# Module:Color contrast

---
-- This module implements  
---
---
---
---
---
local p = {}  
local HTMLcolor = mw.loadData( 'Module:Color contrast/colors' )  

local function sRGB (v)  
if (v <= 0.03928) then  
v = v / 12.92  
else  
v = math.pow((v+0.055)/1.055, 2.4)  
end  
return v  
end  

local function rgbdec2lum(R, G, B)  
if ( 0 <= R and R < 256 and 0 <= G and G < 256 and 0 <= B and B < 256 ) then  
return 0.2126 * sRGB(R/255) + 0.7152 * sRGB(G/255) + 0.0722 * sRGB(B/255)  
else  
return ''  
end  
end  

local function hsl2lum(h, s, l)  
if ( 0 <= h and h < 360 and 0 <= s and s <= 1 and 0 <= l and l <= 1 ) then  
local c = (1 - math.abs(2*l - 1))*s  
local x = c*(1 - math.abs( math.fmod(h/60, 2) - 1) )  
local m = l - c/2  

local r, g, b = m, m, m  
if( 0 <= h and h < 60 ) then  
r = r + c  
g = g + x  
elseif( 60 <= h and h < 120 ) then  
r = r + x  
g = g + c  
elseif( 120 <= h and h < 180 ) then  
g = g + c  
b = b + x  
elseif( 180 <= h and h < 240 ) then  
g = g + x  
b = b + c  
elseif( 240 <= h and h < 300 ) then  
r = r + x  
b = b + c  
elseif( 300 <= h and h < 360 ) then  
r = r + c  
b = b + x  
end  
return rgbdec2lum(255*r, 255*g, 255*b)  
else  
return ''  
end  
end  

local function color2lum(c)  

if (c == nil) then  
return ''  
end  

-- html '#' entity  
c = c:gsub("&#35;", "#")  

-- whitespace  
c = c:match( '^%s*(.-)[%s;]*$' )  

-- unstrip nowiki strip markers  
c = mw.text.unstripNoWiki(c)  

-- lowercase  
c = c:lower  

-- first try to look it up  
local L = HTMLcolor[c]  
if (L ~= nil) then  
return L  
end  

-- convert from hsl  
if mw.ustring.match(c,'^hsl%([%s]*[0-9][0-9%.]*[%s]*,[%s]*[0-9][0-9%.]*%%[%s]*,[%s]*[0-9][0-9%.]*%%[%s]*%)$') then  
local h, s, l = mw.ustring.match(c,'^hsl%([%s]*([0-9][0-9%.]*)[%s]*,[%s]*([0-9][0-9%.]*)%%[%s]*,[%s]*([0-9][0-9%.]*)%%[%s]*%)$')  
return hsl2lum(tonumber(h), tonumber(s)/100, tonumber(l)/100)  
end  

-- convert from rgb  
if mw.ustring.match(c,'^rgb%([%s]*[0-9][0-9]*[%s]*,[%s]*[0-9][0-9]*[%s]*,[%s]*[0-9][0-9]*[%s]*%)$') then  
local R, G, B = mw.ustring.match(c,'^rgb%([%s]*([0-9][0-9]*)[%s]*,[%s]*([0-9][0-9]*)[%s]*,[%s]*([0-9][0-9]*)[%s]*%)$')  
return rgbdec2lum(tonumber(R), tonumber(G), tonumber(B))  
end  

-- convert from rgb percent  
if mw.ustring.match(c,'^rgb%([%s]*[0-9][0-9%.]*%%[%s]*,[%s]*[0-9][0-9%.]*%%[%s]*,[%s]*[0-9][0-9%.]*%%[%s]*%)$') then  
local R, G, B = mw.ustring.match(c,'^rgb%([%s]*([0-9][0-9%.]*)%%[%s]*,[%s]*([0-9][0-9%.]*)%%[%s]*,[%s]*([0-9][0-9%.]*)%%[%s]*%)$')  
return rgbdec2lum(255*tonumber(R)/100, 255*tonumber(G)/100, 255*tonumber(B)/100)  
end  

-- remove leading # (if there is one) and whitespace  
c = mw.ustring.match(c, '^[%s#]*([a-f0-9]*)[%s]*$')  

-- split into rgb  
local cs = mw.text.split(c or *, *)  
if( #cs == 6 ) then  
local R = 16*tonumber('0x' .. cs[1]) + tonumber('0x' .. cs[2])  
local G = 16*tonumber('0x' .. cs[3]) + tonumber('0x' .. cs[4])  
local B = 16*tonumber('0x' .. cs[5]) + tonumber('0x' .. cs[6])  

return rgbdec2lum(R, G, B)  
elseif ( #cs == 3 ) then  
local R = 16*tonumber('0x' .. cs[1]) + tonumber('0x' .. cs[1])  
local G = 16*tonumber('0x' .. cs[2]) + tonumber('0x' .. cs[2])  
local B = 16*tonumber('0x' .. cs[3]) + tonumber('0x' .. cs[3])  

return rgbdec2lum(R, G, B)  
end  

-- failure, return blank  
return ''  
end  

-- This exports the function for use in other modules.  
-- The colour is passed as a string.  
function p._lum(color)  
return color2lum(color)  
end  

function p._greatercontrast(args)  
local bias = tonumber(args['bias'] or '0') or 0  
local css = (args['css'] and args['css'] ~= '') and true or false  
local v1 = color2lum(args[1] or '')  
local c2 = args[2] or 'white'  
local v2 = color2lum(c2)  
local c3 = args[3] or 'black'  
local v3 = color2lum(c3)  
local ratio1 = -1;  
local ratio2 = -1;  
if (type(v1) == 'number' and type(v2) == 'number') then  
ratio1 = (v2 + 0.05)/(v1 + 0.05)  
ratio1 = (ratio1 < 1) and 1/ratio1 or ratio1  
end  
if (type(v1) == 'number' and type(v3) == 'number') then  
ratio2 = (v3 + 0.05)/(v1 + 0.05)  
ratio2 = (ratio2 < 1) and 1/ratio2 or ratio2  
end  

if css then  
local c1 = args[1] or ''  
if mw.ustring.match(c1, '^[A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9]$') or  
mw.ustring.match(c1, '^[A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9]$') then  
c1 = '#' .. c1  
end  
if mw.ustring.match(c2, '^[A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9]$') or  
mw.ustring.match(c2, '^[A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9]$') then  
c2 = '#' .. c2  
end  
if mw.ustring.match(v3, '^[A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9]$') or  
mw.ustring.match(v3, '^[A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9][A-Fa-f0-9]$') then  
c3 = '#' .. c3  
end  
return 'background-color:' .. c1 .. '; color:' .. ((ratio1 > 0) and (ratio2 > 0) and ((ratio1 + bias > ratio2) and c2 or c3) or '') .. ';'  
end  

return (ratio1 > 0) and (ratio2 > 0) and ((ratio1 + bias > ratio2) and c2 or c3) or ''  
end  

function p._ratio(args)  
local v1 = color2lum(args[1])  
local v2 = color2lum(args[2])  
if (type(v1) == 'number' and type(v2) == 'number') then  
-- v1 should be the brighter of the two.  
if v2 > v1 then  
v1, v2 = v2, v1  
end  
return (v1 + 0.05)/(v2 + 0.05)  
else  
return args['error'] or '?'  
end  
end  

function p._styleratio(args)  
local style = (args[1] or ''):lower  
local bg, fg = 'white', 'black'  
local lum_bg, lum_fg = 1, 0  

if args[2] then  
local lum = color2lum(args[2])  
if lum ~= '' then bg, lum_bg = args[2], lum end  
end  
if args[3] then  
local lum = color2lum(args[3])  
if lum ~= '' then fg, lum_fg = args[3], lum end  
end  

local slist = mw.text.split(mw.ustring.gsub(mw.ustring.gsub(style or '', '&#[Xx]23;', '#'), '&#35;', '#'), ';')  
for k = 1,#slist do  
local s = slist[k]  
local k,v = s:match( '^[%s]*([^:]-):([^:]-)[%s;]*$' )  
k = k or ''  
v = v or ''  
if (k:match('^[%s]*(background)[%s]*$') or k:match('^[%s]*(background%-color)[%s]*$')) then  
local lum = color2lum(v)  
if( lum ~= '' ) then bg, lum_bg = v, lum end  
elseif (k:match('^[%s]*(color)[%s]*$')) then  
local lum = color2lum(v)  
if( lum ~= '' ) then bg, lum_fg = v, lum end  
end  
end  
if lum_bg > lum_fg then  
return (lum_bg + 0.05)/(lum_fg + 0.05)  
else  
return (lum_fg + 0.05)/(lum_bg + 0.05)  
end  
end  

--1= — required; A color to check.  
---
function p.lum  
local color = .args[1] or :getParent.args[1]  
return p._lum(color)  
end  

function p.ratio  
local args = .args[1] and .args or :getParent.args  
return p._ratio(args)  
end  

function p.styleratio  
local args = .args[1] and .args or :getParent.args  
return p._styleratio(args)  
end  

function p.greatercontrast  
local args = .args[1] and .args or :getParent.args  
return p._greatercontrast(args)  
end  

return p