# -*- coding: utf-8 -*-

# Copyright (C) 2010-2020 RhodeCode GmbH
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License, version 3
# (only), 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 Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# This program is dual-licensed. If you wish to learn more about the
# RhodeCode Enterprise Edition, including its added features, Support services,
# and proprietary license terms, please see https://rhodecode.com/licenses/

import os
import time
import logging
import tempfile
import traceback
import threading
import socket
import random

from BaseHTTPServer import BaseHTTPRequestHandler
from SocketServer import TCPServer

import rhodecode
from rhodecode.lib.exceptions import HTTPLockedRC, HTTPBranchProtected
from rhodecode.model import meta
from rhodecode.lib.base import bootstrap_request, bootstrap_config
from rhodecode.lib import hooks_base
from rhodecode.lib.utils2 import AttributeDict
from rhodecode.lib.ext_json import json
from rhodecode.lib import rc_cache

log = logging.getLogger(__name__)


class HooksHttpHandler(BaseHTTPRequestHandler):

    def do_POST(self):
        method, extras = self._read_request()
        txn_id = getattr(self.server, 'txn_id', None)
        if txn_id:
            log.debug('Computing TXN_ID based on `%s`:`%s`',
                      extras['repository'], extras['txn_id'])
            computed_txn_id = rc_cache.utils.compute_key_from_params(
                extras['repository'], extras['txn_id'])
            if txn_id != computed_txn_id:
                raise Exception(
                    'TXN ID fail: expected {} got {} instead'.format(
                        txn_id, computed_txn_id))

        try:
            result = self._call_hook(method, extras)
        except Exception as e:
            exc_tb = traceback.format_exc()
            result = {
                'exception': e.__class__.__name__,
                'exception_traceback': exc_tb,
                'exception_args': e.args
            }
        self._write_response(result)

    def _read_request(self):
        length = int(self.headers['Content-Length'])
        body = self.rfile.read(length).decode('utf-8')
        data = json.loads(body)
        return data['method'], data['extras']

    def _write_response(self, result):
        self.send_response(200)
        self.send_header("Content-type", "text/json")
        self.end_headers()
        self.wfile.write(json.dumps(result))

    def _call_hook(self, method, extras):
        hooks = Hooks()
        try:
            result = getattr(hooks, method)(extras)
        finally:
            meta.Session.remove()
        return result

    def log_message(self, format, *args):
        """
        This is an overridden method of BaseHTTPRequestHandler which logs using
        logging library instead of writing directly to stderr.
        """

        message = format % args

        log.debug(
            "%s - - [%s] %s", self.client_address[0],
            self.log_date_time_string(), message)


class DummyHooksCallbackDaemon(object):
    hooks_uri = ''

    def __init__(self):
        self.hooks_module = Hooks.__module__

    def __enter__(self):
        log.debug('Running `%s` callback daemon', self.__class__.__name__)
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        log.debug('Exiting `%s` callback daemon', self.__class__.__name__)


class ThreadedHookCallbackDaemon(object):

    _callback_thread = None
    _daemon = None
    _done = False

    def __init__(self, txn_id=None, host=None, port=None):
        self._prepare(txn_id=txn_id, host=host, port=port)

    def __enter__(self):
        log.debug('Running `%s` callback daemon', self.__class__.__name__)
        self._run()
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        log.debug('Exiting `%s` callback daemon', self.__class__.__name__)
        self._stop()

    def _prepare(self, txn_id=None, host=None, port=None):
        raise NotImplementedError()

    def _run(self):
        raise NotImplementedError()

    def _stop(self):
        raise NotImplementedError()


class HttpHooksCallbackDaemon(ThreadedHookCallbackDaemon):
    """
    Context manager which will run a callback daemon in a background thread.
    """

    hooks_uri = None

    # From Python docs: Polling reduces our responsiveness to a shutdown
    # request and wastes cpu at all other times.
    POLL_INTERVAL = 0.01

    def get_hostname(self):
        return socket.gethostname() or '127.0.0.1'

    def get_available_port(self, min_port=20000, max_port=65535):
        from rhodecode.lib.utils2 import get_available_port as _get_port
        return _get_port(min_port, max_port)

    def _prepare(self, txn_id=None, host=None, port=None):
        if not host or host == "*":
            host = self.get_hostname()
        if not port:
            port = self.get_available_port()

        server_address = (host, port)
        self.hooks_uri = '{}:{}'.format(host, port)
        self.txn_id = txn_id
        self._done = False

        log.debug(
            "Preparing HTTP callback daemon at `%s` and registering hook object: %s",
            self.hooks_uri, HooksHttpHandler)

        self._daemon = TCPServer(server_address, HooksHttpHandler)
        # inject transaction_id for later verification
        self._daemon.txn_id = self.txn_id

    def _run(self):
        log.debug("Running event loop of callback daemon in background thread")
        callback_thread = threading.Thread(
            target=self._daemon.serve_forever,
            kwargs={'poll_interval': self.POLL_INTERVAL})
        callback_thread.daemon = True
        callback_thread.start()
        self._callback_thread = callback_thread

    def _stop(self):
        log.debug("Waiting for background thread to finish.")
        self._daemon.shutdown()
        self._callback_thread.join()
        self._daemon = None
        self._callback_thread = None
        if self.txn_id:
            txn_id_file = get_txn_id_data_path(self.txn_id)
            log.debug('Cleaning up TXN ID %s', txn_id_file)
            if os.path.isfile(txn_id_file):
                os.remove(txn_id_file)

        log.debug("Background thread done.")


def get_txn_id_data_path(txn_id):
    import rhodecode

    root = rhodecode.CONFIG.get('cache_dir') or tempfile.gettempdir()
    final_dir = os.path.join(root, 'svn_txn_id')

    if not os.path.isdir(final_dir):
        os.makedirs(final_dir)
    return os.path.join(final_dir, 'rc_txn_id_{}'.format(txn_id))


def store_txn_id_data(txn_id, data_dict):
    if not txn_id:
        log.warning('Cannot store txn_id because it is empty')
        return

    path = get_txn_id_data_path(txn_id)
    try:
        with open(path, 'wb') as f:
            f.write(json.dumps(data_dict))
    except Exception:
        log.exception('Failed to write txn_id metadata')


def get_txn_id_from_store(txn_id):
    """
    Reads txn_id from store and if present returns the data for callback manager
    """
    path = get_txn_id_data_path(txn_id)
    try:
        with open(path, 'rb') as f:
            return json.loads(f.read())
    except Exception:
        return {}


def prepare_callback_daemon(extras, protocol, host, use_direct_calls, txn_id=None):
    txn_details = get_txn_id_from_store(txn_id)
    port = txn_details.get('port', 0)
    if use_direct_calls:
        callback_daemon = DummyHooksCallbackDaemon()
        extras['hooks_module'] = callback_daemon.hooks_module
    else:
        if protocol == 'http':
            callback_daemon = HttpHooksCallbackDaemon(
                txn_id=txn_id, host=host, port=port)
        else:
            log.error('Unsupported callback daemon protocol "%s"', protocol)
            raise Exception('Unsupported callback daemon protocol.')

    extras['hooks_uri'] = callback_daemon.hooks_uri
    extras['hooks_protocol'] = protocol
    extras['time'] = time.time()

    # register txn_id
    extras['txn_id'] = txn_id
    log.debug('Prepared a callback daemon: %s at url `%s`',
              callback_daemon.__class__.__name__, callback_daemon.hooks_uri)
    return callback_daemon, extras


class Hooks(object):
    """
    Exposes the hooks for remote call backs
    """

    def repo_size(self, extras):
        log.debug("Called repo_size of %s object", self)
        return self._call_hook(hooks_base.repo_size, extras)

    def pre_pull(self, extras):
        log.debug("Called pre_pull of %s object", self)
        return self._call_hook(hooks_base.pre_pull, extras)

    def post_pull(self, extras):
        log.debug("Called post_pull of %s object", self)
        return self._call_hook(hooks_base.post_pull, extras)

    def pre_push(self, extras):
        log.debug("Called pre_push of %s object", self)
        return self._call_hook(hooks_base.pre_push, extras)

    def post_push(self, extras):
        log.debug("Called post_push of %s object", self)
        return self._call_hook(hooks_base.post_push, extras)

    def _call_hook(self, hook, extras):
        extras = AttributeDict(extras)
        server_url = extras['server_url']
        request = bootstrap_request(application_url=server_url)

        bootstrap_config(request)  # inject routes and other interfaces

        # inject the user for usage in hooks
        request.user = AttributeDict({'username': extras.username,
                                      'ip_addr': extras.ip,
                                      'user_id': extras.user_id})

        extras.request = request

        try:
            result = hook(extras)
            if result is None:
                raise Exception(
                    'Failed to obtain hook result from func: {}'.format(hook))
        except HTTPBranchProtected as handled_error:
            # Those special cases doesn't need error reporting. It's a case of
            # locked repo or protected branch
            result = AttributeDict({
                'status': handled_error.code,
                'output': handled_error.explanation
            })
        except (HTTPLockedRC, Exception) as error:
            # locked needs different handling since we need to also
            # handle PULL operations
            exc_tb = ''
            if not isinstance(error, HTTPLockedRC):
                exc_tb = traceback.format_exc()
                log.exception('Exception when handling hook %s', hook)
            error_args = error.args
            return {
                'status': 128,
                'output': '',
                'exception': type(error).__name__,
                'exception_traceback': exc_tb,
                'exception_args': error_args,
            }
        finally:
            meta.Session.remove()

        log.debug('Got hook call response %s', result)
        return {
            'status': result.status,
            'output': result.output,
        }

    def __enter__(self):
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        pass