from __future__ import annotations

from typing import Any, Mapping


MULTIPART_AUTH_HEADERS = {
    "timestamp": "X-Mayvins-Timestamp",
    "signature": "X-Mayvins-Signature",
}


def validation_payload(
    data: Mapping[str, Any],
    headers: Mapping[str, Any],
    content_type: str | None,
) -> dict[str, Any]:
    payload = data.copy()
    if not (content_type or "").lower().startswith("multipart/form-data"):
        return payload

    for field, header in MULTIPART_AUTH_HEADERS.items():
        if field not in payload:
            value = headers.get(header)
            if value is not None:
                payload[field] = value

    return payload