"""Exception hierarchy for the FablePool reference node."""


class FablePoolError(Exception):
    """Base class for all FablePool errors."""


class WireError(FablePoolError):
    """A wire-format violation: bad envelope, bad body schema, bad encoding."""


class SignatureError(FablePoolError):
    """A signature failed to verify, or an author identifier is malformed."""


class ChainError(FablePoolError):
    """The per-author hash chain in the operation log is broken."""


class StoreError(FablePoolError):
    """A semantic violation against the materialized store
    (e.g. refuting an already-refuted claim, missing inputs)."""


class NotFoundError(StoreError):
    """No object matches the given identifier or prefix."""

    def __init__(self, ref: str):
        super().__init__(f"no object matches identifier {ref!r}")
        self.ref = ref


class AmbiguousIdError(StoreError):
    """An identifier prefix matches more than one object."""

    def __init__(self, ref: str, matches):
        matches = sorted(matches)
        shown = ", ".join(matches[:6])
        more = "" if len(matches) <= 6 else f" (+{len(matches) - 6} more)"
        super().__init__(
            f"identifier prefix {ref!r} is ambiguous: matches {shown}{more}"
        )
        self.ref = ref
        self.matches = matches