"""Reusable hypothesis strategies for CSS selectors."""

from typing import cast

from hypothesis import strategies as st

# CSS identifier (used for tag, class, ID names)
css_ident = st.from_regex(r"[_a-zA-Z][_a-zA-Z0-9-]*", fullmatch=True)

css_tag = css_ident
css_class = css_ident.map(lambda x: f".{x}")
css_class_multi = st.lists(css_class, min_size=1).map("".join)
css_id = css_ident.map(lambda x: f"#{x}")

# Any amount of whitespace, including none (spaces only)
_whitespace = st.from_regex(r" *", fullmatch=True)


def simple_selector() -> st.SearchStrategy[str]:
    """Returns a strategy for simple seletors: tag, .class, #id (all optional, at least one)."""

    # Optional tag + (one or more classes) + optional id, at least one item present
    parts = st.tuples(
        st.none() | css_tag,
        st.none() | css_class_multi,
        st.none() | css_id,
    ).filter(lambda parts: any(parts))

    return parts.map(lambda parts: "".join(p for p in parts if p))


# nth-child pseudo-classes
nth_child_suffix = st.from_regex(r":nth-child\([1-9][0-9]*\)", fullmatch=True)
_specific_child_pseudo_classes = st.sampled_from([":first-child", ":last-child"])
any_nth_child_suffix = st.one_of(nth_child_suffix, _specific_child_pseudo_classes)


def not_selector(inner: st.SearchStrategy[str]) -> st.SearchStrategy[str]:
    return st.tuples(st.just(":not("), _whitespace, inner, _whitespace, st.just(")")).map("".join)


def pseudo_suffixes(inner: st.SearchStrategy[str]) -> st.SearchStrategy[str]:
    """Generate a single random pseudo-class suffix."""
    return st.one_of(
        not_selector(inner),
        any_nth_child_suffix,
    )


combinator = st.tuples(_whitespace, st.sampled_from([">", " ", "+", ",", "~"]), _whitespace).map("".join)

selector = st.recursive(
    # Base: simple selector + pseudo-classes
    base=simple_selector(),
    extend=lambda s: st.one_of(
        # Add combinator + selector sequence
        cast(
            "st.SearchStrategy[str]",
            st.builds(
                lambda left, comb, right: left + comb + right,
                s,
                combinator,
                s,
            ),
        ),
        # Apply pseudo-suffix
        st.tuples(s, pseudo_suffixes(s)).map("".join),
        # Optionally add classes / id after the pseudo-suffix
        st.one_of(
            s,  # no append, keep as-is
            st.tuples(
                s,
                st.lists(st.one_of(css_class, css_id), min_size=1).map("".join),
            ).map("".join),
        ),
    ),
    max_leaves=10,
)