"""Connector to S3 buckets."""

import logging
from typing import cast

import boto3
from botocore.exceptions import ClientError

logger = logging.getLogger(__name__)


class FailedDownloadException(Exception):
    """Raised when file download fails."""

    pass


class S3:
    """Connect to S3 bucket and read files."""

    def __init__(self) -> None:
        """Initialize the S3 client using provided AWS credentials."""
        self._client = boto3.client("s3")

    def does_file_exist(self, bucket: str, key: str) -> bool:
        """Check if a file exists in the S3 bucket using head_object."""
        try:
            response = self._client.head_object(Bucket=bucket, Key=key)
            return "ResponseMetadata" in response
        except ClientError as e:
            if e.response["Error"]["Code"] == "404":
                return False
            logger.warning(
                "Failed to check existence of file in bucket %s with key %s",
                bucket,
                key,
            )
            raise e

    def download_file(self, bucket: str, key: str, local_path: str) -> str:
        """Download a file from S3 bucket to a local path."""
        try:
            self._client.download_file(bucket, key, local_path)
            return local_path
        except ClientError as e:
            logger.warning(
                "Failed to download file from bucket %s with key %s", bucket, key
            )
            raise FailedDownloadException(
                "Failed to download file from bucket %s with key %s", bucket, key
            ) from e

    def get_file_content(self, bucket: str, key: str) -> str:
        """Read passed file from a bucket."""
        try:
            response = self._client.get_object(Bucket=bucket, Key=key)
            body = cast(bytes, response["Body"].read())
            return body.decode(encoding="utf-8-sig")
        except ClientError as e:
            logger.warning(
                "Failed to read file content from bucket %s with key %s", bucket, key
            )
            raise e