#
#    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.

import collections
import copy
import fnmatch
import glob
import itertools
import os.path
import warnings

from oslo_config import cfg
from oslo_log import log
from oslo_utils import encodeutils
import six

from heat.common import environment_format as env_fmt
from heat.common import exception
from heat.common.i18n import _
from heat.common.i18n import _LE
from heat.common.i18n import _LI
from heat.common.i18n import _LW
from heat.engine import support

LOG = log.getLogger(__name__)


HOOK_TYPES = (HOOK_PRE_CREATE, HOOK_PRE_UPDATE) = ('pre-create', 'pre-update')


def valid_hook_type(hook):
    return hook in HOOK_TYPES


def is_hook_definition(key, value):
    if key == 'hooks':
        if isinstance(value, six.string_types):
            return valid_hook_type(value)
        elif isinstance(value, collections.Sequence):
            return all(valid_hook_type(hook) for hook in value)
        else:
            return False
    return False


class ResourceInfo(object):
    """Base mapping of resource type to implementation."""

    def __new__(cls, registry, path, value, **kwargs):
        '''Create a new ResourceInfo of the appropriate class.'''

        if cls != ResourceInfo:
            # Call is already for a subclass, so pass it through
            return super(ResourceInfo, cls).__new__(cls)

        name = path[-1]
        if name.endswith(('.yaml', '.template')):
            # a template url for the resource "Type"
            return TemplateResourceInfo(registry, path, value)
        elif not isinstance(value, six.string_types):
            return ClassResourceInfo(registry, path, value)
        elif value.endswith(('.yaml', '.template')):
            # a registered template
            return TemplateResourceInfo(registry, path, value)
        elif name.endswith('*'):
            return GlobResourceInfo(registry, path, value)
        else:
            return MapResourceInfo(registry, path, value)

    def __init__(self, registry, path, value):
        self.registry = registry
        self.path = path
        self.name = path[-1]
        self.value = value
        self.user_resource = True

    def __eq__(self, other):
        if other is None:
            return False
        return (self.path == other.path and
                self.value == other.value and
                self.user_resource == other.user_resource)

    def __ne__(self, other):
        return not self.__eq__(other)

    def __lt__(self, other):
        if self.user_resource != other.user_resource:
            # user resource must be sorted above system ones.
            return self.user_resource > other.user_resource
        if len(self.path) != len(other.path):
            # more specific (longer) path must be sorted above system ones.
            return len(self.path) > len(other.path)
        return self.path < other.path

    def __gt__(self, other):
        return other.__lt__(self)

    def get_resource_info(self, resource_type=None, resource_name=None):
        return self

    def matches(self, resource_type):
        return False

    def __str__(self):
        return '[%s](User:%s) %s -> %s' % (self.description,
                                           self.user_resource,
                                           self.name, str(self.value))


class ClassResourceInfo(ResourceInfo):
    """Store the mapping of resource name to python class implementation."""
    description = 'Plugin'

    def get_class(self):
        return self.value


class TemplateResourceInfo(ResourceInfo):
    """Store the info needed to start a TemplateResource."""
    description = 'Template'

    def __init__(self, registry, path, value):
        super(TemplateResourceInfo, self).__init__(registry, path, value)
        if self.name.endswith(('.yaml', '.template')):
            self.template_name = self.name
        else:
            self.template_name = value
        self.value = self.template_name

    def get_class(self):
        from heat.engine.resources import template_resource
        env = self.registry.environment
        return template_resource.generate_class(str(self.name),
                                                self.template_name,
                                                env)


class MapResourceInfo(ResourceInfo):
    """Store the mapping of one resource type to another.

    like: OS::Networking::FloatingIp -> OS::Neutron::FloatingIp
    """
    description = 'Mapping'

    def get_class(self):
        return None

    def get_resource_info(self, resource_type=None, resource_name=None):
        return self.registry.get_resource_info(self.value, resource_name)


class GlobResourceInfo(MapResourceInfo):
    """Store the mapping (with wild cards) of one resource type to another.

    like: OS::Networking::* -> OS::Neutron::*
    """
    description = 'Wildcard Mapping'

    def get_resource_info(self, resource_type=None, resource_name=None):
        orig_prefix = self.name[:-1]
        new_type = self.value[:-1] + resource_type[len(orig_prefix):]
        return self.registry.get_resource_info(new_type, resource_name)

    def matches(self, resource_type):
        return resource_type.startswith(self.name[:-1])


class ResourceRegistry(object):
    """By looking at the environment, find the resource implementation."""

    def __init__(self, global_registry, env):
        self._registry = {'resources': {}}
        self.global_registry = global_registry
        self.environment = env

    def load(self, json_snippet):
        self._load_registry([], json_snippet)

    def register_class(self, resource_type, resource_class):
        ri = ResourceInfo(self, [resource_type], resource_class)
        self._register_info([resource_type], ri)

    def _load_registry(self, path, registry):
        for k, v in iter(registry.items()):
            if v is None:
                self._register_info(path + [k], None)
            elif is_hook_definition(k, v):
                self._register_hook(path + [k], v)
            elif isinstance(v, dict):
                self._load_registry(path + [k], v)
            else:
                self._register_info(path + [k],
                                    ResourceInfo(self, path + [k], v))

    def _register_hook(self, path, hook):
        name = path[-1]
        registry = self._registry
        for key in path[:-1]:
            if key not in registry:
                registry[key] = {}
            registry = registry[key]
        registry[name] = hook

    def _register_info(self, path, info):
        """place the new info in the correct location in the registry.
        path: a list of keys ['resources', 'my_server', 'OS::Nova::Server']
        """
        descriptive_path = '/'.join(path)
        name = path[-1]
        # create the structure if needed
        registry = self._registry
        for key in path[:-1]:
            if key not in registry:
                registry[key] = {}
            registry = registry[key]

        if info is None:
            if name.endswith('*'):
                # delete all matching entries.
                for res_name in registry.keys():
                    if (isinstance(registry[res_name], ResourceInfo) and
                            res_name.startswith(name[:-1])):
                        LOG.warn(_LW('Removing %(item)s from %(path)s'), {
                            'item': res_name,
                            'path': descriptive_path})
                        del registry[res_name]
            else:
                # delete this entry.
                LOG.warn(_LW('Removing %(item)s from %(path)s'), {
                    'item': name,
                    'path': descriptive_path})
                registry.pop(name, None)
            return

        if name in registry and isinstance(registry[name], ResourceInfo):
            if registry[name] == info:
                return
            details = {
                'path': descriptive_path,
                'was': str(registry[name].value),
                'now': str(info.value)}
            LOG.warn(_LW('Changing %(path)s from %(was)s to %(now)s'),
                     details)
        else:
            LOG.info(_LI('Registering %(path)s -> %(value)s'), {
                'path': descriptive_path,
                'value': str(info.value)})

        if isinstance(info, ClassResourceInfo):
            if info.value.support_status.status != support.SUPPORTED:
                warnings.warn(encodeutils.safe_encode(
                    info.value.support_status.message))

        info.user_resource = (self.global_registry is not None)
        registry[name] = info

    def remove_item(self, info):
        if not isinstance(info, TemplateResourceInfo):
            return

        registry = self._registry
        for key in info.path[:-1]:
            registry = registry[key]
        if info.path[-1] in registry:
            registry.pop(info.path[-1])

    def matches_hook(self, resource_name, hook):
        '''Return whether a resource have a hook set in the environment.

        For a given resource and a hook type, we check to see if the the passed
        group of resources has the right hook associated with the name.

        Hooks are set in this format via `resources`:

            {
                "res_name": {
                    "hooks": [pre-create, pre-update]
                },
                "*_suffix": {
                    "hooks": pre-create
                },
                "prefix_*": {
                    "hooks": pre-update
                }
            }

        A hook value is either `pre-create`, `pre-update` or a list of those
        values. Resources support wildcard matching. The asterisk sign matches
        everything.
        '''
        ress = self._registry['resources']
        for name_pattern, resource in six.iteritems(ress):
            if fnmatch.fnmatchcase(resource_name, name_pattern):
                if 'hooks' in resource:
                    hooks = resource['hooks']
                    if isinstance(hooks, six.string_types):
                        if hook == hooks:
                            return True
                    elif isinstance(hooks, collections.Sequence):
                        if hook in hooks:
                            return True
        return False

    def remove_resources_except(self, resource_name):
        ress = self._registry['resources']
        new_resources = {}
        for name, res in six.iteritems(ress):
            if fnmatch.fnmatchcase(resource_name, name):
                new_resources.update(res)
        if resource_name in ress:
            new_resources.update(ress[resource_name])
        self._registry['resources'] = new_resources

    def iterable_by(self, resource_type, resource_name=None):
        is_templ_type = resource_type.endswith(('.yaml', '.template'))
        if self.global_registry is not None and is_templ_type:
            # we only support dynamic resource types in user environments
            # not the global environment.
            # resource with a Type == a template
            # we dynamically create an entry as it has not been registered.
            if resource_type not in self._registry:
                res = ResourceInfo(self, [resource_type], None)
                self._register_info([resource_type], res)
            yield self._registry[resource_type]

        # handle a specific resource mapping.
        if resource_name:
            impl = self._registry['resources'].get(resource_name)
            if impl and resource_type in impl:
                yield impl[resource_type]

        # handle: "OS::Nova::Server" -> "Rackspace::Cloud::Server"
        impl = self._registry.get(resource_type)
        if impl:
            yield impl

        # handle: "OS::*" -> "Dreamhost::*"
        def is_a_glob(resource_type):
            return resource_type.endswith('*')
        globs = itertools.ifilter(is_a_glob, self._registry.keys())
        for pattern in globs:
            if self._registry[pattern].matches(resource_type):
                yield self._registry[pattern]

    def get_resource_info(self, resource_type, resource_name=None,
                          registry_type=None):
        """Find possible matches to the resource type and name.
        chain the results from the global and user registry to find
        a match.
        """
        # use cases
        # 1) get the impl.
        #    - filter_by(res_type=X), sort_by(res_name=W, is_user=True)
        # 2) in TemplateResource we need to get both the
        #    TemplateClass and the ResourceClass
        #    - filter_by(res_type=X, impl_type=TemplateResourceInfo),
        #      sort_by(res_name=W, is_user=True)
        #    - filter_by(res_type=X, impl_type=ClassResourceInfo),
        #      sort_by(res_name=W, is_user=True)
        # 3) get_types() from the api
        #    - filter_by(is_user=False)
        # 4) as_dict() to write to the db
        #    - filter_by(is_user=True)
        if self.global_registry is not None:
            giter = self.global_registry.iterable_by(resource_type,
                                                     resource_name)
        else:
            giter = []

        matches = itertools.chain(self.iterable_by(resource_type,
                                                   resource_name),
                                  giter)

        for info in sorted(matches):
            match = info.get_resource_info(resource_type,
                                           resource_name)
            if registry_type is None or isinstance(match, registry_type):
                # NOTE(prazumovsky): if resource_type defined in outer env
                # there is a risk to lose it due to h-eng restarting, so
                # store it to local env (exclude ClassResourceInfo because it
                # loads from resources; TemplateResourceInfo handles by
                # template_resource module).
                if (match and not match.user_resource and
                    not isinstance(info, (TemplateResourceInfo,
                                          ClassResourceInfo))):
                        self._register_info([resource_type], info)
                return match

    def get_class(self, resource_type, resource_name=None):
        if resource_type == "":
            msg = _('Resource "%s" has no type') % resource_name
            raise exception.StackValidationFailed(message=msg)
        elif resource_type is None:
            msg = _('Non-empty resource type is required '
                    'for resource "%s"') % resource_name
            raise exception.StackValidationFailed(message=msg)
        elif not isinstance(resource_type, six.string_types):
            msg = _('Resource "%s" type is not a string') % resource_name
            raise exception.StackValidationFailed(message=msg)

        info = self.get_resource_info(resource_type,
                                      resource_name=resource_name)
        if info is None:
            msg = _("Unknown resource Type : %s") % resource_type
            raise exception.StackValidationFailed(message=msg)
        return info.get_class()

    def as_dict(self):
        """Return user resources in a dict format."""
        def _as_dict(level):
            tmp = {}
            for k, v in iter(level.items()):
                if isinstance(v, dict):
                    tmp[k] = _as_dict(v)
                elif is_hook_definition(k, v):
                    tmp[k] = v
                elif v.user_resource:
                    tmp[k] = v.value
            return tmp

        return _as_dict(self._registry)

    def get_types(self, support_status):
        '''Return a list of valid resource types.'''

        def is_resource(key):
            return isinstance(self._registry[key], (ClassResourceInfo,
                                                    TemplateResourceInfo))

        def status_matches(cls):
            return (support_status is None or
                    cls.get_class().support_status.status ==
                    support_status.encode())

        return [name for name, cls in six.iteritems(self._registry)
                if is_resource(name) and status_matches(cls)]


class Environment(object):

    def __init__(self, env=None, user_env=True):
        """Create an Environment from a dict of varying format.
        1) old-school flat parameters
        2) or newer {resource_registry: bla, parameters: foo}

        :param env: the json environment
        :param user_env: boolean, if false then we manage python resources too.
        """
        if env is None:
            env = {}
        if user_env:
            from heat.engine import resources
            global_registry = resources.global_env().registry
        else:
            global_registry = None

        self.registry = ResourceRegistry(global_registry, self)
        self.registry.load(env.get(env_fmt.RESOURCE_REGISTRY, {}))

        if env_fmt.PARAMETER_DEFAULTS in env:
            self.param_defaults = env[env_fmt.PARAMETER_DEFAULTS]
        else:
            self.param_defaults = {}

        if env_fmt.PARAMETERS in env:
            self.params = env[env_fmt.PARAMETERS]
        else:
            self.params = dict((k, v) for (k, v) in six.iteritems(env)
                               if k not in (env_fmt.PARAMETER_DEFAULTS,
                                            env_fmt.RESOURCE_REGISTRY))
        self.constraints = {}
        self.stack_lifecycle_plugins = []

    def load(self, env_snippet):
        self.registry.load(env_snippet.get(env_fmt.RESOURCE_REGISTRY, {}))
        self.params.update(env_snippet.get(env_fmt.PARAMETERS, {}))
        self.param_defaults.update(
            env_snippet.get(env_fmt.PARAMETER_DEFAULTS, {}))

    def patch_previous_parameters(self, previous_env, clear_parameters=[]):
        """This instance of Environment is the new environment where
        we are reusing as default the previous parameter values.
        """
        previous_parameters = copy.deepcopy(previous_env.params)
        # clear the parameters from the previous set as requested
        for p in clear_parameters:
            previous_parameters.pop(p, None)

        # patch the new set of parameters
        previous_parameters.update(self.params)
        self.params = previous_parameters

    def user_env_as_dict(self):
        """Get the environment as a dict, ready for storing in the db."""
        return {env_fmt.RESOURCE_REGISTRY: self.registry.as_dict(),
                env_fmt.PARAMETERS: self.params,
                env_fmt.PARAMETER_DEFAULTS: self.param_defaults}

    def register_class(self, resource_type, resource_class):
        self.registry.register_class(resource_type, resource_class)

    def register_constraint(self, constraint_name, constraint):
        self.constraints[constraint_name] = constraint

    def register_stack_lifecycle_plugin(self, stack_lifecycle_name,
                                        stack_lifecycle_class):
        self.stack_lifecycle_plugins.append((stack_lifecycle_name,
                                             stack_lifecycle_class))

    def get_class(self, resource_type, resource_name=None):
        return self.registry.get_class(resource_type, resource_name)

    def get_types(self, support_status=None):
        return self.registry.get_types(support_status)

    def get_resource_info(self, resource_type, resource_name=None,
                          registry_type=None):
        return self.registry.get_resource_info(resource_type, resource_name,
                                               registry_type)

    def get_constraint(self, name):
        return self.constraints.get(name)

    def get_stack_lifecycle_plugins(self):
        return self.stack_lifecycle_plugins


def get_child_environment(parent_env, child_params, item_to_remove=None,
                          child_resource_name=None):
    """Build a child environment using the parent environment and params.

    This is built from the child_params and the parent env so some
    resources can use user-provided parameters as if they come from an
    environment.

    1. resource_registry must be merged (child env should be loaded after the
       parent env to take presdence).
    2. child parameters must overwrite the parent's as they won't be relevant
       in the child template.

    If `child_resource_name` is provided, resources in the registry will be
    replaced with the contents of the matching child resource plus anything
    that passes a wildcard match.
    """
    def is_flat_params(env_or_param):
        if env_or_param is None:
            return False
        for sect in env_fmt.SECTIONS:
            if sect in env_or_param:
                return False
        return True

    child_env = parent_env.user_env_as_dict()
    child_env[env_fmt.PARAMETERS] = {}
    flat_params = is_flat_params(child_params)
    new_env = Environment()
    if flat_params and child_params is not None:
        child_env[env_fmt.PARAMETERS] = child_params

    new_env.load(child_env)
    if not flat_params and child_params is not None:
        new_env.load(child_params)

    if item_to_remove is not None:
        new_env.registry.remove_item(item_to_remove)

    if child_resource_name:
        new_env.registry.remove_resources_except(child_resource_name)
    return new_env


def read_global_environment(env, env_dir=None):
    if env_dir is None:
        cfg.CONF.import_opt('environment_dir', 'heat.common.config')
        env_dir = cfg.CONF.environment_dir

    try:
        env_files = glob.glob(os.path.join(env_dir, '*'))
    except OSError as osex:
        LOG.error(_LE('Failed to read %s'), env_dir)
        LOG.exception(osex)
        return

    for file_path in env_files:
        try:
            with open(file_path) as env_fd:
                LOG.info(_LI('Loading %s'), file_path)
                env_body = env_fmt.parse(env_fd.read())
                env_fmt.default_for_missing(env_body)
                env.load(env_body)
        except ValueError as vex:
            LOG.error(_LE('Failed to parse %(file_path)s'), {
                      'file_path': file_path})
            LOG.exception(vex)
        except IOError as ioex:
            LOG.error(_LE('Failed to read %(file_path)s'), {
                      'file_path': file_path})
            LOG.exception(ioex)
