# This file is part of Hypothesis, which may be found at
# https://github.com/HypothesisWorks/hypothesis/
#
# Copyright the Hypothesis Authors.
# Individual contributors are listed in AUTHORS.rst and the git log.
#
# This Source Code Form is subject to the terms of the Mozilla Public License,
# v. 2.0. If a copy of the MPL was not distributed with this file, You can
# obtain one at https://mozilla.org/MPL/2.0/.

import math
from random import Random

import pytest

from hypothesis import HealthCheck, assume, example, given, settings
from hypothesis.internal.conjecture.choice import ChoiceNode
from hypothesis.internal.conjecture.data import Status
from hypothesis.internal.conjecture.datatree import compute_max_children
from hypothesis.internal.conjecture.engine import ConjectureRunner, RunIsComplete
from hypothesis.internal.intervalsets import IntervalSet

from tests.conjecture.common import (
    buffer_size_limit,
    integer_constr,
    nodes,
)

runner_settings = settings(
    max_examples=100, database=None, suppress_health_check=list(HealthCheck)
)


def test_optimises_to_maximum():
    def test(data):
        data.target_observations["m"] = data.draw_integer(0, 2**8 - 1)

    runner = ConjectureRunner(test, settings=runner_settings, random=Random(0))
    runner.cached_test_function((0,))

    try:
        runner.optimise_targets()
    except RunIsComplete:
        pass

    assert runner.best_observed_targets["m"] == 255


def test_optimises_multiple_targets():
    def test(data):
        n = data.draw_integer(0, 2**8 - 1)
        m = data.draw_integer(0, 2**8 - 1)
        if n + m > 256:
            data.mark_invalid()
        data.target_observations["m"] = m
        data.target_observations["n"] = n
        data.target_observations["m + n"] = m + n

    runner = ConjectureRunner(test, settings=runner_settings, random=Random(0))
    runner.cached_test_function((200, 0))
    runner.cached_test_function((0, 200))

    try:
        runner.optimise_targets()
    except RunIsComplete:
        pass

    assert runner.best_observed_targets["m"] == 255
    assert runner.best_observed_targets["n"] == 255
    assert runner.best_observed_targets["m + n"] == 256


def test_optimises_when_last_element_is_empty():
    def test(data):
        data.target_observations["n"] = data.draw_integer(0, 2**8 - 1)
        data.start_span(label=1)
        data.stop_span()

    runner = ConjectureRunner(test, settings=runner_settings, random=Random(0))
    runner.cached_test_function((250,))

    try:
        runner.optimise_targets()
    except RunIsComplete:
        pass

    assert runner.best_observed_targets["n"] == 255


def test_can_optimise_last_with_following_empty():
    def test(data):
        for _ in range(100):
            data.draw_integer(0, 3)
        data.target_observations[""] = data.draw_integer(0, 2**8 - 1)
        data.start_span(1)
        data.stop_span()

    runner = ConjectureRunner(
        test, settings=settings(runner_settings, max_examples=100), random=Random(0)
    )
    runner.cached_test_function((0,) * 101)

    with pytest.raises(RunIsComplete):
        runner.optimise_targets()
    assert runner.best_observed_targets[""] == 255


@pytest.mark.parametrize("lower, upper", [(0, 1000), (13, 100), (1000, 2**16 - 1)])
@pytest.mark.parametrize("score_up", [False, True])
def test_can_find_endpoints_of_a_range(lower, upper, score_up):
    def test(data):
        n = data.draw_integer(0, 2**16 - 1)
        if n < lower or n > upper:
            data.mark_invalid()
        if not score_up:
            n = -n
        data.target_observations["n"] = n

    runner = ConjectureRunner(
        test, settings=settings(runner_settings, max_examples=1000), random=Random(0)
    )
    runner.cached_test_function(((lower + upper) // 2,))

    try:
        runner.optimise_targets()
    except RunIsComplete:
        pass
    if score_up:
        assert runner.best_observed_targets["n"] == upper
    else:
        assert runner.best_observed_targets["n"] == -lower


def test_targeting_can_drive_length_very_high():
    def test(data):
        count = 0
        while data.draw_boolean(0.25):
            count += 1
        data.target_observations[""] = min(count, 100)

    runner = ConjectureRunner(test, settings=runner_settings, random=Random(0))
    # extend here to ensure we get a valid (non-overrun) test case. The
    # outcome of the test case doesn't really matter as long as we have
    # something for the runner to optimize.
    runner.cached_test_function([], extend=50)

    try:
        runner.optimise_targets()
    except RunIsComplete:
        pass

    assert runner.best_observed_targets[""] == 100


def test_optimiser_when_test_grows_buffer_to_invalid():
    def test(data):
        m = data.draw_integer(0, 2**8 - 1)
        data.target_observations["m"] = m
        if m > 100:
            data.draw_integer(0, 2**16 - 1)
            data.mark_invalid()

    runner = ConjectureRunner(test, settings=runner_settings, random=Random(0))
    runner.cached_test_function((0,) * 10)

    try:
        runner.optimise_targets()
    except RunIsComplete:
        pass

    assert runner.best_observed_targets["m"] == 100


def test_can_patch_up_examples():
    def test(data):
        data.start_span(42)
        m = data.draw_integer(0, 2**6 - 1)
        data.target_observations["m"] = m
        for _ in range(m):
            data.draw_boolean()
        data.stop_span()
        for i in range(4):
            if i != data.draw_integer(0, 2**8 - 1):
                data.mark_invalid()

    runner = ConjectureRunner(
        test, settings=settings(runner_settings, max_examples=1000), random=Random(0)
    )
    d = runner.cached_test_function((0, 0, 1, 2, 3, 4))
    assert d.status == Status.VALID

    try:
        runner.optimise_targets()
    except RunIsComplete:
        pass

    assert runner.best_observed_targets["m"] == 63


def test_optimiser_when_test_grows_buffer_to_overflow():
    def test(data):
        m = data.draw_integer(0, 2**8 - 1)
        data.target_observations["m"] = m
        if m > 100:
            data.draw_integer(0, 2**64 - 1)
            data.mark_invalid()

    runner = ConjectureRunner(test, settings=runner_settings, random=Random(0))

    with buffer_size_limit(2):
        runner.cached_test_function((0,) * 10)

        try:
            runner.optimise_targets()
        except RunIsComplete:
            pass

    assert runner.best_observed_targets["m"] == 100


@given(nodes())
@example(
    ChoiceNode(
        type="bytes",
        value=b"\xb1",
        constraints={"min_size": 1, "max_size": 1},
        was_forced=False,
    )
)
@example(
    ChoiceNode(
        type="string",
        value="aaaa",
        constraints={
            "min_size": 0,
            "max_size": 10,
            "intervals": IntervalSet.from_string("abcd"),
        },
        was_forced=False,
    )
)
@example(
    ChoiceNode(
        type="integer", value=1, constraints=integer_constr(0, 200), was_forced=False
    )
)
def test_optimising_all_nodes(node):
    assume(compute_max_children(node.type, node.constraints) > 50)
    size_function = {
        "integer": lambda n: n,
        "float": lambda f: f if math.isfinite(f) else 0,
        "string": lambda s: len(s),
        "bytes": lambda b: len(b),
        "boolean": lambda b: int(b),
    }

    def test(data):
        v = getattr(data, f"draw_{node.type}")(**node.constraints)
        data.target_observations["v"] = size_function[node.type](v)

    runner = ConjectureRunner(
        test, settings=settings(runner_settings, max_examples=50), random=Random(0)
    )
    runner.cached_test_function([node.value])

    try:
        runner.optimise_targets()
    except RunIsComplete:
        pass