"""Handle application level errors."""
import traceback

from http.client import RemoteDisconnected
from urllib.error import URLError
from sqlite3 import OperationalError
from SPARQLWrapper.SPARQLExceptions import (
    EndPointInternalError,
    EndPointNotFound,
    QueryBadFormed,
    URITooLong,
    Unauthorized
)
from werkzeug.exceptions import NotFound
from authlib.oauth2.rfc6749.errors import OAuth2Error
from flask import Flask, jsonify, Response, current_app

from gn3.oauth2 import errors as oautherrors
from gn3.auth.authorisation.errors import AuthorisationError


def add_trace(exc: Exception, jsonmsg: dict) -> dict:
    """Add the traceback to the error handling object."""
    return {
        **jsonmsg,
        "error-trace": "".join(traceback.format_exception(exc))
    }


def page_not_found(pnf):
    """Generic 404 handler."""
    current_app.logger.error("Handling 404 errors", exc_info=True)
    return jsonify(add_trace(pnf, {
        "error": pnf.name,
        "error_description": pnf.description
    })), 404


def internal_server_error(pnf):
    """Generic 404 handler."""
    current_app.logger.error("Handling internal server errors", exc_info=True)
    return jsonify(add_trace(pnf, {
        "error": pnf.name,
        "error_description": pnf.description
    })), 500


def url_server_error(pnf):
    """Handler for an exception with a url connection."""
    current_app.logger.error("Handling url server errors", exc_info=True)
    return jsonify(add_trace(pnf, {
        "error": f"URLLib Error no: {pnf.reason.errno}",
        "error_description": pnf.reason.strerror,
    })), 500


def handle_authorisation_error(exc: AuthorisationError):
    """Handle AuthorisationError if not handled anywhere else."""
    current_app.logger.error("Handling external auth errors", exc_info=True)
    return jsonify(add_trace(exc, {
        "error": type(exc).__name__,
        "error_description": " :: ".join(exc.args)
    })), exc.error_code


def handle_oauth2_errors(exc: OAuth2Error):
    """Handle OAuth2Error if not handled anywhere else."""
    current_app.logger.error("Handling external oauth2 errors", exc_info=True)
    return jsonify(add_trace(exc, {
        "error": exc.error,
        "error_description": exc.description,
    })), exc.status_code


def handle_sqlite3_errors(exc: OperationalError):
    """Handle sqlite3 errors if not handled anywhere else."""
    current_app.logger.error("Handling sqlite3 errors", exc_info=True)
    return jsonify({
        "error": "DatabaseError",
        "error_description": exc.args[0],
    }), 500


def handle_sparql_errors(exc):
    """Handle sqlite3 errors if not handled anywhere else."""
    current_app.logger.error("Handling sparql errors", exc_info=True)
    code = {
        "EndPointInternalError": 500,
        "EndPointNotFound": 404,
        "QueryBadFormed": 400,
        "Unauthorized": 401,
        "URITooLong": 414,
    }
    return jsonify({
        "error": exc.msg,
    }), code.get(exc.__class__.__name__)


def handle_generic(exc: Exception) -> Response:
    """Handle generic exception."""
    current_app.logger.error("Handling generic errors", exc_info=True)
    resp = jsonify({
        "error": type(exc).__name__,
        "error_description": (
            exc.args[0] if bool(exc.args) else "Generic Exception"),
        "trace": traceback.format_exc()
    })
    resp.status_code = 500
    return resp


def handle_local_authorisation_errors(exc: oautherrors.AuthorisationError):
    """Handle errors relating to authorisation that are raised locally."""
    current_app.logger.error("Handling local auth errors", exc_info=True)
    return jsonify(add_trace(exc, {
        "error": type(exc).__name__,
        "error_description": " ".join(exc.args)
    })), 400


def register_error_handlers(app: Flask):
    """Register application-level error handlers."""
    app.register_error_handler(NotFound, page_not_found)
    app.register_error_handler(Exception, handle_generic)
    app.register_error_handler(OAuth2Error, handle_oauth2_errors)
    app.register_error_handler(OperationalError, handle_sqlite3_errors)
    app.register_error_handler(AuthorisationError, handle_authorisation_error)
    app.register_error_handler(RemoteDisconnected, internal_server_error)
    app.register_error_handler(URLError, url_server_error)
    for exc in (
            EndPointInternalError,
            EndPointNotFound,
            QueryBadFormed,
            URITooLong,
            Unauthorized
    ):
        app.register_error_handler(exc, handle_sparql_errors)