import importlib
import re
import sys


TEST_MODULE = re.compile(r'tests\.((?:\w.+\.)*)test_(\w+)')
FIDDLE_WITH_COVERAGE = False


def module_path(test_module):
    match = TEST_MODULE.fullmatch(test_module)
    if match:
        yield ''.join(match.groups())


def pytest_addoption(parser):
    parser.addoption('--divide-and-cover', action='store_true',
                     help='activate divide and cover tracing')


def pytest_configure(config):
    if config.option.divide_and_cover:
        from coverage_handler import UNDER_WRAPPER
        if UNDER_WRAPPER:
            global FIDDLE_WITH_COVERAGE
            FIDDLE_WITH_COVERAGE = True
        else:
            print('Warning: called with --divide-and-cover, but not running '
                  'under divide_and_cover. Not activating plugin.')


# This is probably wrong
def pytest_collection_modifyitems(session, config, items):
    if FIDDLE_WITH_COVERAGE:
        from .coverage_handler import coverage_script
        modules = sys.modules.copy()
        paths = []
        for test_path in modules:
            for module_path_ in module_path(test_path):
                paths.append(module_path_)
                coverage_script.new_coverage(test_path, module_path_)
        # This next bit needs to be run under a coverage tracer, with source
        # based on paths. Specifically, it should use the root package from
        # each path
        roots = sorted({path.split('.', 1)[0] for path in paths})
        coverage_script.make_import_coverage(roots)
        print('Covering packages under: {}'.format(roots))
        coverage_script.switch_coverage(coverage_script.import_coverage)
        try:
            for path in paths:
                try:
                    importlib.import_module(path)
                except ImportError:
                    print('Could not import {}'.format(path))
        finally:
            coverage_script.deactivate_coverage()


def pytest_runtest_setup(item):
    if FIDDLE_WITH_COVERAGE:
        from .coverage_handler import coverage_script
        coverage_script.activate_coverage(item.obj.__module__)


def pytest_runtest_teardown(item, nextitem):
    if FIDDLE_WITH_COVERAGE:
        from .coverage_handler import coverage_script
        coverage_script.deactivate_coverage()