from copy import deepcopy
import pytest

import build.phase0.spec as spec

from build.phase0.state_transition import (
    state_transition,
)
from build.phase0.spec import (
    ZERO_HASH,
    get_current_epoch,
    process_attestation,
    slot_to_epoch,
)
from tests.phase0.helpers import (
    build_empty_block_for_next_slot,
    get_valid_attestation,
)


# mark entire file as 'attestations'
pytestmark = pytest.mark.attestations


def run_attestation_processing(state, attestation, valid=True):
    """
    Run ``process_attestation`` returning the pre and post state.
    If ``valid == False``, run expecting ``AssertionError``
    """
    post_state = deepcopy(state)

    if not valid:
        with pytest.raises(AssertionError):
            process_attestation(post_state, attestation)
        return state, None

    process_attestation(post_state, attestation)

    current_epoch = get_current_epoch(state)
    target_epoch = slot_to_epoch(attestation.data.slot)
    if target_epoch == current_epoch:
        assert len(post_state.current_epoch_attestations) == len(state.current_epoch_attestations) + 1
    else:
        assert len(post_state.previous_epoch_attestations) == len(state.previous_epoch_attestations) + 1

    return state, post_state


def test_success(state):
    attestation = get_valid_attestation(state)
    state.slot += spec.MIN_ATTESTATION_INCLUSION_DELAY

    pre_state, post_state = run_attestation_processing(state, attestation)

    return pre_state, attestation, post_state


def test_success_prevous_epoch(state):
    attestation = get_valid_attestation(state)
    block = build_empty_block_for_next_slot(state)
    block.slot = state.slot + spec.SLOTS_PER_EPOCH
    state_transition(state, block)

    pre_state, post_state = run_attestation_processing(state, attestation)

    return pre_state, attestation, post_state


def test_before_inclusion_delay(state):
    attestation = get_valid_attestation(state)
    # do not increment slot to allow for inclusion delay

    pre_state, post_state = run_attestation_processing(state, attestation, False)

    return pre_state, attestation, post_state


def test_after_epoch_slots(state):
    attestation = get_valid_attestation(state)
    block = build_empty_block_for_next_slot(state)
    # increment past latest inclusion slot
    block.slot = state.slot + spec.SLOTS_PER_EPOCH + 1
    state_transition(state, block)

    pre_state, post_state = run_attestation_processing(state, attestation, False)

    return pre_state, attestation, post_state


def test_bad_source_epoch(state):
    attestation = get_valid_attestation(state)
    state.slot += spec.MIN_ATTESTATION_INCLUSION_DELAY

    attestation.data.source_epoch += 10

    pre_state, post_state = run_attestation_processing(state, attestation, False)

    return pre_state, attestation, post_state


def test_bad_source_root(state):
    attestation = get_valid_attestation(state)
    state.slot += spec.MIN_ATTESTATION_INCLUSION_DELAY

    attestation.data.source_root = b'\x42'*32

    pre_state, post_state = run_attestation_processing(state, attestation, False)

    return pre_state, attestation, post_state


def test_non_zero_crosslink_data_root(state):
    attestation = get_valid_attestation(state)
    state.slot += spec.MIN_ATTESTATION_INCLUSION_DELAY

    attestation.data.crosslink_data_root = b'\x42'*32

    pre_state, post_state = run_attestation_processing(state, attestation, False)

    return pre_state, attestation, post_state


def test_bad_previous_crosslink(state):
    attestation = get_valid_attestation(state)
    state.slot += spec.MIN_ATTESTATION_INCLUSION_DELAY

    state.latest_crosslinks[attestation.data.shard].epoch += 10

    pre_state, post_state = run_attestation_processing(state, attestation, False)

    return pre_state, attestation, post_state


def test_non_empty_custody_bitfield(state):
    attestation = get_valid_attestation(state)
    state.slot += spec.MIN_ATTESTATION_INCLUSION_DELAY

    attestation.custody_bitfield = deepcopy(attestation.aggregation_bitfield)

    pre_state, post_state = run_attestation_processing(state, attestation, False)

    return pre_state, attestation, post_state


def test_empty_aggregation_bitfield(state):
    attestation = get_valid_attestation(state)
    state.slot += spec.MIN_ATTESTATION_INCLUSION_DELAY

    attestation.aggregation_bitfield = b'\x00' * len(attestation.aggregation_bitfield)

    pre_state, post_state = run_attestation_processing(state, attestation, False)

    return pre_state, attestation, post_state