"""
mbed SDK
Copyright (c) 2011-2015 ARM Limited

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

Author: Przemyslaw Wirkus <Przemyslaw.Wirkus@arm.com>
"""

try:
    from imp import load_source
except ImportError:
    import importlib
    import sys

    def load_source(module_name, file_path):
        spec = importlib.util.spec_from_file_location(module_name, file_path)
        module = importlib.util.module_from_spec(spec)
        spec.loader.exec_module(module)
        sys.modules[module_name] = module
        return module


from inspect import getmembers, isclass
from os import listdir
from os.path import abspath, exists, isdir, isfile, join

from ..host_tests.base_host_test import BaseHostTest


class HostRegistry:
    """ Class stores registry with host tests and objects representing them
    """
    HOST_TESTS = {}  # Map between host_test_name -> host_test_object

    def register_host_test(self, ht_name, ht_object):
        """! Registers host test object by name

        @param ht_name Host test unique name
        @param ht_object Host test class object
        """
        if ht_name not in self.HOST_TESTS:
            self.HOST_TESTS[ht_name] = ht_object

    def unregister_host_test(self, ht_name):
        """! Unregisters host test object by name

        @param ht_name Host test unique name
        """
        if ht_name in self.HOST_TESTS:
            del self.HOST_TESTS[ht_name]

    def get_host_test(self, ht_name):
        """! Fetches host test object by name

        @param ht_name Host test unique name

        @return Host test callable object or None if object is not found
        """
        return self.HOST_TESTS[ht_name] if ht_name in self.HOST_TESTS else None

    def is_host_test(self, ht_name):
        """! Checks (by name) if host test object is registered already

        @param ht_name Host test unique name

        @return True if ht_name is registered (available), else False
        """
        return (ht_name in self.HOST_TESTS and
                self.HOST_TESTS[ht_name] is not None)

    def table(self, verbose=False):
        """! Prints list of registered host test classes (by name)
            @Detail For devel & debug purposes
        """
        from prettytable import PrettyTable, HEADER
        column_names = ['name', 'class', 'origin']
        pt = PrettyTable(column_names, junction_char="|", hrules=HEADER)
        for column in column_names:
            pt.align[column] = 'l'

        for name, host_test in sorted(self.HOST_TESTS.items()):
            cls_str = str(host_test.__class__)
            if host_test.script_location:
                src_path = host_test.script_location
            else:
                src_path = 'mbed-host-tests'
            pt.add_row([name, cls_str, src_path])
        return pt.get_string()

    def register_from_path(self, path, verbose=False):
        """ Enumerates and registers locally stored host tests
            Host test are derived from mbed_host_tests.BaseHostTest classes
        """
        if path:
            path = path.strip('"')
            if verbose:
                print("HOST: Inspecting '%s' for local host tests..." % path)
            if exists(path) and isdir(path):
                python_modules = [
                    f for f in listdir(path)
                    if isfile(join(path, f)) and f.endswith(".py")
                ]
                for module_file in python_modules:
                    self._add_module_to_registry(path, module_file, verbose)

    def _add_module_to_registry(self, path, module_file, verbose):
        module_name = module_file[:-3]
        try:
            mod = load_source(module_name, abspath(join(path, module_file)))
        except Exception as e:
            print(
                "HOST: Error! While loading local host test module '%s'"
                % join(path, module_file)
            )
            print("HOST: %s" % str(e))
            return
        if verbose:
            print("HOST: Loading module '%s': %s" % (module_file, str(mod)))

        for name, obj in getmembers(mod):
            if (
                isclass(obj) and
                issubclass(obj, BaseHostTest) and
                str(obj) != str(BaseHostTest)
            ):
                if obj.name:
                    host_test_name = obj.name
                else:
                    host_test_name = module_name
                host_test_cls = obj
                host_test_cls.script_location = join(path, module_file)
                if verbose:
                    print(
                        "HOST: Found host test implementation: %s -|> %s"
                        % (str(obj), str(BaseHostTest))
                    )
                    print(
                        "HOST: Registering '%s' as '%s'"
                        % (str(host_test_cls), host_test_name)
                    )
                self.register_host_test(
                    host_test_name, host_test_cls()
                )