# -*- coding: utf-8 -*-
# pylint: disable=protected-access,too-many-branches
from __future__ import absolute_import

import collections
import importlib
import inspect
import json
import os
import pkgutil
import sys
from six import add_metaclass

if sys.version_info >= (3, 0):
    from urllib.parse import unquote  # pylint: disable=no-name-in-module,import-error
else:
    from urllib import unquote  # pylint: disable=no-name-in-module

# pylint: disable=wrong-import-position
import cherrypy

from .. import logger
from ..security import Scope, Permission
from ..tools import wraps, getargspec, TaskManager, get_request_body_params
from ..exceptions import ScopeNotValid, PermissionNotValid
from ..services.auth import AuthManager, JwtManager


class Controller(object):
    def __init__(self, path, base_url=None, security_scope=None, secure=True):
        if security_scope and not Scope.valid_scope(security_scope):
            logger.debug("Invalid security scope name: %s\n Possible values: "
                         "%s", security_scope, Scope.all_scopes())
            raise ScopeNotValid(security_scope)
        self.path = path
        self.base_url = base_url
        self.security_scope = security_scope
        self.secure = secure

        if self.path and self.path[0] != "/":
            self.path = "/" + self.path

        if self.base_url is None:
            self.base_url = ""
        elif self.base_url == "/":
            self.base_url = ""

        if self.base_url == "" and self.path == "":
            self.base_url = "/"

    def __call__(self, cls):
        cls._cp_controller_ = True
        cls._cp_path_ = "{}{}".format(self.base_url, self.path)
        cls._security_scope = self.security_scope

        config = {
            'tools.dashboard_exception_handler.on': True,
            'tools.authenticate.on': self.secure,
        }
        if not hasattr(cls, '_cp_config'):
            cls._cp_config = {}
        cls._cp_config.update(config)
        return cls


class ApiController(Controller):
    def __init__(self, path, security_scope=None, secure=True):
        super(ApiController, self).__init__(path, base_url="/api",
                                            security_scope=security_scope,
                                            secure=secure)

    def __call__(self, cls):
        cls = super(ApiController, self).__call__(cls)
        cls._api_endpoint = True
        return cls


class UiApiController(Controller):
    def __init__(self, path, security_scope=None, secure=True):
        super(UiApiController, self).__init__(path, base_url="/ui-api",
                                              security_scope=security_scope,
                                              secure=secure)


def Endpoint(method=None, path=None, path_params=None, query_params=None,
             json_response=True, proxy=False, xml=False):

    if method is None:
        method = 'GET'
    elif not isinstance(method, str) or \
            method.upper() not in ['GET', 'POST', 'DELETE', 'PUT']:
        raise TypeError("Possible values for method are: 'GET', 'POST', "
                        "'DELETE', or 'PUT'")

    method = method.upper()

    if method in ['GET', 'DELETE']:
        if path_params is not None:
            raise TypeError("path_params should not be used for {} "
                            "endpoints. All function params are considered"
                            " path parameters by default".format(method))

    if path_params is None:
        if method in ['POST', 'PUT']:
            path_params = []

    if query_params is None:
        query_params = []

    def _wrapper(func):
        if method in ['POST', 'PUT']:
            func_params = _get_function_params(func)
            for param in func_params:
                if param['name'] in path_params and not param['required']:
                    raise TypeError("path_params can only reference "
                                    "non-optional function parameters")

        if func.__name__ == '__call__' and path is None:
            e_path = ""
        else:
            e_path = path

        if e_path is not None:
            e_path = e_path.strip()
            if e_path and e_path[0] != "/":
                e_path = "/" + e_path
            elif e_path == "/":
                e_path = ""

        func._endpoint = {
            'method': method,
            'path': e_path,
            'path_params': path_params,
            'query_params': query_params,
            'json_response': json_response,
            'proxy': proxy,
            'xml': xml
        }
        return func
    return _wrapper


def Proxy(path=None):
    if path is None:
        path = ""
    elif path == "/":
        path = ""
    path += "/{path:.*}"
    return Endpoint(path=path, proxy=True)


def load_controllers():
    # setting sys.path properly when not running under the mgr
    controllers_dir = os.path.dirname(os.path.realpath(__file__))
    dashboard_dir = os.path.dirname(controllers_dir)
    mgr_dir = os.path.dirname(dashboard_dir)
    logger.debug("LC: controllers_dir=%s", controllers_dir)
    logger.debug("LC: dashboard_dir=%s", dashboard_dir)
    logger.debug("LC: mgr_dir=%s", mgr_dir)
    if mgr_dir not in sys.path:
        sys.path.append(mgr_dir)

    controllers = []
    mods = [mod for _, mod, _ in pkgutil.iter_modules([controllers_dir])]
    logger.debug("LC: mods=%s", mods)
    for mod_name in mods:
        mod = importlib.import_module('.controllers.{}'.format(mod_name),
                                      package='dashboard')
        for _, cls in mod.__dict__.items():
            # Controllers MUST be derived from the class BaseController.
            if inspect.isclass(cls) and issubclass(cls, BaseController) and \
                    hasattr(cls, '_cp_controller_'):
                if cls._cp_path_.startswith(':'):
                    # invalid _cp_path_ value
                    logger.error("Invalid url prefix '%s' for controller '%s'",
                                 cls._cp_path_, cls.__name__)
                    continue
                controllers.append(cls)

    return controllers


ENDPOINT_MAP = collections.defaultdict(list)


def generate_controller_routes(endpoint, mapper, base_url):
    inst = endpoint.inst
    ctrl_class = endpoint.ctrl
    endp_base_url = None

    if endpoint.proxy:
        conditions = None
    else:
        conditions = dict(method=[endpoint.method])

    endp_url = endpoint.url
    if base_url == "/":
        base_url = ""
    if endp_url == "/" and base_url:
        endp_url = ""
    url = "{}{}".format(base_url, endp_url)

    if '/' in url[len(base_url)+1:]:
        endp_base_url = url[:len(base_url)+1+endp_url[1:].find('/')]
    else:
        endp_base_url = url

    logger.debug("Mapped [%s] to %s:%s restricted to %s",
                 url, ctrl_class.__name__, endpoint.action,
                 endpoint.method)

    ENDPOINT_MAP[endpoint.url].append(endpoint)

    name = ctrl_class.__name__ + ":" + endpoint.action
    mapper.connect(name, url, controller=inst, action=endpoint.action,
                   conditions=conditions)

    # adding route with trailing slash
    name += "/"
    url += "/"
    mapper.connect(name, url, controller=inst, action=endpoint.action,
                   conditions=conditions)

    return endp_base_url


def generate_routes(url_prefix):
    mapper = cherrypy.dispatch.RoutesDispatcher()
    ctrls = load_controllers()

    parent_urls = set()

    endpoint_list = []
    for ctrl in ctrls:
        inst = ctrl()
        for endpoint in ctrl.endpoints():
            endpoint.inst = inst
            endpoint_list.append(endpoint)

    endpoint_list = sorted(endpoint_list, key=lambda e: e.url)
    for endpoint in endpoint_list:
        parent_urls.add(generate_controller_routes(endpoint, mapper,
                                                   "{}".format(url_prefix)))

    logger.debug("list of parent paths: %s", parent_urls)
    return mapper, parent_urls


def json_error_page(status, message, traceback, version):
    cherrypy.response.headers['Content-Type'] = 'application/json'
    return json.dumps(dict(status=status, detail=message, traceback=traceback,
                           version=version))


def _get_function_params(func):
    """
    Retrieves the list of parameters declared in function.
    Each parameter is represented as dict with keys:
      * name (str): the name of the parameter
      * required (bool): whether the parameter is required or not
      * default (obj): the parameter's default value
    """
    fspec = getargspec(func)

    func_params = []
    nd = len(fspec.args) if not fspec.defaults else -len(fspec.defaults)
    for param in fspec.args[1:nd]:
        func_params.append({'name': param, 'required': True})

    if fspec.defaults:
        for param, val in zip(fspec.args[nd:], fspec.defaults):
            func_params.append({
                'name': param,
                'required': False,
                'default': val
            })

    return func_params


class Task(object):
    def __init__(self, name, metadata, wait_for=5.0, exception_handler=None):
        self.name = name
        if isinstance(metadata, list):
            self.metadata = dict([(e[1:-1], e) for e in metadata])
        else:
            self.metadata = metadata
        self.wait_for = wait_for
        self.exception_handler = exception_handler

    def _gen_arg_map(self, func, args, kwargs):
        arg_map = {}
        params = _get_function_params(func)

        args = args[1:]  # exclude self
        for idx, param in enumerate(params):
            if idx < len(args):
                arg_map[param['name']] = args[idx]
            else:
                if param['name'] in kwargs:
                    arg_map[param['name']] = kwargs[param['name']]
                else:
                    assert not param['required']
                    arg_map[param['name']] = param['default']

            if param['name'] in arg_map:
                # This is not a type error. We are using the index here.
                arg_map[idx+1] = arg_map[param['name']]

        return arg_map

    def __call__(self, func):
        @wraps(func)
        def wrapper(*args, **kwargs):
            arg_map = self._gen_arg_map(func, args, kwargs)
            md = {}
            for k, v in self.metadata.items():
                if isinstance(v, str) and v and v[0] == '{' and v[-1] == '}':
                    param = v[1:-1]
                    try:
                        pos = int(param)
                        md[k] = arg_map[pos]
                    except ValueError:
                        md[k] = arg_map[v[1:-1]]
                else:
                    md[k] = v
            task = TaskManager.run(self.name, md, func, args, kwargs,
                                   exception_handler=self.exception_handler)
            try:
                status, value = task.wait(self.wait_for)
            except Exception as ex:
                if task.ret_value:
                    # exception was handled by task.exception_handler
                    if 'status' in task.ret_value:
                        status = task.ret_value['status']
                    else:
                        status = getattr(ex, 'status', 500)
                    cherrypy.response.status = status
                    return task.ret_value
                raise ex
            if status == TaskManager.VALUE_EXECUTING:
                cherrypy.response.status = 202
                return {'name': self.name, 'metadata': md}
            return value
        return wrapper


class BaseController(object):
    """
    Base class for all controllers providing API endpoints.
    """

    class Endpoint(object):
        """
        An instance of this class represents an endpoint.
        """
        def __init__(self, ctrl, func):
            self.ctrl = ctrl
            self.inst = None
            self.func = func

            if not self.config['proxy']:
                setattr(self.ctrl, func.__name__, self.function)

        @property
        def config(self):
            func = self.func
            while not hasattr(func, '_endpoint'):
                if hasattr(func, "__wrapped__"):
                    func = func.__wrapped__
                else:
                    return None
            return func._endpoint

        @property
        def function(self):
            return self.ctrl._request_wrapper(self.func, self.method,
                                              self.config['json_response'],
                                              self.config['xml'])

        @property
        def method(self):
            return self.config['method']

        @property
        def proxy(self):
            return self.config['proxy']

        @property
        def url(self):
            if self.config['path'] is not None:
                url = "{}{}".format(self.ctrl.get_path(), self.config['path'])
            else:
                url = "{}/{}".format(self.ctrl.get_path(), self.func.__name__)

            ctrl_path_params = self.ctrl.get_path_param_names(
                self.config['path'])
            path_params = [p['name'] for p in self.path_params
                           if p['name'] not in ctrl_path_params]
            path_params = ["{{{}}}".format(p) for p in path_params]
            if path_params:
                url += "/{}".format("/".join(path_params))

            return url

        @property
        def action(self):
            return self.func.__name__

        @property
        def path_params(self):
            ctrl_path_params = self.ctrl.get_path_param_names(
                self.config['path'])
            func_params = _get_function_params(self.func)

            if self.method in ['GET', 'DELETE']:
                assert self.config['path_params'] is None

                return [p for p in func_params if p['name'] in ctrl_path_params
                        or (p['name'] not in self.config['query_params']
                            and p['required'])]

            # elif self.method in ['POST', 'PUT']:
            return [p for p in func_params if p['name'] in ctrl_path_params
                    or p['name'] in self.config['path_params']]

        @property
        def query_params(self):
            if self.method in ['GET', 'DELETE']:
                func_params = _get_function_params(self.func)
                path_params = [p['name'] for p in self.path_params]
                return [p for p in func_params if p['name'] not in path_params]

            # elif self.method in ['POST', 'PUT']:
            func_params = _get_function_params(self.func)
            return [p for p in func_params
                    if p['name'] in self.config['query_params']]

        @property
        def body_params(self):
            func_params = _get_function_params(self.func)
            path_params = [p['name'] for p in self.path_params]
            query_params = [p['name'] for p in self.query_params]
            return [p for p in func_params
                    if p['name'] not in path_params
                    and p['name'] not in query_params]

        @property
        def group(self):
            return self.ctrl.__name__

        @property
        def is_api(self):
            return hasattr(self.ctrl, '_api_endpoint')

        @property
        def is_secure(self):
            return self.ctrl._cp_config['tools.authenticate.on']

        def __repr__(self):
            return "Endpoint({}, {}, {})".format(self.url, self.method,
                                                 self.action)

    def __init__(self):
        logger.info('Initializing controller: %s -> %s',
                    self.__class__.__name__, self._cp_path_)

    def _has_permissions(self, permissions, scope=None):
        if not self._cp_config['tools.authenticate.on']:
            raise Exception("Cannot verify permission in non secured "
                            "controllers")

        if not isinstance(permissions, list):
            permissions = [permissions]

        if scope is None:
            scope = getattr(self, '_security_scope', None)
        if scope is None:
            raise Exception("Cannot verify permissions without scope security"
                            " defined")
        username = JwtManager.LOCAL_USER.username
        return AuthManager.authorize(username, scope, permissions)

    @classmethod
    def get_path_param_names(cls, path_extension=None):
        if path_extension is None:
            path_extension = ""
        full_path = cls._cp_path_[1:] + path_extension
        path_params = []
        for step in full_path.split('/'):
            param = None
            if not step:
                continue
            if step[0] == ':':
                param = step[1:]
            elif step[0] == '{' and step[-1] == '}':
                param, _, _ = step[1:-1].partition(':')
            if param:
                path_params.append(param)
        return path_params

    @classmethod
    def get_path(cls):
        return cls._cp_path_

    @classmethod
    def endpoints(cls):
        """
        This method iterates over all the methods decorated with ``@endpoint``
        and creates an Endpoint object for each one of the methods.

        :return: A list of endpoint objects
        :rtype: list[BaseController.Endpoint]
        """
        result = []
        for _, func in inspect.getmembers(cls, predicate=callable):
            if hasattr(func, '_endpoint'):
                result.append(cls.Endpoint(cls, func))
        return result

    @staticmethod
    def _request_wrapper(func, method, json_response, xml):  # pylint: disable=unused-argument
        @wraps(func)
        def inner(*args, **kwargs):
            for key, value in kwargs.items():
                # pylint: disable=undefined-variable
                if (sys.version_info < (3, 0) and isinstance(value, unicode)) \
                        or isinstance(value, str):
                    kwargs[key] = unquote(value)

            # Process method arguments.
            params = get_request_body_params(cherrypy.request)
            kwargs.update(params)

            ret = func(*args, **kwargs)
            if isinstance(ret, bytes):
                ret = ret.decode('utf-8')
            if xml:
                cherrypy.response.headers['Content-Type'] = 'application/xml'
                return ret.encode('utf8')
            if json_response:
                cherrypy.response.headers['Content-Type'] = 'application/json'
                ret = json.dumps(ret).encode('utf8')
            return ret
        return inner

    @property
    def _request(self):
        return self.Request(cherrypy.request)

    class Request(object):
        def __init__(self, cherrypy_req):
            self._creq = cherrypy_req

        @property
        def scheme(self):
            return self._creq.scheme

        @property
        def host(self):
            base = self._creq.base
            base = base[len(self.scheme)+3:]
            return base[:base.find(":")] if ":" in base else base

        @property
        def port(self):
            base = self._creq.base
            base = base[len(self.scheme)+3:]
            default_port = 443 if self.scheme == 'https' else 80
            return int(base[base.find(":")+1:]) if ":" in base else default_port

        @property
        def path_info(self):
            return self._creq.path_info


class RESTController(BaseController):
    """
    Base class for providing a RESTful interface to a resource.

    To use this class, simply derive a class from it and implement the methods
    you want to support.  The list of possible methods are:

    * list()
    * bulk_set(data)
    * create(data)
    * bulk_delete()
    * get(key)
    * set(data, key)
    * delete(key)

    Test with curl:

    curl -H "Content-Type: application/json" -X POST \
         -d '{"username":"xyz","password":"xyz"}'  https://127.0.0.1:8443/foo
    curl https://127.0.0.1:8443/foo
    curl https://127.0.0.1:8443/foo/0

    """

    # resource id parameter for using in get, set, and delete methods
    # should be overridden by subclasses.
    # to specify a composite id (two parameters) use '/'. e.g., "param1/param2".
    # If subclasses don't override this property we try to infer the structure
    # of the resourse ID.
    RESOURCE_ID = None

    _permission_map = {
        'GET': Permission.READ,
        'POST': Permission.CREATE,
        'PUT': Permission.UPDATE,
        'DELETE': Permission.DELETE
    }

    _method_mapping = collections.OrderedDict([
        ('list', {'method': 'GET', 'resource': False, 'status': 200}),
        ('create', {'method': 'POST', 'resource': False, 'status': 201}),
        ('bulk_set', {'method': 'PUT', 'resource': False, 'status': 200}),
        ('bulk_delete', {'method': 'DELETE', 'resource': False, 'status': 204}),
        ('get', {'method': 'GET', 'resource': True, 'status': 200}),
        ('delete', {'method': 'DELETE', 'resource': True, 'status': 204}),
        ('set', {'method': 'PUT', 'resource': True, 'status': 200})
    ])

    @classmethod
    def infer_resource_id(cls):
        if cls.RESOURCE_ID is not None:
            return cls.RESOURCE_ID.split('/')
        for k, v in cls._method_mapping.items():
            func = getattr(cls, k, None)
            while hasattr(func, "__wrapped__"):
                func = func.__wrapped__
            if v['resource'] and func:
                path_params = cls.get_path_param_names()
                params = _get_function_params(func)
                return [p['name'] for p in params
                        if p['required'] and p['name'] not in path_params]
        return None

    @classmethod
    def endpoints(cls):
        result = super(RESTController, cls).endpoints()
        res_id_params = cls.infer_resource_id()

        for _, func in inspect.getmembers(cls, predicate=callable):
            no_resource_id_params = False
            status = 200
            method = None
            query_params = None
            path = ""
            sec_permissions = hasattr(func, '_security_permissions')
            permission = None

            if func.__name__ in cls._method_mapping:
                meth = cls._method_mapping[func.__name__]

                if meth['resource']:
                    if not res_id_params:
                        no_resource_id_params = True
                    else:
                        path_params = ["{{{}}}".format(p) for p in res_id_params]
                        path += "/{}".format("/".join(path_params))

                status = meth['status']
                method = meth['method']
                if not sec_permissions:
                    permission = cls._permission_map[method]

            elif hasattr(func, "_collection_method_"):
                if func._collection_method_['path']:
                    path = func._collection_method_['path']
                else:
                    path = "/{}".format(func.__name__)
                status = func._collection_method_['status']
                method = func._collection_method_['method']
                query_params = func._collection_method_['query_params']
                if not sec_permissions:
                    permission = cls._permission_map[method]

            elif hasattr(func, "_resource_method_"):
                if not res_id_params:
                    no_resource_id_params = True
                else:
                    path_params = ["{{{}}}".format(p) for p in res_id_params]
                    path += "/{}".format("/".join(path_params))
                    if func._resource_method_['path']:
                        path += func._resource_method_['path']
                    else:
                        path += "/{}".format(func.__name__)
                status = func._resource_method_['status']
                method = func._resource_method_['method']
                query_params = func._resource_method_['query_params']
                if not sec_permissions:
                    permission = cls._permission_map[method]

            else:
                continue

            if no_resource_id_params:
                raise TypeError("Could not infer the resource ID parameters for"
                                " method {} of controller {}. "
                                "Please specify the resource ID parameters "
                                "using the RESOURCE_ID class property"
                                .format(func.__name__, cls.__name__))

            if method in ['GET', 'DELETE']:
                params = _get_function_params(func)
                if res_id_params is None:
                    res_id_params = []
                if query_params is None:
                    query_params = [p['name'] for p in params
                                    if p['name'] not in res_id_params]

            func = cls._status_code_wrapper(func, status)
            endp_func = Endpoint(method, path=path,
                                 query_params=query_params)(func)
            if permission:
                _set_func_permissions(endp_func, [permission])
            result.append(cls.Endpoint(cls, endp_func))

        return result

    @classmethod
    def _status_code_wrapper(cls, func, status_code):
        @wraps(func)
        def wrapper(*vpath, **params):
            cherrypy.response.status = status_code
            return func(*vpath, **params)

        return wrapper

    @staticmethod
    def Resource(method=None, path=None, status=None, query_params=None):
        if not method:
            method = 'GET'

        if status is None:
            status = 200

        def _wrapper(func):
            func._resource_method_ = {
                'method': method,
                'path': path,
                'status': status,
                'query_params': query_params
            }
            return func
        return _wrapper

    @staticmethod
    def Collection(method=None, path=None, status=None, query_params=None):
        if not method:
            method = 'GET'

        if status is None:
            status = 200

        def _wrapper(func):
            func._collection_method_ = {
                'method': method,
                'path': path,
                'status': status,
                'query_params': query_params
            }
            return func
        return _wrapper


# Role-based access permissions decorators

def _set_func_permissions(func, permissions):
    if not isinstance(permissions, list):
        permissions = [permissions]

    for perm in permissions:
        if not Permission.valid_permission(perm):
            logger.debug("Invalid security permission: %s\n "
                         "Possible values: %s", perm,
                         Permission.all_permissions())
            raise PermissionNotValid(perm)

    if not hasattr(func, '_security_permissions'):
        func._security_permissions = permissions
    else:
        permissions.extend(func._security_permissions)
        func._security_permissions = list(set(permissions))


def ReadPermission(func):
    _set_func_permissions(func, Permission.READ)
    return func


def CreatePermission(func):
    _set_func_permissions(func, Permission.CREATE)
    return func


def DeletePermission(func):
    _set_func_permissions(func, Permission.DELETE)
    return func


def UpdatePermission(func):
    _set_func_permissions(func, Permission.UPDATE)
    return func