from mdgrep.snippets import ELLIPSIS, segments


def join(segs):
    return "".join(s["t"] for s in segs)


def test_short_text_full_with_hits():
    segs = segments("hello world", [(6, 11)])
    assert segs == [{"t": "hello ", "hit": False}, {"t": "world", "hit": True}]


def test_no_spans_returns_whole_text():
    assert segments("abc", []) == [{"t": "abc", "hit": False}]


def test_long_text_windowed_around_hit():
    text = " ".join(f"w{i}" for i in range(400))
    hit_start = text.index("w200")
    segs = segments(text, [(hit_start, hit_start + 4)], max_chars=100, context=30)
    assert segs[0]["t"] == ELLIPSIS and segs[-1]["t"] == ELLIPSIS
    assert any(s["hit"] and s["t"] == "w200" for s in segs)
    assert len(join(segs)) < 150


def test_windows_snap_to_word_boundaries():
    text = "alpha beta gamma delta epsilon zeta eta theta iota kappa lambda"
    start = text.index("epsilon")
    segs = segments(text, [(start, start + 7)], max_chars=20, context=8)
    inner = join(s for s in segs if s["t"] != ELLIPSIS)
    assert not inner.startswith("lta") and inner.split()[0] in ("gamma", "delta")


def test_multiple_hits_separate_windows():
    text = "x " * 300 + "foo " + "y " * 300 + "bar " + "z " * 300
    f, b = text.index("foo"), text.index("bar")
    segs = segments(text, [(f, f + 3), (b, b + 3)], max_chars=200, context=20)
    hits = [s["t"] for s in segs if s["hit"]]
    assert hits == ["foo", "bar"]
    assert sum(1 for s in segs if s["t"] == ELLIPSIS) == 3


def test_budget_limits_windows_but_keeps_first_hit():
    text = ("filler " * 50 + "hit ") * 10
    spans = []
    pos = 0
    while (i := text.find("hit", pos)) != -1:
        spans.append((i, i + 3))
        pos = i + 3
    segs = segments(text, spans, max_chars=60, context=20)
    assert sum(1 for s in segs if s["hit"]) >= 1
    assert len(join(segs)) < 200


def test_no_hits_long_text_shows_beginning():
    text = "start " + "word " * 200
    segs = segments(text, [], max_chars=50)
    assert segs[0]["t"].startswith("start")
    assert segs[-1]["t"] == ELLIPSIS