#!/usr/share/vyos-http-api-tools/bin/python3
#
# Copyright (C) 2019-2021 VyOS maintainers and contributors
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 or later as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
#

import os
import sys
import grp
import copy
import json
import logging
import traceback
import threading
from typing import List, Union, Callable, Dict

import uvicorn
from fastapi import FastAPI, Depends, Request, Response, HTTPException
from fastapi.responses import HTMLResponse
from fastapi.exceptions import RequestValidationError
from fastapi.routing import APIRoute
from pydantic import BaseModel, StrictStr, validator
from starlette.middleware.cors import CORSMiddleware
from starlette.datastructures import FormData
from starlette.formparsers import FormParser, MultiPartParser
from multipart.multipart import parse_options_header

from ariadne.asgi import GraphQL

import vyos.config
from vyos.configsession import ConfigSession, ConfigSessionError

import api.graphql.state

DEFAULT_CONFIG_FILE = '/etc/vyos/http-api.conf'
CFG_GROUP = 'vyattacfg'

debug = True

logger = logging.getLogger(__name__)
logs_handler = logging.StreamHandler()
logger.addHandler(logs_handler)

if debug:
    logger.setLevel(logging.DEBUG)
else:
    logger.setLevel(logging.INFO)

# Giant lock!
lock = threading.Lock()

def load_server_config():
    with open(DEFAULT_CONFIG_FILE) as f:
        config = json.load(f)
    return config

def check_auth(key_list, key):
    key_id = None
    for k in key_list:
        if k['key'] == key:
            key_id = k['id']
    return key_id

def error(code, msg):
    resp = {"success": False, "error": msg, "data": None}
    resp = json.dumps(resp)
    return HTMLResponse(resp, status_code=code)

def success(data):
    resp = {"success": True, "data": data, "error": None}
    resp = json.dumps(resp)
    return HTMLResponse(resp)

# Pydantic models for validation
# Pydantic will cast when possible, so use StrictStr
# validators added as needed for additional constraints
# schema_extra adds anotations to OpenAPI, to add examples

class ApiModel(BaseModel):
    key: StrictStr

class BaseConfigureModel(BaseModel):
    op: StrictStr
    path: List[StrictStr]
    value: StrictStr = None

    @validator("path", pre=True, always=True)
    def check_non_empty(cls, path):
        assert len(path) > 0
        return path

class ConfigureModel(ApiModel):
    op: StrictStr
    path: List[StrictStr]
    value: StrictStr = None

    @validator("path", pre=True, always=True)
    def check_non_empty(cls, path):
        assert len(path) > 0
        return path

    class Config:
        schema_extra = {
            "example": {
                "key": "id_key",
                "op": "set | delete | comment",
                "path": ['config', 'mode', 'path'],
            }
        }

class ConfigureListModel(ApiModel):
    commands: List[BaseConfigureModel]

    class Config:
        schema_extra = {
            "example": {
                "key": "id_key",
                "commands": "list of commands",
            }
        }

class RetrieveModel(ApiModel):
    op: StrictStr
    path: List[StrictStr]
    configFormat: StrictStr = None

    class Config:
        schema_extra = {
            "example": {
                "key": "id_key",
                "op": "returnValue | returnValues | exists | showConfig",
                "path": ['config', 'mode', 'path'],
                "configFormat": "json (default) | json_ast | raw",

            }
        }

class ConfigFileModel(ApiModel):
    op: StrictStr
    file: StrictStr = None

    class Config:
        schema_extra = {
            "example": {
                "key": "id_key",
                "op": "save | load",
                "file": "filename",
            }
        }

class ImageModel(ApiModel):
    op: StrictStr
    url: StrictStr = None
    name: StrictStr = None

    class Config:
        schema_extra = {
            "example": {
                "key": "id_key",
                "op": "add | delete",
                "url": "imagelocation",
                "name": "imagename",
            }
        }

class GenerateModel(ApiModel):
    op: StrictStr
    path: List[StrictStr]

    class Config:
        schema_extra = {
            "example": {
                "key": "id_key",
                "op": "generate",
                "path": ["op", "mode", "path"],
            }
        }

class ShowModel(ApiModel):
    op: StrictStr
    path: List[StrictStr]

    class Config:
        schema_extra = {
            "example": {
                "key": "id_key",
                "op": "show",
                "path": ["op", "mode", "path"],
            }
        }

class Success(BaseModel):
    success: bool
    data: Union[str, bool, Dict]
    error: str

class Error(BaseModel):
    success: bool = False
    data: Union[str, bool, Dict]
    error: str

responses = {
    200: {'model': Success},
    400: {'model': Error},
    422: {'model': Error, 'description': 'Validation Error'},
    500: {'model': Error}
}

def auth_required(data: ApiModel):
    key = data.key
    api_keys = app.state.vyos_keys
    key_id = check_auth(api_keys, key)
    if not key_id:
        raise HTTPException(status_code=401, detail="Valid API key is required")
    app.state.vyos_id = key_id

# override Request and APIRoute classes in order to convert form request to json;
# do all explicit validation here, for backwards compatability of error messages;
# the explicit validation may be dropped, if desired, in favor of native
# validation by FastAPI/Pydantic, as is used for application/json requests
class MultipartRequest(Request):
    ERR_MISSING_KEY = False
    ERR_MISSING_DATA = False
    ERR_NOT_JSON = False
    ERR_NOT_DICT = False
    ERR_NO_OP = False
    ERR_NO_PATH = False
    ERR_EMPTY_PATH = False
    ERR_PATH_NOT_LIST = False
    ERR_VALUE_NOT_STRING = False
    ERR_PATH_NOT_LIST_OF_STR = False
    offending_command = {}
    exception = None

    @property
    def orig_headers(self):
        self._orig_headers = super().headers
        return self._orig_headers

    @property
    def headers(self):
        self._headers = super().headers.mutablecopy()
        self._headers['content-type'] = 'application/json'
        return self._headers

    async def form(self) -> FormData:
        if not hasattr(self, "_form"):
            assert (
                parse_options_header is not None
            ), "The `python-multipart` library must be installed to use form parsing."
            content_type_header = self.orig_headers.get("Content-Type")
            content_type, options = parse_options_header(content_type_header)
            if content_type == b"multipart/form-data":
                multipart_parser = MultiPartParser(self.orig_headers, self.stream())
                self._form = await multipart_parser.parse()
            elif content_type == b"application/x-www-form-urlencoded":
                form_parser = FormParser(self.orig_headers, self.stream())
                self._form = await form_parser.parse()
            else:
                self._form = FormData()
        return self._form

    async def body(self) -> bytes:
        if not hasattr(self, "_body"):
            forms = {}
            merge = {}
            body = await super().body()
            self._body = body

            form_data = await self.form()
            if form_data:
                logger.debug("processing form data")
                for k, v in form_data.multi_items():
                    forms[k] = v

                if 'data' not in forms:
                    self.ERR_MISSING_DATA = True
                else:
                    try:
                        tmp = json.loads(forms['data'])
                    except json.JSONDecodeError as e:
                        self.ERR_NOT_JSON = True
                        self.exception = e
                        tmp = {}
                    if isinstance(tmp, list):
                        merge['commands'] = tmp
                    else:
                        merge = tmp

                if 'commands' in merge:
                    cmds = merge['commands']
                else:
                    cmds = copy.deepcopy(merge)
                    cmds = [cmds]

                for c in cmds:
                    if not isinstance(c, dict):
                        self.ERR_NOT_DICT = True
                        self.offending_command = c
                    elif 'op' not in c:
                        self.ERR_NO_OP = True
                        self.offending_command = c
                    elif 'path' not in c:
                        self.ERR_NO_PATH = True
                        self.offending_command = c
                    elif not c['path']:
                        self.ERR_EMPTY_PATH = True
                        self.offending_command = c
                    elif not isinstance(c['path'], list):
                        self.ERR_PATH_NOT_LIST = True
                        self.offending_command = c
                    elif not all(isinstance(el, str) for el in c['path']):
                        self.ERR_PATH_NOT_LIST_OF_STR = True
                        self.offending_command = c
                    elif 'value' in c and not isinstance(c['value'], str):
                        self.ERR_VALUE_NOT_STRING = True
                        self.offending_command = c

                if 'key' not in forms and 'key' not in merge:
                    self.ERR_MISSING_KEY = True
                if 'key' in forms and 'key' not in merge:
                    merge['key'] = forms['key']

                new_body = json.dumps(merge)
                new_body = new_body.encode()
                self._body = new_body

        return self._body

class MultipartRoute(APIRoute):
    def get_route_handler(self) -> Callable:
        original_route_handler = super().get_route_handler()

        async def custom_route_handler(request: Request) -> Response:
            request = MultipartRequest(request.scope, request.receive)
            endpoint = request.url.path
            try:
                response: Response = await original_route_handler(request)
            except HTTPException as e:
                return error(e.status_code, e.detail)
            except Exception as e:
                if request.ERR_MISSING_KEY:
                    return error(401, "Valid API key is required")
                if request.ERR_MISSING_DATA:
                    return error(422, "Non-empty data field is required")
                if request.ERR_NOT_JSON:
                    return error(400, "Failed to parse JSON: {0}".format(request.exception))
                if endpoint == '/configure':
                    if request.ERR_NOT_DICT:
                        return error(400, "Malformed command \"{0}\": any command must be a dict".format(json.dumps(request.offending_command)))
                    if request.ERR_NO_OP:
                        return error(400, "Malformed command \"{0}\": missing \"op\" field".format(json.dumps(request.offending_command)))
                    if request.ERR_NO_PATH:
                        return error(400, "Malformed command \"{0}\": missing \"path\" field".format(json.dumps(request.offending_command)))
                    if request.ERR_EMPTY_PATH:
                        return error(400, "Malformed command \"{0}\": empty path".format(json.dumps(request.offending_command)))
                    if request.ERR_PATH_NOT_LIST:
                        return error(400, "Malformed command \"{0}\": \"path\" field must be a list".format(json.dumps(request.offending_command)))
                    if request.ERR_VALUE_NOT_STRING:
                        return error(400, "Malformed command \"{0}\": \"value\" field must be a string".format(json.dumps(request.offending_command)))
                    if request.ERR_PATH_NOT_LIST_OF_STR:
                        return error(400, "Malformed command \"{0}\": \"path\" field must be a list of strings".format(json.dumps(request.offending_command)))
                if endpoint in ('/retrieve','/generate','/show'):
                    if request.ERR_NO_OP or request.ERR_NO_PATH:
                        return error(400, "Missing required field. \"op\" and \"path\" fields are required")
                if endpoint in ('/config-file', '/image'):
                    if request.ERR_NO_OP:
                        return error(400, "Missing required field \"op\"")

                raise e

            return response

        return custom_route_handler

app = FastAPI(debug=True,
              title="VyOS API",
              version="0.1.0",
              responses={**responses},
              dependencies=[Depends(auth_required)])

app.router.route_class = MultipartRoute

@app.exception_handler(RequestValidationError)
async def validation_exception_handler(request, exc):
    return error(400, str(exc.errors()[0]))

@app.post('/configure')
def configure_op(data: Union[ConfigureModel, ConfigureListModel]):
    session = app.state.vyos_session
    env = session.get_session_env()
    config = vyos.config.Config(session_env=env)

    # Allow users to pass just one command
    if not isinstance(data, ConfigureListModel):
        data = [data]
    else:
        data = data.commands

    # We don't want multiple people/apps to be able to commit at once,
    # or modify the shared session while someone else is doing the same,
    # so the lock is really global
    lock.acquire()

    status = 200
    error_msg = None
    try:
        for c in data:
            op = c.op
            path = c.path

            if c.value:
                value = c.value
            else:
                value = ""

            # For vyos.configsession calls that have no separate value arguments,
            # and for type checking too
            cfg_path = " ".join(path + [value]).strip()

            if op == 'set':
                # XXX: it would be nice to do a strict check for "path already exists",
                # but there's probably no way to do that
                session.set(path, value=value)
            elif op == 'delete':
                if app.state.vyos_strict and not config.exists(cfg_path):
                    raise ConfigSessionError("Cannot delete [{0}]: path/value does not exist".format(cfg_path))
                session.delete(path, value=value)
            elif op == 'comment':
                session.comment(path, value=value)
            else:
                raise ConfigSessionError("\"{0}\" is not a valid operation".format(op))
        # end for
        session.commit()
        logger.info(f"Configuration modified via HTTP API using key '{app.state.vyos_id}'")
    except ConfigSessionError as e:
        session.discard()
        status = 400
        if app.state.vyos_debug:
            logger.critical(f"ConfigSessionError:\n {traceback.format_exc()}")
        error_msg = str(e)
    except Exception as e:
        session.discard()
        logger.critical(traceback.format_exc())
        status = 500

        # Don't give the details away to the outer world
        error_msg = "An internal error occured. Check the logs for details."
    finally:
        lock.release()

    if status != 200:
        return error(status, error_msg)

    return success(None)

@app.post("/retrieve")
def retrieve_op(data: RetrieveModel):
    session = app.state.vyos_session
    env = session.get_session_env()
    config = vyos.config.Config(session_env=env)

    op = data.op
    path = " ".join(data.path)

    try:
        if op == 'returnValue':
            res = config.return_value(path)
        elif op == 'returnValues':
            res = config.return_values(path)
        elif op == 'exists':
            res = config.exists(path)
        elif op == 'showConfig':
            config_format = 'json'
            if data.configFormat:
                config_format = data.configFormat

            res = session.show_config(path=data.path)
            if config_format == 'json':
                config_tree = vyos.configtree.ConfigTree(res)
                res = json.loads(config_tree.to_json())
            elif config_format == 'json_ast':
                config_tree = vyos.configtree.ConfigTree(res)
                res = json.loads(config_tree.to_json_ast())
            elif config_format == 'raw':
                pass
            else:
                return error(400, "\"{0}\" is not a valid config format".format(config_format))
        else:
            return error(400, "\"{0}\" is not a valid operation".format(op))
    except ConfigSessionError as e:
        return error(400, str(e))
    except Exception as e:
        logger.critical(traceback.format_exc())
        return error(500, "An internal error occured. Check the logs for details.")

    return success(res)

@app.post('/config-file')
def config_file_op(data: ConfigFileModel):
    session = app.state.vyos_session

    op = data.op

    try:
        if op == 'save':
            if data.file:
                path = data.file
            else:
                path = '/config/config.boot'
            res = session.save_config(path)
        elif op == 'load':
            if data.file:
                path = data.file
            else:
                return error(400, "Missing required field \"file\"")
            res = session.migrate_and_load_config(path)
            res = session.commit()
        else:
            return error(400, "\"{0}\" is not a valid operation".format(op))
    except ConfigSessionError as e:
        return error(400, str(e))
    except Exception as e:
        logger.critical(traceback.format_exc())
        return error(500, "An internal error occured. Check the logs for details.")

    return success(res)

@app.post('/image')
def image_op(data: ImageModel):
    session = app.state.vyos_session

    op = data.op

    try:
        if op == 'add':
            if data.url:
                url = data.url
            else:
                return error(400, "Missing required field \"url\"")
            res = session.install_image(url)
        elif op == 'delete':
            if data.name:
                name = data.name
            else:
                return error(400, "Missing required field \"name\"")
            res = session.remove_image(name)
        else:
            return error(400, "\"{0}\" is not a valid operation".format(op))
    except ConfigSessionError as e:
        return error(400, str(e))
    except Exception as e:
        logger.critical(traceback.format_exc())
        return error(500, "An internal error occured. Check the logs for details.")

    return success(res)

@app.post('/generate')
def generate_op(data: GenerateModel):
    session = app.state.vyos_session

    op = data.op
    path = data.path

    try:
        if op == 'generate':
            res = session.generate(path)
        else:
            return error(400, "\"{0}\" is not a valid operation".format(op))
    except ConfigSessionError as e:
        return error(400, str(e))
    except Exception as e:
        logger.critical(traceback.format_exc())
        return error(500, "An internal error occured. Check the logs for details.")

    return success(res)

@app.post('/show')
def show_op(data: ShowModel):
    session = app.state.vyos_session

    op = data.op
    path = data.path

    try:
        if op == 'show':
            res = session.show(path)
        else:
            return error(400, "\"{0}\" is not a valid operation".format(op))
    except ConfigSessionError as e:
        return error(400, str(e))
    except Exception as e:
        logger.critical(traceback.format_exc())
        return error(500, "An internal error occured. Check the logs for details.")

    return success(res)

###
# GraphQL integration
###

def graphql_init(fast_api_app):
    from api.graphql.bindings import generate_schema

    api.graphql.state.init()
    api.graphql.state.settings['app'] = app

    schema = generate_schema()

    if app.state.vyos_origins:
        origins = app.state.vyos_origins
        app.add_route('/graphql', CORSMiddleware(GraphQL(schema, debug=True), allow_origins=origins, allow_methods=("GET", "POST", "OPTIONS")))
    else:
        app.add_route('/graphql', GraphQL(schema, debug=True))

###

if __name__ == '__main__':
    # systemd's user and group options don't work, do it by hand here,
    # else no one else will be able to commit
    cfg_group = grp.getgrnam(CFG_GROUP)
    os.setgid(cfg_group.gr_gid)

    # Need to set file permissions to 775 too so that every vyattacfg group member
    # has write access to the running config
    os.umask(0o002)

    try:
        server_config = load_server_config()
    except Exception as err:
        logger.critical(f"Failed to load the HTTP API server config: {err}")

    config_session = ConfigSession(os.getpid())

    app.state.vyos_session = config_session
    app.state.vyos_keys = server_config['api_keys']

    app.state.vyos_debug = server_config['debug']
    app.state.vyos_gql = server_config['gql']
    app.state.vyos_strict = server_config['strict']
    app.state.vyos_origins = server_config.get('cors', {}).get('origins', [])

    if app.state.vyos_gql:
        graphql_init(app)

    try:
        if not server_config['socket']:
            uvicorn.run(app, host=server_config["listen_address"],
                             port=int(server_config["port"]),
                             proxy_headers=True)
        else:
            uvicorn.run(app, uds="/run/api.sock",
                             proxy_headers=True)
    except OSError as err:
        logger.critical(f"OSError {err}")
        sys.exit(1)