import re
import random
import string

from django.db import models
from django.utils.translation import gettext_lazy as _
from django_tidb.fields import BigAutoRandomField
from django.conf import settings
from django.core.exceptions import ValidationError


CREDIT_VOUCHER_PATTERN = re.compile(
    r"^[A-Z0-9]{5}-[A-Z0-9]{5}-[A-Z0-9]{5}-[A-Z0-9]{5}-[A-Z0-9]{5}$"
)


def credit_code_generator():
    random_chars = "".join(random.choices(string.ascii_uppercase + string.digits, k=25))
    formatted_string = "-".join(random_chars[i : i + 5] for i in range(0, 25, 5))
    return formatted_string


def credit_code_validator(value):
    if not CREDIT_VOUCHER_PATTERN.match(value):
        raise ValidationError("Invalid credit code format")


def credits_validator(value):
    if value < 1:
        raise ValidationError("Credit must be greater than 0")


class CreditVoucher(models.Model):
    class UsedChoices(models.TextChoices):
        N = "N"
        Y = "Y"

    id = BigAutoRandomField(primary_key=True)
    unique_code = models.CharField(
        max_length=29,
        unique=True,
        default=credit_code_generator,
        help_text="The unique code of the credit voucher",
        validators=[credit_code_validator],
    )
    credits = models.IntegerField(
        null=True,
        validators=[credits_validator],
        help_text="The exchange rate with the USD is 1:1",
    )
    valid_before = models.DateField(null=True)
    used = models.CharField(
        max_length=1, default=UsedChoices.N, choices=UsedChoices.choices
    )
    marketing_code = models.CharField(max_length=100)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)
    category = models.CharField(max_length=30, default="Others")
    customer_organization = models.CharField(max_length=100, default="N/A")
    redeem_at = models.DateTimeField(blank=True, null=True)
    redeem_by = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        on_delete=models.DO_NOTHING,
        blank=True,
        null=True,
    )

    class Meta:
        db_table = "credit_vouchers"
        managed = False