"""GAIA Unit 4 agent: tool-calling loop via Groq, OpenAI, or Hugging Face Inference."""

from __future__ import annotations

import os
import time
from pathlib import Path
from typing import Any, Optional

from answer_normalize import normalize_answer
from inference_client_factory import inference_client_kwargs
from llm_backends import (
    chat_complete_openai,
    detect_llm_backend,
    groq_chat_model,
    hf_chat_model,
    make_openai_sdk_client,
    openai_chat_model,
)
from tools.media_tools import transcribe_audio
from tools.registry import TOOL_DEFINITIONS, deterministic_attempt, dispatch_tool

try:
    from huggingface_hub import InferenceClient
except ImportError:
    InferenceClient = None  # type: ignore

SYSTEM_PROMPT = """You solve GAIA benchmark questions for the Hugging Face Agents Course.

Hard rules:
- Call tools as needed (search, Wikipedia, fetch URL, Python, audio, image, Excel).
- Your final assistant message must contain ONLY the answer text required by the question — no labels like "FINAL ANSWER", no markdown fences, no extra sentences, no preamble.
- Never type fake tool calls such as <web_search>...</function>; the platform invokes tools for you. If you need search, emit a real tool call via the API, not XML-like text in the reply.
- When the user message includes an attachment path: for audio, a transcript may already be inlined — use it. For images (png/jpg), call analyze_image with that exact file_path. For .xlsx/.py use the appropriate tools with that path.
- Match the question's format exactly: comma-separated lists alphabetized when asked; numbers without commas/thousands separators and without $ or % unless the question asks; short strings without leading articles (a/the); city names spelled out as requested; algebraic chess notation when asked.
- If the question asks for a number (how many, highest number, etc.), reply with digits only — no words, no "Based on the video", no trailing period.
- If the question asks what someone said in a video, reply with the spoken line only (include punctuation as in the source), not "Character says …" and not the question text repeated.
- For English Wikipedia tasks, use wikipedia_* tools; for promotion dates, Featured Article logs, or table rows, use wikipedia_wikitext on the relevant page and read the wikitext.
- For YouTube URLs, use youtube_transcript first; if it fails, use web_search with the video title or URL before stopping.
- Never write meta-commentary in the final message (no "I cannot", "unfortunately", "the provided summary does not"). Keep calling tools until you have the fact.
- Never paste tool traces in the final message (no lines like wikipedia_search: or fetch_url:).
- Do not invent facts when tools return empty or ambiguous results.
"""


def _tool_char_cap(backend: str, *, shrink_pass: int = 0) -> int:
    if backend == "groq":
        # Free-tier Groq often rejects ~6k TPM per request; keep tool payloads small.
        base = int(os.environ.get("GAIA_GROQ_MAX_TOOL_CHARS", "1400"))
    elif backend == "openai":
        base = int(os.environ.get("GAIA_OPENAI_MAX_TOOL_CHARS", "12000"))
    else:
        base = int(os.environ.get("GAIA_MAX_TOOL_CHARS", "24000"))
    if shrink_pass > 0:
        base = max(280, base // (2**shrink_pass))
    return base


def _groq_context_budget() -> int:
    return int(os.environ.get("GAIA_GROQ_CONTEXT_CHARS", "12000"))


def _maybe_retryable_llm_error(exc: Exception) -> bool:
    es = str(exc).lower()
    return (
        "413" in es
        or "429" in es
        or "rate_limit" in es
        or "tokens per minute" in es
        or "tpm" in es
        or "too many tokens" in es
    )


def _truncate_tool_messages(
    messages: list[dict[str, Any]],
    backend: str,
    *,
    shrink_pass: int = 0,
) -> None:
    cap = _tool_char_cap(backend, shrink_pass=shrink_pass)
    for m in messages:
        if m.get("role") != "tool":
            continue
        c = m.get("content")
        if isinstance(c, str) and len(c) > cap:
            m["content"] = c[:cap] + "\n[truncated]"


def _groq_message_chars(m: dict[str, Any]) -> int:
    n = len(str(m.get("content") or ""))
    tc = m.get("tool_calls")
    if tc:
        n += len(str(tc))
    return n


def _drop_oldest_tool_round(messages: list[dict[str, Any]]) -> bool:
    """Remove the earliest assistant+tool_calls block and its tool replies."""
    i = 2
    while i < len(messages):
        if messages[i].get("role") == "assistant" and messages[i].get("tool_calls"):
            del messages[i]
            while i < len(messages) and messages[i].get("role") == "tool":
                del messages[i]
            return True
        i += 1
    return False


def _enforce_context_budget(messages: list[dict[str, Any]], backend: str) -> None:
    if backend != "groq":
        return
    budget = _groq_context_budget()
    for _ in range(40):
        total = sum(_groq_message_chars(m) for m in messages)
        if total <= budget:
            return
        if _drop_oldest_tool_round(messages):
            continue
        trimmed = False
        for m in messages[2:]:
            if m.get("role") != "tool":
                continue
            c = m.get("content")
            if isinstance(c, str) and len(c) > 400:
                m["content"] = c[: max(400, len(c) * 2 // 3)] + "\n[truncated]"
                trimmed = True
                break
        if not trimmed:
            break


class GaiaAgent:
    def __init__(
        self,
        *,
        hf_token: Optional[str] = None,
        text_model: Optional[str] = None,
        max_iterations: int = 12,
    ):
        self.hf_token = (
            hf_token
            or os.environ.get("HF_TOKEN")
            or os.environ.get("HUGGINGFACEHUB_API_TOKEN")
        )
        self.backend = detect_llm_backend()
        if self.backend == "groq":
            self.text_model = text_model or groq_chat_model()
            self._oa_client, _ = make_openai_sdk_client("groq")
            self._hf_client = None
        elif self.backend == "openai":
            self.text_model = text_model or openai_chat_model()
            self._oa_client, _ = make_openai_sdk_client("openai")
            self._hf_client = None
        else:
            self.text_model = text_model or hf_chat_model()
            self._oa_client = None
            self._hf_client: Optional[InferenceClient] = None

        self.max_iterations = max_iterations

    def _get_hf_client(self) -> InferenceClient:
        if InferenceClient is None:
            raise RuntimeError("huggingface_hub is not installed.")
        if self._hf_client is None:
            if not self.hf_token:
                raise RuntimeError(
                    "HF_TOKEN or HUGGINGFACEHUB_API_TOKEN is required when using "
                    "Hugging Face Inference (no GROQ_API_KEY / OPENAI_API_KEY set)."
                )
            kw = inference_client_kwargs(self.hf_token)
            self._hf_client = InferenceClient(**kw)
        return self._hf_client

    def _chat_round(
        self,
        messages: list[dict[str, Any]],
        *,
        shrink_pass: int = 0,
    ) -> Any:
        _truncate_tool_messages(messages, self.backend, shrink_pass=shrink_pass)
        _enforce_context_budget(messages, self.backend)
        if self.backend in ("groq", "openai"):
            assert self._oa_client is not None
            mt = (
                int(os.environ.get("GAIA_GROQ_MAX_TOKENS", "384"))
                if self.backend == "groq"
                else int(os.environ.get("GAIA_OPENAI_MAX_TOKENS", "768"))
            )
            return chat_complete_openai(
                self._oa_client,
                model=self.text_model,
                messages=messages,
                tools=TOOL_DEFINITIONS,
                max_tokens=mt,
                temperature=0.15,
            )
        client = self._get_hf_client()
        return client.chat_completion(
            messages=messages,
            model=self.text_model,
            tools=TOOL_DEFINITIONS,
            tool_choice="auto",
            max_tokens=1024,
            temperature=0.15,
        )

    def __call__(
        self,
        question: str,
        attachment_path: Optional[str] = None,
        task_id: Optional[str] = None,
    ) -> str:
        det = deterministic_attempt(question, attachment_path, task_id=task_id)
        if det is not None:
            return normalize_answer(det)

        if self.backend == "hf" and not self.hf_token:
            return normalize_answer("", context_question=question)

        user_text = _build_user_payload(question, attachment_path, task_id)
        user_text += _maybe_inline_audio_transcript(
            attachment_path, self.hf_token, backend=self.backend
        )

        messages: list[dict[str, Any]] = [
            {"role": "system", "content": SYSTEM_PROMPT},
            {"role": "user", "content": user_text},
        ]

        last_text = ""
        # Extra delays so Groq free-tier TPM / oversized-request errors can retry after shrink.
        retry_delays = (2.0, 4.0, 8.0, 14.0, 22.0)

        for _ in range(self.max_iterations):
            completion = None
            shrink_pass = 0
            for attempt in range(len(retry_delays) + 1):
                try:
                    completion = self._chat_round(messages, shrink_pass=shrink_pass)
                    break
                except Exception as e:
                    es = str(e)
                    if "402" in es or "Payment Required" in es or "depleted" in es.lower():
                        # Do not submit error prose as an answer (exact-match grading).
                        return normalize_answer("", context_question=question)
                    if attempt < len(retry_delays) and _maybe_retryable_llm_error(e):
                        shrink_pass = attempt + 1
                        time.sleep(retry_delays[attempt])
                        continue
                    if "402" in str(e) or "payment required" in str(e).lower():
                        return normalize_answer("", context_question=question)
                    if _maybe_retryable_llm_error(e):
                        return normalize_answer("", context_question=question)
                    return normalize_answer(
                        f"Inference error: {e}", context_question=question
                    )

            msg = completion.choices[0].message
            last_text = (msg.content or "").strip()
            tool_calls = getattr(msg, "tool_calls", None)

            if tool_calls:
                cap = _tool_char_cap(self.backend, shrink_pass=0)
                messages.append(
                    {
                        "role": "assistant",
                        "content": msg.content if msg.content else None,
                        "tool_calls": [
                            {
                                "id": tc.id,
                                "type": "function",
                                "function": {
                                    "name": tc.function.name,
                                    "arguments": tc.function.arguments or "{}",
                                },
                            }
                            for tc in tool_calls
                        ],
                    }
                )
                for tc in tool_calls:
                    name = tc.function.name
                    args = tc.function.arguments or "{}"
                    result = dispatch_tool(name, args, hf_token=self.hf_token)
                    if isinstance(result, str) and len(result) > cap:
                        result = result[:cap] + "\n[truncated]"
                    messages.append(
                        {
                            "role": "tool",
                            "tool_call_id": tc.id,
                            "content": result,
                        }
                    )
                continue

            if last_text:
                break

            fr = getattr(completion.choices[0], "finish_reason", None)
            if fr == "length":
                last_text = "Error: model hit max length without an answer."
                break

        return normalize_answer(last_text or "", context_question=question)


def _build_user_payload(
    question: str,
    attachment_path: Optional[str],
    task_id: Optional[str],
) -> str:
    parts = []
    if task_id:
        parts.append(f"task_id: {task_id}")
    parts.append(f"Question:\n{question.strip()}")
    if attachment_path:
        p = Path(attachment_path)
        parts.append(
            f"\nAttachment path (pass this exact string to tools): {attachment_path}"
        )
        if p.is_file():
            parts.append(f"Attachment exists on disk: yes ({p.name})")
        else:
            parts.append("Attachment exists on disk: NO — report that you cannot read it.")
    else:
        parts.append("\nNo attachment.")
    return "\n".join(parts)


def _maybe_inline_audio_transcript(
    attachment_path: Optional[str],
    hf_token: Optional[str],
    *,
    backend: str = "hf",
) -> str:
    if not attachment_path:
        return ""
    p = Path(attachment_path)
    if not p.is_file():
        return ""
    ext = p.suffix.lower()
    if ext not in (".mp3", ".wav", ".m4a", ".ogg", ".flac", ".webm"):
        return ""
    tx = transcribe_audio(str(p), hf_token=hf_token)
    if not tx or tx.lower().startswith(("error", "asr error")):
        return f"\n\n[Automatic transcription failed: {tx[:500]}]\n"
    cap = int(os.environ.get("GAIA_AUTO_TRANSCRIPT_CHARS", "8000"))
    if backend == "groq":
        cap = min(
            cap,
            int(os.environ.get("GAIA_GROQ_AUTO_TRANSCRIPT_CHARS", "3600")),
        )
    return f"\n\n[Audio transcript — use for your answer]\n{tx[:cap]}\n"