"""Application.

The API application is a `flask` application. It provides simple features such
as registering a url for a specific handlers.
"""

from abacus_common_logic.connectors.database import db
from abacus_common_logic.marshalling.custom_fields import ma
from abacus_common_logic.utils.users import set_flask_user_details_from_headers
from flask import Flask
from owslogger import flask_logger
from owsrequest import flask_request
from owsresponse import response
from owsresponse.adaptors.flask import flaskify
from werkzeug.exceptions import HTTPException, InternalServerError


def create_app(config):
    """Create an app."""
    app = Flask(config.SERVICE_NAME)
    app.config.from_object(config)
    app.url_map.strict_slashes = False
    setup_application_log(app, config)
    setup_owsrequest(app, config)
    setup_db(app, config)
    setup_marshmallow(app)
    register_blueprints(app)
    register_error_handlers(app)
    register_request_handler(app)

    return app


def setup_owsrequest(app, config):
    """Set up request framework."""
    try:
        import uwsgi

        uwsgi_running = True
    except ImportError:
        uwsgi_running = False
    flask_request.setup(
        app,
        config.ENVIRONMENT,
        add_request_context=True,
        label_profile=True,
        verify_access=True,
        rules_file='abacus_worksheet/access_rules.yml',
        access_log_only=config.ONLY_LOG_ACCESS_ERRORS,
        exclude_paths=[config.HEALTH_CHECK],
        uwsgi_cache_enabled=uwsgi_running,
    )


def setup_application_log(app, config):
    """Set up the application log."""
    flask_logger.setup(
        app,
        config.ENVIRONMENT,
        config.LOGGER_NAME,
        config.LOGGER_LEVEL,
        config.SERVICE_NAME,
        config.SERVICE_VERSION,
        exclude_paths=[config.HEALTH_CHECK],
    )


def setup_db(app, config):
    """Set up the database."""
    app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
    app.config['SQLALCHEMY_DATABASE_URI'] = (
        'mysql+pymysql://{}:{}@{}:{}/{}?charset=UTF8MB4'.format(
            config.MYSQL_DB_USER,
            config.MYSQL_DB_PASS,
            config.MYSQL_DB_HOST,
            config.MYSQL_DB_PORT,
            config.MYSQL_DB_NAME,
        )
    )
    db.init_app(app)


def setup_marshmallow(app):
    """Set up marshmallow."""
    ma.init_app(app)


def register_blueprints(app):
    """Register blueprints."""
    from abacus_worksheet.blueprints.base import base_api
    from abacus_worksheet.blueprints.worksheet_adjustment import (
        worksheet_adjustment_api,
    )
    from abacus_worksheet.blueprints.worksheet_adjustment_detail import (
        worksheet_adjustment_detail_api,
    )
    from abacus_worksheet.blueprints.worksheet_correction import (
        worksheet_correction_api,
    )

    app.register_blueprint(base_api)
    app.register_blueprint(worksheet_adjustment_api)
    app.register_blueprint(worksheet_adjustment_detail_api)
    app.register_blueprint(worksheet_correction_api)


def register_error_handlers(app):
    """Register error handlers."""

    def http_error_handler(error):
        """Handle http errors."""
        return flaskify(
            response.create_error_response(
                message=error.description, status=error.code, code='error'
            )
        )

    app.register_error_handler(HTTPException, http_error_handler)

    def exception_handler(_):
        """Handle exceptions."""
        message = (
            'The server encountered an internal error '
            'and was unable to complete your request.'
        )
        return flaskify(response.create_fatal_response(message))

    app.register_error_handler(InternalServerError, exception_handler)


def register_request_handler(app):
    """Register function to preprocess request data."""

    @app.before_request
    def before_request_start():
        set_flask_user_details_from_headers()