Build a Website Accessibility Scanner Using Python

import requests
from urllib.parse import urljoin
from html.parser import HTMLParser
import re

class AccessibilityParser(HTMLParser):
    def __init__(self):
        super().__init__()
        self.images_without_alt = []
        self.missing_headings = True
        self.has_main_tag = False
        self.label_for_input = {}
        self.inputs_without_label = []
    
    def handle_starttag(self, tag, attrs):
        attrs_dict = dict(attrs)
        if tag == 'img' and 'alt' not in attrs_dict:
            self.images_without_alt.append(attrs_dict.get('src', 'unknown'))
        if tag in ('h1', 'h2', 'h3', 'h4', 'h5', 'h6'):
            self.missing_headings = False
        if tag == 'main':
            self.has_main_tag = True
        if tag == 'label':
            for attr in attrs:
                if attr[0] == 'for':
                    self.label_for_input[attr[1]] = True
        if tag == 'input':
            input_id = attrs_dict.get('id', '')
            if input_id not in self.label_for_input:
                self.inputs_without_label.append(attrs_dict.get('name', 'unknown'))

def scan_url(url):
    try:
        response = requests.get(url, timeout=10)
        response.raise_for_status()
        parser = AccessibilityParser()
        parser.feed(response.text)
        
        issues = []
        if parser.images_without_alt:
            issues.append(f"Missing alt text on {len(parser.images_without_alt)} images")
        if parser.missing_headings:
            issues.append("No heading tags (h1-h6) found")
        if parser.inputs_without_label:
            issues.append(f"{len(parser.inputs_without_label)} inputs missing associated labels")
        if not parser.has_main_tag:
            issues.append("No <main> landmark element found")
        
        if not issues:
            return f"{url}: No accessibility issues found"
        else:
            return f"{url}: Found accessibility issues:\n" + "\n".join(issues)
    except requests.RequestException as e:
        return f"{url}: Error scanning - {str(e)}"

if __name__ == "__main__":
    test_url = "https://example.com"
    print(scan_url(test_url))