import csv
from datetime import datetime
from io import StringIO
import logging
from typing import Any, Dict, List

log = logging.getLogger(__name__)


def generate_random_filename(filename_prefix: str) -> str:
    """Generates a random filename with a given prefix and current datetime."""
    now = datetime.now()
    timestamp = now.strftime('%Y%m%d%H%M%S')
    generated_filename = f'{filename_prefix}IntegrationTest_{timestamp}.csv'
    return generated_filename


def create_csv_buffer(data: List[Dict[str, Any]]) -> StringIO:
    """Creates an in-memory CSV buffer from the provided data."""
    fieldnames = data[0].keys()
    csv_buffer = StringIO()
    writer = csv.DictWriter(csv_buffer, fieldnames=fieldnames)
    writer.writeheader()
    writer.writerows(data)
    return csv_buffer


def read_csv_from_buffer(buffer: StringIO) -> List[Dict[str, str]]:
    """
    Reads CSV content from a StringIO buffer and returns it as a list of dictionaries.
    """
    buffer.seek(0)  # Ensure we're reading from the beginning
    reader = csv.DictReader(buffer)
    return [row for row in reader]


def create_and_upload_csv_to_s3(
    s3_client: Any,
    file_data: List[Dict[str, Any]],
    filename_prefix: str,
    s3_folder: str,
    bucket: str,
) -> tuple[StringIO, str]:
    """
    Creates a CSV file in memory, uploads it to S3, and returns the buffer and S3 key.
    """
    local_filename = generate_random_filename(filename_prefix)
    s3_key = f'{s3_folder}/{local_filename}'

    csv_buffer = create_csv_buffer(file_data)
    s3_client.put(bucket, s3_key, csv_buffer.getvalue().encode('utf-8'))

    log.info(f'Uploaded {local_filename} to S3 bucket {bucket}')
    return csv_buffer, s3_key