//+------------------------------------------------------------------+
//|                                                      CkTheme.mqh |
//|                                      Copyright 2026, Allan Niñal |
//|                                  https://www.allanninal.dev/mql5 |
//+------------------------------------------------------------------+
//| Chart kit colour tokens. Semantic names, never literals in the   |
//| products: pos/neg (profit/loss, buy/sell), acc (entry, neutral), |
//| warn, ink/label/dim (text), zone fills pre-blended with the      |
//| chart background (a fill never hides candles and never relies on |
//| object alpha). Theme AUTO reads the chart background.            |
//| Colour-blind mode swaps green/red for blue/orange (Okabe-Ito);   |
//| shapes and text carry the meaning too, never colour alone.       |
//| Values are checked by tests/test_tokens.py (contrast >= 3:1).    |
//+------------------------------------------------------------------+
#ifndef CK_THEME_MQH
#define CK_THEME_MQH

enum ENUM_CK_THEME
  {
   CK_THEME_AUTO=0,     // Auto (from the chart background)
   CK_THEME_DARK=1,     // Dark
   CK_THEME_LIGHT=2     // Light
  };

struct CkTheme
  {
   bool  light,cb;
   color bg;                        // the chart background the fills are blended with
   color ink,label,dim;
   color pos,neg,warn,acc;
   color zone_pos,zone_neg;         // risk box fills
  };

#define CK_ZONE_DARK   0.22         // fill strength over a dark chart
#define CK_ZONE_LIGHT  0.16         // over a light chart

color CkRGB(const int r,const int g,const int b) { return((color)((r&255)|((g&255)<<8)|((b&255)<<16))); }
int   CkR(const color c) { return((int)(c&255)); }
int   CkG(const color c) { return((int)((c>>8)&255)); }
int   CkB(const color c) { return((int)((c>>16)&255)); }

//--- WCAG relative luminance, 0 (black) .. 1 (white)
double CkLin(const int v) { double s=v/255.0; return(s<=0.04045 ? s/12.92 : MathPow((s+0.055)/1.055,2.4)); }
double CkLuma(const color c) { return(0.2126*CkLin(CkR(c))+0.7152*CkLin(CkG(c))+0.0722*CkLin(CkB(c))); }

//--- `fg` laid over `bg` at strength `a` (0..1), as an opaque colour
color CkBlend(const color fg,const color bg,const double a)
  {
   return(CkRGB((int)MathRound(CkR(bg)+(CkR(fg)-CkR(bg))*a),(int)MathRound(CkG(bg)+(CkG(fg)-CkG(bg))*a),
                (int)MathRound(CkB(bg)+(CkB(fg)-CkB(bg))*a)));
  }

//--- fill the tokens for `mode`; `cb` = colour-blind friendly; `chart_bg` < 0 reads the chart's own background
void CkThemeLoad(CkTheme &t,const ENUM_CK_THEME mode,const bool cb,const long chart_bg=-1)
  {
   color bg=(color)(chart_bg>=0 ? chart_bg : ChartGetInteger(0,CHART_COLOR_BACKGROUND));
   t.bg=bg;
   t.cb=cb;
   t.light=(mode==CK_THEME_LIGHT || (mode==CK_THEME_AUTO && CkLuma(bg)>0.4));
   if(t.light)
     {
      t.ink=CkRGB(30,37,40);   t.label=CkRGB(95,107,113); t.dim=CkRGB(154,164,169);
      t.pos=cb ? CkRGB(0,114,178)  : CkRGB(46,134,87);
      t.neg=cb ? CkRGB(213,94,0)   : CkRGB(193,73,62);
      t.warn=cb ? CkRGB(150,120,0) : CkRGB(168,118,26);
      t.acc=CkRGB(47,111,166);
      if(cb)
         t.acc=CkRGB(90,90,90);             // keep the entry apart from the blue of "buy/profit"
     }
   else
     {
      t.ink=CkRGB(215,222,226); t.label=CkRGB(139,151,158); t.dim=CkRGB(91,102,108);
      t.pos=cb ? CkRGB(86,180,233) : CkRGB(98,184,140);
      t.neg=cb ? CkRGB(230,159,0)  : CkRGB(224,123,112);
      t.warn=cb ? CkRGB(240,228,66): CkRGB(217,166,72);
      t.acc=CkRGB(115,169,214);
      if(cb)
         t.acc=CkRGB(200,200,200);
     }
   double a=t.light ? CK_ZONE_LIGHT : CK_ZONE_DARK;
   t.zone_pos=CkBlend(t.pos,bg,a);
   t.zone_neg=CkBlend(t.neg,bg,a);
  }

#endif
//+------------------------------------------------------------------+