Create selectable PDF files with Lambda Python and ReportLab

pip install reportlab -t python

zip -r my_lambda_layer.zip python

{    "Version": "2012-10-17",    "Statement": [        {            "Effect": "Allow",            "Action": "sns:Publish",            "Resource": "arn:aws:sns:REGION:ACCOUNT_ID:your-sns-topic-arn"        },        {            "Effect": "Allow",            "Action": [                "s3:PutObject",                "s3:GetObject",                "s3:ListBucket"            ],            "Resource": [                "arn:aws:s3:::your-bucket-name/*",                "arn:aws:s3:::your-bucket-name"            ]        }    ]}

import ioimport osimport uuidfrom datetime import datetimeimport boto3from reportlab.lib import colorsfrom reportlab.lib.pagesizes import A4, landscapefrom reportlab.lib.units import inch, mmfrom reportlab.pdfgen import canvasdef percentage_of_year_passed(start_of_year, end_of_year, now):    total_days = (end_of_year - start_of_year).days + 1    days_passed = (now - start_of_year).days + 1    percentage_passed = int((days_passed / total_days) * 100)    return percentage_passeddef calculate_days():    now = datetime.now()    start_of_year = datetime(now.year, 1, 1)    end_of_year = datetime(now.year, 12, 31, 23, 59, 59)    percentage_passed = percentage_of_year_passed(start_of_year, end_of_year, now)    days_left = (end_of_year - now).days + 1    return percentage_passed, days_leftdef draw_grid(c, width, height, unit):    step = 25 if unit == mm else 1    c.setLineWidth(1 / unit)    c.setStrokeColor(colors.grey)    c.setFont("Helvetica", 25 / unit)    for i in range(0, int(height) + 1, step):        c.line(0, i, width, i)        c.drawString(0, i, f"{i}")    for i in range(0, int(width) + 1, step):        c.line(i, 0, i, height)        c.drawString(i, 0, f"{i}")def draw_gauge(c, x, y, radius, percentage, base_color, fill_color):    """    Draw gauge with two arches: base 180 deg arch and filled with percentage.    """    # Draw base half-circle    c.setLineWidth(15)    c.setStrokeColor(base_color)    c.arc(x - radius, y - radius, x + radius, y + radius, 180, -179.9)    # Draw filled half-circle    c.setStrokeColor(fill_color)    gauge = -180 * percentage / 100 + 0.01    c.arc(x - radius, y - radius, x + radius, y + radius, 180, gauge)def draw_str(c, x, y, item, font_size, font_color="black"):    c.setFont("Helvetica", font_size)    c.setFillColor(font_color)    c.drawCentredString(x, y, f"{item}")def create_pdf_days_passed_left(page_size, x, y, radius, on_grid = False):    unit = mm  # mm or inch    buffer = io.BytesIO()    c = canvas.Canvas(buffer, pagesize=page_size)    c.scale(unit, unit)    if on_grid:        width = page_size[0] / unit        height = page_size[1] / unit        draw_grid(c, width, height, unit)    base_color = colors.HexColor("#c8c8c8")  # light grey    fill_color = colors.HexColor("#1f77b4")  # light blue    percentage_passed, days_left = calculate_days()    message = f'Created at {datetime.now().strftime("%Y-%m-%d %H:%M:%S")}'    draw_str(c, x + 50, y + 55, message, 8)    draw_gauge(c, x, y, radius, percentage_passed, base_color, fill_color)    draw_str(c, x, y, f"{percentage_passed}%", font_size=20)    draw_str(c, x, y - 25, "This year passed", font_size=10)    draw_str(c, x + 100, y, days_left, font_size=20, font_color="green")    draw_str(c, x + 100, y - 25, "days left", font_size=10)    c.showPage()    c.save()    buffer.seek(0)    return bufferdef generate_n_char_id(n: int):    unique_id = uuid.uuid4()    short_id = str(unique_id)[:n]    return short_iddef generate_presigned_url(bucket_name, object_name, expiration_sec=3600):    s3_client = boto3.client("s3")    response = s3_client.generate_presigned_url(        "get_object",        Params={"Bucket": bucket_name, "Key": object_name},        ExpiresIn=expiration_sec,    )    return responsedef send_sns_message(topic_arn, message):    sns_client = boto3.client("sns")    response = sns_client.publish(        TopicArn=topic_arn,        Message=message,    )    return responsedef lambda_handler(event, context):    s3 = boto3.client("s3")    bucket_name = os.environ["BUCKET_NAME"]    sns_topic_arn = os.environ["SNS_ARN"]    dt = datetime.now().strftime("%Y%m%d-%H%M%S")    uuid = generate_n_char_id(8)    filename = f"demo-{dt}-{uuid}.pdf"    page_size = landscape(A4)    x, y = 100, 125  # Center of gauge. Use this point as anchoring    radius = 40  # radius of gauge    pdf_buffer = create_pdf_days_passed_left(page_size, x, y, radius)    s3.upload_fileobj(pdf_buffer, bucket_name, filename)    url = generate_presigned_url(bucket_name, filename, expiration_sec=3600)    if url:        print(f"Generated presigned URL: {url}")        message = f"Download the PDF file here: {url}"        send_sns_message(sns_topic_arn, message)    else:        print("Failed to generate presigned URL")    return {        "statusCode": 200,        "body": "PDF created and uploaded to S3. Presigned url has sent with SNS.",    }