from django.core.validators import MinValueValidator
from django.db import models

from backend_app.models.abstract.module import Module, ModuleSerializer, ModuleViewSet

from backend_app.models.currency import Currency
from rest_framework import serializers

SCHOLARSHIP_FREQUENCIES = (
    ("w", "week"),
    ("m", "month"),
    ("s", "semester"),
    ("y", "year"),
    ("o", "one_shot"),
)


class Scholarship(Module):
    """
    Abstract model for scholarships
    """

    short_description = models.CharField(max_length=200)
    currency = models.ForeignKey(Currency, null=True, on_delete=models.PROTECT)
    other_advantages = models.CharField(default="", blank=True, max_length=5000)

    frequency = models.CharField(
        max_length=1,
        choices=SCHOLARSHIP_FREQUENCIES,
        default="m",
        null=True,
        blank=True,
    )

    amount_min = models.DecimalField(
        null=True, max_digits=20, decimal_places=2, validators=[MinValueValidator(0)]
    )

    amount_max = models.DecimalField(
        null=True, max_digits=20, decimal_places=2, validators=[MinValueValidator(0)]
    )

    class Meta:
        abstract = True


class ScholarshipSerializer(ModuleSerializer):
    """
    Serializer for the scholarship class
    """

    def validate(self, attrs):
        """
        Custom attribute validation
        """

        attrs = super().validate(attrs)

        if attrs["amount_min"] is not None:
            if attrs["currency"] is None:
                raise serializers.ValidationError(
                    "A currency must be specified when there is a value"
                )
            if (
                attrs["amount_max"] is not None
                and attrs["amount_max"] < attrs["amount_min"]
            ):
                raise serializers.ValidationError(
                    "amount_max should be greater or equal than amount_min"
                )

        return attrs

    class Meta:
        model = Scholarship
        fields = "__all__"


class ScholarshipViewSet(ModuleViewSet):
    serializer_class = ScholarshipSerializer