from django.conf import settings
from django.db import models
from django.db.models import Q


class SkillDefinition(models.Model):
    code = models.SlugField(max_length=80, unique=True)
    name = models.CharField(max_length=120)
    description = models.TextField(blank=True)
    active_version = models.ForeignKey(
        "SkillVersion",
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name="active_for_definitions",
    )
    created_by = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name="created_skills",
    )
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        ordering = ["name"]


class SkillVersion(models.Model):
    definition = models.ForeignKey(
        SkillDefinition,
        on_delete=models.CASCADE,
        related_name="versions",
    )
    version = models.PositiveIntegerField()
    status = models.CharField(max_length=24, default="draft")
    prompt_template = models.TextField()
    input_schema = models.JSONField(default=dict)
    output_schema = models.JSONField(default=dict)
    example_input = models.JSONField(default=dict, blank=True)
    created_by = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name="created_skill_versions",
    )
    published_by = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name="published_skill_versions",
    )
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)
    published_at = models.DateTimeField(null=True, blank=True)

    class Meta:
        ordering = ["-version"]
        constraints = [
            models.UniqueConstraint(
                fields=["definition", "version"],
                name="unique_skill_version",
            ),
            models.UniqueConstraint(
                fields=["definition"],
                condition=Q(status="draft"),
                name="unique_skill_draft",
            ),
        ]