/**
 * Inline script that runs in <head> before hydration.
 *
 * Reads the persisted theme id + mode from localStorage and applies them
 * to <html> so the user never sees a flash of the default theme.
 *
 * MUST stay dependency-free — it's bundled as a string and inlined.
 */
export function ThemeBootstrapScript() {
  const code = `
    (function() {
      try {
        var themeId = localStorage.getItem('wfdash-theme') || 'crisp';
        var mode = localStorage.getItem('wfdash-mode') || 'warm';
        var root = document.documentElement;
        root.setAttribute('data-theme', themeId);
        root.classList.remove('warm', 'dark');
        root.classList.add(mode);
        var radiusMap = {
          'crisp': '0.625rem',
          'midnight': '0.75rem',
          'editorial': '0.375rem',
          'bento': '1.125rem',
          'field-ops': '0.5rem',
          'terminal': '0',
          'blueprint': '0.125rem',
          'confetti': '1.25rem'
        };
        if (radiusMap[themeId]) root.style.setProperty('--radius', radiusMap[themeId]);

        // If the active theme is a custom theme, apply its inline token overrides
        // so the page renders correctly before React hydrates.
        var activeCustomId = localStorage.getItem('wfdash-active-custom-id');
        if (activeCustomId) {
          try {
            var raw = localStorage.getItem('wfdash-custom-themes');
            if (raw) {
              var list = JSON.parse(raw);
              var found = null;
              for (var i = 0; i < list.length; i++) {
                if (list[i].id === activeCustomId) { found = list[i]; break; }
              }
              if (found && found.colors) {
                var c = found.colors;
                // Direct mappings
                root.style.setProperty('--background', c.background);
                root.style.setProperty('--foreground', c.foreground);
                root.style.setProperty('--primary', c.primary);
                root.style.setProperty('--accent', c.accent);
                root.style.setProperty('--destructive', c.destructive);
                root.style.setProperty('--sidebar', c.sidebar);
                root.style.setProperty('--border', c.border);
                // Contrast foregrounds
                function lum(hex){
                  var r = parseInt(hex.slice(1,3),16)/255;
                  var g = parseInt(hex.slice(3,5),16)/255;
                  var b = parseInt(hex.slice(5,7),16)/255;
                  var f = function(v){return v<=0.03928 ? v/12.92 : Math.pow((v+0.055)/1.055,2.4);};
                  return 0.2126*f(r)+0.7152*f(g)+0.0722*f(b);
                }
                function fgFor(bg){ return lum(bg) > 0.55 ? '#0F172A' : '#FFFFFF'; }
                root.style.setProperty('--primary-foreground', fgFor(c.primary));
                root.style.setProperty('--accent-foreground', fgFor(c.accent));
                root.style.setProperty('--destructive-foreground', fgFor(c.destructive));
                root.style.setProperty('--sidebar-foreground', fgFor(c.sidebar));
                // Derived
                function hexA(hex,a){return hex+(Math.round(a*2.55).toString(16).padStart(2,'0'));}
                function mix(a,b,p){var ar=parseInt(a.slice(1,3),16),ag=parseInt(a.slice(3,5),16),ab=parseInt(a.slice(5,7),16),br=parseInt(b.slice(1,3),16),bg=parseInt(b.slice(3,5),16),bb=parseInt(b.slice(5,7),16);var k=p/100;var r=Math.round(ar*k+br*(1-k)),g=Math.round(ag*k+bg*(1-k)),bb2=Math.round(ab*k+bb*(1-k));var h=function(n){return n.toString(16).padStart(2,'0');};return '#'+h(r)+h(g)+h(bb2);}
                root.style.setProperty('--card', mix('#FFFFFF', c.background, 2));
                root.style.setProperty('--popover', mix('#FFFFFF', c.background, 2));
                root.style.setProperty('--muted', mix('#000000', c.background, 4));
                root.style.setProperty('--secondary', mix('#000000', c.background, 3));
                root.style.setProperty('--card-foreground', c.foreground);
                root.style.setProperty('--popover-foreground', c.foreground);
                root.style.setProperty('--secondary-foreground', c.foreground);
                root.style.setProperty('--muted-foreground', mix('#94A3B8', c.foreground, 60));
                root.style.setProperty('--input', c.border);
                root.style.setProperty('--ring', c.primary);
                root.style.setProperty('--sidebar-primary', c.primary);
                root.style.setProperty('--sidebar-primary-foreground', fgFor(c.primary));
                root.style.setProperty('--sidebar-accent', mix('#FFFFFF', c.sidebar, 8));
                root.style.setProperty('--sidebar-accent-foreground', fgFor(c.sidebar));
                root.style.setProperty('--sidebar-border', mix('#FFFFFF', c.sidebar, 12));
                root.style.setProperty('--sidebar-ring', c.primary);
              }
            }
          } catch(e2) { /* ignore */ }
        }
      } catch (e) {
        // localStorage may be blocked — fall back to defaults silently
      }
    })();
  `;
  return <script dangerouslySetInnerHTML={{ __html: code }} />;
}