# documentation/models.py
from django.conf import settings
from django.db import models
from django.contrib.contenttypes.fields import GenericForeignKey
from django.contrib.contenttypes.models import ContentType
import uuid

class NoteType(models.TextChoices):
    ADMISSION = "ADMISSION", "Admission Note"
    PROGRESS = "PROGRESS", "Progress Note"
    DISCHARGE = "DISCHARGE", "Discharge Summary"
    RADIOLOGY_REPORT = "RADIOLOGY_REPORT", "Radiology Report"
    LAB_REPORT = "LAB_REPORT", "Laboratory Narrative"
    PROCEDURE = "PROCEDURE", "Procedure Note"
    ANESTHESIA = "ANESTHESIA", "Anesthesia Note"
    OTHER = "OTHER", "Other"

class Document(models.Model):
    """
    Canonical clinical document (note/report).
    Stores content, metadata, provenance, and links to any domain object.
    """
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    tenant = models.ForeignKey("core.Tenant", on_delete=models.CASCADE, related_name="documents")
    patient = models.ForeignKey("core.Patient", on_delete=models.CASCADE, related_name="documents")
    encounter = models.ForeignKey("core.Encounter", on_delete=models.SET_NULL, null=True, blank=True, related_name="documents")

    doc_type = models.CharField(max_length=40, choices=NoteType.choices)
    title = models.CharField(max_length=255)
    status = models.CharField(max_length=20, default="final")  # draft | amended | final | entered-in-error
    authored_at = models.DateTimeField(auto_now_add=True)
    authored_by = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.SET_NULL, null=True, related_name="documents_authored")
    signed_at = models.DateTimeField(null=True, blank=True)
    signed_by = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.SET_NULL, null=True, blank=True, related_name="documents_signed")

    # Content
    # Store both rich text and structured JSON to support templates, tokens, smart fields.
    body_markdown = models.TextField(blank=True, default="")
    body_json = models.JSONField(blank=True, null=True)  # optional structured representation

    # FHIR mapping hints (optional)
    fhir_profile = models.CharField(max_length=120, blank=True, default="")  # e.g., Composition/DiagnosticReport
    code = models.CharField(max_length=64, blank=True, default="")          # LOINC/SNOMED if used

    # Full-text search (enable GIN index in migration)
    search_vector = models.TextField(blank=True, default="")  # or use a dedicated SearchVector field

    # Soft flags
    is_confidential = models.BooleanField(default=False)
    is_amendment = models.BooleanField(default=False)

    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

class DocumentVersion(models.Model):
    document = models.ForeignKey(Document, on_delete=models.CASCADE, related_name="versions")
    version = models.PositiveIntegerField()
    snapshot_markdown = models.TextField(blank=True, default="")
    snapshot_json = models.JSONField(blank=True, null=True)
    changed_by = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.SET_NULL, null=True)
    changed_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        unique_together = [("document", "version")]
        ordering = ["-version"]

class DocumentLink(models.Model):
    """
    Generic relation to ANY object (lab order, study, admission, procedure, etc.)
    Allows many-to-many linking without embedding foreign keys in every domain app.
    """
    document = models.ForeignKey(Document, on_delete=models.CASCADE, related_name="links")
    content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
    object_id = models.CharField(max_length=64)
    target = GenericForeignKey("content_type", "object_id")
    role = models.CharField(max_length=40, blank=True, default="context")  # context | source | result | followup
    created_at = models.DateTimeField(auto_now_add=True)

class DocumentAttachment(models.Model):
    document = models.ForeignKey(Document, on_delete=models.CASCADE, related_name="attachments")
    file = models.FileField(upload_to="documents/%Y/%m/")
    title = models.CharField(max_length=255, blank=True, default="")
    created_at = models.DateTimeField(auto_now_add=True)