"""S3 storage for validation results."""

import json
from functools import cache
from typing import Any

import boto3
import config


@cache
def _client() -> Any:
    return boto3.client("s3", region_name=config.AWS_REGION)


def load_from_s3(s3_uri: str) -> dict[str, Any]:
    """Fetch and deserialize a JSON object from S3."""
    without_scheme = s3_uri.removeprefix("s3://")
    bucket, _, key = without_scheme.partition("/")
    response = _client().get_object(
        Bucket=bucket, Key=key, ExpectedBucketOwner=config.EXPECTED_BUCKET_OWNER
    )
    return json.loads(response["Body"].read())


def build_object_key(prefix: str, output_s3_path: str) -> str:
    """Compose the object key under the prepare-payload prefix."""
    return f"{prefix.rstrip('/')}/{output_s3_path.rstrip('/')}.json".lstrip("/")


def store_result(output_s3_path: str, result: dict[str, Any]) -> str:
    """Write the validation result to S3 and return its s3:// URL."""
    if not config.RESULTS_BUCKET:
        raise ValueError("RESULTS_BUCKET is not configured")
    if not config.RESULTS_BUCKET_PREFIX:
        raise ValueError("RESULTS_BUCKET_PREFIX is not configured")

    key = build_object_key(config.RESULTS_BUCKET_PREFIX, output_s3_path)
    put_kwargs: dict[str, Any] = {
        "Bucket": config.RESULTS_BUCKET,
        "Key": key,
        "Body": json.dumps(result).encode("utf-8"),
        "ContentType": "application/json",
    }
    if config.EXPECTED_BUCKET_OWNER:
        put_kwargs["ExpectedBucketOwner"] = config.EXPECTED_BUCKET_OWNER

    _client().put_object(**put_kwargs)
    return f"s3://{config.RESULTS_BUCKET}/{key}"