import boto3
import tempfile
import os
from botocore.client import Config
from fastapi import UploadFile
from app.config import settings
from app.logger import get_logger

logger = get_logger(__name__)

def get_client():
    return boto3.client(
        "s3",
        endpoint_url=settings.s3_endpoint,
        aws_access_key_id=settings.s3_access_key,
        aws_secret_access_key=settings.s3_secret_key,
        config=Config(signature_version="s3v4"),
        region_name=settings.s3_region
    )

def ensure_bucket_exists() -> None:
    """Ensure the S3 bucket exists, create it if it doesn't exist.
    
    Raises:
        Exception: If bucket creation fails (service will fail to start)
    """
    client = get_client()
    try:
        client.head_bucket(Bucket=settings.s3_bucket)
        logger.info(f"Bucket '{settings.s3_bucket}' already exists")
    except client.exceptions.ClientError as e:
        error_code = e.response['Error']['Code']
        if error_code == '404':
            try:
                client.create_bucket(
                    Bucket=settings.s3_bucket,
                    CreateBucketConfiguration={
                        'LocationConstraint': settings.s3_region
                    }
                )
                logger.info(f"Created bucket '{settings.s3_bucket}'")
            except Exception as create_error:
                logger.error(f"Failed to create bucket '{settings.s3_bucket}': {create_error}")
                raise
        else:
            logger.error(f"Error checking bucket: {e}")
            raise

def upload_file(file: UploadFile, s3_key: str, content_type: str, metadata: dict = None) -> str:
    """Upload file to S3 with metadata"""
    client = get_client()

    extra_args = {"ContentType": content_type}
    if metadata:
        extra_args["Metadata"] = metadata

    client.upload_fileobj(
        file.file,
        settings.s3_bucket,
        s3_key,
        ExtraArgs=extra_args
    )
    return s3_key

def delete_file(s3_key: str) -> None:
    """Delete file from S3"""
    client = get_client()
    client.delete_object(Bucket=settings.s3_bucket, Key=s3_key)

def file_exists(s3_key: str) -> bool:
    """Check if file exists in S3"""
    client = get_client()
    try:
        client.head_object(Bucket=settings.s3_bucket, Key=s3_key)
        return True
    except client.exceptions.ClientError:
        return False

def get_file_metadata(s3_key: str) -> dict:
    """Get file metadata from S3"""
    client = get_client()
    response = client.head_object(Bucket=settings.s3_bucket, Key=s3_key)
    return response.get("Metadata", {})

def download_to_temp(s3_key: str) -> str:
    """Download file from S3 to temp file"""
    client = get_client()
    suffix = os.path.splitext(s3_key)[-1] or ".tmp"
    tmp = tempfile.NamedTemporaryFile(delete=False, suffix=suffix)
    client.download_fileobj(settings.s3_bucket, s3_key, tmp)
    tmp.close()
    return tmp.name

def presigned_download_url(s3_key: str, expires_in: int = 3600) -> str:
    """Generate presigned download URL"""
    client = get_client()
    return client.generate_presigned_url(
        "get_object",
        Params={"Bucket": settings.s3_bucket, "Key": s3_key},
        ExpiresIn=expires_in
    )