import unittest
import numpy as np
import backend


class ReproducibilityTest(unittest.TestCase):
    def setUp(self):
        backend.history, backend.configuration = [], None
        rng = np.random.default_rng(10)
        self.points = [{"x": float(x), "y": float(y), "label": -1 if x < y else 1}
                       for x, y in rng.random((60, 2))]

    def request(self, method, seed=42, count=0, params=None):
        return {"points": self.points, "method": method, "seed": seed,
                "count": count, "classifier": "DecisionTreeClassifier",
                "params": params if params is not None else {"max_depth": 3}}

    def test_rebuild_and_remove_readd(self):
        for method in ("boosting", "bagging", "random_forest", "extra_trees"):
            with self.subTest(method=method):
                backend.history, backend.configuration = [], None
                original = [backend.train(self.request(method, count=i)) for i in range(3)]
                self.assertEqual(original[2], backend.train(self.request(method, count=2)))
                backend.history, backend.configuration = [], None
                rebuilt = [backend.train(self.request(method, count=i)) for i in range(3)]
                self.assertEqual(original, rebuilt)

    def test_seed_changes_random_models(self):
        for method in ("bagging", "random_forest", "extra_trees"):
            with self.subTest(method=method):
                first = backend.train(self.request(method, seed=42))
                other = backend.train(self.request(method, seed=43))
                self.assertNotEqual(first["tree"], other["tree"])

    def test_explicit_random_state_still_reproduces_bagging(self):
        request = self.request("bagging", params={"random_state": 7, "max_depth": 3})
        first = backend.train(request)
        self.assertEqual(first, backend.train(request))
        self.assertEqual(backend.history[0]["estimator"].random_state, 7)

    def test_invalid_seeds(self):
        for seed in (-1, 2**32, 1.5, True, None, "42"):
            with self.subTest(seed=seed), self.assertRaisesRegex(ValueError, "Random seed"):
                backend.train(self.request("bagging", seed=seed))


if __name__ == "__main__":
    unittest.main()