"""Functions to perform common checks.

These are useful for reusability, and hence maintainability of the code.
"""
from functools import wraps

from gn_libs.mysqldb import database_connection
from flask import flash, url_for, redirect, current_app as app

from uploader.species.models import species_by_id
from uploader.population.models import population_by_species_and_id

def with_species(redirect_uri: str):
    """Ensure the species actually exists."""
    def __decorator__(function):
        @wraps(function)
        def __with_species__(**kwargs):
            try:
                species_id = int(kwargs.get("species_id"))
                if not bool(species_id):
                    flash("Expected species_id value to be present!",
                          "alert-danger")
                    return redirect(url_for(redirect_uri))
                with database_connection(app.config["SQL_URI"]) as conn:
                    species = species_by_id(conn, species_id)
                    if not bool(species):
                        flash("Could not find species with that ID",
                              "alert-danger")
                        return redirect(url_for(redirect_uri))
            except ValueError as _verr:
                app.logger.debug(
                    "Exception converting value to integer: %s",
                    kwargs.get("species_id"),
                    exc_info=True)
                flash("Expected an integer for 'species_id' value.",
                      "alert-danger")
                return redirect(url_for(redirect_uri))
            return function(**{**kwargs, "species": species})
        return __with_species__
    return __decorator__


def with_population(species_redirect_uri: str, redirect_uri: str):
    """Ensure the population actually exists."""
    def __decorator__(function):
        @wraps(function)
        @with_species(redirect_uri=species_redirect_uri)
        def __with_population__(**kwargs):
            try:
                species_id = int(kwargs["species_id"])
                population_id = int(kwargs.get("population_id"))
                select_population_uri = redirect(url_for(
                    redirect_uri, species_id=species_id))
                if not bool(population_id):
                    flash("Expected population_id value to be present!",
                          "alert-danger")
                    return select_population_uri
                with database_connection(app.config["SQL_URI"]) as conn:
                    population = population_by_species_and_id(
                        conn, species_id, population_id)
                    if not bool(population):
                        flash("Could not find population with that ID",
                              "alert-danger")
                        return select_population_uri
            except ValueError as _verr:
                app.logger.debug(
                    "Exception converting value to integer: %s",
                    kwargs.get("population_id"),
                    exc_info=True)
                flash("Expected an integer for 'population_id' value.",
                      "alert-danger")
                return select_population_uri
            return function(**{**kwargs, "population": population})
        return __with_population__
    return __decorator__