import os
import uuid
from datetime import datetime
from flask import Response, current_app
from PIL import Image
from reportlab.lib.pagesizes import letter
from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
from reportlab.lib.units import inch
from reportlab.platypus import SimpleDocTemplate, Paragraph, Spacer, Table, TableStyle
from reportlab.lib import colors
from io import BytesIO

ALLOWED_EXTENSIONS = {'png', 'jpg', 'jpeg', 'gif'}

def allowed_file(filename):
    """Check if the uploaded file has an allowed extension."""
    return '.' in filename and \
           filename.rsplit('.', 1)[1].lower() in ALLOWED_EXTENSIONS

def save_uploaded_image(file):
    """Save an uploaded image file with a unique filename."""
    if not file:
        return None
    
    # Generate unique filename
    filename = str(uuid.uuid4()) + '.' + file.filename.rsplit('.', 1)[1].lower()
    filepath = os.path.join(current_app.config['UPLOAD_FOLDER'], filename)
    
    # Save and optimize the image
    try:
        image = Image.open(file.stream)
        
        # Convert RGBA to RGB if necessary
        if image.mode in ('RGBA', 'LA'):
            background = Image.new('RGB', image.size, (255, 255, 255))
            background.paste(image, mask=image.split()[-1] if image.mode == 'RGBA' else None)
            image = background
        
        # Resize if image is too large (max 1920px on longest side)
        max_size = 1920
        if max(image.size) > max_size:
            image.thumbnail((max_size, max_size), Image.Resampling.LANCZOS)
        
        # Save with optimization
        image.save(filepath, optimize=True, quality=85)
        
    except Exception as e:
        current_app.logger.error(f"Error processing image: {e}")
        # Fallback to direct save
        file.seek(0)
        file.save(filepath)
    
    return filename

def generate_treatment_pdf(treatment_plan):
    """Generate a PDF for the treatment plan."""
    buffer = BytesIO()
    doc = SimpleDocTemplate(buffer, pagesize=letter)
    
    # Styles
    styles = getSampleStyleSheet()
    title_style = ParagraphStyle(
        'CustomTitle',
        parent=styles['Heading1'],
        fontSize=18,
        spaceAfter=30,
        textColor=colors.HexColor('#0F766E')
    )
    
    heading_style = ParagraphStyle(
        'CustomHeading',
        parent=styles['Heading2'],
        fontSize=14,
        spaceBefore=20,
        spaceAfter=10,
        textColor=colors.HexColor('#1E40AF')
    )
    
    # Build the PDF content
    content = []
    
    # Header
    content.append(Paragraph("Doctor's Sidekick - Treatment Plan", title_style))
    content.append(Spacer(1, 20))
    
    # Patient and plan information
    patient_info = [
        ['Patient:', treatment_plan.patient.full_name],
        ['Patient ID:', treatment_plan.patient.patient_id],
        ['Date of Birth:', treatment_plan.patient.date_of_birth.strftime('%B %d, %Y')],
        ['Plan Date:', treatment_plan.created_at.strftime('%B %d, %Y')],
        ['Created By:', treatment_plan.created_by.full_name]
    ]
    
    patient_table = Table(patient_info, colWidths=[1.5*inch, 4*inch])
    patient_table.setStyle(TableStyle([
        ('ALIGN', (0, 0), (-1, -1), 'LEFT'),
        ('FONTNAME', (0, 0), (0, -1), 'Helvetica-Bold'),
        ('FONTSIZE', (0, 0), (-1, -1), 12),
        ('BOTTOMPADDING', (0, 0), (-1, -1), 6),
    ]))
    
    content.append(patient_table)
    content.append(Spacer(1, 30))
    
    # Diagnosis
    content.append(Paragraph("Diagnosis", heading_style))
    content.append(Paragraph(treatment_plan.diagnosis or "Not specified", styles['Normal']))
    content.append(Spacer(1, 15))
    
    # Medications
    if treatment_plan.medications:
        content.append(Paragraph("Medications", heading_style))
        content.append(Paragraph(treatment_plan.medications, styles['Normal']))
        content.append(Spacer(1, 15))
    
    # Instructions
    if treatment_plan.instructions:
        content.append(Paragraph("Instructions", heading_style))
        content.append(Paragraph(treatment_plan.instructions, styles['Normal']))
        content.append(Spacer(1, 15))
    
    # Duration and Follow-up
    if treatment_plan.duration or treatment_plan.follow_up_date:
        content.append(Paragraph("Treatment Details", heading_style))
        
        if treatment_plan.duration:
            content.append(Paragraph(f"<b>Duration:</b> {treatment_plan.duration}", styles['Normal']))
        
        if treatment_plan.follow_up_date:
            content.append(Paragraph(
                f"<b>Follow-up Date:</b> {treatment_plan.follow_up_date.strftime('%B %d, %Y')}", 
                styles['Normal']
            ))
        
        content.append(Spacer(1, 15))
    
    # Additional Notes
    if treatment_plan.notes:
        content.append(Paragraph("Additional Notes", heading_style))
        content.append(Paragraph(treatment_plan.notes, styles['Normal']))
    
    # Footer
    content.append(Spacer(1, 50))
    footer_style = ParagraphStyle(
        'Footer',
        parent=styles['Normal'],
        fontSize=10,
        textColor=colors.grey,
        alignment=1  # Center alignment
    )
    content.append(Paragraph(
        f"Generated on {datetime.now().strftime('%B %d, %Y at %I:%M %p')}", 
        footer_style
    ))
    
    # Build PDF
    doc.build(content)
    
    # Return PDF as response
    buffer.seek(0)
    return Response(
        buffer.getvalue(),
        mimetype='application/pdf',
        headers={
            'Content-Disposition': f'attachment; filename=treatment_plan_{treatment_plan.id}.pdf'
        }
    )

def calculate_age(birth_date):
    """Calculate age from birth date."""
    today = datetime.now().date()
    return today.year - birth_date.year - ((today.month, today.day) < (birth_date.month, birth_date.day))

def format_phone_number(phone):
    """Format phone number for display."""
    if not phone:
        return ""
    
    # Remove all non-digit characters
    digits = ''.join(filter(str.isdigit, phone))
    
    # Format as (XXX) XXX-XXXX for 10-digit numbers
    if len(digits) == 10:
        return f"({digits[:3]}) {digits[3:6]}-{digits[6:]}"
    
    return phone

def get_dashboard_stats():
    """Get statistics for the dashboard."""
    from models import Patient, Visit, Inventory
    from datetime import date, timedelta
    
    today = date.today()
    week_ago = today - timedelta(days=7)
    
    stats = {
        'total_patients': Patient.query.count(),
        'new_patients_week': Patient.query.filter(Patient.created_at >= week_ago).count(),
        'visits_today': Visit.query.filter(Visit.visit_date >= today).count(),
        'low_stock_items': Inventory.query.filter(
            Inventory.current_stock <= Inventory.min_threshold
        ).count()
    }
    
    return stats