#!/usr/bin/env python3
"""Calculate the exact contrast ratio for the new white header text."""


def calculate_contrast_ratio():
    """Calculate contrast ratio between dark background and white text."""

    def get_luminance(color_str):
        """Calculate relative luminance of a color."""
        if not color_str or not color_str.startswith("#"):
            return 0.5
        try:
            rgb = tuple(int(color_str[i : i + 2], 16) for i in (1, 3, 5))
            # Calculate relative luminance using sRGB formula
            return (0.299 * rgb[0] + 0.587 * rgb[1] + 0.114 * rgb[2]) / 255
        except (ValueError, IndexError):
            return 0.5

    # Our new header colors
    header_bg = "#1e1e1e"  # Very dark gray
    header_fg = "#ffffff"  # Pure white

    bg_lum = get_luminance(header_bg)
    fg_lum = get_luminance(header_fg)

    # Calculate proper contrast ratio
    lighter = max(bg_lum, fg_lum)
    darker = min(bg_lum, fg_lum)
    contrast_ratio = (lighter + 0.05) / (darker + 0.05)

    print("=== HEADER CONTRAST ANALYSIS ===")
    print(f"Background: {header_bg} (luminance: {bg_lum:.3f})")
    print(f"Foreground: {header_fg} (luminance: {fg_lum:.3f})")
    print(f"Contrast ratio: {contrast_ratio:.2f}:1")
    print()

    # WCAG AA guidelines
    if contrast_ratio >= 7.0:
        print("✅ EXCELLENT contrast (WCAG AAA compliant)")
    elif contrast_ratio >= 4.5:
        print("✅ GOOD contrast (WCAG AA compliant)")
    elif contrast_ratio >= 3.0:
        print("⚠️  FAIR contrast (minimum acceptable)")
    else:
        print("❌ POOR contrast")

    return contrast_ratio


if __name__ == "__main__":
    calculate_contrast_ratio()