from collections import OrderedDict
import itertools
from typing import Dict
from typing import List
from typing import Mapping
from typing import Sequence
from typing import Union
from typing import ValuesView

import numpy as np
import pytest

import optuna
from optuna import samplers
from optuna.samplers._grid import GridValueType
from optuna.storages import RetryFailedTrialCallback
from optuna.trial import Trial


def test_study_optimize_with_single_search_space() -> None:
    def objective(trial: Trial) -> float:

        a = trial.suggest_int("a", 0, 100)
        b = trial.suggest_float("b", -0.1, 0.1)
        c = trial.suggest_categorical("c", ("x", "y"))
        d = trial.suggest_float("d", -5, 5, step=1)
        e = trial.suggest_float("e", 0.0001, 1, log=True)

        if c == "x":
            return a * d
        else:
            return b * e

    # Test that all combinations of the grid is sampled.
    search_space = {
        "b": np.arange(-0.1, 0.1, 0.05),
        "c": ["x", "y"],
        "d": [-0.5, 0.5],
        "e": [0.1],
        "a": list(range(0, 100, 20)),
    }
    study = optuna.create_study(sampler=samplers.GridSampler(search_space))  # type: ignore
    study.optimize(objective)

    def sorted_values(
        d: Mapping[str, Sequence[GridValueType]]
    ) -> ValuesView[Sequence[GridValueType]]:

        return OrderedDict(sorted(d.items())).values()

    all_grids = itertools.product(*sorted_values(search_space))  # type: ignore
    all_suggested_values = [tuple([p for p in sorted_values(t.params)]) for t in study.trials]
    assert set(all_grids) == set(all_suggested_values)

    # Test a non-existing parameter name in the grid.
    search_space = {"a": list(range(0, 100, 20))}
    study = optuna.create_study(sampler=samplers.GridSampler(search_space))  # type: ignore
    with pytest.raises(ValueError):
        study.optimize(objective)

    # Test a value with out of range.
    search_space = {
        "a": [110],  # 110 is out of range specified by the suggest method.
        "b": [0],
        "c": ["x"],
        "d": [0],
        "e": [0.1],
    }
    study = optuna.create_study(sampler=samplers.GridSampler(search_space))  # type: ignore
    with pytest.warns(UserWarning):
        study.optimize(objective)


def test_study_optimize_with_exceeding_number_of_trials() -> None:
    def objective(trial: Trial) -> float:

        return trial.suggest_int("a", 0, 100)

    # When `n_trials` is `None`, the optimization stops just after all grids are evaluated.
    search_space: Dict[str, List[GridValueType]] = {"a": [0, 50]}
    study = optuna.create_study(sampler=samplers.GridSampler(search_space))
    study.optimize(objective, n_trials=None)
    assert len(study.trials) == 2

    # If the optimization is triggered after all grids are evaluated, an additional trial runs.
    study.optimize(objective, n_trials=None)
    assert len(study.trials) == 3


def test_study_optimize_with_pruning() -> None:
    def objective(trial: Trial) -> float:
        raise optuna.TrialPruned

    # Pruned trials should count towards grid consumption.
    search_space: Dict[str, List[GridValueType]] = {"a": [0, 50]}
    study = optuna.create_study(sampler=samplers.GridSampler(search_space))
    study.optimize(objective, n_trials=None)
    assert len(study.trials) == 2


def test_study_optimize_with_multiple_search_spaces() -> None:
    def objective(trial: Trial) -> float:

        a = trial.suggest_int("a", 0, 100)
        b = trial.suggest_float("b", -100, 100)

        return a * b

    # Run 3 trials with a search space.
    search_space_0 = {"a": [0, 50], "b": [-50, 0, 50]}
    sampler_0 = samplers.GridSampler(search_space_0)
    study = optuna.create_study(sampler=sampler_0)
    study.optimize(objective, n_trials=3)

    assert len(study.trials) == 3
    for t in study.trials:
        assert sampler_0._same_search_space(t.system_attrs["search_space"])

    # Run 2 trials with another space.
    search_space_1 = {"a": [0, 25], "b": [-50]}
    sampler_1 = samplers.GridSampler(search_space_1)
    study.sampler = sampler_1
    study.optimize(objective, n_trials=2)

    assert not sampler_0._same_search_space(sampler_1._search_space)
    assert len(study.trials) == 5
    for t in study.trials[:3]:
        assert sampler_0._same_search_space(t.system_attrs["search_space"])
    for t in study.trials[3:5]:
        assert sampler_1._same_search_space(t.system_attrs["search_space"])

    # Run 3 trials with the first search space again.
    study.sampler = sampler_0
    study.optimize(objective, n_trials=3)

    assert len(study.trials) == 8
    for t in study.trials[:3]:
        assert sampler_0._same_search_space(t.system_attrs["search_space"])
    for t in study.trials[3:5]:
        assert sampler_1._same_search_space(t.system_attrs["search_space"])
    for t in study.trials[5:]:
        assert sampler_0._same_search_space(t.system_attrs["search_space"])


def test_cast_value() -> None:

    samplers.GridSampler._check_value("x", None)
    samplers.GridSampler._check_value("x", True)
    samplers.GridSampler._check_value("x", False)
    samplers.GridSampler._check_value("x", -1)
    samplers.GridSampler._check_value("x", -1.5)
    samplers.GridSampler._check_value("x", float("nan"))
    samplers.GridSampler._check_value("x", "foo")
    samplers.GridSampler._check_value("x", "")

    with pytest.raises(ValueError):
        samplers.GridSampler._check_value("x", [1])


def test_has_same_search_space() -> None:

    search_space: Dict[str, List[Union[int, str]]] = {"x": [3, 2, 1], "y": ["a", "b", "c"]}
    sampler = samplers.GridSampler(search_space)
    assert sampler._same_search_space(search_space)
    assert sampler._same_search_space({"x": [3, 2, 1], "y": ["a", "b", "c"]})
    assert sampler._same_search_space({"y": ["c", "a", "b"], "x": [1, 2, 3]})

    assert not sampler._same_search_space({"x": [3, 2, 1, 0], "y": ["a", "b", "c"]})
    assert not sampler._same_search_space({"x": [3, 2], "y": ["a", "b", "c"]})


def test_retried_trial() -> None:
    sampler = samplers.GridSampler({"a": [0, 50]})
    study = optuna.create_study(sampler=sampler)
    trial = study.ask()
    trial.suggest_int("a", 0, 100)

    callback = RetryFailedTrialCallback()
    callback(study, study.trials[0])

    study.optimize(lambda trial: trial.suggest_int("a", 0, 100))

    assert len(study.trials) == 3
    assert study.trials[0].params["a"] == study.trials[1].params["a"]
    assert study.trials[0].system_attrs["grid_id"] == study.trials[1].system_attrs["grid_id"]


def test_enqueued_trial() -> None:
    sampler = samplers.GridSampler({"a": [0, 50]})
    study = optuna.create_study(sampler=sampler)
    study.enqueue_trial({"a": 100})

    study.optimize(lambda trial: trial.suggest_int("a", 0, 100))

    assert len(study.trials) == 3
    assert study.trials[0].params["a"] == 100
    assert sorted([study.trials[1].params["a"], study.trials[2].params["a"]]) == [0, 50]


def test_enqueued_insufficient_trial() -> None:
    sampler = samplers.GridSampler({"a": [0, 50]})
    study = optuna.create_study(sampler=sampler)
    study.enqueue_trial({})

    with pytest.raises(ValueError):
        study.optimize(lambda trial: trial.suggest_int("a", 0, 100))
