from django.db import models
from django.conf import settings
from django.utils.translation import gettext_lazy as _


class CreditTransaction(models.Model):
    class TransactionType(models.TextChoices):
        BONUS = "bonus", _("Bonus")
        RECHARGE = "recharge", _("Recharge")
        REDEEM_LAB = "redeem_lab", _("Redeem Lab")
        REDEEM_EXAM = "redeem_exam", _("Redeem Exam")
        # Lab was failed, refund the credit.
        REDEEM_LAB_REFUND = "redeem_lab_refund", _("Redeem Lab Refund")
        BUY_CREDITS = "buy_credits", _("Buy Credits")
        OTHER = "other", _("Other")

    user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.DO_NOTHING)
    transaction_type = models.CharField(max_length=20, choices=TransactionType.choices)
    paid_credits = models.IntegerField(default=0)
    free_credits = models.IntegerField(default=0)
    # Credit transaction log for debugging purposes.
    # {
    #     "paid_credit": {
    #         "id": 1,
    #         "amount": -100,
    #     },
    #     "free_credit": [
    #         {"id": 2, "amount": -100, "expires_at": "2025-01-01 00:00:00"},
    #         {"id": 3, "amount": -50, "expires_at": "2025-01-01 00:00:00"},
    #     ]
    # }
    log = models.JSONField(
        default=dict, help_text=("The log of the credit transaction.")
    )
    redemption = models.ForeignKey(
        "labs.UserLabRedemption",
        on_delete=models.DO_NOTHING,
        null=True,
        blank=True,
        help_text="The lab redemption of the credit transaction.",
    )
    exam_redemption = models.ForeignKey(
        "labs.UserExamRedemption",
        on_delete=models.DO_NOTHING,
        null=True,
        blank=True,
        help_text="The exam redemption of the credit transaction.",
    )
    reference_transaction = models.ForeignKey(
        "self",
        on_delete=models.DO_NOTHING,
        null=True,
        blank=True,
        help_text="The reference transaction of the credit transaction.",
    )
    remark = models.CharField(max_length=255, null=True, blank=True)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        db_table = "billing_credit_transactions"