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


class KnowledgeBase(models.Model):
    name = models.CharField(max_length=160)
    description = models.TextField(blank=True)
    scope = models.CharField(max_length=120, blank=True)
    enabled = models.BooleanField(default=True)
    created_by = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
    )
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        ordering = ["-updated_at"]

    def __str__(self) -> str:
        return self.name


class KnowledgeDocument(models.Model):
    knowledge_base = models.ForeignKey(
        KnowledgeBase,
        on_delete=models.CASCADE,
        related_name="documents",
    )
    file_name = models.CharField(max_length=255)
    file_type = models.CharField(max_length=80, blank=True)
    storage_path = models.CharField(max_length=500, blank=True)
    content_text = models.TextField(blank=True)
    parse_status = models.CharField(max_length=40, default="pending")
    parse_error = models.TextField(blank=True)
    created_by = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
    )
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        ordering = ["-created_at"]


class KnowledgeItem(models.Model):
    knowledge_base = models.ForeignKey(
        KnowledgeBase,
        on_delete=models.CASCADE,
        related_name="items",
    )
    title = models.CharField(max_length=200)
    problem = models.TextField()
    applicable_scope = models.TextField(blank=True)
    error_code = models.CharField(max_length=120, blank=True)
    root_cause = models.TextField(blank=True)
    troubleshooting_steps = models.TextField(blank=True)
    solution = models.TextField()
    risk_note = models.TextField(blank=True)
    status = models.CharField(max_length=40, default="draft")
    source_type = models.CharField(max_length=40, default="manual")
    source_ticket_id = models.BigIntegerField(null=True, blank=True)
    created_by = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name="created_knowledge_items",
    )
    reviewed_by = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name="reviewed_knowledge_items",
    )
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        ordering = ["-updated_at"]


class KnowledgeChunk(models.Model):
    knowledge_base = models.ForeignKey(
        KnowledgeBase,
        on_delete=models.CASCADE,
        related_name="chunks",
    )
    document = models.ForeignKey(
        KnowledgeDocument,
        null=True,
        blank=True,
        on_delete=models.CASCADE,
        related_name="chunks",
    )
    item = models.ForeignKey(
        KnowledgeItem,
        null=True,
        blank=True,
        on_delete=models.CASCADE,
        related_name="chunks",
    )
    chunk_index = models.PositiveIntegerField(default=0)
    content = models.TextField()
    embedding = models.JSONField(default=list, blank=True)
    embedding_model = models.CharField(max_length=120, default="local-hash-v1")
    metadata = models.JSONField(default=dict, blank=True)
    created_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        ordering = ["knowledge_base_id", "document_id", "item_id", "chunk_index"]
        indexes = [
            models.Index(fields=["knowledge_base", "chunk_index"]),
        ]