"""Tests for the union-find / representative-picker / normalization helpers."""

from __future__ import annotations

from sdg.preprocessing.dedupe.base import UnionFind, normalize_text, pick_representatives


# ── UnionFind ────────────────────────────────────────────────────────────────

def test_unionfind_each_singleton():
    uf = UnionFind(5)
    assert {uf.find(i) for i in range(5)} == {0, 1, 2, 3, 4}


def test_unionfind_simple_merge():
    uf = UnionFind(5)
    uf.union(0, 1)
    assert uf.find(0) == uf.find(1)
    assert uf.find(2) != uf.find(0)


def test_unionfind_transitive_chain():
    uf = UnionFind(5)
    uf.union(0, 1)
    uf.union(1, 2)
    uf.union(2, 3)
    assert uf.find(0) == uf.find(3)
    assert uf.find(0) != uf.find(4)


def test_unionfind_idempotent_self_union():
    uf = UnionFind(3)
    uf.union(1, 1)
    uf.union(0, 1)
    uf.union(0, 1)  # repeat
    assert uf.find(0) == uf.find(1)


# ── pick_representatives ─────────────────────────────────────────────────────

def test_pick_reps_no_pairs_keeps_all():
    keep = pick_representatives(4, [], key_fn=None)
    assert keep == [0, 1, 2, 3]


def test_pick_reps_collapses_pair():
    keep = pick_representatives(3, [(0, 1)], key_fn=None)
    assert keep == [0, 2]  # (0,1) collapsed to smallest index 0; 2 alone


def test_pick_reps_collapses_chain():
    keep = pick_representatives(5, [(0, 1), (1, 2), (3, 4)], key_fn=None)
    assert keep == [0, 3]


def test_pick_reps_key_fn_selects_max_by_negative_length():
    lengths = [10, 50, 5, 100]
    key_fn = lambda i: -lengths[i]  # longest wins
    keep = pick_representatives(4, [(0, 1), (2, 3)], key_fn=key_fn)
    assert keep == [1, 3]  # idx 1 (len 50) > idx 0 (10); idx 3 (100) > idx 2 (5)


def test_pick_reps_returns_sorted():
    keep = pick_representatives(6, [(2, 5), (0, 3)], key_fn=None)
    assert keep == sorted(keep)


def test_pick_reps_empty():
    assert pick_representatives(0, [], key_fn=None) == []


# ── normalize_text ───────────────────────────────────────────────────────────

def test_normalize_lowercases():
    assert normalize_text("Hello WORLD") == "hello world"


def test_normalize_collapses_whitespace():
    assert normalize_text("a  b\t\tc\n\nd") == "a b c d"


def test_normalize_strips_edges():
    assert normalize_text("  hi  ") == "hi"


def test_normalize_idempotent():
    text = "Hello\t\tWorld\n"
    assert normalize_text(normalize_text(text)) == normalize_text(text)