#
#    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 abc
import six

from toscaparser.common.exception import ExceptionCollector
from toscaparser.common.exception import UnknownInputError
from toscaparser.dataentity import DataEntity
from toscaparser.utils.gettextutils import _


GET_PROPERTY = 'get_property'
GET_ATTRIBUTE = 'get_attribute'
GET_INPUT = 'get_input'

SELF = 'SELF'
HOST = 'HOST'

HOSTED_ON = 'tosca.relationships.HostedOn'


@six.add_metaclass(abc.ABCMeta)
class Function(object):
    """An abstract type for representing a Tosca template function."""

    def __init__(self, tosca_tpl, context, name, args):
        self.tosca_tpl = tosca_tpl
        self.context = context
        self.name = name
        self.args = args
        self.validate()

    @abc.abstractmethod
    def result(self):
        """Invokes the function and returns its result

        Some methods invocation may only be relevant on runtime (for example,
        getting runtime properties) and therefore its the responsibility of
        the orchestrator/translator to take care of such functions invocation.

        :return: Function invocation result.
        """
        return {self.name: self.args}

    @abc.abstractmethod
    def validate(self):
        """Validates function arguments."""
        pass


class GetInput(Function):
    """Get a property value declared within the input of the service template.

    Arguments:

    * Input name.

    Example:

    * get_input: port
    """

    def validate(self):
        if len(self.args) != 1:
            ExceptionCollector.appendException(
                ValueError(_(
                    'Expected one argument for function "get_input" but '
                    'received "%s".') % self.args))
        inputs = [input.name for input in self.tosca_tpl.inputs]
        if self.args[0] not in inputs:
            ExceptionCollector.appendException(
                UnknownInputError(input_name=self.args[0]))

    def result(self):
        if self.tosca_tpl.parsed_params and \
           self.input_name in self.tosca_tpl.parsed_params:
            return DataEntity.validate_datatype(
                self.tosca_tpl.tpl['inputs'][self.input_name]['type'],
                self.tosca_tpl.parsed_params[self.input_name])

        input = [input_def for input_def in self.tosca_tpl.inputs
                 if self.input_name == input_def.name][0]
        return input.default

    @property
    def input_name(self):
        return self.args[0]


class GetAttribute(Function):
    """Get an attribute value of an entity defined in the service template

    Node template attributes values are set in runtime and therefore its the
    responsibility of the Tosca engine to implement the evaluation of
    get_attribute functions.

    Arguments:

    * Node template name | HOST.
    * Attribute name.

    If the HOST keyword is passed as the node template name argument the
    function will search each node template along the HostedOn relationship
    chain until a node which contains the attribute is found.

    Examples:

    * { get_attribute: [ server, private_address ] }
    * { get_attribute: [ HOST, private_address ] }
    """

    def validate(self):
        if len(self.args) != 2:
            ExceptionCollector.appendException(
                ValueError(_('Illegal arguments for function "{0}". Expected '
                             'arguments: "node-template-name", '
                             '"attribute-name"').format(GET_ATTRIBUTE)))
        self._find_node_template_containing_attribute()

    def result(self):
        return self.args

    def get_referenced_node_template(self):
        """Gets the NodeTemplate instance the get_attribute function refers to.

        If HOST keyword was used as the node template argument, the node
        template which contains the attribute along the HostedOn relationship
        chain will be returned.
        """
        return self._find_node_template_containing_attribute()

    def _find_node_template_containing_attribute(self):
        if self.node_template_name == HOST:
            # Currently this is the only way to tell whether the function
            # is used within the outputs section of the TOSCA template.
            if isinstance(self.context, list):
                ExceptionCollector.appendException(
                    ValueError(_(
                        '"get_attribute: [ HOST, ... ]" is not allowed in '
                        '"outputs" section of the TOSCA template.')))
                return
            node_tpl = self._find_host_containing_attribute()
            if not node_tpl:
                ExceptionCollector.appendException(
                    ValueError(_(
                        '"get_attribute: [ HOST, ... ]" was used in node '
                        'template "{0}" but "{1}" was not found in '
                        'the relationship chain.').format(self.context.name,
                                                          HOSTED_ON)))
        else:
            node_tpl = self._find_node_template(self.args[0])
        if node_tpl and \
            not self._attribute_exists_in_type(node_tpl.type_definition):
            ExceptionCollector.appendException(
                KeyError(_('Attribute "%(att)s" was not found in node '
                           'template "%(ntpl)s".') %
                         {'att': self.attribute_name,
                          'ntpl': node_tpl.name}))
        return node_tpl

    def _attribute_exists_in_type(self, type_definition):
        attrs_def = type_definition.get_attributes_def()
        found = [attrs_def[self.attribute_name]] \
            if self.attribute_name in attrs_def else []
        return len(found) == 1

    def _find_host_containing_attribute(self, node_template_name=SELF):
        node_template = self._find_node_template(node_template_name)
        if node_template:
            from toscaparser.elements.entity_type import EntityType
            hosted_on_rel = EntityType.TOSCA_DEF[HOSTED_ON]
            for r in node_template.requirements:
                for requirement, target_name in r.items():
                    target_node = self._find_node_template(target_name)
                    target_type = target_node.type_definition
                    for capability in target_type.get_capabilities_objects():
                        if capability.type in \
                            hosted_on_rel['valid_target_types']:
                            if self._attribute_exists_in_type(target_type):
                                return target_node
                            return self._find_host_containing_attribute(
                                target_name)

    def _find_node_template(self, node_template_name):
        name = self.context.name \
            if node_template_name == SELF and \
            not isinstance(self.context, list) \
            else node_template_name
        for node_template in self.tosca_tpl.nodetemplates:
            if node_template.name == name:
                return node_template
        ExceptionCollector.appendException(
            KeyError(_(
                'Node template "{0}" was not found.'
                ).format(node_template_name)))

    @property
    def node_template_name(self):
        return self.args[0]

    @property
    def attribute_name(self):
        return self.args[1]


class GetProperty(Function):
    """Get a property value of an entity defined in the same service template.

    Arguments:

    * Node template name.
    * Requirement or capability name (optional).
    * Property name.

    If requirement or capability name is specified, the behavior is as follows:
    The req or cap name is first looked up in the specified node template's
    requirements.
    If found, it would search for a matching capability
    of an other node template and get its property as specified in function
    arguments.
    Otherwise, the req or cap name would be looked up in the specified
    node template's capabilities and if found, it would return  the property of
    the capability as specified in function arguments.

    Examples:

    * { get_property: [ mysql_server, port ] }
    * { get_property: [ SELF, db_port ] }
    * { get_property: [ SELF, database_endpoint, port ] }
    """

    def validate(self):
        if len(self.args) < 2 or len(self.args) > 3:
            ExceptionCollector.appendException(
                ValueError(_(
                    'Expected arguments: "node-template-name", "req-or-cap" '
                    '(optional), "property name".')))
            return
        if len(self.args) == 2:
            found_prop = self._find_property(self.args[1])
            if not found_prop:
                return
            prop = found_prop.value
            if not isinstance(prop, Function):
                get_function(self.tosca_tpl, self.context, prop)
        elif len(self.args) == 3:
            get_function(self.tosca_tpl,
                         self.context,
                         self._find_req_or_cap_property(self.args[1],
                                                        self.args[2]))
        else:
            ExceptionCollector.appendException(
                NotImplementedError(_(
                    'Nested properties are not supported.')))

    def _find_req_or_cap_property(self, req_or_cap, property_name):
        node_tpl = self._find_node_template(self.args[0])
        # Find property in node template's requirements
        for r in node_tpl.requirements:
            for req, node_name in r.items():
                if req == req_or_cap:
                    node_template = self._find_node_template(node_name)
                    return self._get_capability_property(
                        node_template,
                        req,
                        property_name)
        # If requirement was not found, look in node template's capabilities
        return self._get_capability_property(node_tpl,
                                             req_or_cap,
                                             property_name)

    def _get_capability_property(self,
                                 node_template,
                                 capability_name,
                                 property_name):
        """Gets a node template capability property."""
        caps = node_template.get_capabilities()
        if caps and capability_name in caps.keys():
            cap = caps[capability_name]
            property = None
            props = cap.get_properties()
            if props and property_name in props.keys():
                property = props[property_name].value
            if not property:
                ExceptionCollector.appendException(
                    KeyError(_('Property "%(prop)s" was not found in '
                               'capability "%(cap)s" of node template '
                               '"%(ntpl1)s" referenced from node template '
                               '"%(ntpl2)s".') % {'prop': property_name,
                                                  'cap': capability_name,
                                                  'ntpl1': node_template.name,
                                                  'ntpl2': self.context.name}))
            return property
        msg = _('Requirement/Capability "{0}" referenced from node template '
                '"{1}" was not found in node template "{2}".').format(
                    capability_name,
                    self.context.name,
                    node_template.name)
        ExceptionCollector.appendException(KeyError(msg))

    def _find_property(self, property_name):
        node_tpl = self._find_node_template(self.args[0])
        if not node_tpl:
            return
        props = node_tpl.get_properties()
        found = [props[property_name]] if property_name in props else []
        if len(found) == 0:
            ExceptionCollector.appendException(
                KeyError(_('Property "%(prop)s" was not found in node '
                           'template "%(ntpl)s".') %
                         {'prop': property_name,
                          'ntpl': node_tpl.name}))
            return None
        return found[0]

    def _find_node_template(self, node_template_name):
        if node_template_name == SELF:
            return self.context
        if not hasattr(self.tosca_tpl, 'nodetemplates'):
            return
        for node_template in self.tosca_tpl.nodetemplates:
            if node_template.name == node_template_name:
                return node_template
        ExceptionCollector.appendException(
            KeyError(_(
                'Node template "{0}" was not found.'
                ).format(node_template_name)))

    def result(self):
        if len(self.args) == 3:
            property_value = self._find_req_or_cap_property(self.args[1],
                                                            self.args[2])
        else:
            property_value = self._find_property(self.args[1]).value
        if isinstance(property_value, Function):
            return property_value.result()
        return get_function(self.tosca_tpl,
                            self.context,
                            property_value)

    @property
    def node_template_name(self):
        return self.args[0]

    @property
    def property_name(self):
        if len(self.args) > 2:
            return self.args[2]
        return self.args[1]

    @property
    def req_or_cap(self):
        if len(self.args) > 2:
            return self.args[1]
        return None


function_mappings = {
    GET_PROPERTY: GetProperty,
    GET_INPUT: GetInput,
    GET_ATTRIBUTE: GetAttribute
}


def is_function(function):
    """Returns True if the provided function is a Tosca intrinsic function.

    Examples:

    * "{ get_property: { SELF, port } }"
    * "{ get_input: db_name }"
    * Function instance

    :param function: Function as string or a Function instance.
    :return: True if function is a Tosca intrinsic function, otherwise False.
    """
    if isinstance(function, dict) and len(function) == 1:
        func_name = list(function.keys())[0]
        return func_name in function_mappings
    return isinstance(function, Function)


def get_function(tosca_tpl, node_template, raw_function):
    """Gets a Function instance representing the provided template function.

    If the format provided raw_function format is not relevant for template
    functions or if the function name doesn't exist in function mapping the
    method returns the provided raw_function.

    :param tosca_tpl: The tosca template.
    :param node_template: The node template the function is specified for.
    :param raw_function: The raw function as dict.
    :return: Template function as Function instance or the raw_function if
     parsing was unsuccessful.
    """
    if is_function(raw_function):
        func_name = list(raw_function.keys())[0]
        if func_name in function_mappings:
            func = function_mappings[func_name]
            func_args = list(raw_function.values())[0]
            if not isinstance(func_args, list):
                func_args = [func_args]
            return func(tosca_tpl, node_template, func_name, func_args)
    return raw_function