from django.db import models

from apps.core.models import TimeStampedModel, UUIDModel


class StepExecution(UUIDModel, TimeStampedModel):
    class State(models.TextChoices):
        PENDING = "pending", "Pending"
        READY = "ready", "Ready"
        IN_PROGRESS = "in_progress", "In progress"
        PAUSED = "paused", "Paused"
        WAITING = "waiting", "Waiting"
        COMPLETED = "completed", "Completed"
        FAILED = "failed", "Failed"
        REJECTED = "rejected", "Rejected"
        SKIPPED = "skipped", "Skipped"
        CANCELLED = "cancelled", "Cancelled"
        REWORK_REQUIRED = "rework_required", "Rework required"

    order = models.ForeignKey("orders.ProcessingOrder", on_delete=models.CASCADE, related_name="step_executions")
    step = models.ForeignKey("workflows.WorkflowStep", on_delete=models.PROTECT)
    state = models.CharField(max_length=20, choices=State.choices, default=State.PENDING)
    attempt = models.PositiveIntegerField(default=1)
    assigned_to = models.ForeignKey(
        "accounts.User", null=True, blank=True, on_delete=models.SET_NULL, related_name="assigned_steps"
    )
    started_at = models.DateTimeField(null=True, blank=True)
    completed_at = models.DateTimeField(null=True, blank=True)
    notes = models.TextField(blank=True)
    measurements = models.JSONField(default=dict, blank=True)
    # For rework history: a rework execution points back to the failed one.
    parent = models.ForeignKey(
        "self", null=True, blank=True, on_delete=models.SET_NULL, related_name="rework_children"
    )

    class Meta:
        ordering = ["created_at"]
        constraints = [
            models.UniqueConstraint(fields=["order", "step", "attempt"], name="uniq_step_execution_attempt")
        ]

    def __str__(self) -> str:
        return f"{self.order.order_number} / {self.step.key} (attempt {self.attempt})"