import os
import operator
import sys
import contextlib
import itertools
import unittest
from distutils.errors import DistutilsError, DistutilsOptionError
from distutils import log
from unittest import TestLoader

from setuptools.extern import six
from setuptools.extern.six.moves import map, filter

from pkg_resources import (resource_listdir, resource_exists, normalize_path,
                           working_set, _namespace_packages, evaluate_marker,
                           add_activation_listener, require, EntryPoint)
from setuptools import Command
from .build_py import _unique_everseen

__metaclass__ = type


class ScanningLoader(TestLoader):

    def __init__(self):
        TestLoader.__init__(self)
        self._visited = set()

    def loadTestsFromModule(self, module, pattern=None):
        """Return a suite of all tests cases contained in the given module

        If the module is a package, load tests from all the modules in it.
        If the module has an ``additional_tests`` function, call it and add
        the return value to the tests.
        """
        if module in self._visited:
            return None
        self._visited.add(module)

        tests = []
        tests.append(TestLoader.loadTestsFromModule(self, module))

        if hasattr(module, "additional_tests"):
            tests.append(module.additional_tests())

        if hasattr(module, '__path__'):
            for file in resource_listdir(module.__name__, ''):
                if file.endswith('.py') and file != '__init__.py':
                    submodule = module.__name__ + '.' + file[:-3]
                else:
                    if resource_exists(module.__name__, file + '/__init__.py'):
                        submodule = module.__name__ + '.' + file
                    else:
                        continue
                tests.append(self.loadTestsFromName(submodule))

        if len(tests) != 1:
            return self.suiteClass(tests)
        else:
            return tests[0]  # don't create a nested suite for only one return


# adapted from jaraco.classes.properties:NonDataProperty
class NonDataProperty:
    def __init__(self, fget):
        self.fget = fget

    def __get__(self, obj, objtype=None):
        if obj is None:
            return self
        return self.fget(obj)


class test(Command):
    """Command to run unit tests after in-place build"""

    description = "run unit tests after in-place build"

    user_options = [
        ('test-module=', 'm', "Run 'test_suite' in specified module"),
        ('test-suite=', 's',
         "Run single test, case or suite (e.g. 'module.test_suite')"),
        ('test-runner=', 'r', "Test runner to use"),
    ]

    def initialize_options(self):
        self.test_suite = None
        self.test_module = None
        self.test_loader = None
        self.test_runner = None

    def finalize_options(self):

        if self.test_suite and self.test_module:
            msg = "You may specify a module or a suite, but not both"
            raise DistutilsOptionError(msg)

        if self.test_suite is None:
            if self.test_module is None:
                self.test_suite = self.distribution.test_suite
            else:
                self.test_suite = self.test_module + ".test_suite"

        if self.test_loader is None:
            self.test_loader = getattr(self.distribution, 'test_loader', None)
        if self.test_loader is None:
            self.test_loader = "setuptools.command.test:ScanningLoader"
        if self.test_runner is None:
            self.test_runner = getattr(self.distribution, 'test_runner', None)

    @NonDataProperty
    def test_args(self):
        return list(self._test_args())

    def _test_args(self):
        if not self.test_suite and sys.version_info >= (2, 7):
            yield 'discover'
        if self.verbose:
            yield '--verbose'
        if self.test_suite:
            yield self.test_suite

    def with_project_on_sys_path(self, func):
        """
        Backward compatibility for project_on_sys_path context.
        """
        with self.project_on_sys_path():
            func()

    @contextlib.contextmanager
    def project_on_sys_path(self, include_dists=[]):
        with_2to3 = six.PY3 and getattr(self.distribution, 'use_2to3', False)

        if with_2to3:
            # If we run 2to3 we can not do this inplace:

            # Ensure metadata is up-to-date
            self.reinitialize_command('build_py', inplace=0)
            self.run_command('build_py')
            bpy_cmd = self.get_finalized_command("build_py")
            build_path = normalize_path(bpy_cmd.build_lib)

            # Build extensions
            self.reinitialize_command('egg_info', egg_base=build_path)
            self.run_command('egg_info')

            self.reinitialize_command('build_ext', inplace=0)
            self.run_command('build_ext')
        else:
            # Without 2to3 inplace works fine:
            self.run_command('egg_info')

            # Build extensions in-place
            self.reinitialize_command('build_ext', inplace=1)
            self.run_command('build_ext')

        ei_cmd = self.get_finalized_command("egg_info")

        old_path = sys.path[:]
        old_modules = sys.modules.copy()

        try:
            project_path = normalize_path(ei_cmd.egg_base)
            sys.path.insert(0, project_path)
            working_set.__init__()
            add_activation_listener(lambda dist: dist.activate())
            require('%s==%s' % (ei_cmd.egg_name, ei_cmd.egg_version))
            with self.paths_on_pythonpath([project_path]):
                yield
        finally:
            sys.path[:] = old_path
            sys.modules.clear()
            sys.modules.update(old_modules)
            working_set.__init__()

    @staticmethod
    @contextlib.contextmanager
    def paths_on_pythonpath(paths):
        """
        Add the indicated paths to the head of the PYTHONPATH environment
        variable so that subprocesses will also see the packages at
        these paths.

        Do this in a context that restores the value on exit.
        """
        nothing = object()
        orig_pythonpath = os.environ.get('PYTHONPATH', nothing)
        current_pythonpath = os.environ.get('PYTHONPATH', '')
        try:
            prefix = os.pathsep.join(_unique_everseen(paths))
            to_join = filter(None, [prefix, current_pythonpath])
            new_path = os.pathsep.join(to_join)
            if new_path:
                os.environ['PYTHONPATH'] = new_path
            yield
        finally:
            if orig_pythonpath is nothing:
                os.environ.pop('PYTHONPATH', None)
            else:
                os.environ['PYTHONPATH'] = orig_pythonpath

    @staticmethod
    def install_dists(dist):
        """
        Install the requirements indicated by self.distribution and
        return an iterable of the dists that were built.
        """
        ir_d = dist.fetch_build_eggs(dist.install_requires)
        tr_d = dist.fetch_build_eggs(dist.tests_require or [])
        er_d = dist.fetch_build_eggs(
            v for k, v in dist.extras_require.items()
            if k.startswith(':') and evaluate_marker(k[1:])
        )
        return itertools.chain(ir_d, tr_d, er_d)

    def run(self):
        installed_dists = self.install_dists(self.distribution)

        cmd = ' '.join(self._argv)
        if self.dry_run:
            self.announce('skipping "%s" (dry run)' % cmd)
            return

        self.announce('running "%s"' % cmd)

        paths = map(operator.attrgetter('location'), installed_dists)
        with self.paths_on_pythonpath(paths):
            with self.project_on_sys_path():
                self.run_tests()

    def run_tests(self):
        # Purge modules under test from sys.modules. The test loader will
        # re-import them from the build location. Required when 2to3 is used
        # with namespace packages.
        if six.PY3 and getattr(self.distribution, 'use_2to3', False):
            module = self.test_suite.split('.')[0]
            if module in _namespace_packages:
                del_modules = []
                if module in sys.modules:
                    del_modules.append(module)
                module += '.'
                for name in sys.modules:
                    if name.startswith(module):
                        del_modules.append(name)
                list(map(sys.modules.__delitem__, del_modules))

        test = unittest.main(
            None, None, self._argv,
            testLoader=self._resolve_as_ep(self.test_loader),
            testRunner=self._resolve_as_ep(self.test_runner),
            exit=False,
        )
        if not test.result.wasSuccessful():
            msg = 'Test failed: %s' % test.result
            self.announce(msg, log.ERROR)
            raise DistutilsError(msg)

    @property
    def _argv(self):
        return ['unittest'] + self.test_args

    @staticmethod
    def _resolve_as_ep(val):
        """
        Load the indicated attribute value, called, as a as if it were
        specified as an entry point.
        """
        if val is None:
            return
        parsed = EntryPoint.parse("x=" + val)
        return parsed.resolve()()
