from django.db import models
from django.db.models import Q

from infrasynth.shared.enums import ChannelType
from infrasynth.tenancy.mixins import GlobalOrTenantModel, TenantOwnedModel


class NotificationTemplate(GlobalOrTenantModel):
    """A template. ``tenant IS NULL`` is the platform default; a tenant row overrides it."""

    slug = models.SlugField(max_length=100)
    name = models.CharField(max_length=200)
    channel = models.CharField(max_length=20, choices=ChannelType.choices)
    subject_template = models.CharField(max_length=500)
    body_template = models.TextField()
    is_html = models.BooleanField(default=False)
    namespace = models.CharField(max_length=100, default="", blank=True)
    metadata = models.JSONField(default=dict)

    class Meta:
        db_table = "notifications_template"
        constraints = [
            models.UniqueConstraint(
                fields=["tenant", "slug", "namespace"],
                name="uniq_template_slug_namespace_per_tenant",
            ),
            models.UniqueConstraint(
                fields=["slug", "namespace"],
                condition=Q(tenant__isnull=True),
                name="uniq_global_template_slug_namespace",
            ),
        ]


class NotificationDispatch(TenantOwnedModel):
    class Status(models.TextChoices):
        PENDING = "pending", "Pending"
        SENT = "sent", "Sent"
        FAILED = "failed", "Failed"
        RETRYING = "retrying", "Retrying"

    template = models.ForeignKey(
        NotificationTemplate,
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name="dispatches",
    )
    recipient = models.CharField(max_length=255)
    channel = models.CharField(max_length=20, choices=ChannelType.choices)
    subject = models.CharField(max_length=500)
    body = models.TextField()
    status = models.CharField(max_length=20, choices=Status.choices, default=Status.PENDING)
    error_message = models.TextField(blank=True, default="")
    attempt = models.PositiveSmallIntegerField(default=0)
    next_retry_at = models.DateTimeField(null=True, blank=True)
    context_snapshot = models.JSONField(default=dict, blank=True)
    created_at = models.DateTimeField(auto_now_add=True)
    completed_at = models.DateTimeField(null=True, blank=True)
    request_id = models.UUIDField(null=True, blank=True)

    class Meta:
        db_table = "notifications_dispatch"
        indexes = [models.Index(fields=["tenant_id", "status"])]


class ChannelConfig(TenantOwnedModel):
    slug = models.SlugField(max_length=100)
    channel_type = models.CharField(max_length=20, choices=ChannelType.choices)
    display_name = models.CharField(max_length=200)
    config = models.JSONField(default=dict)
    is_active = models.BooleanField(default=True)
    priority = models.PositiveSmallIntegerField(default=0)

    class Meta:
        db_table = "notifications_channel_config"
        constraints = [
            models.UniqueConstraint(fields=["tenant", "slug"], name="uniq_channel_config_slug_per_tenant"),
        ]