"""Resumable local CLI for the Agents Course evaluation and submission API."""

from __future__ import annotations

import argparse
import hashlib
import importlib
import json
import os
import re
import shutil
import sys
from dataclasses import dataclass
from datetime import UTC, datetime
from pathlib import Path
from typing import Any, Iterable

import requests

from agent_system import AgentConfigurationError, AgentSettings, LocalAgentSystem
from attachment_processing import AttachmentProcessingError, AttachmentProcessor


PROJECT_ROOT = Path(__file__).resolve().parent
DEFAULT_API_URL = "https://agents-course-unit4-scoring.hf.space"
DEFAULT_SPACE_ID = "BmanClark/Agents_Course_final"
DEFAULT_GAIA_REPO_ID = "gaia-benchmark/GAIA"
DEFAULT_GAIA_DATA_DIR = "2023/validation"
MAX_ATTACHMENT_BYTES = 100 * 1024 * 1024


class EvaluationError(RuntimeError):
    """Raised for invalid API responses, cache data, or submission state."""


@dataclass(frozen=True)
class RunnerSettings:
    api_url: str
    username: str
    space_id: str
    local_dir: Path
    gaia_repo_id: str
    gaia_data_dir: str

    @classmethod
    def from_env(cls) -> "RunnerSettings":
        return cls(
            api_url=os.getenv("EVALUATION_API_URL", DEFAULT_API_URL).rstrip("/"),
            username=os.getenv("HF_USERNAME", "").strip(),
            space_id=os.getenv("SPACE_ID", DEFAULT_SPACE_ID).strip(),
            local_dir=Path(
                os.getenv("LOCAL_DATA_DIR", str(PROJECT_ROOT / ".local"))
            ).resolve(),
            gaia_repo_id=os.getenv(
                "GAIA_DATASET_REPO", DEFAULT_GAIA_REPO_ID
            ).strip(),
            gaia_data_dir=os.getenv(
                "GAIA_DATASET_DIR", DEFAULT_GAIA_DATA_DIR
            ).strip("/"),
        )

    @property
    def agent_code_url(self) -> str:
        if "/" not in self.space_id:
            raise EvaluationError(
                "SPACE_ID must use the form username/space-name."
            )
        return f"https://huggingface.co/spaces/{self.space_id}/tree/main"


class EvaluationClient:
    def __init__(self, settings: RunnerSettings) -> None:
        self.settings = settings
        self.session = requests.Session()
        self.session.headers.update(
            {"User-Agent": "BmanClark-agents-course-local-runner/1.0"}
        )

    def questions(self, random_only: bool = False) -> list[dict[str, Any]]:
        endpoint = "random-question" if random_only else "questions"
        try:
            response = self.session.get(
                f"{self.settings.api_url}/{endpoint}", timeout=30
            )
            response.raise_for_status()
            data = response.json()
        except (requests.RequestException, ValueError) as exc:
            raise EvaluationError(f"Could not fetch {endpoint}: {exc}") from exc

        if isinstance(data, dict):
            data = [data]
        if not isinstance(data, list) or not data:
            raise EvaluationError(f"The {endpoint} endpoint returned no tasks.")
        for item in data:
            if not isinstance(item, dict) or not item.get("task_id") or not item.get(
                "question"
            ):
                raise EvaluationError(f"Malformed question record: {item!r}")
        return data

    def download_attachment(self, question: dict[str, Any]) -> Path | None:
        file_name = str(question.get("file_name") or "").strip()
        if not file_name:
            return None

        task_id = safe_component(str(question["task_id"]))
        destination_dir = self.settings.local_dir / "attachments" / task_id
        destination_dir.mkdir(parents=True, exist_ok=True)
        destination = destination_dir / safe_filename(file_name)
        if destination.is_file() and destination.stat().st_size > 0:
            return destination

        partial = destination.with_suffix(destination.suffix + ".part")
        total = 0
        try:
            with self.session.get(
                f"{self.settings.api_url}/files/{question['task_id']}",
                timeout=120,
                stream=True,
            ) as response:
                response.raise_for_status()
                declared_size = int(response.headers.get("content-length", "0") or 0)
                if declared_size > MAX_ATTACHMENT_BYTES:
                    raise EvaluationError(
                        f"Attachment {file_name} exceeds the 100 MB safety limit."
                    )
                with partial.open("wb") as handle:
                    for chunk in response.iter_content(chunk_size=1024 * 1024):
                        if not chunk:
                            continue
                        total += len(chunk)
                        if total > MAX_ATTACHMENT_BYTES:
                            raise EvaluationError(
                                f"Attachment {file_name} exceeds the 100 MB safety limit."
                            )
                        handle.write(chunk)
            partial.replace(destination)
        except requests.HTTPError as exc:
            partial.unlink(missing_ok=True)
            if exc.response is not None and exc.response.status_code == 404:
                return self._download_gaia_attachment(file_name, destination)
            raise EvaluationError(f"Could not download {file_name}: {exc}") from exc
        except (requests.RequestException, OSError, ValueError) as exc:
            partial.unlink(missing_ok=True)
            raise EvaluationError(f"Could not download {file_name}: {exc}") from exc
        except EvaluationError:
            partial.unlink(missing_ok=True)
            raise
        return destination

    def _download_gaia_attachment(self, file_name: str, destination: Path) -> Path:
        """Fall back to the official gated GAIA repository after a service 404."""

        try:
            from huggingface_hub import hf_hub_download
        except ImportError as exc:
            raise EvaluationError(
                "The course file endpoint returned 404 and huggingface_hub is not "
                "installed for the official GAIA fallback."
            ) from exc

        repository_path = f"{self.settings.gaia_data_dir}/{safe_filename(file_name)}"
        fallback_dir = self.settings.local_dir / "hf-downloads"
        try:
            downloaded = Path(
                hf_hub_download(
                    repo_id=self.settings.gaia_repo_id,
                    filename=repository_path,
                    repo_type="dataset",
                    local_dir=fallback_dir,
                )
            )
            if downloaded.stat().st_size > MAX_ATTACHMENT_BYTES:
                raise EvaluationError(
                    f"Attachment {file_name} exceeds the 100 MB safety limit."
                )
            destination.parent.mkdir(parents=True, exist_ok=True)
            shutil.copyfile(downloaded, destination)
        except EvaluationError:
            raise
        except Exception as exc:
            raise EvaluationError(
                "The course file endpoint returned 404 and the official gated GAIA "
                "fallback could not download the attachment. Accept access at "
                "https://huggingface.co/datasets/gaia-benchmark/GAIA, then run "
                r".\.venv\Scripts\hf.exe auth login. "
                f"Underlying error: {exc}"
            ) from exc
        return destination

    def submit(self, answers: list[dict[str, str]]) -> dict[str, Any]:
        if not self.settings.username:
            raise EvaluationError(
                "HF_USERNAME is required for submission. Set it in the shell first."
            )
        payload = {
            "username": self.settings.username,
            "agent_code": self.settings.agent_code_url,
            "answers": answers,
        }
        try:
            response = self.session.post(
                f"{self.settings.api_url}/submit", json=payload, timeout=120
            )
            response.raise_for_status()
            result = response.json()
        except requests.HTTPError as exc:
            detail = exc.response.text[:1_000] if exc.response is not None else str(exc)
            raise EvaluationError(f"Submission was rejected: {detail}") from exc
        except (requests.RequestException, ValueError) as exc:
            raise EvaluationError(f"Submission failed: {exc}") from exc
        if not isinstance(result, dict):
            raise EvaluationError("Submission response was not a JSON object.")
        return result


class AnswerCache:
    """Private, atomic local cache keyed by evaluation task ID."""

    VERSION = 1

    def __init__(self, path: Path) -> None:
        self.path = path
        self.data: dict[str, Any] = {"version": self.VERSION, "answers": {}}
        self.load()

    def load(self) -> None:
        if not self.path.exists():
            return
        try:
            data = json.loads(self.path.read_text(encoding="utf-8"))
        except (OSError, ValueError) as exc:
            raise EvaluationError(f"Could not read answer cache {self.path}: {exc}") from exc
        if data.get("version") != self.VERSION or not isinstance(
            data.get("answers"), dict
        ):
            raise EvaluationError(
                f"Unsupported or malformed answer cache: {self.path}"
            )
        self.data = data

    def get_valid(self, question: dict[str, Any]) -> str | None:
        entry = self.data["answers"].get(str(question["task_id"]))
        if not isinstance(entry, dict):
            return None
        if entry.get("question_sha256") != question_digest(str(question["question"])):
            return None
        answer = entry.get("answer")
        return answer if isinstance(answer, str) and answer.strip() else None

    def record(
        self,
        question: dict[str, Any],
        answer: str,
        agent_signature: str,
        attachment_name: str | None,
    ) -> None:
        self.data["answers"][str(question["task_id"])] = {
            "answer": answer,
            "question_sha256": question_digest(str(question["question"])),
            "agent_signature": agent_signature,
            "attachment_name": attachment_name,
            "completed_at": datetime.now(UTC).isoformat(),
        }
        self.save()

    def save(self) -> None:
        self.path.parent.mkdir(parents=True, exist_ok=True)
        temporary = self.path.with_suffix(self.path.suffix + ".tmp")
        temporary.write_text(
            json.dumps(self.data, indent=2, ensure_ascii=False) + "\n",
            encoding="utf-8",
        )
        temporary.replace(self.path)


def question_digest(question: str) -> str:
    return hashlib.sha256(question.encode("utf-8")).hexdigest()


def safe_component(value: str) -> str:
    cleaned = re.sub(r"[^A-Za-z0-9._-]", "_", value)
    if not cleaned or cleaned in {".", ".."}:
        raise EvaluationError(f"Unsafe path component: {value!r}")
    return cleaned


def safe_filename(value: str) -> str:
    name = Path(value.replace("\\", "/")).name
    return safe_component(name)


def build_parser() -> argparse.ArgumentParser:
    parser = argparse.ArgumentParser(
        description="Run and submit the Hugging Face Agents Course evaluation locally."
    )
    commands = parser.add_subparsers(dest="command", required=True)
    commands.add_parser("check", help="Check dependencies, Ollama, and local models.")
    commands.add_parser("test", help="Solve and cache one random evaluation task.")

    run = commands.add_parser("run", help="Solve and cache evaluation tasks.")
    run.add_argument("--task-id", action="append", help="Only run this task ID.")
    run.add_argument("--limit", type=int, help="Run at most this many selected tasks.")
    run.add_argument("--force", action="store_true", help="Ignore valid cached answers.")

    commands.add_parser("status", help="Show cache coverage without displaying answers.")
    submit = commands.add_parser("submit", help="Submit all valid cached answers.")
    submit.add_argument(
        "--yes", action="store_true", help="Skip the interactive SUBMIT confirmation."
    )
    return parser


def check_environment() -> None:
    required_modules = [
        "av",
        "requests",
        "smolagents",
        "litellm",
        "openpyxl",
        "faster_whisper",
    ]
    missing = []
    for module in required_modules:
        try:
            importlib.import_module(module)
        except ImportError:
            missing.append(module)
    if missing:
        raise EvaluationError(
            "Missing Python modules: "
            + ", ".join(missing)
            + ". Run: python -m pip install -r requirements.txt"
        )
    models = LocalAgentSystem.check_ollama(AgentSettings.from_env())
    print(f"Ollama is reachable; {len(models)} local model(s) found.")
    print("Required text and multimodal models are installed.")


def selected_questions(
    questions: Iterable[dict[str, Any]], task_ids: list[str] | None, limit: int | None
) -> list[dict[str, Any]]:
    selected = list(questions)
    if task_ids:
        wanted = set(task_ids)
        selected = [q for q in selected if str(q["task_id"]) in wanted]
        found = {str(q["task_id"]) for q in selected}
        missing = sorted(wanted - found)
        if missing:
            raise EvaluationError("Unknown task ID(s): " + ", ".join(missing))
    if limit is not None:
        if limit < 1:
            raise EvaluationError("--limit must be at least 1.")
        selected = selected[:limit]
    return selected


def solve_tasks(
    questions: list[dict[str, Any]],
    client: EvaluationClient,
    cache: AnswerCache,
    force: bool,
) -> int:
    agent: LocalAgentSystem | None = None
    processor = AttachmentProcessor()
    failures = 0
    for index, question in enumerate(questions, start=1):
        task_id = str(question["task_id"])
        cached = cache.get_valid(question)
        if cached is not None and not force:
            print(f"[{index}/{len(questions)}] {task_id}: cached; skipping")
            continue
        print(f"[{index}/{len(questions)}] {task_id}: solving")
        try:
            attachment = client.download_attachment(question)
            evidence = processor.process(attachment, str(question["question"]))
            if agent is None:
                LocalAgentSystem.check_ollama(AgentSettings.from_env())
                agent = LocalAgentSystem()
            answer = agent.solve(task_id, str(question["question"]), evidence)
            cache.record(
                question,
                answer,
                agent.signature,
                attachment.name if attachment else None,
            )
            print(f"[{index}/{len(questions)}] {task_id}: answer cached: {answer}")
        except (
            AgentConfigurationError,
            AttachmentProcessingError,
            EvaluationError,
            ValueError,
        ) as exc:
            failures += 1
            print(f"[{index}/{len(questions)}] {task_id}: ERROR: {exc}", file=sys.stderr)
    return failures


def print_status(questions: list[dict[str, Any]], cache: AnswerCache) -> int:
    complete = sum(cache.get_valid(question) is not None for question in questions)
    print(f"Valid cached answers: {complete}/{len(questions)}")
    for question in questions:
        state = "ready" if cache.get_valid(question) is not None else "missing"
        attachment = str(question.get("file_name") or "none")
        print(f"  {question['task_id']}: {state}; attachment={attachment}")
    return complete


def submit_cached(
    questions: list[dict[str, Any]],
    client: EvaluationClient,
    cache: AnswerCache,
    assume_yes: bool,
) -> None:
    answers = []
    missing = []
    for question in questions:
        answer = cache.get_valid(question)
        if answer is None:
            missing.append(str(question["task_id"]))
        else:
            answers.append(
                {"task_id": str(question["task_id"]), "submitted_answer": answer}
            )
    if missing:
        raise EvaluationError(
            f"Refusing a partial submission: {len(missing)} task(s) are missing."
        )

    print(f"Username: {client.settings.username or '<not set>'}")
    print(f"Agent code: {client.settings.agent_code_url}")
    print(f"Answers ready: {len(answers)}")
    if not assume_yes:
        confirmation = input("Type SUBMIT to send these answers for scoring: ").strip()
        if confirmation != "SUBMIT":
            print("Submission cancelled.")
            return

    result = client.submit(answers)
    submission_dir = client.settings.local_dir / "submissions"
    submission_dir.mkdir(parents=True, exist_ok=True)
    timestamp = datetime.now(UTC).strftime("%Y%m%dT%H%M%SZ")
    (submission_dir / f"{timestamp}.json").write_text(
        json.dumps(result, indent=2, ensure_ascii=False) + "\n", encoding="utf-8"
    )
    print(
        "Submission successful: "
        f"{result.get('score', 'N/A')}% "
        f"({result.get('correct_count', '?')}/{result.get('total_attempted', '?')})"
    )
    if result.get("message"):
        print(result["message"])


def main(argv: list[str] | None = None) -> int:
    args = build_parser().parse_args(argv)
    settings = RunnerSettings.from_env()
    client = EvaluationClient(settings)
    cache = AnswerCache(settings.local_dir / "answers.json")

    try:
        if args.command == "check":
            check_environment()
            return 0

        if args.command == "test":
            questions = client.questions(random_only=True)
            return 1 if solve_tasks(questions, client, cache, force=True) else 0

        questions = client.questions()
        if args.command == "status":
            print_status(questions, cache)
            return 0
        if args.command == "run":
            chosen = selected_questions(questions, args.task_id, args.limit)
            return 1 if solve_tasks(chosen, client, cache, args.force) else 0
        if args.command == "submit":
            submit_cached(questions, client, cache, args.yes)
            return 0
    except (AgentConfigurationError, EvaluationError) as exc:
        print(f"Error: {exc}", file=sys.stderr)
        return 2

    raise AssertionError(f"Unhandled command: {args.command}")