from collections.abc import Iterable
from pathlib import Path
from urllib.parse import urlparse

from haiku.rag.client.exceptions import UnsupportedSourceError
from haiku.rag.ingester.sources.base import Source
from haiku.rag.ingester.sources.fs import FSSource
from haiku.rag.ingester.sources.http import HTTPSource
from haiku.rag.ingester.sources.s3 import S3Source


def resolve_fetcher(
    uri: str,
    sources: Iterable[Source] | None = None,
    *,
    storage_options: dict[str, str] | None = None,
) -> Source:
    """Pick a Source adapter for ``uri``.

    Configured ``sources`` win — the first whose ``supports(uri)`` returns True
    is returned. Without a configured match, an ad-hoc adapter is built from
    the URI scheme so one-shot calls (``add-src <uri>``) work without any
    configuration.
    """
    if sources:
        for src in sources:
            if src.supports(uri):
                return src

    scheme = urlparse(uri).scheme
    if scheme in ("", "file"):
        # Root only matters for discover(); fetch() needs an absolute path
        # that already encodes the location, so any root is correct.
        return FSSource(root=Path("/"))
    if scheme in ("http", "https"):
        return HTTPSource(source_id="http:adhoc")
    if scheme == "s3":
        bucket = urlparse(uri).netloc
        if not bucket:
            raise UnsupportedSourceError(f"Invalid S3 URI: {uri}")
        return S3Source(uri=f"s3://{bucket}/", storage_options=storage_options)

    raise UnsupportedSourceError(f"No source adapter for URI scheme {scheme!r}: {uri}")