# retoor <retoor@molodetz.nl>

from __future__ import annotations

from starlette.requests import Request

HOP_HEADERS = frozenset(
    {
        "connection",
        "keep-alive",
        "proxy-authenticate",
        "proxy-authorization",
        "te",
        "trailers",
        "transfer-encoding",
        "upgrade",
        "host",
        "content-length",
        "content-encoding",
    }
)


def forward_headers(request: Request, prefix: str) -> dict[str, str]:
    headers = {
        k: v for k, v in request.headers.items() if k.lower() not in HOP_HEADERS
    }
    headers["X-Forwarded-Prefix"] = prefix
    headers["X-Script-Name"] = prefix
    headers["X-Forwarded-Host"] = request.headers.get(
        "host", request.url.hostname or ""
    )
    headers["X-Forwarded-Proto"] = request.headers.get(
        "x-forwarded-proto", request.url.scheme
    )
    headers["Accept-Encoding"] = "identity"
    return headers