"""
User models for KeepItGoing.
"""

import uuid
from django.contrib.auth.models import AbstractUser
from django.db import models


class User(AbstractUser):
    """
    Custom user model for KeepItGoing.

    Uses email as the primary identifier instead of username.
    """
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    email = models.EmailField(unique=True)

    # Profile fields
    timezone = models.CharField(max_length=50, default='UTC')
    avatar = models.ImageField(upload_to='avatars/', null=True, blank=True)

    # Preferences
    default_reminder_minutes = models.IntegerField(default=30)
    email_notifications = models.BooleanField(default=True)
    push_notifications = models.BooleanField(default=True)

    # Email verification
    email_verified = models.BooleanField(default=False)
    email_verified_at = models.DateTimeField(null=True, blank=True)

    # Admin approval
    is_approved = models.BooleanField(default=False)
    approved_by = models.ForeignKey(
        'self',
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name='approved_users',
        limit_choices_to={'is_staff': True}
    )
    approved_at = models.DateTimeField(null=True, blank=True)

    # Timestamps
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    # Use email as the username field
    USERNAME_FIELD = 'email'
    REQUIRED_FIELDS = ['username']

    class Meta:
        db_table = 'users'
        verbose_name = 'user'
        verbose_name_plural = 'users'

    def __str__(self):
        return self.email

    @classmethod
    def from_db(cls, db, field_names, values):
        instance = super().from_db(db, field_names, values)
        instance._loaded_default_reminder_minutes = dict(zip(field_names, values)).get('default_reminder_minutes')
        return instance

    def save(self, *args, **kwargs):
        loaded_reminder_minutes = getattr(self, '_loaded_default_reminder_minutes', None)
        reminder_minutes_changed = (
            loaded_reminder_minutes is not None and loaded_reminder_minutes != self.default_reminder_minutes
        )

        super().save(*args, **kwargs)
        self._loaded_default_reminder_minutes = self.default_reminder_minutes

        if reminder_minutes_changed:
            self.reschedule_reminder_notifications()

    def reschedule_reminder_notifications(self):
        """
        Recompute "before due" reminders for active tasks using the current
        default_reminder_minutes. Task.reschedule_reminders() only captures
        this setting at the moment a task's own due_date/due_time is set,
        so it doesn't apply retroactively on its own - this is what makes a
        profile-level change to the setting reach existing tasks. Tasks
        with their own explicit reminder_at override are left alone.
        """
        tasks = self.tasks.filter(
            due_date__isnull=False, is_deleted=False, reminder_at__isnull=True,
        ).exclude(status__in=('completed', 'cancelled'))
        for task in tasks:
            task.reschedule_reminders()


class DeviceToken(models.Model):
    """
    Stores push notification tokens for user devices.
    """
    PLATFORM_CHOICES = [
        ('android', 'Android'),
        ('web', 'Web'),
        ('desktop', 'Desktop'),
    ]

    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    user = models.ForeignKey(User, on_delete=models.CASCADE, related_name='device_tokens')
    platform = models.CharField(max_length=20, choices=PLATFORM_CHOICES)
    token = models.TextField()
    device_name = models.CharField(max_length=255, blank=True)
    is_active = models.BooleanField(default=True)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        db_table = 'device_tokens'
        unique_together = ['user', 'token']

    def __str__(self):
        return f"{self.user.email} - {self.platform} - {self.device_name}"


class EmailVerificationToken(models.Model):
    """
    Token for email verification.
    Uses UUID tokens with expiration for security.
    """
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    user = models.ForeignKey(User, on_delete=models.CASCADE, related_name='verification_tokens')
    token = models.UUIDField(default=uuid.uuid4, unique=True, editable=False)
    created_at = models.DateTimeField(auto_now_add=True)
    expires_at = models.DateTimeField()
    is_used = models.BooleanField(default=False)
    used_at = models.DateTimeField(null=True, blank=True)

    class Meta:
        db_table = 'email_verification_tokens'
        ordering = ['-created_at']

    def is_expired(self):
        from django.utils import timezone
        return timezone.now() > self.expires_at

    def __str__(self):
        return f"Verification token for {self.user.email}"