"""S3-compatible object storage service for file uploads."""
import logging
import uuid
from io import BytesIO

import boto3
from botocore.config import Config as BotoConfig
from botocore.exceptions import ClientError

from app.core.config import settings

logger = logging.getLogger(__name__)

ALLOWED_IMAGE_TYPES = {"image/png", "image/jpeg", "image/gif", "image/webp"}
ALLOWED_TEXT_TYPES = {"text/plain", "text/csv", "application/octet-stream"}
ALLOWED_TYPES = ALLOWED_IMAGE_TYPES | ALLOWED_TEXT_TYPES

MAX_IMAGE_SIZE = 5 * 1024 * 1024  # 5MB
MAX_TEXT_SIZE = 1 * 1024 * 1024   # 1MB
MAX_FILES_PER_SESSION = 20
MAX_BYTES_PER_SESSION = 50 * 1024 * 1024  # 50MB

PRESIGNED_URL_EXPIRY = 3600  # 1 hour


def _get_client():
    """Get S3 client configured for Railway Object Storage."""
    if not settings.STORAGE_ENDPOINT:
        raise RuntimeError("Object storage not configured (STORAGE_ENDPOINT missing)")
    return boto3.client(
        "s3",
        endpoint_url=settings.STORAGE_ENDPOINT,
        aws_access_key_id=settings.STORAGE_ACCESS_KEY,
        aws_secret_access_key=settings.STORAGE_SECRET_KEY,
        region_name=settings.STORAGE_REGION,
        config=BotoConfig(signature_version="s3v4"),
    )


def validate_upload(content_type: str, size_bytes: int) -> str | None:
    """Validate file type and size. Returns error message or None."""
    if content_type not in ALLOWED_TYPES:
        return f"File type {content_type} not allowed"
    max_size = MAX_IMAGE_SIZE if content_type in ALLOWED_IMAGE_TYPES else MAX_TEXT_SIZE
    if size_bytes > max_size:
        return f"File too large ({size_bytes} bytes, max {max_size})"
    return None


async def upload_file(
    file_data: bytes,
    filename: str,
    content_type: str,
    account_id: str,
) -> str:
    """Upload file to S3, returns the storage key."""
    ext = filename.rsplit(".", 1)[-1] if "." in filename else "bin"
    storage_key = f"uploads/{account_id}/{uuid.uuid4()}.{ext}"

    client = _get_client()
    client.upload_fileobj(
        BytesIO(file_data),
        settings.STORAGE_BUCKET_NAME,
        storage_key,
        ExtraArgs={"ContentType": content_type},
    )
    return storage_key


def get_presigned_url(storage_key: str) -> str:
    """Generate a time-limited presigned URL for downloading a file."""
    client = _get_client()
    return client.generate_presigned_url(
        "get_object",
        Params={"Bucket": settings.STORAGE_BUCKET_NAME, "Key": storage_key},
        ExpiresIn=PRESIGNED_URL_EXPIRY,
    )


async def delete_file(storage_key: str) -> None:
    """Delete a file from S3."""
    try:
        client = _get_client()
        client.delete_object(Bucket=settings.STORAGE_BUCKET_NAME, Key=storage_key)
    except ClientError:
        logger.warning(f"Failed to delete S3 object: {storage_key}")