app.py

from flask import Flask, render_template, make_response, url_for
from weasyprint import HTML, CSS
import io

app = Flask(__name__)


@app.route('/')
def index():
    return 'WeasyPrint PDF prototype. Use /report to get a PDF.'


@app.route('/report')
def report():
    # Example data for the template
    data = {
        'title': 'Sample Report',
        'items': [
            {'name': 'Apples', 'qty': 10, 'price': 0.5},
            {'name': 'Bananas', 'qty': 5, 'price': 0.3},
            {'name': 'Oranges', 'qty': 8, 'price': 0.4},
        ],
        # sections used for the TOC (title and anchor)
        'sections': [
            {'id': 'section-items', 'title': 'Items'},
            {'id': 'section-long', 'title': 'Long Content'},
        ],
        # long content to force multiple pages
        'long_text': '\n\n'.join([('This is a long paragraph intended to demonstrate page breaks and multi-page output. ' \
                    'It repeats to create a sizeable block of text. ' * 4) for _ in range(60)])
    }

    html = render_template('report.html', **data)

    # Build a file:// base_url so WeasyPrint can load static assets directly from the container filesystem
    import pathlib
    base_path = pathlib.Path(app.root_path).as_uri()
    base_url = base_path + '/'

    try:
        pdf_io = io.BytesIO()
        css_path = str(pathlib.Path(app.root_path) / 'static' / 'css' / 'report.css')
        HTML(string=html, base_url=base_url).write_pdf(target=pdf_io, stylesheets=[CSS(filename=css_path)])
        pdf_io.seek(0)

        response = make_response(pdf_io.read())
        response.headers['Content-Type'] = 'application/pdf'
        response.headers['Content-Disposition'] = 'inline; filename=report.pdf'
        return response
    except Exception as e:
        app.logger.exception('PDF generation failed')
        return (f'PDF generation error: {e}', 500)


@app.route('/report-timing')
def report_timing():
    """Render the PDF server-side but only return the elapsed rendering time in milliseconds.
    This helps measure raw server rendering time without transferring the PDF bytes back to client."""
    from flask import request
    pages = int(request.args.get('pages', '3'))

    paras_per_page = 8
    total_paras = max(1, pages * paras_per_page)

    data = {
        'title': 'Sample Report',
        'items': [
            {'name': 'Apples', 'qty': 10, 'price': 0.5},
            {'name': 'Bananas', 'qty': 5, 'price': 0.3},
            {'name': 'Oranges', 'qty': 8, 'price': 0.4},
        ],
        'sections': [
            {'id': 'section-items', 'title': 'Items'},
            {'id': 'section-long', 'title': 'Long Content'},
            {'id': 'section-images', 'title': 'Images'},
        ],
        'long_text': '\n\n'.join([('This is paragraph %d. ' % (i+1)) + ('Long content. ' * 10) for i in range(total_paras)])
    }

    html = render_template('report.html', **data)
    import time, pathlib
    base_path = pathlib.Path(app.root_path).as_uri()
    base_url = base_path + '/'
    css_path = str(pathlib.Path(app.root_path) / 'static' / 'css' / 'report.css')

    start = time.perf_counter()
    pdf_io = io.BytesIO()
    HTML(string=html, base_url=base_url).write_pdf(target=pdf_io, stylesheets=[CSS(filename=css_path)])
    end = time.perf_counter()

    elapsed_ms = int((end - start) * 1000)
    return {'elapsed_ms': elapsed_ms}


if __name__ == '__main__':
    app.run(host='0.0.0.0', port=5000)