"""
Complaints models - Complaint management with SLA tracking

This module implements the complaint management system that:
- Tracks complaints with SLA deadlines
- Manages complaint workflow (open → in progress → resolved → closed)
- Triggers resolution satisfaction surveys
- Creates PX actions for negative resolution satisfaction
- Maintains complaint timeline and attachments
"""
from datetime import timedelta

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

from apps.core.models import PriorityChoices, SeverityChoices, TimeStampedModel, UUIDModel


class ComplaintStatus(models.TextChoices):
    """Complaint status choices"""
    OPEN = 'open', 'Open'
    IN_PROGRESS = 'in_progress', 'In Progress'
    RESOLVED = 'resolved', 'Resolved'
    CLOSED = 'closed', 'Closed'
    CANCELLED = 'cancelled', 'Cancelled'


class ComplaintSource(models.TextChoices):
    """Complaint source choices"""
    PATIENT = 'patient', 'Patient'
    FAMILY = 'family', 'Family Member'
    STAFF = 'staff', 'Staff'
    SURVEY = 'survey', 'Survey'
    SOCIAL_MEDIA = 'social_media', 'Social Media'
    CALL_CENTER = 'call_center', 'Call Center'
    MOH = 'moh', 'Ministry of Health'
    CHI = 'chi', 'Council of Health Insurance'
    OTHER = 'other', 'Other'


class Complaint(UUIDModel, TimeStampedModel):
    """
    Complaint model with SLA tracking.
    
    Workflow:
    1. OPEN - Complaint received
    2. IN_PROGRESS - Being investigated
    3. RESOLVED - Solution provided
    4. CLOSED - Confirmed closed (triggers resolution satisfaction survey)
    
    SLA:
    - Calculated based on severity and hospital configuration
    - Reminders sent before due date
    - Escalation triggered when overdue
    """
    # Patient and encounter information
    patient = models.ForeignKey(
        'organizations.Patient',
        on_delete=models.CASCADE,
        related_name='complaints'
    )
    encounter_id = models.CharField(
        max_length=100,
        blank=True,
        db_index=True,
        help_text="Related encounter ID if applicable"
    )
    
    # Organization
    hospital = models.ForeignKey(
        'organizations.Hospital',
        on_delete=models.CASCADE,
        related_name='complaints'
    )
    department = models.ForeignKey(
        'organizations.Department',
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name='complaints'
    )
    physician = models.ForeignKey(
        'organizations.Physician',
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name='complaints'
    )
    
    # Complaint details
    title = models.CharField(max_length=500)
    description = models.TextField()
    
    # Classification
    category = models.CharField(
        max_length=100,
        choices=[
            ('clinical_care', 'Clinical Care'),
            ('staff_behavior', 'Staff Behavior'),
            ('facility', 'Facility & Environment'),
            ('wait_time', 'Wait Time'),
            ('billing', 'Billing'),
            ('communication', 'Communication'),
            ('other', 'Other'),
        ],
        db_index=True
    )
    subcategory = models.CharField(max_length=100, blank=True)
    
    # Priority and severity
    priority = models.CharField(
        max_length=20,
        choices=PriorityChoices.choices,
        default=PriorityChoices.MEDIUM,
        db_index=True
    )
    severity = models.CharField(
        max_length=20,
        choices=SeverityChoices.choices,
        default=SeverityChoices.MEDIUM,
        db_index=True
    )
    
    # Source
    source = models.CharField(
        max_length=50,
        choices=ComplaintSource.choices,
        default=ComplaintSource.PATIENT,
        db_index=True
    )
    
    # Status and workflow
    status = models.CharField(
        max_length=20,
        choices=ComplaintStatus.choices,
        default=ComplaintStatus.OPEN,
        db_index=True
    )
    
    # Assignment
    assigned_to = models.ForeignKey(
        'accounts.User',
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name='assigned_complaints'
    )
    assigned_at = models.DateTimeField(null=True, blank=True)
    
    # SLA tracking
    due_at = models.DateTimeField(
        db_index=True,
        help_text="SLA deadline"
    )
    is_overdue = models.BooleanField(default=False, db_index=True)
    reminder_sent_at = models.DateTimeField(null=True, blank=True)
    escalated_at = models.DateTimeField(null=True, blank=True)
    
    # Resolution
    resolution = models.TextField(blank=True)
    resolved_at = models.DateTimeField(null=True, blank=True)
    resolved_by = models.ForeignKey(
        'accounts.User',
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name='resolved_complaints'
    )
    
    # Closure
    closed_at = models.DateTimeField(null=True, blank=True)
    closed_by = models.ForeignKey(
        'accounts.User',
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name='closed_complaints'
    )
    
    # Resolution satisfaction survey
    resolution_survey = models.ForeignKey(
        'surveys.SurveyInstance',
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name='complaint_resolution'
    )
    resolution_survey_sent_at = models.DateTimeField(null=True, blank=True)
    
    # Metadata
    metadata = models.JSONField(default=dict, blank=True)
    
    class Meta:
        ordering = ['-created_at']
        indexes = [
            models.Index(fields=['status', '-created_at']),
            models.Index(fields=['hospital', 'status', '-created_at']),
            models.Index(fields=['is_overdue', 'status']),
            models.Index(fields=['due_at', 'status']),
        ]
    
    def __str__(self):
        return f"{self.title} - {self.patient.get_full_name()} ({self.status})"
    
    def save(self, *args, **kwargs):
        """Calculate SLA due date on creation"""
        if not self.due_at:
            self.due_at = self.calculate_sla_due_date()
        super().save(*args, **kwargs)
    
    def calculate_sla_due_date(self):
        """
        Calculate SLA due date based on severity and hospital configuration.
        
        First tries to use ComplaintSLAConfig from database.
        Falls back to settings.SLA_DEFAULTS if no config exists.
        """
        # Try to get SLA config from database
        try:
            sla_config = ComplaintSLAConfig.objects.get(
                hospital=self.hospital,
                severity=self.severity,
                priority=self.priority,
                is_active=True
            )
            sla_hours = sla_config.sla_hours
        except ComplaintSLAConfig.DoesNotExist:
            # Fall back to settings
            sla_hours = settings.SLA_DEFAULTS['complaint'].get(
                self.severity,
                settings.SLA_DEFAULTS['complaint']['medium']
            )
        
        return timezone.now() + timedelta(hours=sla_hours)
    
    def check_overdue(self):
        """Check if complaint is overdue and update status"""
        if self.status in [ComplaintStatus.CLOSED, ComplaintStatus.CANCELLED]:
            return False
        
        if timezone.now() > self.due_at:
            if not self.is_overdue:
                self.is_overdue = True
                self.save(update_fields=['is_overdue'])
            return True
        return False


class ComplaintAttachment(UUIDModel, TimeStampedModel):
    """Complaint attachment (images, documents, etc.)"""
    complaint = models.ForeignKey(
        Complaint,
        on_delete=models.CASCADE,
        related_name='attachments'
    )
    
    file = models.FileField(upload_to='complaints/%Y/%m/%d/')
    filename = models.CharField(max_length=500)
    file_type = models.CharField(max_length=100, blank=True)
    file_size = models.IntegerField(help_text="File size in bytes")
    
    uploaded_by = models.ForeignKey(
        'accounts.User',
        on_delete=models.SET_NULL,
        null=True,
        related_name='complaint_attachments'
    )
    
    description = models.TextField(blank=True)
    
    class Meta:
        ordering = ['-created_at']
    
    def __str__(self):
        return f"{self.complaint} - {self.filename}"


class ComplaintUpdate(UUIDModel, TimeStampedModel):
    """
    Complaint update/timeline entry.
    
    Tracks all updates, status changes, and communications.
    """
    complaint = models.ForeignKey(
        Complaint,
        on_delete=models.CASCADE,
        related_name='updates'
    )
    
    # Update details
    update_type = models.CharField(
        max_length=50,
        choices=[
            ('status_change', 'Status Change'),
            ('assignment', 'Assignment'),
            ('note', 'Note'),
            ('resolution', 'Resolution'),
            ('escalation', 'Escalation'),
            ('communication', 'Communication'),
        ],
        db_index=True
    )
    
    message = models.TextField()
    
    # User who made the update
    created_by = models.ForeignKey(
        'accounts.User',
        on_delete=models.SET_NULL,
        null=True,
        related_name='complaint_updates'
    )
    
    # Status change tracking
    old_status = models.CharField(max_length=20, blank=True)
    new_status = models.CharField(max_length=20, blank=True)
    
    # Metadata
    metadata = models.JSONField(default=dict, blank=True)
    
    class Meta:
        ordering = ['-created_at']
        indexes = [
            models.Index(fields=['complaint', '-created_at']),
        ]
    
    def __str__(self):
        return f"{self.complaint} - {self.update_type} - {self.created_at.strftime('%Y-%m-%d %H:%M')}"


class ComplaintSLAConfig(UUIDModel, TimeStampedModel):
    """
    SLA configuration for complaints per hospital, severity, and priority.
    
    Allows flexible SLA configuration instead of hardcoded values.
    """
    hospital = models.ForeignKey(
        'organizations.Hospital',
        on_delete=models.CASCADE,
        related_name='complaint_sla_configs'
    )
    
    severity = models.CharField(
        max_length=20,
        choices=SeverityChoices.choices,
        help_text="Severity level for this SLA"
    )
    
    priority = models.CharField(
        max_length=20,
        choices=PriorityChoices.choices,
        help_text="Priority level for this SLA"
    )
    
    sla_hours = models.IntegerField(
        help_text="Number of hours until SLA deadline"
    )
    
    reminder_hours_before = models.IntegerField(
        default=24,
        help_text="Send reminder X hours before deadline"
    )
    
    is_active = models.BooleanField(default=True)
    
    class Meta:
        ordering = ['hospital', 'severity', 'priority']
        unique_together = [['hospital', 'severity', 'priority']]
        indexes = [
            models.Index(fields=['hospital', 'is_active']),
        ]
    
    def __str__(self):
        return f"{self.hospital.name_en} - {self.severity}/{self.priority} - {self.sla_hours}h"


class ComplaintCategory(UUIDModel, TimeStampedModel):
    """
    Custom complaint categories per hospital.
    
    Replaces hardcoded category choices with flexible, hospital-specific categories.
    """
    hospital = models.ForeignKey(
        'organizations.Hospital',
        on_delete=models.CASCADE,
        related_name='complaint_categories',
        null=True,
        blank=True,
        help_text="Leave blank for system-wide categories"
    )
    
    code = models.CharField(
        max_length=50,
        help_text="Unique code for this category"
    )
    
    name_en = models.CharField(max_length=200)
    name_ar = models.CharField(max_length=200, blank=True)
    
    description_en = models.TextField(blank=True)
    description_ar = models.TextField(blank=True)
    
    parent = models.ForeignKey(
        'self',
        on_delete=models.CASCADE,
        null=True,
        blank=True,
        related_name='subcategories',
        help_text="Parent category for hierarchical structure"
    )
    
    order = models.IntegerField(
        default=0,
        help_text="Display order"
    )
    
    is_active = models.BooleanField(default=True)
    
    class Meta:
        ordering = ['hospital', 'order', 'name_en']
        verbose_name_plural = 'Complaint Categories'
        indexes = [
            models.Index(fields=['hospital', 'is_active']),
            models.Index(fields=['code']),
        ]
    
    def __str__(self):
        hospital_name = self.hospital.name_en if self.hospital else "System-wide"
        return f"{hospital_name} - {self.name_en}"


class EscalationRule(UUIDModel, TimeStampedModel):
    """
    Configurable escalation rules for complaints.
    
    Defines who receives escalated complaints based on conditions.
    """
    hospital = models.ForeignKey(
        'organizations.Hospital',
        on_delete=models.CASCADE,
        related_name='escalation_rules'
    )
    
    name = models.CharField(max_length=200)
    description = models.TextField(blank=True)
    
    # Trigger conditions
    trigger_on_overdue = models.BooleanField(
        default=True,
        help_text="Trigger when complaint is overdue"
    )
    
    trigger_hours_overdue = models.IntegerField(
        default=0,
        help_text="Trigger X hours after overdue (0 = immediately)"
    )
    
    # Escalation target
    escalate_to_role = models.CharField(
        max_length=50,
        choices=[
            ('department_manager', 'Department Manager'),
            ('hospital_admin', 'Hospital Admin'),
            ('px_admin', 'PX Admin'),
            ('specific_user', 'Specific User'),
        ],
        help_text="Role to escalate to"
    )
    
    escalate_to_user = models.ForeignKey(
        'accounts.User',
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name='escalation_target_rules',
        help_text="Specific user if escalate_to_role is 'specific_user'"
    )
    
    # Conditions
    severity_filter = models.CharField(
        max_length=20,
        choices=SeverityChoices.choices,
        blank=True,
        help_text="Only escalate complaints with this severity (blank = all)"
    )
    
    priority_filter = models.CharField(
        max_length=20,
        choices=PriorityChoices.choices,
        blank=True,
        help_text="Only escalate complaints with this priority (blank = all)"
    )
    
    order = models.IntegerField(
        default=0,
        help_text="Escalation order (lower = first)"
    )
    
    is_active = models.BooleanField(default=True)
    
    class Meta:
        ordering = ['hospital', 'order']
        indexes = [
            models.Index(fields=['hospital', 'is_active']),
        ]
    
    def __str__(self):
        return f"{self.hospital.name_en} - {self.name}"


class ComplaintThreshold(UUIDModel, TimeStampedModel):
    """
    Configurable thresholds for complaint-related triggers.
    
    Defines when to trigger actions based on metrics (e.g., survey scores).
    """
    hospital = models.ForeignKey(
        'organizations.Hospital',
        on_delete=models.CASCADE,
        related_name='complaint_thresholds'
    )
    
    threshold_type = models.CharField(
        max_length=50,
        choices=[
            ('resolution_survey_score', 'Resolution Survey Score'),
            ('response_time', 'Response Time'),
            ('resolution_time', 'Resolution Time'),
        ],
        help_text="Type of threshold"
    )
    
    threshold_value = models.FloatField(
        help_text="Threshold value (e.g., 50 for 50% score)"
    )
    
    comparison_operator = models.CharField(
        max_length=10,
        choices=[
            ('lt', 'Less Than'),
            ('lte', 'Less Than or Equal'),
            ('gt', 'Greater Than'),
            ('gte', 'Greater Than or Equal'),
            ('eq', 'Equal'),
        ],
        default='lt',
        help_text="How to compare against threshold"
    )
    
    action_type = models.CharField(
        max_length=50,
        choices=[
            ('create_px_action', 'Create PX Action'),
            ('send_notification', 'Send Notification'),
            ('escalate', 'Escalate'),
        ],
        help_text="Action to take when threshold is breached"
    )
    
    is_active = models.BooleanField(default=True)
    
    class Meta:
        ordering = ['hospital', 'threshold_type']
        indexes = [
            models.Index(fields=['hospital', 'is_active']),
            models.Index(fields=['threshold_type', 'is_active']),
        ]
    
    def __str__(self):
        return f"{self.hospital.name_en} - {self.threshold_type} {self.comparison_operator} {self.threshold_value}"
    
    def check_threshold(self, value):
        """Check if value breaches threshold"""
        if self.comparison_operator == 'lt':
            return value < self.threshold_value
        elif self.comparison_operator == 'lte':
            return value <= self.threshold_value
        elif self.comparison_operator == 'gt':
            return value > self.threshold_value
        elif self.comparison_operator == 'gte':
            return value >= self.threshold_value
        elif self.comparison_operator == 'eq':
            return value == self.threshold_value
        return False


class Inquiry(UUIDModel, TimeStampedModel):
    """
    Inquiry model for general questions/requests.
    
    Similar to complaints but for non-complaint inquiries.
    """
    # Patient information
    patient = models.ForeignKey(
        'organizations.Patient',
        on_delete=models.CASCADE,
        null=True,
        blank=True,
        related_name='inquiries'
    )
    
    # Contact information (if patient not in system)
    contact_name = models.CharField(max_length=200, blank=True)
    contact_phone = models.CharField(max_length=20, blank=True)
    contact_email = models.EmailField(blank=True)
    
    # Organization
    hospital = models.ForeignKey(
        'organizations.Hospital',
        on_delete=models.CASCADE,
        related_name='inquiries'
    )
    department = models.ForeignKey(
        'organizations.Department',
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name='inquiries'
    )
    
    # Inquiry details
    subject = models.CharField(max_length=500)
    message = models.TextField()
    
    # Category
    category = models.CharField(
        max_length=100,
        choices=[
            ('appointment', 'Appointment'),
            ('billing', 'Billing'),
            ('medical_records', 'Medical Records'),
            ('general', 'General Information'),
            ('other', 'Other'),
        ]
    )
    
    # Status
    status = models.CharField(
        max_length=20,
        choices=[
            ('open', 'Open'),
            ('in_progress', 'In Progress'),
            ('resolved', 'Resolved'),
            ('closed', 'Closed'),
        ],
        default='open',
        db_index=True
    )
    
    # Assignment
    assigned_to = models.ForeignKey(
        'accounts.User',
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name='assigned_inquiries'
    )
    
    # Response
    response = models.TextField(blank=True)
    responded_at = models.DateTimeField(null=True, blank=True)
    responded_by = models.ForeignKey(
        'accounts.User',
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name='responded_inquiries'
    )
    
    class Meta:
        ordering = ['-created_at']
        verbose_name_plural = 'Inquiries'
        indexes = [
            models.Index(fields=['status', '-created_at']),
            models.Index(fields=['hospital', 'status']),
        ]
    
    def __str__(self):
        return f"{self.subject} ({self.status})"