יחידה:WCAG

היחידה נועדה לאפשר הצגת טקסט תוך שמירה על ניגודיות מומלצת בהתאם לתקן .

היחידה מייצאת שלוש פונקציות.

1. _getContrastTextColor - מקבלת צבע רקע ומחזירה את הצבע הרצוי לטקסט
2. _getContrastRatio - קבלת שני צבעים ובדיקה האם הניגודיות ביניהם תואמת לתקן
3. getContrastTextColor - להכללה {{#invoke:getContrastTextColor|<צבע רקע>}}

---

local WCAG = {}
-- Function to determine the optimal text color (black or white) based on background color
-- according to WCAG (Web Content Accessibility Guidelines) standards
-- Input: Background color in hex format (e.g., "#FF5733" or "FF5733") or RGB values (0-255)
-- Output: Suitable text color ("#000000" for black or "#FFFFFF" for white)

function WCAG._getContrastTextColor(backgroundColor)
	mw.logObject("backgroundColor: "..backgroundColor)
    local r, g, b
    
    -- Handle different input formats
    if type(backgroundColor) == "string" then
        -- Remove # if present
        backgroundColor = backgroundColor:gsub("#", "")
        
        -- Convert hex to RGB
        r = tonumber(backgroundColor:sub(1, 2), 16) or 0
        g = tonumber(backgroundColor:sub(3, 4), 16) or 0
        b = tonumber(backgroundColor:sub(5, 6), 16) or 0
    elseif type(backgroundColor) == "table" then
        r = backgroundColor.r or backgroundColor[1] or 0
        g = backgroundColor.g or backgroundColor[2] or 0
        b = backgroundColor.b or backgroundColor[3] or 0
    else
        return "#000000" -- default to black on error
    end
    
    -- Normalize RGB values to range 0-1
    r = r / 255
    g = g / 255
    b = b / 255
    
    -- Calculate luminance according to WCAG formula
    -- Convert RGB to sRGB
    r = r <= 0.03928 and r/12.92 or ((r+0.055)/1.055)^2.4
    g = g <= 0.03928 and g/12.92 or ((g+0.055)/1.055)^2.4
    b = b <= 0.03928 and b/12.92 or ((b+0.055)/1.055)^2.4
    
    -- Calculate relative luminance
    local luminance = 0.2126 * r + 0.7152 * g + 0.0722 * b
    
    -- WCAG recommends black text on light backgrounds and white text on dark backgrounds
    -- The threshold is typically at luminance of 0.5 but WCAG suggests 0.179 for better compliance
    if luminance > 0.179 then
        return "#000000" -- black text for light backgrounds
    else
        return "#FFFFFF" -- white text for dark backgrounds
    end
end

-- Calculate contrast ratio between two colors (for advanced usage)
function WCAG._getContrastRatio(color1, color2)
    -- Implementation would convert colors to luminance values
    -- and calculate (L1 + 0.05) / (L2 + 0.05) where L1 is the lighter color
    
    -- This is a stub - expand as needed
    local l1 = 0.9 -- luminance of color1
    local l2 = 0.1 -- luminance of color2
    
    -- Ensure l1 is the lighter color (higher luminance)
    if l2 > l1 then
        l1, l2 = l2, l1
    end
    
    -- Calculate contrast ratio
    return (l1 + 0.05) / (l2 + 0.05)
end

function WCAG.getContrastTextColor(frame)
	local backgroundColor = frame.args[1]
	return WCAG._getContrastTextColor(backgroundColor)
end

-- Example usage:
-- local textColor = getContrastTextColor("#3366FF")
-- local textColor = getContrastTextColor({51, 102, 255})
-- local contrastRatio = getContrastRatio("#FFFFFF", "#000000") -- Would return approximately 21:1

return WCAG