"""
MinIO Storage Service for RAG Documents
Provides S3-compatible object storage for PDFs and other training documents.
"""

import os
from typing import Optional, List, Dict, BinaryIO
from datetime import datetime, timedelta
from pathlib import Path
import io

# MinIO Configuration - Credentials from Vault or environment (test defaults for CI)
MINIO_ENDPOINT = os.getenv("MINIO_ENDPOINT", "localhost:9000")
MINIO_ACCESS_KEY = os.getenv("MINIO_ACCESS_KEY", "test-access-key")
MINIO_SECRET_KEY = os.getenv("MINIO_SECRET_KEY", "test-secret-key")
MINIO_BUCKET = os.getenv("MINIO_BUCKET", "breakpilot-rag")
MINIO_SECURE = os.getenv("MINIO_SECURE", "false").lower() == "true"

# Flag to check if using test defaults (MinIO operations will fail gracefully)
_MINIO_CONFIGURED = MINIO_ACCESS_KEY != "test-access-key"

# Lazy import to avoid issues when minio is not installed
_minio_client = None


def _get_minio_client():
    """Get or create MinIO client singleton."""
    global _minio_client
    if _minio_client is None:
        try:
            from minio import Minio
            _minio_client = Minio(
                MINIO_ENDPOINT,
                access_key=MINIO_ACCESS_KEY,
                secret_key=MINIO_SECRET_KEY,
                secure=MINIO_SECURE,
            )
        except ImportError:
            print("Warning: minio package not installed. MinIO storage disabled.")
            return None
        except Exception as e:
            print(f"Warning: Failed to connect to MinIO: {e}")
            return None
    return _minio_client


async def init_minio_bucket() -> bool:
    """Initialize MinIO bucket if not exists."""
    client = _get_minio_client()
    if client is None:
        return False

    try:
        if not client.bucket_exists(MINIO_BUCKET):
            client.make_bucket(MINIO_BUCKET)
            print(f"Created MinIO bucket: {MINIO_BUCKET}")
        return True
    except Exception as e:
        print(f"Failed to initialize MinIO bucket: {e}")
        return False


async def upload_document(
    file_data: bytes,
    object_name: str,
    content_type: str = "application/pdf",
    metadata: Optional[Dict[str, str]] = None,
) -> Optional[str]:
    """
    Upload a document to MinIO.

    Args:
        file_data: File content as bytes
        object_name: Path in bucket (e.g., "landes-daten/ni/klausur/2024/doc.pdf")
        content_type: MIME type
        metadata: Optional metadata dict

    Returns:
        Full object path or None on failure
    """
    client = _get_minio_client()
    if client is None:
        return None

    try:
        # Ensure bucket exists
        await init_minio_bucket()

        # Upload file
        data_stream = io.BytesIO(file_data)
        client.put_object(
            bucket_name=MINIO_BUCKET,
            object_name=object_name,
            data=data_stream,
            length=len(file_data),
            content_type=content_type,
            metadata=metadata or {},
        )

        return f"{MINIO_BUCKET}/{object_name}"
    except Exception as e:
        print(f"Failed to upload to MinIO: {e}")
        return None


async def download_document(object_name: str) -> Optional[bytes]:
    """
    Download a document from MinIO.

    Args:
        object_name: Path in bucket

    Returns:
        File content as bytes or None on failure
    """
    client = _get_minio_client()
    if client is None:
        return None

    try:
        response = client.get_object(MINIO_BUCKET, object_name)
        data = response.read()
        response.close()
        response.release_conn()
        return data
    except Exception as e:
        print(f"Failed to download from MinIO: {e}")
        return None


async def list_documents(
    prefix: str = "",
    recursive: bool = True,
) -> List[Dict]:
    """
    List documents in MinIO bucket.

    Args:
        prefix: Path prefix to filter (e.g., "landes-daten/ni/")
        recursive: Whether to list recursively

    Returns:
        List of document info dicts
    """
    client = _get_minio_client()
    if client is None:
        return []

    try:
        objects = client.list_objects(
            MINIO_BUCKET,
            prefix=prefix,
            recursive=recursive,
        )

        return [
            {
                "name": obj.object_name,
                "size": obj.size,
                "last_modified": obj.last_modified.isoformat() if obj.last_modified else None,
                "etag": obj.etag,
            }
            for obj in objects
        ]
    except Exception as e:
        print(f"Failed to list MinIO objects: {e}")
        return []


async def delete_document(object_name: str) -> bool:
    """
    Delete a document from MinIO.

    Args:
        object_name: Path in bucket

    Returns:
        True on success
    """
    client = _get_minio_client()
    if client is None:
        return False

    try:
        client.remove_object(MINIO_BUCKET, object_name)
        return True
    except Exception as e:
        print(f"Failed to delete from MinIO: {e}")
        return False


async def get_presigned_url(
    object_name: str,
    expires: int = 3600,
) -> Optional[str]:
    """
    Get a presigned URL for temporary access to a document.

    Args:
        object_name: Path in bucket
        expires: URL expiration time in seconds (default 1 hour)

    Returns:
        Presigned URL or None on failure
    """
    client = _get_minio_client()
    if client is None:
        return None

    try:
        url = client.presigned_get_object(
            MINIO_BUCKET,
            object_name,
            expires=timedelta(seconds=expires),
        )
        return url
    except Exception as e:
        print(f"Failed to generate presigned URL: {e}")
        return None


async def get_storage_stats() -> Dict:
    """Get storage statistics."""
    client = _get_minio_client()
    if client is None:
        return {"error": "MinIO not available", "connected": False}

    try:
        # Count objects and calculate total size
        objects = list(client.list_objects(MINIO_BUCKET, recursive=True))
        total_size = sum(obj.size for obj in objects)
        total_count = len(objects)

        # Group by prefix
        by_prefix: Dict[str, int] = {}
        for obj in objects:
            parts = obj.object_name.split("/")
            if len(parts) >= 2:
                prefix = f"{parts[0]}/{parts[1]}"
                by_prefix[prefix] = by_prefix.get(prefix, 0) + 1

        return {
            "connected": True,
            "bucket": MINIO_BUCKET,
            "total_objects": total_count,
            "total_size_bytes": total_size,
            "total_size_mb": round(total_size / (1024 * 1024), 2),
            "by_prefix": by_prefix,
        }
    except Exception as e:
        return {"error": str(e), "connected": False}


# =============================================================================
# RAG-specific Storage Functions
# =============================================================================

def get_minio_path(
    data_type: str,  # "landes-daten" or "lehrer-daten"
    bundesland: str,  # "ni", "by", etc.
    use_case: str,    # "klausur", "zeugnis", "lehrplan"
    year: int,
    filename: str,
) -> str:
    """
    Generate MinIO path following the RAG-Admin-Spec.md structure.

    Example: landes-daten/ni/klausur/2024/2024_Deutsch_eA_I_EWH.pdf
    """
    return f"{data_type}/{bundesland.lower()}/{use_case}/{year}/{filename}"


async def upload_rag_document(
    file_data: bytes,
    filename: str,
    bundesland: str = "ni",
    use_case: str = "klausur",
    year: Optional[int] = None,
    metadata: Optional[Dict[str, str]] = None,
) -> Optional[str]:
    """
    Upload a document to the RAG storage structure.

    Args:
        file_data: PDF content
        filename: Original filename
        bundesland: State code (ni, by, etc.)
        use_case: klausur, zeugnis, lehrplan
        year: Document year (defaults to current year)
        metadata: Optional metadata

    Returns:
        MinIO path on success
    """
    if year is None:
        year = datetime.now().year

    object_path = get_minio_path(
        data_type="landes-daten",
        bundesland=bundesland,
        use_case=use_case,
        year=year,
        filename=filename,
    )

    # Add RAG metadata
    rag_metadata = {
        "bundesland": bundesland,
        "use_case": use_case,
        "year": str(year),
        "training_allowed": "true",  # Landes-Daten allow training
        **(metadata or {}),
    }

    return await upload_document(
        file_data=file_data,
        object_name=object_path,
        content_type="application/pdf",
        metadata=rag_metadata,
    )


async def upload_teacher_document(
    file_data: bytes,
    filename: str,
    tenant_id: str,
    teacher_id: str,
    metadata: Optional[Dict[str, str]] = None,
) -> Optional[str]:
    """
    Upload a teacher's document (BYOEH - encrypted, no training).

    Args:
        file_data: Encrypted PDF content
        filename: Original filename (will be stored as .enc)
        tenant_id: School/tenant ID
        teacher_id: Teacher ID
        metadata: Optional metadata

    Returns:
        MinIO path on success
    """
    enc_filename = filename if filename.endswith(".enc") else f"{filename}.enc"
    object_path = f"lehrer-daten/{tenant_id}/{teacher_id}/{enc_filename}"

    # Teacher data - never allow training
    teacher_metadata = {
        "tenant_id": tenant_id,
        "teacher_id": teacher_id,
        "training_allowed": "false",  # CRITICAL: Never train on teacher data
        "encrypted": "true",
        **(metadata or {}),
    }

    return await upload_document(
        file_data=file_data,
        object_name=object_path,
        content_type="application/octet-stream",
        metadata=teacher_metadata,
    )