"""Views dealing with populations/inbredsets"""
import re
import json
import base64

from flask import (flash,
                   request,
                   url_for,
                   redirect,
                   Blueprint,
                   current_app as app)

from uploader.ui import make_template_renderer
from uploader.authorisation import require_login
from uploader.db_utils import database_connection
from uploader.species.models import (all_species,
                                     species_by_id,
                                     order_species_by_family)

from .models import (save_population,
                     populations_by_species,
                     population_by_species_and_id)

__active_link__ = "populations"
popbp = Blueprint("populations", __name__)
render_template = make_template_renderer("populations")


@popbp.route("/populations", methods=["GET", "POST"])
@require_login
def index():
    """Entry point for populations."""
    with database_connection(app.config["SQL_URI"]) as conn:
        if not bool(request.args.get("species_id")):
            return render_template(
                "populations/index.html",
                species=order_species_by_family(all_species(conn)))
        species = species_by_id(conn, request.args.get("species_id"))
        if not bool(species):
            flash("Invalid species identifier provided!", "alert-danger")
            return redirect(url_for("species.populations.index"))
        return redirect(url_for("species.populations.list_species_populations",
                                species_id=species["SpeciesId"]))

@popbp.route("/<int:species_id>/populations", methods=["GET"])
@require_login
def list_species_populations(species_id: int):
    """List a particular species' populations."""
    with database_connection(app.config["SQL_URI"]) as conn:
        species = species_by_id(conn, species_id)
        if not bool(species):
            flash("No species was found for given ID.", "alert-danger")
            return redirect(url_for("species.populations.index"))
        return render_template(
            "populations/list-populations.html",
            species=species,
            populations=populations_by_species(conn, species_id),
            activelink="list-populations")


def valid_population_name(population_name: str) -> bool:
    """
    Check whether the given name is a valid population name.

    Parameters
    ----------
    population_name: a string of characters.

    Checks For
    ----------
    * The name MUST start with an alphabet [a-zA-Z]
    * The name MUST end with an alphabet [a-zA-Z] or number [0-9]
    * The name MUST be composed of alphabets [a-zA-Z], numbers [0-9],
      underscores (_) and/or hyphens (-).

    Returns
    -------
    Boolean indicating whether or not the name is valid.
    """
    pattern = re.compile(r"^[a-zA-Z]+[a-zA-Z0-9_-]*[a-zA-Z0-9]$")
    return bool(pattern.match(population_name))


@popbp.route("/<int:species_id>/populations/create", methods=["GET", "POST"])
@require_login
def create_population(species_id: int):
    """Create a new population."""
    with database_connection(app.config["SQL_URI"]) as conn:
        species = species_by_id(conn, species_id)

        if request.method == "GET":
            error_values = request.args.get("error_values")
            if not bool(error_values):
                error_values = base64.b64encode(
                    '{"errors":{}, "error_values": {}}'.encode("utf8")
                ).decode("utf8")

            error_values = json.loads(base64.b64decode(
                error_values.encode("utf8")).decode("utf8"))
            return render_template(
                "populations/create-population.html",
                species=species,
                activelink="create-population",
                **error_values)

        if not bool(species):
            flash("You must select a species.", "alert-danger")
            return redirect(url_for("species.populations.index"))

        errors = tuple()

        population_name = (request.form.get(
            "population_name") or "").strip()
        if not bool(population_name):
            errors = errors + (("population_name",
                                "You must provide a name for the population!"),)

        if not valid_population_name(population_name):
            errors = errors + ((
                "population_name",
                "The population name can only contain letters, numbers, "
                "hyphens and underscores."),)

        population_fullname = (request.form.get(
            "population_fullname") or "").strip()
        if not bool(population_fullname):
            errors = errors + (
                ("population_fullname", "Full Name MUST be provided."),)

        if bool(errors):
            values = base64.b64encode(
                json.dumps({
                    "errors": dict(errors),
                    "error_values": dict(request.form)
                }).encode("utf8"))
            return redirect(url_for("species.populations.create_population",
                                    species_id=species["SpeciesId"],
                                    error_values=values))

        new_population = save_population(conn, {
            "SpeciesId": species["SpeciesId"],
            "Name": population_name,
            "InbredSetName": population_fullname,
            "FullName": population_fullname,
            "Family": request.form.get("inbredset_family") or None,
            "Description": request.form.get("population_description") or None
        })

        return redirect(url_for("species.populations.view_population",
                                species_id=species["SpeciesId"],
                                population_id=new_population["InbredSetId"]))


@popbp.route("/<int:species_id>/populations/<int:population_id>",
             methods=["GET"])
@require_login
def view_population(species_id: int, population_id: int):
    """View the details of a population."""
    with database_connection(app.config["SQL_URI"]) as conn:
        species = species_by_id(conn, species_id)
        population = population_by_species_and_id(conn, species_id, population_id)
        error = False

        if not bool(species):
            flash("You must select a species.", "alert-danger")
            error = True

        if not bool(population):
            flash("You must select a population.", "alert-danger")
            error = True

        if error:
            return redirect(url_for("species.populations.index"))

        return render_template("populations/view-population.html",
                               species=species,
                               population=population,
                               activelink="view-population")