"""Tests for :mod:`app.services.slugs`."""

from __future__ import annotations

import pytest

from app.services.slugs import ensure_unique, slugify


# ---------------------------------------------------------------------------
# slugify
# ---------------------------------------------------------------------------
@pytest.mark.parametrize(
    "title, expected",
    [
        ("Hello World", "hello-world"),
        ("Hello, World!", "hello-world"),
        ("  leading  and   trailing  ", "leading-and-trailing"),
        ("CamelCaseTitle", "camelcasetitle"),
        ("Multiple   spaces", "multiple-spaces"),
        ("dashes---everywhere", "dashes-everywhere"),
        ("mix-of 99 items & stuff", "mix-of-99-items-stuff"),
        ("Café au lait", "caf-au-lait"),  # non-ASCII dropped
        ("", "post"),  # fallback
        ("...", "post"),  # all-punctuation → fallback
        ("123", "123"),  # digits allowed
        ("snake_case", "snake-case"),
    ],
)
def test_slugify_expected(title: str, expected: str) -> None:
    """:func:`slugify` produces the documented output per input."""
    assert slugify(title) == expected


def test_slugify_no_leading_or_trailing_hyphens() -> None:
    """Slugs never have dangling hyphens regardless of input shape."""
    assert slugify("!!hello!!") == "hello"
    assert slugify("--leading and trailing--") == "leading-and-trailing"


# ---------------------------------------------------------------------------
# ensure_unique
# ---------------------------------------------------------------------------
def test_ensure_unique_returns_base_when_free() -> None:
    """If nothing collides, the base slug is returned unchanged."""
    taken: set[str] = set()
    result = ensure_unique("hello", lambda s: s in taken)
    assert result == "hello"


def test_ensure_unique_suffixes_on_collision() -> None:
    """Collisions produce -2, -3, etc. in order."""
    taken = {"hello", "hello-2", "hello-3"}
    result = ensure_unique("hello", lambda s: s in taken)
    assert result == "hello-4"


def test_ensure_unique_suffix_sequence_starts_at_two() -> None:
    """First collision uses ``-2`` — never ``-1`` or ``-0``."""
    taken = {"hello"}
    result = ensure_unique("hello", lambda s: s in taken)
    assert result == "hello-2"


def test_ensure_unique_raises_when_exhausted() -> None:
    """A pathological ``exists`` callable hits the guard ceiling."""
    with pytest.raises(RuntimeError):
        ensure_unique("hello", lambda s: True, max_attempts=3)