from django.db import models
from django.contrib.auth.models import User


class Ticket(models.Model):
    STATUS_CHOICES = [
        ('open', 'Offen'),
        ('in_progress', 'In Bearbeitung'),
        ('closed', 'Geschlossen'),
    ]

    PRIORITY_CHOICES = [
        ('low', 'Niedrig'),
        ('medium', 'Mittel'),
        ('high', 'Hoch'),
    ]

    title = models.CharField(max_length=200)
    description = models.TextField()
    status = models.CharField(max_length=20, choices=STATUS_CHOICES, default='open')
    priority = models.CharField(max_length=10, choices=PRIORITY_CHOICES, default='medium')
    created_by = models.ForeignKey(User, related_name='tickets_created', on_delete=models.CASCADE)
    assigned_to = models.ForeignKey(User, related_name='tickets_assigned', null=True, blank=True, on_delete=models.SET_NULL)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    def __str__(self):
        return f"[{self.get_priority_display()}] {self.title} ({self.get_status_display()})"


class Comment(models.Model):
    ticket = models.ForeignKey("Ticket", on_delete=models.CASCADE, related_name="comments")
    author = models.ForeignKey(User, on_delete=models.CASCADE)
    text = models.TextField()
    created_at = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return f"Kommentar von {self.author} zu Ticket #{self.ticket.id}"


class TicketHistory(models.Model):
    ticket = models.ForeignKey("Ticket", on_delete=models.CASCADE, related_name="history")
    changed_by = models.ForeignKey(User, on_delete=models.SET_NULL, null=True)
    changed_at = models.DateTimeField(auto_now_add=True)

    field = models.CharField(max_length=100)  # z. B. "status" oder "description"
    old_value = models.TextField(null=True, blank=True)
    new_value = models.TextField(null=True, blank=True)

    class Meta:
        ordering = ["-changed_at"]