import uuid

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


class Job(models.Model):
    class Status(models.TextChoices):
        QUEUED = "queued", "Queued"
        RUNNING = "running", "Running"
        SUCCEEDED = "succeeded", "Succeeded"
        FAILED = "failed", "Failed"

    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    type = models.CharField(max_length=120)
    payload = models.JSONField(default=dict, blank=True)
    status = models.CharField(max_length=20, choices=Status.choices, default=Status.QUEUED, db_index=True)
    priority = models.SmallIntegerField(default=50)
    available_at = models.DateTimeField(db_index=True)
    attempts = models.PositiveIntegerField(default=0)
    max_attempts = models.PositiveIntegerField(default=3)
    idempotency_key = models.CharField(max_length=255, null=True, blank=True)
    locked_by = models.CharField(max_length=255, null=True, blank=True)
    locked_until = models.DateTimeField(null=True, blank=True)
    last_error = models.TextField(blank=True, default="")
    result = models.JSONField(null=True, blank=True)
    created_at = models.DateTimeField(auto_now_add=True, db_index=True)
    updated_at = models.DateTimeField(auto_now=True)
    finished_at = models.DateTimeField(null=True, blank=True)

    class Meta:
        ordering = ("-created_at",)
        constraints = [
            models.CheckConstraint(
                name="job_status_valid_shape",
                condition=(
                    Q(
                        status="queued",
                        locked_by__isnull=True,
                        locked_until__isnull=True,
                        finished_at__isnull=True,
                    )
                    | Q(
                        status="running",
                        locked_by__isnull=False,
                        locked_until__isnull=False,
                        finished_at__isnull=True,
                    )
                    | Q(
                        status__in=["succeeded", "failed"],
                        locked_by__isnull=True,
                        locked_until__isnull=True,
                        finished_at__isnull=False,
                    )
                ),
            ),
            models.CheckConstraint(
                name="job_attempts_valid",
                condition=Q(attempts__gte=0, max_attempts__gte=1, attempts__lte=models.F("max_attempts")),
            ),
            models.UniqueConstraint(
                fields=["idempotency_key"],
                condition=Q(idempotency_key__isnull=False),
                name="job_idempotency_key_unique",
            ),
        ]
        indexes = [
            models.Index(
                fields=["available_at", "-priority", "created_at", "id"],
                name="job_claim_idx",
                condition=Q(status="queued"),
            ),
            models.Index(fields=["locked_until"], name="job_timeout_idx", condition=Q(status="running")),
        ]

    def __str__(self):
        return f"{self.type}:{self.id}"


class JobEvent(models.Model):
    class Type(models.TextChoices):
        CREATED = "created", "Created"
        CLAIMED = "claimed", "Claimed"
        PROGRESS = "progress", "Progress"
        LEASE_RENEWED = "lease_renewed", "Lease renewed"
        SUCCEEDED = "succeeded", "Succeeded"
        RETRY_SCHEDULED = "retry_scheduled", "Retry scheduled"
        FAILED = "failed", "Failed"
        TIMEOUT_REQUEUED = "timeout_requeued", "Timeout requeued"
        MANUAL_RETRY = "manual_retry", "Manual retry"

    job = models.ForeignKey(Job, on_delete=models.CASCADE, related_name="events")
    type = models.CharField(max_length=40, choices=Type.choices, db_index=True)
    attempt = models.PositiveIntegerField(default=0)
    worker_id = models.CharField(max_length=255, null=True, blank=True)
    message = models.TextField(blank=True, default="")
    data = models.JSONField(default=dict, blank=True)
    created_at = models.DateTimeField(auto_now_add=True, db_index=True)

    class Meta:
        ordering = ("id",)
        indexes = [
            models.Index(fields=["job", "id"], name="job_event_job_id_idx"),
            models.Index(fields=["id"], name="job_event_id_idx"),
        ]

    def __str__(self):
        return f"{self.type}:{self.job_id}:{self.id}"