import os
import re
import sys

# This must run on Python versions less than 2.4.
dirname = os.path.dirname(sys.modules[__name__].__file__)
common_dir = os.path.abspath(os.path.join(dirname, 'common_lib'))
sys.path.insert(0, common_dir)
import check_version
sys.path.pop(0)


def _get_pyversion_from_args():
    """Extract, format, & pop the current py_version from args, if provided."""
    py_version = 2
    py_version_re = re.compile(r'--py_version=(\w+)\b')

    version_found = False
    for i, arg in enumerate(sys.argv):
        if not arg.startswith('--py_version'):
            continue
        result = py_version_re.search(arg)
        if result:
            if version_found:
                raise ValueError('--py_version may only be specified once.')
            py_version = result.group(1)
            version_found = True
            if py_version not in ('2', '3'):
                raise ValueError('Python version must be "2" or "3".')

            # Remove the arg so other argparsers don't get grumpy.
            sys.argv.pop(i)

    return py_version


def _desired_version():
    """
    Returns desired python version.

    If the PY_VERSION env var is set, just return that. This is the case
    when autoserv kicks of autotest on the server side via a job.run(), or
    a process created a subprocess.

    Otherwise, parse & pop the sys.argv for the '--py_version' flag. If no
    flag is set, default to python 2 (for now).

    """
    # Even if the arg is in the env vars, we will attempt to get it from the
    # args, so that it can be popped prior to other argparsers hitting.
    py_version = _get_pyversion_from_args()

    if os.getenv('PY_VERSION'):
        return int(os.getenv('PY_VERSION'))

    os.environ['PY_VERSION'] = str(py_version)
    return int(py_version)


desired_version = _desired_version()
if desired_version == sys.version_info.major:
    os.environ['AUTOTEST_NO_RESTART'] = 'True'
else:
    # There are cases were this can be set (ie by test_that), but a subprocess
    # is launched in the incorrect version.
    if os.getenv('AUTOTEST_NO_RESTART'):
        del os.environ['AUTOTEST_NO_RESTART']
    check_version.check_python_version(desired_version)

import glob, traceback, types


def _create_module(name):
    """Create a single top-level module"""
    module = types.ModuleType(name)
    sys.modules[name] = module
    return module


def _create_module_and_parents(name):
    """Create a module, and all the necessary parents"""
    parts = name.split('.')
    # first create the top-level module
    parent = _create_module(parts[0])
    created_parts = [parts[0]]
    parts.pop(0)
    # now, create any remaining child modules
    while parts:
        child_name = parts.pop(0)
        module = types.ModuleType(child_name)
        setattr(parent, child_name, module)
        created_parts.append(child_name)
        sys.modules['.'.join(created_parts)] = module
        parent = module


def _import_children_into_module(parent_module_name, path):
    """Import all the packages on a path into a parent module"""
    # find all the packages at 'path'
    names = []
    for filename in os.listdir(path):
        full_name = os.path.join(path, filename)
        if not os.path.isdir(full_name):
            continue   # skip files
        if '.' in filename:
            continue  # if '.' is in the name it's not a valid package name
        if not os.access(full_name, os.R_OK | os.X_OK):
            continue   # need read + exec access to make a dir importable
        if '__init__.py' in os.listdir(full_name):
            names.append(filename)
    # import all the packages and insert them into 'parent_module'
    sys.path.insert(0, path)
    for name in names:
        module = __import__(name)
        # add the package to the parent
        parent_module = sys.modules[parent_module_name]
        setattr(parent_module, name, module)
        full_name = parent_module_name + '.' + name
        sys.modules[full_name] = module
    # restore the system path
    sys.path.pop(0)


def import_module(module, from_where):
    """Equivalent to 'from from_where import module'
    Returns the corresponding module"""
    from_module = __import__(from_where, globals(), locals(), [module])
    return getattr(from_module, module)


def _autotest_logging_handle_error(self, record):
    """Method to monkey patch into logging.Handler to replace handleError."""
    # The same as the default logging.Handler.handleError but also prints
    # out the original record causing the error so there is -some- idea
    # about which call caused the logging error.
    import logging
    if logging.raiseExceptions:
        # Avoid recursion as the below output can end up back in here when
        # something has *seriously* gone wrong in autotest.
        logging.raiseExceptions = 0
        sys.stderr.write('Exception occurred formatting message: '
                         '%r using args %r\n' % (record.msg, record.args))
        traceback.print_stack()
        sys.stderr.write('-' * 50 + '\n')
        traceback.print_exc()
        sys.stderr.write('Future logging formatting exceptions disabled.\n')


def _monkeypatch_logging_handle_error():
    # Hack out logging.py*
    logging_py = os.path.join(os.path.dirname(__file__), 'common_lib',
                              'logging.py*')
    if glob.glob(logging_py):
        os.system('rm -f %s' % logging_py)

    # Monkey patch our own handleError into the logging module's StreamHandler.
    # A nicer way of doing this -might- be to have our own logging module define
    # an autotest Logger instance that added our own Handler subclass with this
    # handleError method in it.  But that would mean modifying tons of code.
    import logging
    assert callable(logging.Handler.handleError)
    logging.Handler.handleError = _autotest_logging_handle_error


def setup(base_path, root_module_name=""):
    """
    Perform all the necessary setup so that all the packages at
    'base_path' can be imported via "import root_module_name.package".
    If root_module_name is empty, then all the packages at base_path
    are inserted as top-level packages.

    Also, setup all the common.* aliases for modules in the common
    library.

    The setup must be different if you are running on an Autotest server
    or on a test machine that just has the client directories installed.
    """
    # Hack... Any better ideas?
    if (root_module_name == 'autotest_lib.client' and
        os.path.exists(os.path.join(os.path.dirname(__file__),
                                    '..', 'server'))):
        root_module_name = 'autotest_lib'
        base_path = os.path.abspath(os.path.join(base_path, '..'))

    _create_module_and_parents(root_module_name)
    _import_children_into_module(root_module_name, base_path)

    if root_module_name == 'autotest_lib':
        # Allow locally installed third party packages to be found
        # before any that are installed on the system itself when not.
        # running as a client.
        # This is primarily for the benefit of frontend and tko so that they
        # may use libraries other than those available as system packages.
        sys.path.insert(0, os.path.join(base_path, 'site-packages'))

    _monkeypatch_logging_handle_error()