headers:
        hdrs.update(headers)
    if auth_token:
        hdrs["Authorization"] = f"Bearer {auth_token}"

    with sess.get(url, headers=hdrs, timeout=(10, 60), stream=True, allow_redirects=True) as r:
        r.raise_for_status()

        # Determine filename
        cd = r.headers.get("Content-Disposition", "")
        fname = _filename_from_cd(cd)

        if not fname:
            # Fallback to URL path
            path = urlparse(r.url).path or urlparse(url).path
            fname = os.path.basename(path) or f"download-{uuid.uuid4().hex}"

        # Ensure we have an extension
        base, ext = os.path.splitext(fname)
        if not ext:
            guess = _pick_extension(r.headers.get("Content-Type"))
            if guess:
                fname = base + guess

        # # Write to a temp folder (unique per call)
        out_dir = tempfile.mkdtemp(prefix="gaia_tmpdl_")
        out_path = os.path.join(out_dir, fname)

        print("out_path:", out_path)

        with open(out_path, "wb") as f:
            for chunk in r.iter_content(chunk_size=1024 * 1024):
                if chunk:
                    f.write(chunk)

        return out_path


# ==== NEW: cache Whisper model so we don't reload each call ====
_WHISPER = None

@tool
def transcribe_audio(path: str, model_size: str = "base") -> str:
    """
    Transcribe an audio file using Whisper (local). Converts to mono/16k WAV first for robustness.
    Returns the transcript text; raises on failure (caller handles).
    """
    print("running transcribe_audio")
    global _WHISPER
    try:
        if _WHISPER is None:
            _WHISPER = whisper.load_model(model_size)
        result = _WHISPER.transcribe(path)
        return (result.get("text") or "").strip()
    except Exception as e:
        raise RuntimeError(f"Whisper error: {e}")


@tool
def ocr_image(path: str) -> str:
    """OCR an image using Tesseract."""
    # Install tesseract binary on your system first
    print("running ocr")
    img = Image.open(path)
    text = pytesseract.image_to_string(img)
    return text.strip()


# ==== NEW: WEB / WIKI / YOUTUBE TOOLS =========================================
# Choose your search backend (Tavily simplest). Set env var before use.
_USE_TAVILY = False  # flip to False to use SerpAPI example

if _USE_TAVILY:
    @tool
    def web_search(query: str, k: int = 6) -> List[Dict[str, str]]:
        """
        Web search via Tavily. Returns a list of {title, url, snippet}.
        Requires TAVILY_API_KEY.
        """
        try:
            tv = TavilyClient(api_key=os.getenv("TAVILY_API_KEY"))
            res = tv.search(
                query=query,
                search_depth="advanced",
                max_results=k,
                include_answer=False,
                include_images=False,
            )
            out = []
            for r in res.get("results", []):
                out.append({
                    "title": r.get("title",""),
                    "url": r.get("url",""),
                    "snippet": (r.get("content","") or "")[:400]
                })
            return out
        except Exception as e:
            return [{"title":"", "url":"", "snippet": f"[search error: {e}]"}]
else:
    @tool
    def web_search(query: str, k: int = 6) -> List[Dict[str, str]]:
        """
        Web search via SerpAPI. Returns a list of {title, url, snippet}.
        Requires SERPAPI_API_KEY.
        """
        try:
            params = {"engine":"google", "q":query, "num":k, "api_key":os.getenv("SERPAPI_API_KEY")}
            search = serpapi.search(params)
            # results = search.get_dict()
            results = search
            items = results.get("organic_results", [])
            out = []
            for it in items[:k]:
                out.append({
                    "title": it.get("title",""),
                    "url": it.get("link",""),
                    "snippet": (it.get("snippet","") or "")[:400]
                })
            return out
        except Exception as e:
            return [{"title":"", "url":"", "snippet": f"[search error: {e}]"}]

@tool
def fetch_url_text(url: str, max_chars: int = 12000, timeout: int = 30) -> Dict[str, Any]:
    """
    Download a web page and extract main article text using trafilatura,
    with a readability-lxml fallback. Returns {url, title, text}.
    """
    sess = requests.Session()
    headers = {
        "User-Agent": "gaia-agent/1.0 (+https://example.org)",
        "Accept": "text/html,*/*;q=0.8",
    }

    try:
        r = sess.get(url, headers=headers, timeout=timeout)
        r.raise_for_status()
        html_content = r.text
    except Exception as e:
        return {"url": url, "title": "", "text": f"[fetch error: {e}]"}

    # 1) try trafilatura (best for boilerplate removal)
    try:
        downloaded = trafilatura.extract(html_content, include_comments=False, include_tables=False, url=url)
        if downloaded and len(downloaded) > 200:
            text = downloaded
            title = ""
        else:
            raise ValueError("trafilatura extraction too short")
    except Exception:
        # 2) fallback: readability
        try:
            doc = Document(html_content)
            title = doc.short_title() or ""
            text = doc.summary(html_partial=False)
            # rudimentary HTML strip
            text = re.sub(r"<[^>]+>", " ", text)
            text = re.sub(r"\s+", " ", text).strip()
        except Exception as e2:
            return {"url": url, "title": "", "text": f"[extraction error: {e2}]"}

    if len(text) > max_chars:
        text = text[:max_chars] + " …"

    # Try to fill title if empty
    if not title:
        m = re.search(r"<title[^>]*>(.*?)</title>", html_content, flags=re.I|re.S)
        if m:
            title = _html.unescape(m.group(1).strip())

    return {"url": url, "title": title or "", "text": text}

@tool
def wikipedia_lookup(query: str, sentences: int = 4) -> Dict[str, Any]:
    """
    Simple Wikipedia lookup. Returns {title, url, summary}.
    """
    try:
        wikipedia.set_lang("en")
        try:
            title = wikipedia.search(query, results=1)[0]
        except Exception as e:
            return {"title":"", "url":"", "summary": f"[wikipedia search error: {e}]"}
        try:
            summary = wikipedia.summary(title, sentences=sentences, auto_suggest=False)
            page = wikipedia.page(title, auto_suggest=False, preload=False)
            return {"title": page.title, "url": page.url, "summary": summary}
        except Exception as e:
            return {"title": title, "url":"", "summary": f"[wikipedia fetch error: {e}]"}
    except Exception as e:
        return {"title":"", "url":"", "summary": f"[wikipedia import error: {e}]"}

@tool
def youtube_get_transcript(url_or_id: str, prefer_langs: List[str] | None = None) -> str:
    """
    Get YouTube transcript via API (no download). Returns plain text.
    """
    print('try to get youtube video transcript')
    try:
        prefer_langs = prefer_langs or ["en", "en-US", "en-GB", "auto"]
        vid = url_or_id
        print("vid: ", vid)
        if "youtube.com" in url_or_id or "youtu.be" in url_or_id:
            u = urlparse(url_or_id)
            if u.netloc.endswith("youtu.be"):
                vid = u.path.lstrip("/")
            else:
                vid = parse_qs(u.query).get("v", [""])[0]
        ytt_api = YouTubeTranscriptApi()
        trs_list = ytt_api.list(vid)
        # choose first matching language
        for lang in prefer_langs:
            try:
                trs = trs_list.find_transcript([lang])
                chunks = trs.fetch()
                print("transcript from youtube website?")
                print(" ".join([c["text"] for c in chunks if c.get("text")]).strip())
                return " ".join([c["text"] for c in chunks if c.get("text")]).strip()
            except Exception:
                continue
        # fallback: first any transcript
        trs = list(trs_list)[0]
        chunks = trs.fetch()
        print("transcript from youtube website?")
        print(" ".join([c["text"] for c in chunks if c.get("text")]).strip())
        return " ".join([c["text"] for c in chunks if c.get("text")]).strip()
    except (TranscriptsDisabled, NoTranscriptFound):
        return "[no captions available]"
    except Exception as e:
        return f"[youtube transcript error: {e}]"

@tool
def youtube_transcribe_audio(url: str, model_size: str = "base") -> str:
    """
    Download YouTube audio (yt-dlp) and transcribe with Whisper.
    """
    tmpdir = tempfile.mkdtemp(prefix="gaia_yt_")
    outfile = os.path.join(tmpdir, "%(id)s.%(ext)s")

    ydl_opts = {
        "format": "bestaudio/best",
        "outtmpl": outfile,
        "quiet": True,
        "no_warnings": True,
        "noplaylist": True,
    }
    try:
        with yt_dlp.YoutubeDL(ydl_opts) as ydl:
            info = ydl.extract_info(url, download=True)
            path = ydl.prepare_filename(info)
        # convert & transcribe
        wav = _convert_to_wav_mono16k(path)
        txt = transcribe_audio.invoke({"path": wav, "model_size": model_size})
        return txt
    except Exception as e:
        return f"[youtube download/transcribe error: {e}]"

# ------------------------------- Nodes ------------------------------
def check_attachment_node(state: AgentState) -> AgentState:
    """Check if there is attachment."""
    print("enter check attachment node")

    # 1) Try HEAD first
    urls = state.get("attachment_urls")
    if not urls:
      print("No attachment URLs provided.")
      state["attachment_urls"] = []
      return state

    url = urls[0] # Get the first URL from the list
    headers = {"Accept": "application/json"}
    timeout = 30
    r = requests.head(url, headers=headers, allow_redirects=True, timeout=timeout)
    # Some servers don't support HEAD; 405/501 are common. Fallback to GET (stream) to read headers only.
    if r.status_code in (405, 501):
        r.close()
        r = requests.get(url, headers=headers, stream=True, allow_redirects=True, timeout=timeout)
    try:
        cd = r.headers.get("Content-Disposition", "") or r.headers.get("content-disposition", "")
        is_attachment = "attachment" in cd.lower()

        filename = None
        if is_attachment:
            m = re.search(r"filename\*=UTF-8''([^;]+)", cd, flags=re.I)
            if m:
                filename = unquote(m.group(1))
            else:
                m = re.search(r'filename="?([^";]+)"?', cd, flags=re.I)
                if m:
                    filename = m.group(1)
            print("Need to download attachment:", filename)
        else:
            print("No attachment header; skip downloading.")
            state["attachment_urls"] = []
        return state
    finally:
        # If we fell back to GET(stream=True), make sure we don't keep the connection open.
        try:
            r.close()
        except Exception:
          pass

def fetch_node(state: AgentState) -> AgentState:
    print("enter fetch_node")

    local_files = []
    for u in state["attachment_urls"]:
        # If already local file paths, just append them
        if os.path.exists(u):
            local_files.append(u)
        else:
            p = download_file.invoke({"url": u})
            local_files.append(p)
    state["local_files"] = local_files
    return state

def preprocess_node(state: AgentState) -> AgentState:

    """
    For each local file:
      - audio/*  -> ASR transcript
      - image/*  -> OCR text (basic enhancement to help OCR)
      - application/pdf -> text extraction (if pdfplumber available)
    Produces EvidenceItem entries and stores in state['evidence'].
    """
    print("enter preprocessing node")

    ev: List[Dict[str, Any]] = list(state.get("evidence", []))

    for path in state.get("local_files", []):
        mime, _ = mimetypes.guess_type(path)
        meta = {"mime": mime or "application/octet-stream", "filename": os.path.basename(path)}

        print("mime", mime)

        try:
            if mime and mime.startswith("audio"):
                print("mime start with audio")
                # --- ASR ---
                try:
                    wav = _convert_to_wav_mono16k(path)
                except Exception as e:
                    raise RuntimeError(f"Pre-conversion error: {e}")

                print("after conversion saving at tmp_wav path: ", wav)
                txt = transcribe_audio.invoke({"path": wav})
                ev.append({"kind": "audio_transcript", "text": txt, "path": path, "meta": meta})

            elif mime and mime.startswith("image"):
                print("mime start with image")
                # --- OCR with simple pre-enhancement ---
                try:
                    print("upscaling original small image: ", path)
                    img = Image.open(path)
                    img = img.convert("L")  # grayscale
                    w, h = img.size
                    if max(w, h) < 1600:  # upscale small images to help OCR
                        img = img.resize((w * 2, h * 2))
                    tmp_ocr = os.path.join(tempfile.gettempdir(), f"ocr_{uuid.uuid4().hex}.png")
                    img.save(tmp_ocr)
                    print("After upscaling save at tmp_ocr path: ", tmp_ocr)
                    ocr = ocr_image.invoke({"path": tmp_ocr})
                except Exception as e:
                    ocr = f"[OCR error: {e}]"
                ev.append({"kind": "image_ocr", "text": ocr, "path": path, "meta": meta})

            elif mime == "application/pdf" or (mime and mime.startswith("application") and path.lower().endswith(".pdf")):
                # --- PDF extraction (best-effort; image-only PDFs may need OCR) ---
                if _HAS_PDFPLUMBER:
                    try:
                        pages = []
                        with pdfplumber.open(path) as pdf:
                            for pg in pdf.pages:
                                pages.append(pg.extract_text() or "")
                        txt = "\n\n".join(pages).strip() or "[Empty or image-based PDF; try OCR]"
                    except Exception as e:
                        txt = f"[PDF parse error: {e}]"
                else:
                    txt = "[PDF support not installed; pip install pdfplumber]"
                ev.append({"kind": "doc_text", "text": txt, "path": path, "meta": meta})

            else:
                # Unknown/unsupported; keep a breadcrumb so you can inspect later
                ev.append({"kind": "unknown_file", "text": "[Unsupported file type]", "path": path, "meta": meta})

        except Exception as e:
            ev.append({"kind": "preprocess_error", "text": f"[Error processing {path}: {e}]", "path": path, "meta": meta})

    state["evidence"] = ev
    return state

def solve_multimodal_node(state: AgentState) -> AgentState:
    """
    Use a vision-capable model (e.g., gpt-4o) and attach the image(s) PLUS the text evidence (ASR/OCR).
    """
    print("enter solve_multimodal_node")

    emit = bool(state.get("emit_final_answer", True))
    end_instr = "" if not emit else " End your output with a single line: final_answer: <answer>"

    question = state.get("question", "").strip()
    evidence = state.get("evidence", [])

    vision_llm = ChatOpenAI(model="gpt-4o", temperature=0)  # vision-capable
    sys = SystemMessage(content=(
        "You solve GAIA tasks using the provided evidence and attached images.\n"
        "Be precise, quote numbers/strings exactly. If uncertain, say so.\n"
        "Your answer to the GAIA tasks 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. If your answer only include a single word, make the first letter capital.\n" + end_instr
    ))

    # Summarized text evidence (ASR/OCR/PDF text)
    ev_text = _summarize_evidence(evidence)
    text_part = (
        f"Question:\n{question}\n\n"
        f"Textual evidence (summarized):\n{ev_text}\n\n"
        "Use the attached images if any to read fine text, diagrams, or confirm details."
    )

    parts: List[Any] = [{"type": "text", "text": text_part}]

    # Attach up to 4 images (data URLs)
    img_paths = _collect_image_paths(evidence, limit=4)
    for p in img_paths:
        parts.append({"type": "image_url", "image_url": {"url": _image_to_data_url(p)}})

    resp = vision_llm.invoke([sys, HumanMessage(content=parts)])
    text = (resp.content or "").strip()
    text = _ensure_final_answer_line(text, enabled=emit)

    state["answer"] = text
    state["parsed_final_answer"] = _parse_final_answer(text, enabled=emit)
    return state


def solve_text_only_node(state: "AgentState") -> "AgentState":
    """
    Text-only solve path. Consumes the question + textual evidence
    (e.g., audio transcripts from ASR, OCR text, PDF text). No images attached.
    """
    print("enter solve_text_only_node")

    emit = bool(state.get("emit_final_answer", True))
    end_instr = "" if not emit else " End your output with a single line: final_answer: <answer>"

    question = (state.get("question") or "").strip()
    evidence = state.get("evidence", [])

    # Summarized text evidence (ASR/OCR/PDF text)
    ev_text = _summarize_evidence(evidence) or "(none)"

    # LLM (text-only). Swap model as you like.
    llm = ChatOpenAI(model="gpt-4o-mini", temperature=0)

    sys = SystemMessage(content=(
        "You solve GAIA tasks. Use careful step-by-step reasoning but keep it concise.\n"
        "You can use the provided textual evidence if there is any. \n"
        "Your answer to the GAIA tasks 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. If your answer only include a single word, make the first letter capital.\n" + end_instr
    ))

    user = HumanMessage(content=(
        f"Question:\n{question}\n\n"
        f"Textual evidence (summarized):\n{ev_text}"
    ))

    resp = llm.invoke([sys, user])
    text = (resp.content or "").strip()
    text = _ensure_final_answer_line(text, enabled=emit)

    state["answer"] = text
    state["parsed_final_answer"] = _parse_final_answer(text, enabled=emit)
    return state

def validate_format_node(state: AgentState) -> AgentState:
    """
    Ensure the final output contains `final_answer: ...` and capture it separately for scoring.
    Also trims excessive whitespace and removes duplicate final_answer lines if any.
    """
    print("enter validate_format_node")

    emit = bool(state.get("emit_final_answer", True))
    txt = (state.get("answer") or "").strip()

    if not txt:
        if emit:
            state["answer"] = "No answer generated.\n\nfinal_answer: [NO_ANSWER]"
            state["parsed_final_answer"] = "[NO_ANSWER]"
        else:
            state["answer"] = "No answer generated."
            state["parsed_final_answer"] = None
        return state

    if emit:
        # keep only the LAST final_answer line if multiple
        matches = list(re.finditer(r"(?im)^final_answer\s*:\s*(.+)$", txt))
        if len(matches) == 0:
            txt = _ensure_final_answer_line(txt, enabled=True)
        elif len(matches) > 1:
            last = matches[-1].group(0)
            txt_wo = re.sub(r"(?im)^final_answer\s*:\s*.+\s*$", "", txt).strip()
            txt = f"{txt_wo}\n\n{last}"
        state["parsed_final_answer"] = _parse_final_answer(txt, enabled=True)
    else:
        # strip any lingering final_answer lines (paranoia)
        txt = _ensure_final_answer_line(txt, enabled=False)
        state["parsed_final_answer"] = None

    state["answer"] = txt.strip()
    return state

# ------------------------------- Router functions ------------------------------
def route_intake(state: AgentState) -> Literal["with_files","no_files"]:
    """Route based on presence of attachments (purely programmatic)."""
    attachment_urls = state.get("attachment_urls") or []  # safe default
    return "with_files" if attachment_urls else "no_files"

def has_images(state: AgentState) -> bool:
    for e in state.get("evidence", []):
        mime = (e.get("meta") or {}).get("mime", "")
        if str(mime).startswith("image"):
            return True
    return False

# ==== CHANGED: fix return type Literal to match actual branch key ====
def route_after_preprocess(state: AgentState) -> Literal["vision","text"]:
    return "vision" if has_images(state) else "text"

# ==== NEW: Browsing router ====
def needs_browsing(q: str) -> bool:
    q = (q or "").lower()
    hot = ["today","current","latest","price","How","who","where","what","How many",
           "2023","2024","2025","news","wins","Which",
           "http://","https://","wikipedia","youtube.com"]
    # Only browse if we *also* have a search key, so the sample runs without keys.
    return _has_search_key() and any(w in q for w in hot)

# ==== NEW: Decide browse node ====
def decide_browse_node(state: AgentState) -> AgentState:
    print("enter decide_browse_node")
    q = state.get("question", "")
    urls = _extract_urls(q)
    yt_urls = [u for u in urls if _is_youtube(u)]

    # Save for later stages
    state["question_urls"] = urls
    state["question_youtube_urls"] = yt_urls

    # Browse if:
    #  - we have any YouTube links in the question (can handle w/o search key), OR
    #  - the normal heuristic says we should browse (requires a search key)
    state["use_browsing"] = bool(yt_urls) or needs_browsing(q)
    return state


def route_browse(state: AgentState) -> Literal["browse","skip"]:
    return "browse" if state.get("use_browsing") else "skip"

# ==== NEW: Search node ====
def search_node(state: AgentState) -> AgentState:
    print("enter search_node")
    q = state.get("question","")

    # Start with YouTube links found in the question
    preseed = [{"title": "(from question)", "url": u, "snippet": ""}
               for u in (state.get("question_youtube_urls") + state.get("question_urls") or [])]

    # Do a web search only if keys are configured
    hits = []
    if _has_search_key():
        hits = web_search.invoke({"query": q, "k": 6}) or []

    # Optionally seed Wikipedia for short queries
    if len(q.split()) <= 30:  #8
        wiki = wikipedia_lookup.invoke({"query": q, "sentences": 4})
        if (wiki.get("summary") or "").strip():
            state.setdefault("evidence", []).append({
                "kind": "doc_text",
                "text": wiki["summary"],
                "path": None,
                "meta": {"source": "wikipedia", "title": wiki.get("title",""),
                         "url": wiki.get("url",""), "mime":"text/plain"}
            })

    # Combine: question YouTube links first, then search hits
    state["web_hits"] = preseed + hits
    return state


def _is_youtube(u: str) -> bool:
    try:
        net = urlparse(u).netloc.lower()
        return ("youtube.com" in net) or ("youtu.be" in net)
    except Exception:
        return False

def crawl_node(state: AgentState) -> AgentState:
    print("enter crawl_node")
    ev = list(state.get("evidence", []))
    hits: List[Dict[str,str]] = state.get("web_hits", []) or []
    print("hits: ", hits)

    # choose top M distinct domains
    def _domain(u: str) -> str:
        try: return urlparse(u).netloc.lower().lstrip("www.")
        except: return ""

    seen_domains = set()
    picked = []
    for h in hits:
        u = h.get("url","")
        d = _domain(u)
        if not u or not d:
            continue
        if d in seen_domains:
            continue
        seen_domains.add(d)
        picked.append(h)
        if len(picked) >= 4:
            break

    print("picked: ", picked)

    # Fetch & extract
    for h in picked:
        u = h["url"]
        print("url: ", u)
        title = h.get("title","")
        # Special-case YouTube
        if _is_youtube(u):
            print("is_youtube? ", _is_youtube(u))
            cap = youtube_get_transcript.invoke({"url_or_id": u})
            print('cap: ', cap)
            if cap and not cap.startswith("[no captions"):
                ev.append({"kind":"doc_text","text":cap,"path":None,
                           "meta":{"source":"youtube","title": title, "url":u,"mime":"text/plain"}})
                continue
            # fallback: download+ASR (heavier)
            cap2 = youtube_transcribe_audio.invoke({"url": u, "model_size":"base"})
            ev.append({"kind":"audio_transcript","text":cap2,"path":None,
                       "meta":{"source":"youtube","title": title, "url":u,"mime":"audio"}})
            continue

        out = fetch_url_text.invoke({"url": u, "max_chars": 12000})
        text = out.get("text","") or ""
        page_title = out.get("title","") or title
        if not text:
            continue
        ev.append({
            "kind": "doc_text",
            "text": text,
            "path": None,
            "meta": {"source":"web", "title": page_title, "url": u, "mime":"text/html"}
        })

    state["evidence"] = ev
    return state

# ---------- Graph ----------
# Build graph function
def build_graph():
    g = StateGraph(AgentState)

    # ==== NEW: browsing nodes ====
    g.add_node("decide_browse", decide_browse_node)
    g.add_node("search", search_node)
    g.add_node("crawl", crawl_node)

    # Existing nodes
    g.add_node("check_attachment", check_attachment_node)
    g.add_node("fetch", fetch_node)
    g.add_node("preprocess", preprocess_node)
    g.add_node("solve_multimodal", solve_multimodal_node)
    g.add_node("solve_text_only", solve_text_only_node)
    g.add_node("validate", validate_format_node)

    # Start the edges
    g.add_edge(START, "decide_browse")

    # Browse or skip
    g.add_conditional_edges("decide_browse", route_browse, {
        "browse": "search",
        "skip": "check_attachment"
    })
    g.add_edge("search", "crawl")
    g.add_edge("crawl", "check_attachment")

    # Add conditional branching from check_attachment
    g.add_conditional_edges(
        "check_attachment",
        route_intake, # returns "with_files" or "no_files"
        {
            "with_files": "fetch",
            "no_files": "solve_text_only"
        }
    )

    # files branch
    g.add_edge("fetch", "preprocess")

    g.add_conditional_edges(
        "preprocess",
        route_after_preprocess,
        {
            "vision": "solve_multimodal",   # question + evidence + attach images
            "text": "solve_text_only",      # question + transcript/other text
        }
    )

    # both branches converge
    g.add_edge("solve_multimodal", "validate")
    g.add_edge("solve_text_only", "validate")
    g.add_edge("validate", END)

    # Compile the graph
    graph_complied = g.compile()
    return graph_complied


# test
if __name__ == "__main__":
    task_id = '0001'
    task_q = 'Who is the current president of France'
    # ==== CHANGED: make it a flat empty list (not `[[]]`)
    attachment_urls: List[str] = []
    sample: AgentState = {
        "task_id": task_id,
        "question": task_q,
        "attachment_urls": attachment_urls,  # from GAIA sample
        "local_files": [],
        "evidence": [],
        "answer": None,
        "parsed_final_answer": None,
        # Tip: set True to force a final_answer line for scoring
        "emit_final_answer": False,   # <<< pure output mode
        # new optional fields:
        "use_browsing": None,
        "web_hits": None,
        "question_urls": None,
        "question_youtube_urls": None
    }
    agent_GAIA = build_graph()
    out = agent_GAIA.invoke(sample)
    print("---------------------------")
    print(out["answer"])