def adjust_brightness(rgb_color, brightness):
    r, g, b = rgb_color
    # Convert 0-255 brightness to a scale of 0-1
    scale_factor = brightness / 255.0

    adjusted_r = int(r * scale_factor)
    adjusted_g = int(g * scale_factor)
    adjusted_b = int(b * scale_factor)

    # Ensure values are within 0-255
    adjusted_r = max(0, min(255, adjusted_r))
    adjusted_g = max(0, min(255, adjusted_g))
    adjusted_b = max(0, min(255, adjusted_b))

    return (adjusted_r, adjusted_g, adjusted_b)


def hex_to_rgb(hex_color: str) -> tuple[int, int, int]:
    """Converts a hex color string (e.g., "#RRGGBB") to an RGB tuple."""
    hex_color = hex_color.lstrip('#')
    return int(hex_color[0:2], 16), int(hex_color[2:4], 16), int(hex_color[4:6], 16)

def rgb_to_hex(r: int, g: int, b: int) -> str:
    """Converts an RGB tuple to a hex color string (e.g., "#RRGGBB")."""
    return f"#{r:02x}{g:02x}{b:02x}"

def get_contrast_text_color(background_hex_color: str) -> str:
    """
    Determines whether black or white text is more readable on a given background color.
    Uses the WCAG 2.0 contrast recommendations (Luminosity calculation).
    """
    r, g, b = hex_to_rgb(background_hex_color)

    # Convert RGB to sRGB (0-1 range)
    # The linear RGB values are normalized by dividing by 255
    r_linear = r / 255.0
    g_linear = g / 255.0
    b_linear = b / 255.0

    # Apply the sRGB to linear conversion for gamma correction
    # This is a simplified approximation for readability, a more accurate one involves if/else for values <= 0.03928
    # For a general "light vs dark" determination, this simplified approach is often sufficient.
    # The formula used here is often simplified as (R*0.299 + G*0.587 + B*0.114) for quick luminance.
    # A more precise relative luminance (L) calculation:
    def srgb_to_linear(c):
        if c <= 0.03928:
            return c / 12.92
        else:
            return ((c + 0.055) / 1.055) ** 2.4

    L = (0.2126 * srgb_to_linear(r_linear) +
         0.7152 * srgb_to_linear(g_linear) +
         0.0722 * srgb_to_linear(b_linear))

    # For general UI elements, a luminance threshold around 0.179 (sqrt(0.032)) is often used
    # or simply checking if (R*0.299 + G*0.587 + B*0.114) is > 186 for light background / dark text
    # A common rule of thumb for perceived brightness (closer to the one used in many UIs):
    # (R*299 + G*587 + B*114) / 1000
    # Let's use a simpler luminance check based on the first example's intention:
    # If the perceived brightness is above a certain threshold, use black text. Otherwise, use white.

    # A simpler luminance check often used for text contrast:
    luminance = (0.299 * r + 0.587 * g + 0.114 * b) / 255

    if luminance > 0.5: # Adjust this threshold as needed for perceived contrast
        return "black"
    else:
        return "white"