from django.db import models
from django.conf import settings
from events.models import Event


class AdSurface(models.Model):
    """
    A display surface where ad placements can appear.
    e.g. HOME_FEATURED_CAROUSEL, HOME_TOP_EVENTS, CATEGORY_FEATURED
    """
    LAYOUT_CHOICES = [
        ('carousel', 'Carousel'),
        ('grid', 'Grid'),
        ('list', 'List'),
    ]
    SORT_CHOICES = [
        ('rank', 'By Rank'),
        ('date', 'By Date'),
        ('popularity', 'By Popularity'),
    ]

    key = models.CharField(max_length=50, unique=True, db_index=True)
    name = models.CharField(max_length=100)
    description = models.TextField(blank=True, default='')
    max_slots = models.IntegerField(default=8)
    layout_type = models.CharField(max_length=20, choices=LAYOUT_CHOICES, default='carousel')
    sort_behavior = models.CharField(max_length=20, choices=SORT_CHOICES, default='rank')
    is_active = models.BooleanField(default=True)
    created_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        ordering = ['name']
        verbose_name = 'Ad Surface'
        verbose_name_plural = 'Ad Surfaces'

    def __str__(self):
        return f"{self.name} ({self.key})"

    @property
    def active_count(self):
        return self.placements.filter(status__in=['ACTIVE', 'SCHEDULED']).count()


class AdPlacement(models.Model):
    """
    A single placement of an event on a surface.
    Supports scheduling, ranking, scope-based targeting, and lifecycle status.
    """
    STATUS_CHOICES = [
        ('DRAFT', 'Draft'),
        ('ACTIVE', 'Active'),
        ('SCHEDULED', 'Scheduled'),
        ('EXPIRED', 'Expired'),
        ('DISABLED', 'Disabled'),
    ]
    PRIORITY_CHOICES = [
        ('SPONSORED', 'Sponsored'),
        ('MANUAL', 'Manual'),
        ('ALGO', 'Algorithm'),
    ]
    SCOPE_CHOICES = [
        ('GLOBAL', 'Global — shown to all users'),
        ('LOCAL', 'Local — shown to nearby users (50 km radius)'),
    ]

    surface = models.ForeignKey(
        AdSurface, on_delete=models.CASCADE, related_name='placements',
    )
    event = models.ForeignKey(
        Event, on_delete=models.CASCADE, related_name='ad_placements',
    )
    status = models.CharField(max_length=20, choices=STATUS_CHOICES, default='DRAFT', db_index=True)
    priority = models.CharField(max_length=20, choices=PRIORITY_CHOICES, default='MANUAL')
    scope = models.CharField(max_length=10, choices=SCOPE_CHOICES, default='GLOBAL', db_index=True)
    rank = models.IntegerField(default=0, help_text='Lower rank = higher position')
    start_at = models.DateTimeField(null=True, blank=True, help_text='When this placement becomes active')
    end_at = models.DateTimeField(null=True, blank=True, help_text='When this placement expires')
    boost_label = models.CharField(
        max_length=50, blank=True, default='',
        help_text='Display label e.g. "Featured", "Top Pick", "Sponsored"',
    )
    notes = models.TextField(blank=True, default='')
    created_by = models.ForeignKey(
        settings.AUTH_USER_MODEL, on_delete=models.SET_NULL,
        null=True, blank=True, related_name='created_placements',
    )
    updated_by = models.ForeignKey(
        settings.AUTH_USER_MODEL, on_delete=models.SET_NULL,
        null=True, blank=True, related_name='updated_placements',
    )
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        ordering = ['rank', '-created_at']
        verbose_name = 'Ad Placement'
        verbose_name_plural = 'Ad Placements'
        constraints = [
            models.UniqueConstraint(
                fields=['surface', 'event'],
                condition=models.Q(status__in=['DRAFT', 'ACTIVE', 'SCHEDULED']),
                name='unique_active_placement_per_surface',
            ),
        ]

    def __str__(self):
        return f"{self.event.name} on {self.surface.key} [{self.status}]"