import csv
from io import StringIO
from flask import Blueprint, render_template, redirect, request, send_file, url_for, flash
from app.models import Reading, db
from flask_login import login_required, current_user
from datetime import datetime

data = Blueprint('data', __name__)

@data.route('/', methods=['GET', 'POST'])
@login_required
def manage_data():
    if request.method == 'POST':
        # Handle CSV file upload
        file = request.files.get('file')
        if file and file.filename.endswith('.csv'):
            try:
                csv_data = csv.reader(StringIO(file.read().decode('utf-8')))
                next(csv_data)  # Skip the header row
                for row in csv_data:
                    timestamp, systolic, diastolic, heart_rate = row
                    reading = Reading(
                        user_id=current_user.id,
                        timestamp=datetime.strptime(timestamp, '%Y-%m-%d %H:%M:%S'),
                        systolic=int(systolic),
                        diastolic=int(diastolic),
                        heart_rate=int(heart_rate),
                    )
                    db.session.add(reading)
                db.session.commit()
                flash('Data imported successfully!', 'success')
            except Exception as e:
                flash(f'Error importing data: {str(e)}', 'danger')
        else:
            flash('Please upload a valid CSV file.', 'danger')
        return redirect(url_for('data.manage_data'))

    return render_template('data.html')

@data.route('/export', methods=['GET'])
@login_required
def export_data():
    import io

    output = io.StringIO()
    writer = csv.writer(output)

    # Write CSV header
    writer.writerow(['Timestamp', 'Systolic', 'Diastolic', 'Heart Rate'])

    # Write user readings to the CSV
    readings = Reading.query.filter_by(user_id=current_user.id).all()
    for reading in readings:
        writer.writerow([
            reading.timestamp.strftime('%Y-%m-%d %H:%M:%S'),
            reading.systolic,
            reading.diastolic,
            reading.heart_rate,
        ])

    # Convert text to bytes for `send_file`
    output.seek(0)
    response = io.BytesIO(output.getvalue().encode('utf-8'))
    output.close()

    return send_file(
        response,
        mimetype='text/csv',
        as_attachment=True,
        download_name='readings.csv'
    )