from __future__ import annotations

from leanbench.anchors import find, resolve_span

TEXT = (
    "Theorem 1.6.2. Let a, b and c be integers. If a divides b and a divides c,\n"
    "then a divides b + c.\n\nProof. Write b = a k."
)


def test_exact_match() -> None:
    match = find(TEXT, "Theorem 1.6.2.")
    assert match is not None and match.method == "exact"
    assert TEXT[match.start : match.end] == "Theorem 1.6.2."


def test_whitespace_insensitive_match_across_a_line_break() -> None:
    match = find(TEXT, "a divides c, then a divides b + c.")
    assert match is not None
    assert match.method == "whitespace"
    assert TEXT[match.start : match.end].replace("\n", " ") == "a divides c, then a divides b + c."


def test_fuzzy_match_survives_a_typo() -> None:
    match = find(TEXT, "Let a, b and c be integres. If a divides b")
    assert match is not None
    assert match.method == "fuzzy"
    assert "integers" in TEXT[match.start : match.end]


def test_missing_anchor_is_reported_not_guessed() -> None:
    assert find(TEXT, "nothing like this appears anywhere in the page") is None


def test_resolve_span_covers_start_to_end() -> None:
    span = resolve_span(TEXT, "Theorem 1.6.2.", "a divides b + c.")
    assert span is not None and span.resolved
    assert TEXT[span.start : span.end].startswith("Theorem 1.6.2.")
    assert TEXT[span.start : span.end].endswith("a divides b + c.")


def test_resolve_span_falls_back_when_the_end_quote_is_wrong() -> None:
    span = resolve_span(TEXT, "Theorem 1.6.2.", "this ending was invented", fallback_length=40)
    assert span is not None
    assert "truncated" in span.method
    assert span.end - span.start == 40


def test_resolve_span_searches_forward_from_the_cursor() -> None:
    text = "alpha beta alpha gamma"
    first = resolve_span(text, "alpha", "beta")
    assert first is not None and first.start == 0
    second = resolve_span(text, "alpha", "gamma", search_from=first.end)
    assert second is not None and second.start == text.rindex("alpha")