Glass tab bar

import { useState, type CSSProperties, type MouseEvent, type ReactNode } from "react";
import { motion } from "framer-motion";
import { Compass, Home, Library, Search } from "lucide-react";

type Wallpaper = "aurora" | "sunset" | "ocean" | "light";

const spring = { type: "spring" as const, stiffness: 400, damping: 30 };

const walls: Record<Wallpaper, { base: string; blobs: string[] }> = {
  aurora: { base: "#0b0b1a", blobs: ["#5b21b6", "#2563eb", "#ec4899"] },
  sunset: { base: "#1a0b14", blobs: ["#f97316", "#f43f5e", "#8b5cf6"] },
  ocean: { base: "#031a1f", blobs: ["#06b6d4", "#3b82f6", "#10b981"] },
  light: { base: "#f8fafc", blobs: ["#fed7aa", "#ddd6fe", "#bae6fd"] },
};

const blobPositions = [
  ["-10%", "-15%"],
  ["45%", "5%"],
  ["5%", "50%"],
];

const grain = "url(\"data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='160' height='160'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.9' numOctaves='3' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E\")";

const glassCss = `
.lg-font {
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Display", "Inter", sans-serif;
  -webkit-font-smoothing: antialiased;
}
.lg-glass {
  position: relative;
  overflow: hidden;
  background: rgba(255, 255, 255, var(--lg-a, 0.12));
  -webkit-backdrop-filter: blur(var(--lg-blur, 20px)) saturate(180%);
  backdrop-filter: blur(var(--lg-blur, 20px)) saturate(180%);
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.5),
    inset 0 -1px 0 rgba(255, 255, 255, 0.1),
    inset 0 0 20px rgba(255, 255, 255, 0.08),
    0 8px 32px rgba(0, 0, 0, 0.18);
}
/* Borde de luz */
.lg-glass::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 2;
  padding: 1px;
  border-radius: inherit;
  pointer-events: none;
  background: linear-gradient(135deg, rgba(255, 255, 255, 0.7), rgba(255, 255, 255, 0.05) 40%, rgba(255, 255, 255, 0.05) 60%, rgba(255, 255, 255, 0.4));
  mask: linear-gradient(#000 0 0) content-box exclude, linear-gradient(#000 0 0);
}
/* Reflejo que sigue al cursor (--x / --y los pone track()) */
.lg-glass::after {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 1;
  border-radius: inherit;
  pointer-events: none;
  opacity: var(--lg-hover, 0);
  transition: opacity 0.3s;
  background: radial-gradient(circle 140px at var(--x, 50%) var(--y, 0%), rgba(255, 255, 255, var(--lg-shine, 0.25)), transparent 70%);
}
.lg-glass:hover {
  --lg-hover: 1;
}
.lg-text {
  color: #fff;
  text-shadow: 0 1px 2px rgba(0, 0, 0, 0.18);
}
.lg-light .lg-text {
  color: #1d1d1f;
  text-shadow: none;
}
@keyframes lg-drift {
  0%, 100% { transform: translate(0, 0) scale(1); }
  33% { transform: translate(8%, -6%) scale(1.12); }
  66% { transform: translate(-6%, 7%) scale(0.94); }
}
`;

// Guarda la posición del cursor para el reflejo de .lg-glass::after
function track(e: MouseEvent<HTMLElement>) {
  const r = e.currentTarget.getBoundingClientRect();
  e.currentTarget.style.setProperty("--x", `${e.clientX - r.left}px`);
  e.currentTarget.style.setProperty("--y", `${e.clientY - r.top}px`);
}

interface StageProps {
  bg: Wallpaper;
  blur: number;
  opacity: number;
  shine: number;
  className?: string;
  children: ReactNode;
}

// Fondo de degradado animado sobre el que se ve el cristal
function Stage({
  bg,
  blur,
  opacity,
  shine,
  className = "relative h-[560px] w-full",
  children,
}: StageProps) {
  const light = bg === "light";
  const wall = walls[bg] ?? walls.aurora;
  const vars = {
    "--lg-blur": `${blur}px`,
    "--lg-a": light ? Math.min(0.6, opacity / 100 + 0.23) : opacity / 100,
    "--lg-shine": shine / 100,
  } as CSSProperties;

  return (
    <div
      className={`lg-font overflow-hidden rounded-[22px] ${className} ${light ? "lg-light" : ""}`}
      style={vars}
    >
      <style>{glassCss}</style>
      <div className="absolute inset-0 overflow-hidden" style={{ background: wall.base }}>
        <div className="absolute inset-0" style={{ filter: "blur(60px)" }}>
          {wall.blobs.map((color, i) => (
            <div
              key={i}
              className="absolute h-[75%] w-[75%] rounded-full"
              style={{
                left: blobPositions[i]?.[0],
                top: blobPositions[i]?.[1],
                background: `radial-gradient(circle, ${color} 0%, transparent 68%)`,
                opacity: light ? 1 : 0.9,
                animation: `lg-drift 20s ease-in-out ${-i * 6}s infinite`,
              }}
            />
          ))}
        </div>
        <div
          className="absolute inset-0"
          style={{ backgroundImage: grain, opacity: 0.04, mixBlendMode: "overlay" }}
        />
      </div>
      <div className="relative grid h-full w-full grid-cols-[100%] place-items-center p-4">{children}</div>
    </div>
  );
}

const tabs = [
  { icon: Home, label: "Home" },
  { icon: Compass, label: "Explore" },
  { icon: Library, label: "Library" },
  { icon: Search, label: "Search" },
];

interface GlassTabBarProps {
  bg?: Wallpaper;
  blur?: number;
  opacity?: number;
  shine?: number;
}

export default function GlassTabBar({
  bg = "aurora",
  blur = 20,
  opacity = 12,
  shine = 25,
}: GlassTabBarProps) {
  const glass = { bg, blur, opacity, shine };
  const [active, setActive] = useState(0);

  return (
    <Stage {...glass}>
      <div className="absolute inset-x-0 bottom-6 flex justify-center">
        <div onMouseMove={track} className="lg-glass flex rounded-full p-1">
          {tabs.map(({ icon: Icon, label }, i) => (
            <motion.button
              key={label}
              type="button"
              aria-pressed={active === i}
              onClick={() => setActive(i)}
              whileTap={{ scale: 0.92 }}
              transition={spring}
              className="lg-text relative z-[3] flex h-[54px] w-[74px] flex-col items-center justify-center gap-0.5"
            >
              {active === i && (
                // La key cambia en cada pulsación para repetir el estirón de la píldora
                <motion.span
                  key={`pill-${active}`}
                  layoutId="lg-tab-pill"
                  className="absolute inset-0 rounded-full"
                  initial={{ scaleX: 1 }}
                  animate={{ scaleX: [1, 1.15, 1] }}
                  transition={{
                    layout: spring,
                    scaleX: { duration: 0.45, ease: [0.25, 0.1, 0.25, 1] },
                  }}
                  style={{
                    background: "rgba(255,255,255,.22)",
                    boxShadow: "inset 0 1px 0 rgba(255,255,255,.55), 0 2px 8px rgba(0,0,0,.08)",
                  }}
                />
              )}
              <Icon className="relative h-[22px] w-[22px]" strokeWidth={1.75} />
              <span className="relative text-[11px] font-medium">{label}</span>
            </motion.button>
          ))}
        </div>
      </div>
    </Stage>
  );
}