# SPDX-License-Identifier: AGPL-3.0-only
# Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0

"""
Datasets API routes
"""

import base64
import io
import json
import sys
from pathlib import Path
from uuid import uuid4
from fastapi import APIRouter, Depends, HTTPException, UploadFile
import structlog
from loggers import get_logger

# Add backend directory to path
backend_path = Path(__file__).parent.parent.parent
if str(backend_path) not in sys.path:
    sys.path.insert(0, str(backend_path))

# Import dataset utilities
from utils.datasets import check_dataset_format
from auth.authentication import get_current_subject

router = APIRouter()
logger = get_logger(__name__)


from models.datasets import (
    AiAssistMappingRequest,
    AiAssistMappingResponse,
    CheckFormatRequest,
    CheckFormatResponse,
    LocalDatasetItem,
    LocalDatasetsResponse,
    UploadDatasetResponse,
)
from utils.paths import (
    dataset_uploads_root,
    ensure_dir,
    recipe_datasets_root,
    resolve_dataset_path,
)


def _serialize_preview_value(value):
    """make it json safe for client preview ⊂(◉‿◉)つ"""
    if value is None or isinstance(value, (str, int, float, bool)):
        return value

    try:
        from PIL.Image import Image as PILImage

        if isinstance(value, PILImage):
            buffer = io.BytesIO()
            value.convert("RGB").save(buffer, format = "JPEG", quality = 85)
            return {
                "type": "image",
                "mime": "image/jpeg",
                "width": value.width,
                "height": value.height,
                "data": base64.b64encode(buffer.getvalue()).decode("ascii"),
            }
    except Exception:
        pass

    if isinstance(value, dict):
        return {str(key): _serialize_preview_value(item) for key, item in value.items()}

    if isinstance(value, (list, tuple)):
        return [_serialize_preview_value(item) for item in value]

    return str(value)


def _serialize_preview_rows(rows):
    return [
        {str(key): _serialize_preview_value(value) for key, value in dict(row).items()}
        for row in rows
    ]


# --- Endpoints ---

# Recognized data-file extensions for the single-file fallback approach.
# Tabular formats are preferred over archives for Tier 1 preview because
# archives (e.g. images.zip) may be loaded as ImageFolder datasets with
# synthetic columns (image/label) that don't match the real dataset schema.
_TABULAR_EXTS = (".parquet", ".json", ".jsonl", ".csv", ".tsv", ".arrow")
_ARCHIVE_EXTS = (".tar", ".tar.gz", ".tgz", ".gz", ".zst", ".zip", ".txt")
DATA_EXTS = _TABULAR_EXTS + _ARCHIVE_EXTS
LOCAL_FILE_EXTS = (".json", ".jsonl", ".csv", ".parquet")
LOCAL_UPLOAD_EXTS = {".csv", ".json", ".jsonl", ".parquet"}
LOCAL_DATASETS_ROOT = recipe_datasets_root()
DATASET_UPLOAD_DIR = dataset_uploads_root()


def _safe_read_metadata(path: Path) -> dict | None:
    try:
        payload = json.loads(path.read_text(encoding = "utf-8"))
    except (OSError, ValueError, TypeError):
        return None
    if not isinstance(payload, dict):
        return None
    return payload


def _safe_read_rows_from_metadata(payload: dict | None) -> int | None:
    if not payload:
        return None
    for key in ("actual_num_records", "target_num_records"):
        value = payload.get(key)
        if isinstance(value, int):
            return value
    return None


def _safe_read_metadata_summary(payload: dict | None) -> dict | None:
    if not payload:
        return None

    actual_num_records = (
        payload.get("actual_num_records")
        if isinstance(payload.get("actual_num_records"), int)
        else None
    )
    target_num_records = (
        payload.get("target_num_records")
        if isinstance(payload.get("target_num_records"), int)
        else actual_num_records
    )

    columns: list[str] | None = None
    schema = payload.get("schema")
    if isinstance(schema, dict):
        columns = [str(key) for key in schema.keys()]
    if not columns:
        stats = payload.get("column_statistics")
        if isinstance(stats, list):
            derived = [
                str(item.get("column_name"))
                for item in stats
                if isinstance(item, dict) and item.get("column_name")
            ]
            columns = derived or None

    parquet_files_count = None
    file_paths = payload.get("file_paths")
    if isinstance(file_paths, dict):
        parquet_files = file_paths.get("parquet-files")
        if isinstance(parquet_files, list):
            parquet_files_count = len(parquet_files)

    total_num_batches = (
        payload.get("total_num_batches")
        if isinstance(payload.get("total_num_batches"), int)
        else parquet_files_count
    )
    num_completed_batches = (
        payload.get("num_completed_batches")
        if isinstance(payload.get("num_completed_batches"), int)
        else total_num_batches
    )

    return {
        "actual_num_records": actual_num_records,
        "target_num_records": target_num_records,
        "total_num_batches": total_num_batches,
        "num_completed_batches": num_completed_batches,
        "columns": columns,
    }


def _build_local_dataset_items() -> list[LocalDatasetItem]:
    if not LOCAL_DATASETS_ROOT.exists():
        return []

    items: list[LocalDatasetItem] = []
    for entry in LOCAL_DATASETS_ROOT.iterdir():
        if not entry.is_dir() or not entry.name.startswith("recipe_"):
            continue
        parquet_dir = entry / "parquet-files"
        if not parquet_dir.exists() or not any(parquet_dir.glob("*.parquet")):
            continue

        rows = None
        metadata_summary = None
        metadata_path = entry / "metadata.json"
        if metadata_path.exists():
            metadata_payload = _safe_read_metadata(metadata_path)
            rows = _safe_read_rows_from_metadata(metadata_payload)
            metadata_summary = _safe_read_metadata_summary(metadata_payload)

        try:
            updated_at = entry.stat().st_mtime
        except OSError:
            updated_at = None

        items.append(
            LocalDatasetItem(
                id = entry.name,
                label = entry.name,
                path = str(parquet_dir.resolve()),
                rows = rows,
                updated_at = updated_at,
                metadata = metadata_summary,
            )
        )

    items.sort(key = lambda item: item.updated_at or 0, reverse = True)
    return items


def _load_local_preview_slice(
    *, dataset_path: Path, train_split: str, preview_size: int
):
    from datasets import load_dataset

    if dataset_path.is_dir():
        parquet_dir = (
            dataset_path / "parquet-files"
            if (dataset_path / "parquet-files").exists()
            else dataset_path
        )
        parquet_files = sorted(parquet_dir.glob("*.parquet"))
        if parquet_files:
            dataset = load_dataset(
                "parquet",
                data_files = [str(path) for path in parquet_files],
                split = train_split,
            )
            total_rows = len(dataset)
            preview_slice = dataset.select(range(min(preview_size, total_rows)))
            return preview_slice, total_rows
        else:
            candidate_files: list[Path] = []
            for ext in LOCAL_FILE_EXTS:
                candidate_files.extend(sorted(dataset_path.glob(f"*{ext}")))
            if not candidate_files:
                raise HTTPException(
                    status_code = 400,
                    detail = "Unsupported local dataset directory (expected parquet/json/jsonl/csv files)",
                )
            dataset_path = candidate_files[0]

    if dataset_path.suffix in [".json", ".jsonl"]:
        dataset = load_dataset("json", data_files = str(dataset_path), split = train_split)
    elif dataset_path.suffix == ".csv":
        dataset = load_dataset("csv", data_files = str(dataset_path), split = train_split)
    elif dataset_path.suffix == ".parquet":
        dataset = load_dataset(
            "parquet", data_files = str(dataset_path), split = train_split
        )
    else:
        raise HTTPException(
            status_code = 400, detail = f"Unsupported file format: {dataset_path.suffix}"
        )

    total_rows = len(dataset)
    preview_slice = dataset.select(range(min(preview_size, total_rows)))
    return preview_slice, total_rows


def _sanitize_filename(filename: str) -> str:
    name = Path(filename).name.strip().replace("\x00", "")
    if not name:
        return "dataset_upload"
    return name


@router.post("/upload", response_model = UploadDatasetResponse)
async def upload_dataset(
    file: UploadFile,
    current_subject: str = Depends(get_current_subject),
) -> UploadDatasetResponse:
    filename = _sanitize_filename(file.filename or "dataset_upload")
    ext = Path(filename).suffix.lower()
    if ext not in LOCAL_UPLOAD_EXTS:
        allowed = ", ".join(sorted(LOCAL_UPLOAD_EXTS))
        raise HTTPException(
            status_code = 400,
            detail = f"Unsupported file type: {ext}. Allowed: {allowed}",
        )

    ensure_dir(DATASET_UPLOAD_DIR)
    stem = Path(filename).stem
    stored_name = f"{uuid4().hex}_{stem}{ext}"
    stored_path = DATASET_UPLOAD_DIR / stored_name

    # Stream file to disk in chunks to avoid holding entire file in memory
    with open(stored_path, "wb") as f:
        while chunk := await file.read(1024 * 1024):
            f.write(chunk)

    if stored_path.stat().st_size == 0:
        stored_path.unlink(missing_ok = True)
        raise HTTPException(status_code = 400, detail = "Empty upload payload")

    return UploadDatasetResponse(filename = filename, stored_path = str(stored_path))


@router.get("/local", response_model = LocalDatasetsResponse)
def list_local_datasets(
    current_subject: str = Depends(get_current_subject),
) -> LocalDatasetsResponse:
    return LocalDatasetsResponse(datasets = _build_local_dataset_items())


@router.post("/check-format", response_model = CheckFormatResponse)
def check_format(
    request: CheckFormatRequest,
    current_subject: str = Depends(get_current_subject),
):
    """
    Check if a dataset requires manual column mapping.

    Strategy for HuggingFace datasets:
      1. list_repo_files → pick the first data file → load_dataset(data_files=[…])
         Avoids resolving thousands of files; typically ~2-4 s.
      2. Full streaming load_dataset as a last-resort fallback.

    Local files are loaded directly.

    Using a plain `def` (not async) so FastAPI runs this in a thread-pool,
    preventing any blocking IO from freezing the event loop.
    """
    try:
        from itertools import islice
        from datasets import Dataset, load_dataset
        from utils.datasets import format_dataset

        PREVIEW_SIZE = 10

        logger.info(f"Checking format for dataset: {request.dataset_name}")

        dataset_path = resolve_dataset_path(request.dataset_name)
        total_rows = None

        if dataset_path.exists():
            # ── Local file ──────────────────────────────────────────
            train_split = request.train_split or "train"
            preview_slice, total_rows = _load_local_preview_slice(
                dataset_path = dataset_path,
                train_split = train_split,
                preview_size = PREVIEW_SIZE,
            )
        else:
            # ── HuggingFace dataset ─────────────────────────────────
            # Tier 1: list_repo_files → load only the first data file
            preview_slice = None

            try:
                from huggingface_hub import HfApi

                api = HfApi()
                repo_files = api.list_repo_files(
                    request.dataset_name,
                    repo_type = "dataset",
                    token = request.hf_token or None,
                )
                data_files = [
                    f for f in repo_files if any(f.endswith(ext) for ext in DATA_EXTS)
                ]

                # Prefer tabular formats over archives (e.g. images.zip → ImageFolder
                # with synthetic image/label columns that don't match the real schema).
                tabular_files = [
                    f
                    for f in data_files
                    if any(f.endswith(ext) for ext in _TABULAR_EXTS)
                ]
                candidates = tabular_files or data_files

                # When a subset is specified, narrow to files whose name matches
                # (e.g. subset="testmini" → prefer "testmini.parquet").
                if request.subset and candidates:
                    subset_matches = [
                        f for f in candidates if request.subset in Path(f).stem
                    ]
                    if subset_matches:
                        candidates = subset_matches

                if candidates:
                    first_file = candidates[0]
                    logger.info(f"Tier 1: loading single file {first_file}")
                    load_kwargs = {
                        "path": request.dataset_name,
                        "data_files": [first_file],
                        "split": "train",
                        "streaming": True,
                    }
                    if request.hf_token:
                        load_kwargs["token"] = request.hf_token

                    streamed_ds = load_dataset(**load_kwargs)
                    rows = list(islice(streamed_ds, PREVIEW_SIZE))
                    if rows:
                        preview_slice = Dataset.from_list(rows)
            except Exception as e:
                logger.warning(f"Tier 1 (single-file) failed: {e}")

            if preview_slice is None:
                # Tier 2: full streaming (resolves all files — slow for large repos)
                logger.info("Tier 2: falling back to full streaming load_dataset")
                load_kwargs = {
                    "path": request.dataset_name,
                    "split": request.train_split,
                    "streaming": True,
                }
                if request.subset:
                    load_kwargs["name"] = request.subset
                if request.hf_token:
                    load_kwargs["token"] = request.hf_token

                streamed_ds = load_dataset(**load_kwargs)

                rows = list(islice(streamed_ds, PREVIEW_SIZE))
                if not rows:
                    raise HTTPException(
                        status_code = 400,
                        detail = "Dataset appears to be empty or could not be streamed",
                    )

                preview_slice = Dataset.from_list(rows)
            total_rows = None

        # Run lightweight format check on the preview slice
        result = check_dataset_format(preview_slice, is_vlm = request.is_vlm)

        logger.info(
            f"Format check result: requires_mapping={result['requires_manual_mapping']}, format={result['detected_format']}, is_image={result.get('is_image', False)}"
        )

        # Generate preview samples
        preview_samples = None
        if not result["requires_manual_mapping"]:
            if result.get("suggested_mapping"):
                # Heuristic-detected: show raw data so columns match the API response.
                # Processing (column stripping) happens at training time, not preview.
                preview_samples = _serialize_preview_rows(preview_slice)
            else:
                try:
                    format_result = format_dataset(
                        preview_slice,
                        format_type = "auto",
                        num_proc = 1,  # Only 10 preview rows — no need for multiprocessing
                    )
                    processed = format_result["dataset"]
                    preview_samples = _serialize_preview_rows(processed)
                except Exception as e:
                    logger.warning(
                        f"Processed preview generation failed (non-fatal): {e}"
                    )
                    preview_samples = _serialize_preview_rows(preview_slice)
        else:
            preview_samples = _serialize_preview_rows(preview_slice)

        # Collect warnings: from check_dataset_format + URL-based image detection
        warning = result.get("warning")
        image_col = result.get("detected_image_column")
        if image_col and image_col in (result.get("columns") or []):
            try:
                sample_val = preview_slice[0][image_col]
                if isinstance(sample_val, str) and sample_val.startswith(
                    ("http://", "https://")
                ):
                    url_warning = (
                        "This dataset contains image URLs instead of embedded images. "
                        "Images will be downloaded during training, which may be slow for large datasets."
                    )
                    logger.info(f"URL-based image column detected: {image_col}")
                    warning = f"{warning} {url_warning}" if warning else url_warning
            except Exception:
                pass

        return CheckFormatResponse(
            requires_manual_mapping = result["requires_manual_mapping"],
            detected_format = result["detected_format"],
            columns = result["columns"],
            is_image = result.get("is_image", False),
            is_audio = result.get("is_audio", False),
            multimodal_columns = result.get("multimodal_columns"),
            suggested_mapping = result.get("suggested_mapping"),
            detected_image_column = result.get("detected_image_column"),
            detected_audio_column = result.get("detected_audio_column"),
            detected_text_column = result.get("detected_text_column"),
            detected_speaker_column = result.get("detected_speaker_column"),
            preview_samples = preview_samples,
            total_rows = total_rows,
            warning = warning,
        )

    except HTTPException:
        raise
    except Exception as e:
        logger.error(f"Error checking dataset format: {e}", exc_info = True)
        raise HTTPException(
            status_code = 500, detail = f"Failed to check dataset format: {str(e)}"
        )


@router.post("/ai-assist-mapping", response_model = AiAssistMappingResponse)
def ai_assist_mapping(
    request: AiAssistMappingRequest,
    current_subject: str = Depends(get_current_subject),
):
    """
    Run LLM-assisted dataset conversion advisor (user-triggered).

    Multi-pass analysis using a 7B helper model:
      Pass 1: Classify dataset type from HF card + samples
      Pass 2: Generate conversion strategy (system prompt, templates)
      Pass 3: Validate conversion quality

    Falls back to simple column classification if the advisor fails.
    """
    try:
        from utils.datasets.llm_assist import llm_conversion_advisor

        # Truncate sample values for the LLM prompt
        truncated = [
            {col: str(s.get(col, ""))[:200] for col in request.columns}
            for s in request.samples[:5]
        ]

        result = llm_conversion_advisor(
            column_names = request.columns,
            samples = truncated,
            dataset_name = request.dataset_name,
            hf_token = request.hf_token,
            model_name = request.model_name,
            model_type = request.model_type,
        )

        if result and result.get("success"):
            return AiAssistMappingResponse(
                success = True,
                suggested_mapping = result.get("suggested_mapping"),
                system_prompt = result.get("system_prompt"),
                user_template = result.get("user_template"),
                assistant_template = result.get("assistant_template"),
                label_mapping = result.get("label_mapping"),
                dataset_type = result.get("dataset_type"),
                is_conversational = result.get("is_conversational"),
                user_notification = result.get("user_notification"),
            )

        return AiAssistMappingResponse(
            success = False,
            warning = "AI could not determine column roles. Please assign them manually.",
        )

    except Exception as e:
        logger.error(f"AI assist mapping failed: {e}", exc_info = True)
        raise HTTPException(status_code = 500, detail = f"AI assist failed: {str(e)}")