import random
import sys
import traceback
import warnings

import pytest

from random_order.bucket_types import bucket_type_keys, bucket_types
from random_order.cache import process_failed_first_last_failed
from random_order.config import Config
from random_order.shuffler import _disable, _get_set_of_item_ids, _shuffle_items


def pytest_addoption(parser):
    group = parser.getgroup('pytest-random-order options')
    group.addoption(
        '--random-order',
        action='store_true',
        dest='random_order_enabled',
        help='Randomise test order (by default, it is disabled) with default configuration.',
    )
    group.addoption(
        '--random-order-bucket',
        action='store',
        dest='random_order_bucket',
        default=Config.default_value('module'),
        choices=bucket_types,
        help='Randomise test order within specified test buckets.',
    )
    group.addoption(
        '--random-order-seed',
        action='store',
        dest='random_order_seed',
        default=Config.default_value(str(random.randint(1, 1000000))),
        help='Randomise test order using a specific seed.',
    )


def pytest_configure(config):
    config.addinivalue_line(
        'markers',
        'random_order(disabled=True): disable reordering of tests within a module or class'
    )


def pytest_report_header(config):
    plugin = Config(config)
    if not plugin.is_enabled:
        return "Test order randomisation NOT enabled. Enable with --random-order or --random-order-bucket=<bucket_type>"
    return (
        'Using --random-order-bucket={plugin.bucket_type}\n'
        'Using --random-order-seed={plugin.seed}\n'
    ).format(plugin=plugin)


def pytest_collection_modifyitems(session, config, items):
    failure = None

    session.random_order_bucket_type_key_handlers = []
    process_failed_first_last_failed(session, config, items)

    item_ids = _get_set_of_item_ids(items)

    plugin = Config(config)

    try:
        seed = plugin.seed
        bucket_type = plugin.bucket_type
        if bucket_type != 'none':
            _shuffle_items(
                items,
                bucket_key=bucket_type_keys[bucket_type],
                disable=_disable,
                seed=seed,
                session=session,
            )

    except Exception as e:
        # See the finally block -- we only fail if we have lost user's tests.
        _, _, exc_tb = sys.exc_info()
        failure = 'pytest-random-order plugin has failed with {0!r}:\n{1}'.format(
            e, ''.join(traceback.format_tb(exc_tb, 10))
        )
        if not hasattr(pytest, "PytestWarning"):
            config.warn(0, failure, None)
        else:
            warnings.warn(pytest.PytestWarning(failure))

    finally:
        # Fail only if we have lost user's tests
        if item_ids != _get_set_of_item_ids(items):
            if not failure:
                failure = 'pytest-random-order plugin has failed miserably'
            raise RuntimeError(failure)
