"""
Constants for radiology app.
Centralized choices and validators for consistency across models.
"""

from django.db import models
from django.core.validators import RegexValidator


class RadiologyChoices:
    """Centralized choices for radiology models."""
    
    class Modality(models.TextChoices):
        CR = 'CR', 'Computed Radiography'
        CT = 'CT', 'Computed Tomography'
        MR = 'MR', 'Magnetic Resonance'
        US = 'US', 'Ultrasound'
        XA = 'XA', 'X-Ray Angiography'
        RF = 'RF', 'Radiofluoroscopy'
        DX = 'DX', 'Digital Radiography'
        MG = 'MG', 'Mammography'
        NM = 'NM', 'Nuclear Medicine'
        PT = 'PT', 'Positron Emission Tomography'
        OT = 'OT', 'Other'

    class BodyPart(models.TextChoices):
        HEAD = 'HEAD', 'Head'
        NECK = 'NECK', 'Neck'
        CHEST = 'CHEST', 'Chest'
        ABDOMEN = 'ABDOMEN', 'Abdomen'
        PELVIS = 'PELVIS', 'Pelvis'
        SPINE = 'SPINE', 'Spine'
        EXTREMITY = 'EXTREMITY', 'Extremity'
        BREAST = 'BREAST', 'Breast'
        HEART = 'HEART', 'Heart'
        BRAIN = 'BRAIN', 'Brain'
        WHOLE_BODY = 'WHOLE_BODY', 'Whole Body'
        OTHER = 'OTHER', 'Other'

    class Priority(models.TextChoices):
        ROUTINE = 'ROUTINE', 'Routine'
        URGENT = 'URGENT', 'Urgent'
        STAT = 'STAT', 'STAT'
        EMERGENCY = 'EMERGENCY', 'Emergency'

    class ImageQuality(models.TextChoices):
        EXCELLENT = 'EXCELLENT', 'Excellent'
        GOOD = 'GOOD', 'Good'
        ADEQUATE = 'ADEQUATE', 'Adequate'
        POOR = 'POOR', 'Poor'
        UNACCEPTABLE = 'UNACCEPTABLE', 'Unacceptable'

    class StudyStatus(models.TextChoices):
        SCHEDULED = 'SCHEDULED', 'Scheduled'
        ARRIVED = 'ARRIVED', 'Arrived'
        IN_PROGRESS = 'IN_PROGRESS', 'In Progress'
        COMPLETED = 'COMPLETED', 'Completed'
        INTERPRETED = 'INTERPRETED', 'Interpreted'
        FINALIZED = 'FINALIZED', 'Finalized'
        CANCELLED = 'CANCELLED', 'Cancelled'

    class OrderStatus(models.TextChoices):
        PENDING = 'PENDING', 'Pending'
        SCHEDULED = 'SCHEDULED', 'Scheduled'
        IN_PROGRESS = 'IN_PROGRESS', 'In Progress'
        COMPLETED = 'COMPLETED', 'Completed'
        CANCELLED = 'CANCELLED', 'Cancelled'
        ON_HOLD = 'ON_HOLD', 'On Hold'

    class ReportStatus(models.TextChoices):
        DRAFT = 'DRAFT', 'Draft'
        PRELIMINARY = 'PRELIMINARY', 'Preliminary'
        FINAL = 'FINAL', 'Final'
        AMENDED = 'AMENDED', 'Amended'
        CORRECTED = 'CORRECTED', 'Corrected'

    class CompletionStatus(models.TextChoices):
        COMPLETE = 'COMPLETE', 'Complete'
        PARTIAL = 'PARTIAL', 'Partial'
        INCOMPLETE = 'INCOMPLETE', 'Incomplete'

    class PatientPosition(models.TextChoices):
        HFP = 'HFP', 'Head First-Prone'
        HFS = 'HFS', 'Head First-Supine'
        HFDR = 'HFDR', 'Head First-Decubitus Right'
        HFDL = 'HFDL', 'Head First-Decubitus Left'
        FFP = 'FFP', 'Feet First-Prone'
        FFS = 'FFS', 'Feet First-Supine'
        FFDR = 'FFDR', 'Feet First-Decubitus Right'
        FFDL = 'FFDL', 'Feet First-Decubitus Left'

    class ContrastRoute(models.TextChoices):
        IV = 'IV', 'Intravenous'
        ORAL = 'ORAL', 'Oral'
        RECTAL = 'RECTAL', 'Rectal'
        INTRATHECAL = 'INTRATHECAL', 'Intrathecal'
        INTRA_ARTICULAR = 'INTRA_ARTICULAR', 'Intra-articular'
        OTHER = 'OTHER', 'Other'


class RadiologyValidators:
    """Validators for radiology-specific fields."""
    
    # DICOM UID validator - must be numeric with dots
    dicom_uid_validator = RegexValidator(
        regex=r'^[0-9]+(\.[0-9]+)*$',
        message='Invalid DICOM UID format. Must contain only numbers and dots.'
    )
    
    # Accession number validator
    accession_number_validator = RegexValidator(
        regex=r'^[A-Z]{2,4}-\d{8}-\d{4}$',
        message='Invalid accession number format. Expected format: RAD-YYYYMMDD-NNNN'
    )
    
    # Order number validator
    order_number_validator = RegexValidator(
        regex=r'^[A-Z]{3}-\d+-\d{6}$',
        message='Invalid order number format. Expected format: IMG-TENANT-NNNNNN'
    )


# DICOM Standard Constants
class DICOMConstants:
    """DICOM standard constants and mappings."""
    
    # Common SOP Class UIDs
    SOP_CLASS_UIDS = {
        'CT_IMAGE': '1.2.840.10008.5.1.4.1.1.2',
        'MR_IMAGE': '1.2.840.10008.5.1.4.1.1.4',
        'US_IMAGE': '1.2.840.10008.5.1.4.1.1.6.1',
        'CR_IMAGE': '1.2.840.10008.5.1.4.1.1.1',
        'DX_IMAGE': '1.2.840.10008.5.1.4.1.1.1.1',
    }
    
    # Transfer Syntax UIDs
    TRANSFER_SYNTAX_UIDS = {
        'IMPLICIT_VR_LITTLE_ENDIAN': '1.2.840.10008.1.2',
        'EXPLICIT_VR_LITTLE_ENDIAN': '1.2.840.10008.1.2.1',
        'EXPLICIT_VR_BIG_ENDIAN': '1.2.840.10008.1.2.2',
        'JPEG_BASELINE': '1.2.840.10008.1.2.4.50',
        'JPEG_LOSSLESS': '1.2.840.10008.1.2.4.70',
    }
    
    # Standard image types
    IMAGE_TYPES = {
        'ORIGINAL': 'Original image',
        'DERIVED': 'Derived image',
        'SECONDARY': 'Secondary capture',
    }


# Business Rules Constants
class RadiologyBusinessRules:
    """Business rules and constraints for radiology workflow."""
    
    # Status transition rules
    VALID_STATUS_TRANSITIONS = {
        'SCHEDULED': ['ARRIVED', 'CANCELLED'],
        'ARRIVED': ['IN_PROGRESS', 'CANCELLED'],
        'IN_PROGRESS': ['COMPLETED', 'CANCELLED'],
        'COMPLETED': ['INTERPRETED'],
        'INTERPRETED': ['FINALIZED'],
        'FINALIZED': ['AMENDED'],
        'CANCELLED': [],  # Terminal state
    }
    
    # Priority escalation rules
    PRIORITY_ESCALATION_HOURS = {
        'ROUTINE': 24,
        'URGENT': 4,
        'STAT': 1,
        'EMERGENCY': 0.5,
    }
    
    # Critical finding communication requirements
    CRITICAL_COMMUNICATION_TIMEFRAMES = {
        'EMERGENCY': 15,  # minutes
        'STAT': 30,       # minutes
        'URGENT': 60,     # minutes
        'ROUTINE': 120,   # minutes
    }
    
    # Quality thresholds
    QUALITY_THRESHOLDS = {
        'MIN_ACCEPTABLE': 'ADEQUATE',
        'PREFERRED': 'GOOD',
        'EXCELLENT': 'EXCELLENT',
    }