"""
.. module: lemur.factory
    :platform: Unix
    :synopsis: This module contains all the needed functions to allow
    the factory app creation.

    :copyright: (c) 2015 by Netflix Inc., see AUTHORS for more
    :license: Apache, see LICENSE for more details.
.. moduleauthor:: Kevin Glisson <kglisson@netflix.com>

"""
import os
import imp
import errno
import pkg_resources

from logging import Formatter
from logging.handlers import RotatingFileHandler

from flask import Flask
from lemur.common.health import mod as health
from lemur.extensions import db, migrate, principal


DEFAULT_BLUEPRINTS = (
    health,
)

API_VERSION = 1


def create_app(app_name=None, blueprints=None, config=None):
    """
    Lemur application factory

    :param config:
    :param app_name:
    :param blueprints:
    :return:
    """
    if not blueprints:
        blueprints = DEFAULT_BLUEPRINTS
    else:
        blueprints = blueprints + DEFAULT_BLUEPRINTS

    if not app_name:
        app_name = __name__

    app = Flask(app_name)
    configure_app(app, config)
    configure_blueprints(app, blueprints)
    configure_extensions(app)
    configure_logging(app)
    install_plugins(app)

    @app.teardown_appcontext
    def teardown(exception=None):
        if db.session:
            db.session.remove()

    return app


def from_file(file_path, silent=False):
    """
    Updates the values in the config from a Python file.  This function
    behaves as if the file was imported as module with the

    :param file_path:
    :param silent:
    """
    d = imp.new_module('config')
    d.__file__ = file_path
    try:
        with open(file_path) as config_file:
            exec(compile(config_file.read(), file_path, 'exec'), d.__dict__)
    except IOError as e:
        if silent and e.errno in (errno.ENOENT, errno.EISDIR):
            return False
        e.strerror = 'Unable to load configuration file (%s)' % e.strerror
        raise
    return d


def configure_app(app, config=None):
    """
    Different ways of configuration

    :param app:
    :param config:
    :return:
    """
    try:
        app.config.from_envvar("LEMUR_CONF")
    except RuntimeError:
        if config and config != 'None':
            app.config.from_object(from_file(config))
        elif os.path.isfile(os.path.expanduser("~/.lemur/lemur.conf.py")):
            app.config.from_object(from_file(os.path.expanduser("~/.lemur/lemur.conf.py")))
        else:
            app.config.from_object(from_file(os.path.join(os.path.dirname(os.path.realpath(__file__)), 'default.conf.py')))


def configure_extensions(app):
    """
    Attaches and configures any needed flask extensions
    to our app.

    :param app:
    """
    db.init_app(app)
    migrate.init_app(app, db)
    principal.init_app(app)


def configure_blueprints(app, blueprints):
    """
    We prefix our APIs with their given version so that we can support
    multiple concurrent API versions.

    :param app:
    :param blueprints:
    """
    for blueprint in blueprints:
        app.register_blueprint(blueprint, url_prefix="/api/{0}".format(API_VERSION))


def configure_logging(app):
    """
    Sets up application wide logging.

    :param app:
    """
    handler = RotatingFileHandler(app.config.get('LOG_FILE', 'lemur.log'), maxBytes=10000000, backupCount=100)

    handler.setFormatter(Formatter(
        '%(asctime)s %(levelname)s: %(message)s '
        '[in %(pathname)s:%(lineno)d]'
    ))

    handler.setLevel(app.config.get('LOG_LEVEL', 'DEBUG'))
    app.logger.setLevel(app.config.get('LOG_LEVEL', 'DEBUG'))
    app.logger.addHandler(handler)


def install_plugins(app):
    """
    Installs new issuers that are not currently bundled with Lemur.

    :param settings:
    :return:
    """
    from lemur.plugins.base import register
    # entry_points={
    #    'lemur.plugins': [
    #         'verisign = lemur_verisign.plugin:VerisignPlugin'
    #     ],
    # },
    for ep in pkg_resources.iter_entry_points('lemur.plugins'):
        try:
            plugin = ep.load()
        except Exception:
            import traceback
            app.logger.error("Failed to load plugin %r:\n%s\n" % (ep.name, traceback.format_exc()))
        else:
            register(plugin)