#  Copyright (c) 2017 Red Hat, Inc.
#
#  This file is part of ARA: Ansible Run Analysis.
#
#  ARA is free software: you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation, either version 3 of the License, or
#  (at your option) any later version.
#
#  ARA 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 ARA.  If not, see <http://www.gnu.org/licenses/>.

import ara.config
import ara.views
import flask_migrate
import logging
import os

from alembic.migration import MigrationContext
from alembic.script import ScriptDirectory
from ara.context_processors import configure_context_processors
from ara.errorhandlers import configure_errorhandlers
from ara.filters import configure_template_filters
from ara.models import db
from flask import abort
from flask import current_app
from flask import Flask
from flask import logging as flask_logging
from flask import send_from_directory
from sqlalchemy.engine.reflection import Inspector


DEFAULT_APP_NAME = 'ara'

views = (
    (ara.views.about, '/about'),
    (ara.views.file, '/file'),
    (ara.views.host, '/host'),
    (ara.views.reports, ''),
    (ara.views.result, '/result'),
)


def create_app(config=None, app_name=None):
    if app_name is None:
        app_name = DEFAULT_APP_NAME

    if current_app:
        return current_app

    app = Flask(app_name)

    configure_app(app, config)
    configure_dirs(app)
    configure_logging(app)
    configure_errorhandlers(app)
    configure_template_filters(app)
    configure_context_processors(app)
    configure_blueprints(app)
    configure_static_route(app)
    configure_db(app)

    return app


def configure_blueprints(app):
    for view, prefix in views:
        app.register_blueprint(view, url_prefix=prefix)

    if app.config.get('ARA_ENABLE_DEBUG_VIEW'):
        app.register_blueprint(ara.views.debug, url_prefix='/debug')


def configure_app(app, config):
    app.config.from_object(ara.config)

    if config is not None:
        app.config.from_object(config)

    app.config.from_envvar('ARA_CONFIG', silent=True)


def configure_dirs(app):
    if not os.path.isdir(app.config['ARA_DIR']):
        os.makedirs(app.config['ARA_DIR'], mode=0o700)


def configure_db(app):
    """
    0.10 is the first version of ARA that ships with a stable database schema.
    We can identify a database that originates from before this by checking if
    there is an alembic revision available.
    If there is no alembic revision available, assume we are running the first
    revision which contains the latest state of the database prior to this.
    """
    db.init_app(app)
    log = logging.getLogger(app.logger_name)

    if app.config.get('ARA_AUTOCREATE_DATABASE'):
        with app.app_context():
            migrations = app.config['DB_MIGRATIONS']
            flask_migrate.Migrate(app, db, directory=migrations)
            config = app.extensions['migrate'].migrate.get_config(migrations)

            # Verify if the database tables have been created at all
            inspector = Inspector.from_engine(db.engine)
            if len(inspector.get_table_names()) == 0:
                log.info('Initializing new DB from scratch')
                flask_migrate.upgrade(directory=migrations)

            # Get current alembic head revision
            script = ScriptDirectory.from_config(config)
            head = script.get_current_head()

            # Get current revision, if available
            connection = db.engine.connect()
            context = MigrationContext.configure(connection)
            current = context.get_current_revision()

            if not current:
                log.info('Unstable DB schema, stamping original revision')
                flask_migrate.stamp(directory=migrations,
                                    revision='da9459a1f71c')

            if head != current:
                log.info('DB schema out of date, upgrading')
                flask_migrate.upgrade(directory=migrations)


def configure_logging(app):
    if app.config['ARA_LOG_FILE']:
        handler = logging.FileHandler(app.config['ARA_LOG_FILE'])
        # Set the ARA log format or fall back to the flask debugging format
        handler.setFormatter(
            logging.Formatter(app.config.get(
                'ARA_LOG_FORMAT', flask_logging.DEBUG_LOG_FORMAT)))
        logger = logging.getLogger(app.logger_name)
        logger.setLevel(app.config['ARA_LOG_LEVEL'])
        del logger.handlers[:]
        logger.addHandler(handler)

        # TODO: Log things from Alembic to ARA_LOG_FILE properly
        alembic_logger = logging.getLogger('alembic')
        alembic_logger.setLevel(logging.WARNING)
        del alembic_logger.handlers[:]
        alembic_logger.addHandler(handler)


def configure_static_route(app):
    # Note (dmsimard)
    # /static/ is provided from in-tree bundled files and libraries.
    # /static/packaged/ is routed to serve packaged (i.e, XStatic) libraries.
    #
    # The reason why this isn't defined as a proper view by itself is due to
    # a limitation in flask-frozen. Blueprint'd views methods are like so:
    # "<view>.<method>. The URL generator of flask-frozen is a method decorator
    # that expects the method name as the function and, obviously, you can't
    # really have dots in functions.
    # By having the route configured at the root of the application, there's no
    # dots and we can decorate "serve_static_packaged" instead of, say,
    # "static.serve_packaged".

    @app.route('/static/packaged/<module>/<path:filename>')
    def serve_static_packaged(module, filename):
        xstatic = current_app.config['XSTATIC']

        if module in xstatic:
            return send_from_directory(xstatic[module], filename)
        else:
            abort(404)
