"""Pure resolution of stored media paths into browser-reachable upload URLs."""

from __future__ import annotations

from pathlib import Path
from urllib.parse import quote

_ABSOLUTE_SCHEMES = ("http://", "https://", "data:")
_UPLOAD_ROUTE_PREFIX = "/uploads/"
_CANONICAL_PREFIXES = ("documents/", "persons/", "photos/")


def absolute_upload_url(path: str, *, base_url: str) -> str:
    """Join an application-relative upload path onto the request base URL."""
    base = base_url.rstrip("/")
    normalized_path = path if path.startswith("/") else f"/{path}"
    return f"{base}{normalized_path}"


def resolve_media_url(path: str | None, *, upload_dir: Path, base_url: str) -> str | None:
    """Map a canonical stored relative media path onto a served upload URL."""
    candidate = (path or "").strip()
    if not candidate:
        return None

    normalized = candidate.replace("\\", "/")
    lowered = normalized.casefold()
    if lowered.startswith(_ABSOLUTE_SCHEMES):
        return normalized
    if normalized.startswith(_UPLOAD_ROUTE_PREFIX):
        return _resolve_upload_relative(normalized.removeprefix(_UPLOAD_ROUTE_PREFIX), upload_dir=upload_dir, base_url=base_url)
    if lowered.startswith(_CANONICAL_PREFIXES):
        return _resolve_upload_relative(normalized, upload_dir=upload_dir, base_url=base_url)

    return None


def _resolve_upload_relative(relative: str, *, upload_dir: Path, base_url: str) -> str | None:
    candidate = relative.strip().replace("\\", "/")
    if not candidate:
        return None
    resolved_upload_dir = upload_dir.resolve()
    try:
        normalized_relative = Path(candidate).as_posix()
        if not normalized_relative.casefold().startswith(_CANONICAL_PREFIXES):
            return None
        absolute_candidate = (resolved_upload_dir / Path(normalized_relative)).resolve()
        safe_relative = absolute_candidate.relative_to(resolved_upload_dir).as_posix()
    except ValueError:
        return None
    if not absolute_candidate.is_file():
        return None
    return absolute_upload_url(f"/uploads/{quote(safe_relative)}", base_url=base_url)


def public_media_path_label(path: str | None, *, upload_dir: Path) -> str:
    """Return a safe, non-local path label for UI metadata display."""
    _ = upload_dir
    candidate = (path or "").strip()
    if not candidate:
        return "unknown"

    normalized = candidate.replace("\\", "/")
    lowered = normalized.casefold()

    if normalized.startswith(_UPLOAD_ROUTE_PREFIX):
        return normalized
    if lowered.startswith(_CANONICAL_PREFIXES):
        return f"/uploads/{normalized}"
    return Path(normalized).name or "unknown"