/**
 * Test text contrast ratios for WCAG AA compliance
 * WCAG AA requires:
 * - 4.5:1 for normal text
 * - 3:1 for large text (18pt+ or 14pt+ bold) and UI components
 */

// Color definitions from tailwind.config.js
const colors = {
  light: {
    bg: '#f1f5f9',
    surface: '#f8fafc',
    post: '#ffffff',
    border: '#cbd5e1',
    text: '#475569',
    'text-light': '#64748b',
    accent: '#94a3b8',
    highlight: '#e2e8f0'
  },
  dark: {
    bg: '#0f172a',
    surface: '#1e293b',
    post: '#334155',
    border: '#475569',
    text: '#cbd5e1',
    'text-light': '#94a3b8',
    accent: '#64748b',
    highlight: '#475569'
  }
};

/**
 * Convert hex to RGB
 */
function hexToRgb(hex) {
  const result = /^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(hex);
  return result ? {
    r: parseInt(result[1], 16),
    g: parseInt(result[2], 16),
    b: parseInt(result[3], 16)
  } : null;
}

/**
 * Calculate relative luminance
 */
function getLuminance(rgb) {
  const [r, g, b] = [rgb.r / 255, rgb.g / 255, rgb.b / 255].map(val => {
    return val <= 0.03928 ? val / 12.92 : Math.pow((val + 0.055) / 1.055, 2.4);
  });
  return 0.2126 * r + 0.7152 * g + 0.0722 * b;
}

/**
 * Calculate contrast ratio
 */
function getContrastRatio(color1, color2) {
  const rgb1 = hexToRgb(color1);
  const rgb2 = hexToRgb(color2);
  
  if (!rgb1 || !rgb2) return 0;
  
  const lum1 = getLuminance(rgb1);
  const lum2 = getLuminance(rgb2);
  
  const lighter = Math.max(lum1, lum2);
  const darker = Math.min(lum1, lum2);
  
  return (lighter + 0.05) / (darker + 0.05);
}

/**
 * Check if contrast meets WCAG AA standards
 */
function checkContrast(ratio, isLargeText = false) {
  if (isLargeText) {
    return ratio >= 3.0; // Large text or UI components
  }
  return ratio >= 4.5; // Normal text
}

/**
 * Format ratio with pass/fail indicator
 */
function formatResult(ratio, isLargeText = false) {
  const passes = checkContrast(ratio, isLargeText);
  const standard = isLargeText ? '3.0:1' : '4.5:1';
  const status = passes ? '✓ PASS' : '✗ FAIL';
  return `${ratio.toFixed(2)}:1 (${status} - requires ${standard})`;
}

console.log('='.repeat(80));
console.log('WCAG AA CONTRAST RATIO TEST');
console.log('='.repeat(80));
console.log('');

// Test Light Mode
console.log('LIGHT MODE:');
console.log('-'.repeat(80));

const lightTests = [
  { name: 'Text on background', fg: colors.light.text, bg: colors.light.bg },
  { name: 'Text-light on background', fg: colors.light['text-light'], bg: colors.light.bg },
  { name: 'Text on post', fg: colors.light.text, bg: colors.light.post },
  { name: 'Text-light on post', fg: colors.light['text-light'], bg: colors.light.post },
  { name: 'Text on surface', fg: colors.light.text, bg: colors.light.surface },
  { name: 'Text-light on surface', fg: colors.light['text-light'], bg: colors.light.surface },
  { name: 'Text on highlight', fg: colors.light.text, bg: colors.light.highlight },
  { name: 'Text-light on highlight', fg: colors.light['text-light'], bg: colors.light.highlight },
  { name: 'Accent on background', fg: colors.light.accent, bg: colors.light.bg },
  { name: 'Accent on post', fg: colors.light.accent, bg: colors.light.post },
  { name: 'Text on accent (buttons)', fg: '#ffffff', bg: colors.light.accent },
];

lightTests.forEach(test => {
  const ratio = getContrastRatio(test.fg, test.bg);
  const normalResult = formatResult(ratio, false);
  const largeResult = formatResult(ratio, true);
  console.log(`${test.name.padEnd(35)} Normal: ${normalResult}`);
  if (!checkContrast(ratio, false) && checkContrast(ratio, true)) {
    console.log(`${' '.repeat(35)} Large:  ${largeResult}`);
  }
});

console.log('');

// Test Dark Mode
console.log('DARK MODE:');
console.log('-'.repeat(80));

const darkTests = [
  { name: 'Text on background', fg: colors.dark.text, bg: colors.dark.bg },
  { name: 'Text-light on background', fg: colors.dark['text-light'], bg: colors.dark.bg },
  { name: 'Text on post', fg: colors.dark.text, bg: colors.dark.post },
  { name: 'Text-light on post', fg: colors.dark['text-light'], bg: colors.dark.post },
  { name: 'Text on surface', fg: colors.dark.text, bg: colors.dark.surface },
  { name: 'Text-light on surface', fg: colors.dark['text-light'], bg: colors.dark.surface },
  { name: 'Text on highlight', fg: colors.dark.text, bg: colors.dark.highlight },
  { name: 'Text-light on highlight', fg: colors.dark['text-light'], bg: colors.dark.highlight },
  { name: 'Accent on background', fg: colors.dark.accent, bg: colors.dark.bg },
  { name: 'Accent on post', fg: colors.dark.accent, bg: colors.dark.post },
  { name: 'Text on accent (buttons)', fg: '#ffffff', bg: colors.dark.accent },
];

darkTests.forEach(test => {
  const ratio = getContrastRatio(test.fg, test.bg);
  const normalResult = formatResult(ratio, false);
  const largeResult = formatResult(ratio, true);
  console.log(`${test.name.padEnd(35)} Normal: ${normalResult}`);
  if (!checkContrast(ratio, false) && checkContrast(ratio, true)) {
    console.log(`${' '.repeat(35)} Large:  ${largeResult}`);
  }
});

console.log('');
console.log('='.repeat(80));

// Summary
let lightFailures = 0;
let darkFailures = 0;

lightTests.forEach(test => {
  const ratio = getContrastRatio(test.fg, test.bg);
  if (!checkContrast(ratio, false)) lightFailures++;
});

darkTests.forEach(test => {
  const ratio = getContrastRatio(test.fg, test.bg);
  if (!checkContrast(ratio, false)) darkFailures++;
});

console.log(`SUMMARY:`);
console.log(`Light mode failures: ${lightFailures}`);
console.log(`Dark mode failures: ${darkFailures}`);
console.log('');

if (lightFailures === 0 && darkFailures === 0) {
  console.log('✓ All contrast ratios meet WCAG AA standards!');
} else {
  console.log('✗ Some contrast ratios need adjustment.');
  console.log('');
  console.log('RECOMMENDATIONS:');
  if (lightFailures > 0) {
    console.log('- Light mode: Consider darkening text colors or lightening backgrounds');
  }
  if (darkFailures > 0) {
    console.log('- Dark mode: Consider lightening text colors or darkening backgrounds');
  }
}