#!/usr/bin/python3
#
# This file is part of Plinth.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as
# published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
#
# 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 Affero 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/>.
#

import argparse
import django.conf
from django.contrib.messages import constants as message_constants
import django.core.management
import django.core.wsgi
import importlib
import logging
import os
import stat
import sys
import warnings

import cherrypy

from plinth import cfg
from plinth import menu
from plinth import module_loader
from plinth import service
from plinth import setup

logger = logging.getLogger(__name__)

arguments = None


def parse_arguments():
    """Parse command line arguments"""
    parser = argparse.ArgumentParser(
        description='Plinth web interface for FreedomBox',
        formatter_class=argparse.ArgumentDefaultsHelpFormatter)
    # TODO: server_dir is actually a url prefix; use a better variable name
    parser.add_argument(
        '--server_dir', default=cfg.server_dir,
        help='web server path under which to serve')
    parser.add_argument(
        '--debug', action='store_true', default=cfg.debug,
        help='enable debugging and run server *insecurely*')
    parser.add_argument(
        '--setup', default=False, nargs='*',
        help='run setup tasks on all essential modules and exit')
    parser.add_argument(
        '--setup-no-install', default=False, nargs='*',
        help='run setup tasks without installing packages and exit')
    parser.add_argument(
        '--diagnose', action='store_true', default=False,
        help='run diagnostic tests and exit')
    parser.add_argument(
        '--list-dependencies', default=False, nargs='*',
        help='list package dependencies for essential modules')
    parser.add_argument(
        '--list-modules', default=False, nargs='*',
        help='list modules')

    global arguments
    arguments = parser.parse_args()
    cfg.server_dir = arguments.server_dir
    cfg.debug = arguments.debug


def setup_logging():
    """Setup logging framework"""
    # Don't propagate cherrypy log messages to root logger
    logging.getLogger('cherrypy').propagate = False

    cherrypy.log.error_file = cfg.status_log_file
    cherrypy.log.access_file = cfg.access_log_file

    # Capture all Python warnings such as deprecation warnings
    logging.captureWarnings(True)

    # Log all deprecation warnings when in debug mode
    if cfg.debug:
        warnings.filterwarnings('default', '', DeprecationWarning)
        warnings.filterwarnings('default', '', PendingDeprecationWarning)
        warnings.filterwarnings('default', '', ImportWarning)


def setup_server():
    """Setup CherryPy server"""
    logger.info('Setting up CherryPy server')

    # Configure default server
    cherrypy.config.update({
        'server.socket_host': cfg.host,
        'server.socket_port': cfg.port,
        'server.thread_pool': 10,
        # Avoid stating files once per second in production
        'engine.autoreload.on': cfg.debug,
    })

    application = django.core.wsgi.get_wsgi_application()
    cherrypy.tree.graft(application, cfg.server_dir)

    static_dir = os.path.join(cfg.file_root, 'static')
    config = {
        '/': {'tools.staticdir.root': static_dir,
              'tools.staticdir.on': True,
              'tools.staticdir.dir': '.'}}
    cherrypy.tree.mount(None, django.conf.settings.STATIC_URL, config)
    logger.debug('Serving static directory %s on %s', static_dir,
                 django.conf.settings.STATIC_URL)

    js_dir = '/usr/share/javascript'
    js_url = '/javascript'
    config = {
        '/': {'tools.staticdir.root': js_dir,
              'tools.staticdir.on': True,
              'tools.staticdir.dir': '.'}}
    cherrypy.tree.mount(None, js_url, config)
    logger.debug('Serving javascript directory %s on %s', js_dir, js_url)

    manual_dir = os.path.join(cfg.doc_dir, 'images')
    manual_url = '/'.join([cfg.server_dir, 'help/manual/images']) \
        .replace('//', '/')
    config = {
        '/': {'tools.staticdir.root': manual_dir,
              'tools.staticdir.on': True,
              'tools.staticdir.dir': '.'}}
    cherrypy.tree.mount(None, manual_url, config)
    logger.debug('Serving manual images %s on %s', manual_dir, manual_url)

    for module_name, module in module_loader.loaded_modules.items():
        module_path = os.path.dirname(module.__file__)
        static_dir = os.path.join(module_path, 'static')
        if not os.path.isdir(static_dir):
            continue

        config = {
            '/': {'tools.staticdir.root': static_dir,
                  'tools.staticdir.on': True,
                  'tools.staticdir.dir': '.'}}
        urlprefix = "%s%s" % (django.conf.settings.STATIC_URL, module_name)
        cherrypy.tree.mount(None, urlprefix, config)
        logger.debug('Serving static directory %s on %s', static_dir,
                     urlprefix)

    cherrypy.engine.signal_handler.subscribe()


def configure_django():
    """Setup Django configuration in the absense of .settings file"""
    logging_configuration = {
        'version': 1,
        'disable_existing_loggers': False,
        'formatters': {
            'default': {
                'format':
                '[%(asctime)s] %(name)-14s %(levelname)-8s %(message)s',
                }
            },
        'handlers': {
            'file': {
                'class': 'logging.FileHandler',
                'filename': cfg.status_log_file,
                'formatter': 'default'
                },
            'console': {
                'class': 'logging.StreamHandler',
                'formatter': 'default'
                }
            },
        'root': {
            'handlers': ['console', 'file'],
            'level': 'DEBUG' if cfg.debug else 'INFO'
            }
        }

    templates = [
        {
            'BACKEND': 'django.template.backends.django.DjangoTemplates',
            'APP_DIRS': True,
            'OPTIONS': {
                'context_processors': [
                    'django.contrib.auth.context_processors.auth',
                    'django.template.context_processors.debug',
                    'django.template.context_processors.i18n',
                    'django.template.context_processors.media',
                    'django.template.context_processors.request',
                    'django.template.context_processors.static',
                    'django.template.context_processors.tz',
                    'django.contrib.messages.context_processors.messages',
                    'plinth.context_processors.common',
                ],
            },
        },
    ]

    applications = ['bootstrapform',
                    'django.contrib.auth',
                    'django.contrib.contenttypes',
                    'django.contrib.messages',
                    'stronghold',
                    'plinth']
    applications += module_loader.get_modules_to_load()
    sessions_directory = os.path.join(cfg.data_dir, 'sessions')

    secure_proxy_ssl_header = None
    if cfg.secure_proxy_ssl_header:
        secure_proxy_ssl_header = (cfg.secure_proxy_ssl_header, 'https')

    django.conf.settings.configure(
        ALLOWED_HOSTS=['*'],
        AUTH_PASSWORD_VALIDATORS = [
            {
                'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
            },
            {
                'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
                'OPTIONS': {
                    'min_length': 8,
                }
            },
            {
                'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
            },
            {
                'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
            },
        ],
        CACHES={'default':
                {'BACKEND': 'django.core.cache.backends.dummy.DummyCache'}},
        DATABASES={'default':
                   {'ENGINE': 'django.db.backends.sqlite3',
                    'NAME': cfg.store_file}},
        DEBUG=cfg.debug,
        FORCE_SCRIPT_NAME=cfg.server_dir,
        INSTALLED_APPS=applications,
        LOGGING=logging_configuration,
        LOGIN_URL='users:login',
        LOGIN_REDIRECT_URL='index',
        MESSAGE_TAGS={message_constants.ERROR: 'danger'},
        MIDDLEWARE_CLASSES=(
            'django.contrib.sessions.middleware.SessionMiddleware',
            'django.middleware.locale.LocaleMiddleware',
            'django.middleware.common.CommonMiddleware',
            'django.middleware.csrf.CsrfViewMiddleware',
            'django.contrib.auth.middleware.AuthenticationMiddleware',
            'django.contrib.messages.middleware.MessageMiddleware',
            'django.middleware.clickjacking.XFrameOptionsMiddleware',
            'stronghold.middleware.LoginRequiredMiddleware',
            'plinth.middleware.AdminRequiredMiddleware',
            'plinth.modules.first_boot.middleware.FirstBootMiddleware',
            'plinth.middleware.SetupMiddleware',
        ),
        ROOT_URLCONF='plinth.urls',
        SECURE_PROXY_SSL_HEADER=secure_proxy_ssl_header,
        SESSION_ENGINE='django.contrib.sessions.backends.file',
        SESSION_FILE_PATH=sessions_directory,
        STATIC_URL='/'.join([cfg.server_dir, 'static/']).replace('//', '/'),
        TEMPLATES=templates,
        USE_L10N=True,
        USE_X_FORWARDED_HOST=cfg.use_x_forwarded_host)
    django.setup(set_prefix=True)

    logger.debug('Configured Django with applications - %s', applications)

    logger.debug('Creating or adding new tables to data file')
    verbosity = 1 if cfg.debug else 0
    django.core.management.call_command('migrate', '--fake-initial',
                                        interactive=False, verbosity=verbosity)
    os.chmod(cfg.store_file, stat.S_IRUSR | stat.S_IWUSR | stat.S_IRGRP)


def run_setup(module_list, allow_install=True):
    try:
        if not module_list:
            setup.setup_modules(essential=True, allow_install=allow_install)
        else:
            setup.setup_modules(module_list, allow_install=allow_install)
    except Exception as exception:
        logger.error('Error running setup - %s', exception)
        return 1
    return 0


def run_setup_and_exit(module_list, allow_install=True):
    """Run setup on all essential modules and exit."""
    error_code = run_setup(module_list, allow_install)
    sys.exit(error_code)


def list_dependencies(module_list):
    """List dependencies for all essential modules and exit."""
    error_code = 0
    try:
        if module_list:
            setup.list_dependencies(module_list=module_list)
        else:
            setup.list_dependencies(essential=True)
    except Exception as exception:
        logger.error('Error listing dependencies - %s', exception)
        error_code = 1

    sys.exit(error_code)


def list_modules(modules_type):
    """List all/essential/optional modules and exit."""
    for module_name, module in module_loader.loaded_modules.items():
        module_is_essential = getattr(module, 'is_essential', False)
        if 'essential' in modules_type and not module_is_essential:
            continue
        elif 'optional' in modules_type and module_is_essential:
            continue
        print('{module_name}'.format(module_name=module_name))
    sys.exit()


def run_diagnostics_and_exit():
    """Run diagostics on all modules and exit."""
    module = importlib.import_module('plinth.modules.diagnostics.diagnostics')
    error_code = 0
    try:
        module.run_on_all_modules()
    except Exception as exception:
        logger.exception('Error running diagnostics - %s', exception)
        error_code = 2

    for module, results in module.current_results['results'].items():
        for test, result_value in results:
            print('{result_value}: {module}: {test}'.format(
                result_value=result_value, test=test, module=module))
            if result_value != 'passed':
                error_code = 1

    sys.exit(error_code)


def main():
    """Intialize and start the application"""
    cfg.read()

    parse_arguments()

    setup_logging()

    service.init()

    configure_django()

    logger.info('Configuration loaded from file - %s', cfg.config_file)
    logger.info('Script prefix - %s', cfg.server_dir)

    module_loader.include_urls()

    menu.init()

    module_loader.load_modules()

    if arguments.setup is not False:
        run_setup_and_exit(arguments.setup, allow_install=True)

    if arguments.setup_no_install is not False:
        run_setup_and_exit(arguments.setup_no_install, allow_install=False)

    if arguments.list_dependencies is not False:
        list_dependencies(arguments.list_dependencies)

    if arguments.list_modules is not False:
        list_modules(arguments.list_modules)

    if arguments.diagnose:
        run_diagnostics_and_exit()

    # Run setup steps for essential modules
    # Installation is not necessary as they are dependencies of Plinth
    run_setup(None, allow_install=False)

    setup_server()

    cherrypy.engine.start()
    cherrypy.engine.block()


if __name__ == '__main__':
    main()
