"""Tests für die Auslosungslogik.

Laufen ohne Abhängigkeiten:  python tests/test_draw.py
(sind aber auch pytest-kompatibel)
"""

from __future__ import annotations

import random
import sys
from pathlib import Path

sys.path.insert(0, str(Path(__file__).resolve().parents[1]))

from app.draw import draw_assignment


def check_mapping(mapping, ids, exclusions):
    assert sorted(mapping.keys()) == sorted(ids), "jeder muss genau einmal geben"
    assert sorted(mapping.values()) == sorted(ids), "jeder muss genau einmal gezogen werden"
    for giver, receiver in mapping.items():
        assert giver != receiver, "niemand darf sich selbst ziehen"
        assert (giver, receiver) not in exclusions, "Ausschlüsse müssen gelten"


def test_basically():
    ids = ["a", "b", "c", "d"]
    mapping = draw_assignment(ids, set())
    assert mapping is not None
    check_mapping(mapping, ids, set())


def test_mindestgroesse():
    assert draw_assignment([], set()) is None
    assert draw_assignment(["a"], set()) is None


def test_ausschluesse_werden_respektiert():
    ids = ["anna", "ben", "clara", "david"]
    # Ehepaar: Anna und Ben dürfen sich nicht gegenseitig ziehen.
    exclusions = {("anna", "ben"), ("ben", "anna")}
    rng = random.Random(42)
    for _ in range(300):
        mapping = draw_assignment(ids, exclusions, rng=rng)
        assert mapping is not None
        check_mapping(mapping, ids, exclusions)


def test_unloesbar_zwei_personen_mit_ausschluss():
    ids = ["a", "b"]
    assert draw_assignment(ids, {("a", "b")}) is None


def test_unloesbar_kein_moeglicher_empfaenger():
    # a darf weder b noch c ziehen → keine gültige Auslosung möglich.
    ids = ["a", "b", "c"]
    exclusions = {("a", "b"), ("a", "c")}
    assert draw_assignment(ids, exclusions) is None


def test_zufall_variiert():
    ids = [f"p{i}" for i in range(8)]
    exclusions = {("p0", "p1"), ("p2", "p3")}
    rng = random.Random(7)
    results = set()
    for _ in range(100):
        mapping = draw_assignment(ids, exclusions, rng=rng)
        assert mapping is not None
        check_mapping(mapping, ids, exclusions)
        results.add(tuple(sorted(mapping.items())))
    assert len(results) > 1, "Auslosung soll zufällig variieren"


if __name__ == "__main__":
    failures = 0
    for name, fn in sorted(globals().items()):
        if name.startswith("test_") and callable(fn):
            try:
                fn()
                print(f"  ✓ {name}")
            except AssertionError as e:
                failures += 1
                print(f"  ✗ {name}: {e}")
    print("ALLE TESTS OK" if failures == 0 else f"{failures} TEST(S) FEHLGESCHLAGEN")
    sys.exit(1 if failures else 0)