from io import BytesIO
import qrcode
from flask import send_file, flash

def generate_qr_code(url):
    qr = qrcode.QRCode(
        version=None,
        error_correction=qrcode.constants.ERROR_CORRECT_M,
        box_size=30,
        border=4,
    )
    qr.add_data(url)
    qr.make(fit=True)
    return qr.make_image(fill_color='black', back_color='white')

def serve_pil_image(pil_img):
    # Source: https://stackoverflow.com/questions/7877282/how-to-send-image-generated-by-pil-to-browser
    img_io = BytesIO()
    pil_img.save(img_io, 'PNG', quality=70)
    img_io.seek(0)
    return send_file(img_io, mimetype='image/png')

def flash_errors(form):
    """Flashes form errors"""
    print('a')
    for field, errors in form.errors.items():
        for error in errors:
            flash(u"Error in the %s field - %s" % (
                getattr(form, field).label.text,
                error
            ), 'error')