"""
Two distinct concerns live in this app:

1. ``Notification`` — consumer-facing in-app inbox entries surfaced on the mobile
   SPA (/api/notifications/list/). One row per user per alert.

2. ``NotificationSchedule`` + ``NotificationRecipient`` — admin-side recurring
   email jobs configured from the Command Center Settings tab and dispatched by
   the ``send_scheduled_notifications`` management command (host cron).
   Not user-facing; strictly operational.
"""
from django.db import models

from accounts.models import User


class Notification(models.Model):
    NOTIFICATION_TYPES = [
        ('event', 'Event'),
        ('promo', 'Promotion'),
        ('system', 'System'),
        ('booking', 'Booking'),
    ]

    user = models.ForeignKey(User, on_delete=models.CASCADE, related_name='notifications')
    title = models.CharField(max_length=255)
    message = models.TextField()
    notification_type = models.CharField(max_length=20, choices=NOTIFICATION_TYPES, default='system')
    is_read = models.BooleanField(default=False)
    action_url = models.URLField(blank=True, null=True)
    created_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        ordering = ['-created_at']

    def __str__(self):
        return f"{self.notification_type}: {self.title} → {self.user.email}"


class NotificationSchedule(models.Model):
    """One configurable recurring email job.

    New types are added by registering a builder in ``notifications/emails.py``
    and adding the slug to ``TYPE_CHOICES`` below. Cron expression is evaluated
    in ``Asia/Kolkata`` by the dispatcher (matches operations team timezone).
    """

    TYPE_EVENTS_EXPIRING_THIS_WEEK = 'events_expiring_this_week'

    TYPE_CHOICES = [
        (TYPE_EVENTS_EXPIRING_THIS_WEEK, 'Events Expiring This Week'),
    ]

    STATUS_SUCCESS = 'success'
    STATUS_ERROR = 'error'

    name = models.CharField(max_length=200)
    notification_type = models.CharField(
        max_length=64, choices=TYPE_CHOICES, db_index=True,
    )
    cron_expression = models.CharField(
        max_length=100, default='0 0 * * 1',
        help_text='Standard 5-field cron (minute hour dom month dow). '
                  'Evaluated in Asia/Kolkata.',
    )
    is_active = models.BooleanField(default=True, db_index=True)
    last_run_at = models.DateTimeField(null=True, blank=True)
    last_status = models.CharField(max_length=20, blank=True, default='')
    last_error = models.TextField(blank=True, default='')
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        ordering = ['-created_at']
        indexes = [models.Index(fields=['is_active', 'notification_type'])]

    def __str__(self):
        return f'{self.name} ({self.notification_type})'


class NotificationRecipient(models.Model):
    """Free-form recipient — not tied to a User row so external stakeholders
    (vendors, partners, sponsors) can receive notifications without needing
    platform accounts."""

    schedule = models.ForeignKey(
        NotificationSchedule,
        on_delete=models.CASCADE,
        related_name='recipients',
    )
    email = models.EmailField()
    display_name = models.CharField(max_length=200, blank=True, default='')
    is_active = models.BooleanField(default=True)
    created_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        unique_together = [('schedule', 'email')]
        ordering = ['display_name', 'email']

    def __str__(self):
        label = self.display_name or self.email
        return f'{label} ({self.schedule.name})'