"""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  # noqa
        uwsgiRunning = True
    except ImportError:
        uwsgiRunning = False

    flask_request.set_rules_validator(app, 'abacus_contract/access_rules.yml')
    flask_request.setup(
        app,
        config.ENVIRONMENT,
        add_request_context=True,
        label_profile=True,
        verify_access=False,
        rules_file=None,
        access_log_only=config.ONLY_LOG_ACCESS_ERRORS,
        exclude_paths=[config.HEALTH_CHECK],
        uwsgi_cache_enabled=uwsgiRunning
    )


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_contract.blueprints.base import base_api
    from abacus_contract.blueprints.contract import contract_api
    from abacus_contract.blueprints.contract_advance import contract_advance_api
    from abacus_contract.blueprints.contract_flowthrough import contract_flowthrough_api
    from abacus_contract.blueprints.contract_lifecycle_schedule_detail \
        import contract_lifecycle_schedule_detail_api
    from abacus_contract.blueprints.contract_lifecycle_schedule \
        import contract_lifecycle_schedule_api
    from abacus_contract.blueprints.contract_lifecycle import contract_lifecycle_api
    from abacus_contract.blueprints.contract_mechanical_deduction import \
        contract_mechanical_deduction_api
    from abacus_contract.blueprints.contract_party import contract_party_api
    from abacus_contract.blueprints.contract_reserve import contract_reserve_api
    from abacus_contract.blueprints.contract_template import contract_template_api
    from abacus_contract.blueprints.contract_term import contract_term_api
    from abacus_contract.blueprints.contract_term_condition import contract_term_condition_api  # noqa: E501
    from abacus_contract.blueprints.contract_term_schedule import contract_term_schedule_api  # noqa: E501
    from abacus_contract.blueprints.contract_exclusion import contract_exclusion_api
    from abacus_contract.blueprints.legacy_contract import legacy_contract_api
    from abacus_contract.blueprints.reference_flowthrough_calculation \
        import reference_flowthrough_calculation_api
    from abacus_contract.blueprints.reference_mechanical_rate \
        import reference_mechanical_rate_api
    from abacus_contract.blueprints.reference_payment_entity \
        import reference_payment_entity_api
    from abacus_contract.blueprints.reference_payment_type \
        import reference_payment_type_api
    from abacus_contract.blueprints.reference_sap_profit_center \
        import reference_sap_profit_center_api
    from abacus_contract.blueprints.reference_signing_entity \
        import reference_signing_entity_api
    from abacus_contract.blueprints.reference_transaction_type \
        import reference_transaction_type_api
    from abacus_contract.blueprints.reference_transaction_type_group \
        import reference_transaction_type_group_api

    app.register_blueprint(base_api)
    app.register_blueprint(contract_api)
    app.register_blueprint(contract_advance_api)
    app.register_blueprint(contract_flowthrough_api)
    app.register_blueprint(contract_lifecycle_schedule_detail_api)
    app.register_blueprint(contract_lifecycle_schedule_api)
    app.register_blueprint(contract_lifecycle_api)
    app.register_blueprint(contract_mechanical_deduction_api)
    app.register_blueprint(contract_party_api)
    app.register_blueprint(contract_reserve_api)
    app.register_blueprint(contract_template_api)
    app.register_blueprint(contract_term_api)
    app.register_blueprint(contract_term_condition_api)
    app.register_blueprint(contract_term_schedule_api)
    app.register_blueprint(contract_exclusion_api)
    app.register_blueprint(legacy_contract_api)
    app.register_blueprint(reference_flowthrough_calculation_api)
    app.register_blueprint(reference_mechanical_rate_api)
    app.register_blueprint(reference_payment_entity_api)
    app.register_blueprint(reference_payment_type_api)
    app.register_blueprint(reference_sap_profit_center_api)
    app.register_blueprint(reference_signing_entity_api)
    app.register_blueprint(reference_transaction_type_api)
    app.register_blueprint(reference_transaction_type_group_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()