features/accessibility.py

"""
Accessibility audit and testing features
"""
import json
import logging
from datetime import datetime
from browser.driver import get_driver, cleanup_driver

logger = logging.getLogger(__name__)

def accessibility_audit(url: str, use_persistent: bool = False) -> str:
    """Perform basic accessibility audit on a page"""
    driver = None
    try:
        driver = get_driver(url, use_persistent)
        
        # Run accessibility checks
        audit_results = driver.execute_script("""
            const results = {
                images_without_alt: [],
                form_inputs_without_labels: [],
                low_contrast_elements: [],
                missing_landmarks: [],
                heading_structure: [],
                interactive_elements_without_text: [],
                links_without_text: [],
                aria_issues: []
            };
            
            // Check images without alt text
            document.querySelectorAll('img:not([alt])').forEach(img => {
                results.images_without_alt.push(img.src || 'no-src');
            });
            
            // Check form inputs without labels
            document.querySelectorAll('input, select, textarea').forEach(input => {
                const id = input.id;
                const hasLabel = id && document.querySelector(`label[for="${id}"]`);
                const hasAriaLabel = input.getAttribute('aria-label');
                const hasAriaLabelledBy = input.getAttribute('aria-labelledby');
                
                if (!hasLabel && !hasAriaLabel && !hasAriaLabelledBy) {
                    results.form_inputs_without_labels.push({
                        type: input.type,
                        name: input.name,
                        id: id || 'no-id'
                    });
                }
            });
            
            // Check heading structure
            const headings = document.querySelectorAll('h1, h2, h3, h4, h5, h6');
            let lastLevel = 0;
            headings.forEach(heading => {
                const level = parseInt(heading.tagName.substring(1));
                results.heading_structure.push({
                    level: level,
                    text: heading.textContent.trim().substring(0, 50),
                    issue: level > lastLevel + 1 ? 'skipped_level' : null
                });
                lastLevel = level;
            });
            
            // Check for landmarks
            const landmarks = {
                header: document.querySelector('header, [role="banner"]'),
                nav: document.querySelector('nav, [role="navigation"]'),
                main: document.querySelector('main, [role="main"]'),
                footer: document.querySelector('footer, [role="contentinfo"]')
            };
            
            for (const [role, element] of Object.entries(landmarks)) {
                if (!element) {
                    results.missing_landmarks.push(role);
                }
            }
            
            // Check interactive elements without text
            document.querySelectorAll('button, a').forEach(elem => {
                const text = elem.textContent.trim();
                const ariaLabel = elem.getAttribute('aria-label');
                const ariaLabelledBy = elem.getAttribute('aria-labelledby');
                
                if (!text && !ariaLabel && !ariaLabelledBy) {
                    results.interactive_elements_without_text.push({
                        tag: elem.tagName,
                        class: elem.className,
                        href: elem.href || null
                    });
                }
            });
            
            // Check links without meaningful text
            document.querySelectorAll('a[href]').forEach(link => {
                const text = link.textContent.trim().toLowerCase();
                if (text === 'click here' || text === 'here' || text === 'read more') {
                    results.links_without_text.push({
                        text: text,
                        href: link.href
                    });
                }
            });
            
            // Check ARIA issues
            document.querySelectorAll('[aria-hidden="true"]').forEach(elem => {
                if (elem.querySelector('a, button, input, select, textarea')) {
                    results.aria_issues.push({
                        issue: 'interactive_element_hidden',
                        element: elem.tagName + (elem.className ? '.' + elem.className : '')
                    });
                }
            });
            
            return results;
        """)
        
        # Calculate score
        issues_count = sum(len(v) if isinstance(v, list) else 0 for v in audit_results.values())
        score = max(0, 100 - (issues_count * 5))  # Deduct 5 points per issue
        
        result = {
            "url": url,
            "accessibility_score": score,
            "grade": get_grade(score),
            "issues": audit_results,
            "total_issues": issues_count,
            "timestamp": datetime.now().isoformat(),
            "recommendations": get_recommendations(audit_results)
        }
        
        return json.dumps(result, indent=2)
    except Exception as e:
        logger.error(f"Error in accessibility_audit: {e}")
        return f"Error: {e}"
    finally:
        cleanup_driver(driver, use_persistent)

def get_grade(score):
    """Convert score to letter grade"""
    if score >= 90:
        return "A"
    elif score >= 80:
        return "B"
    elif score >= 70:
        return "C"
    elif score >= 60:
        return "D"
    else:
        return "F"

def get_recommendations(audit_results):
    """Get recommendations based on audit results"""
    recommendations = []
    
    if audit_results["images_without_alt"]:
        recommendations.append("Add alt text to all images for screen reader users")
    
    if audit_results["form_inputs_without_labels"]:
        recommendations.append("Associate all form inputs with labels using 'for' attribute or aria-label")
    
    if audit_results["missing_landmarks"]:
        recommendations.append("Add semantic HTML5 landmarks (header, nav, main, footer) or ARIA roles")
    
    if audit_results["heading_structure"]:
        has_issues = any(h["issue"] for h in audit_results["heading_structure"])
        if has_issues:
            recommendations.append("Fix heading hierarchy - don't skip heading levels")
    
    if audit_results["interactive_elements_without_text"]:
        recommendations.append("Add descriptive text or aria-labels to all interactive elements")
    
    return recommendations

def check_color_contrast(url: str, use_persistent: bool = False) -> str:
    """Check color contrast for text elements"""
    driver = None
    try:
        driver = get_driver(url, use_persistent)
        
        # Check color contrast
        contrast_results = driver.execute_script("""
            function getLuminance(r, g, b) {
                const sRGB = [r, g, b].map(val => {
                    val = val / 255;
                    return val <= 0.03928 ? val / 12.92 : Math.pow((val + 0.055) / 1.055, 2.4);
                });
                return 0.2126 * sRGB[0] + 0.7152 * sRGB[1] + 0.0722 * sRGB[2];
            }
            
            function getContrastRatio(color1, color2) {
                const l1 = getLuminance(...color1);
                const l2 = getLuminance(...color2);
                const lighter = Math.max(l1, l2);
                const darker = Math.min(l1, l2);
                return (lighter + 0.05) / (darker + 0.05);
            }
            
            function getRGBValues(colorStr) {
                const match = colorStr.match(/rgba?\\((\\d+),\\s*(\\d+),\\s*(\\d+)/);
                if (match) {
                    return [parseInt(match[1]), parseInt(match[2]), parseInt(match[3])];
                }
                return null;
            }
            
            const results = [];
            const textElements = document.querySelectorAll('p, span, div, h1, h2, h3, h4, h5, h6, a, button');
            
            textElements.forEach(elem => {
                const style = window.getComputedStyle(elem);
                const color = getRGBValues(style.color);
                const bgColor = getRGBValues(style.backgroundColor);
                
                if (color && bgColor) {
                    const ratio = getContrastRatio(color, bgColor);
                    const fontSize = parseFloat(style.fontSize);
                    const fontWeight = style.fontWeight;
                    
                    // WCAG AA standards
                    const isLargeText = fontSize >= 18 || (fontSize >= 14 && fontWeight >= 700);
                    const requiredRatio = isLargeText ? 3 : 4.5;
                    
                    if (ratio < requiredRatio) {
                        results.push({
                            element: elem.tagName,
                            text: elem.textContent.trim().substring(0, 50),
                            contrastRatio: ratio.toFixed(2),
                            requiredRatio: requiredRatio,
                            fontSize: fontSize,
                            isLargeText: isLargeText
                        });
                    }
                }
            });
            
            return results;
        """)
        
        return json.dumps({
            "low_contrast_elements": contrast_results,
            "total_issues": len(contrast_results)
        }, indent=2)
    except Exception as e:
        logger.error(f"Error in check_color_contrast: {e}")
        return f"Error: {e}"
    finally:
        cleanup_driver(driver, use_persistent)