"use client";

import { useRef, type CSSProperties, type ElementType, type PointerEvent, type ReactNode } from "react";
import { motion, useInView, useReducedMotion } from "motion/react";

type CTARevealProps = {
  title: string;
  text?: string;
  /** Small line above the title. */
  eyebrow?: string;
  /** Buttons or links. */
  children?: ReactNode;
  /** Panel colour at one corner. */
  from?: string;
  /** Panel colour at the other corner. */
  to?: string;
  /** Colour of the light under the pointer and of the opening flash. */
  glow?: string;
  /** Plays once. false replays each time it comes back on screen. */
  once?: boolean;
  /** h2 by default. */
  headingAs?: ElementType;
  /** Set padding here. The panel sits inside. */
  className?: string;
};

const EASE = [0.16, 1, 0.3, 1] as const;

/* CTAReveal: a call to action that opens from a thin band of light when it comes on screen. The words rise in, then the buttons, and a soft light follows the pointer. */
export function CTAReveal({
  title,
  text,
  eyebrow,
  children,
  from = "#4c1d95",
  to = "#0e7490",
  glow = "#67e8f9",
  once = true,
  headingAs: Heading = "h2",
  className = "bg-[#0b0a14] px-5 py-16",
}: CTARevealProps) {
  const reduce = useReducedMotion();
  const box = useRef<HTMLElement>(null);
  const seen = useInView(box, { once, amount: 0.3 });
  const state = seen ? "open" : "shut";
  const words = title.split(" ");

  const track = (e: PointerEvent<HTMLDivElement>) => {
    const box = e.currentTarget.getBoundingClientRect();
    e.currentTarget.style.setProperty("--cr-x", `${e.clientX - box.left}px`);
    e.currentTarget.style.setProperty("--cr-y", `${e.clientY - box.top}px`);
  };

  const rise = (delay: number) => ({
    shut: reduce ? { opacity: 0 } : { opacity: 0, y: "0.6em" },
    open: { opacity: 1, y: 0, transition: { duration: reduce ? 0.3 : 0.7, delay: reduce ? 0 : delay, ease: EASE } },
  });

  return (
    <section ref={box} className={`@container ${className}`}>
      <motion.div
        onPointerMove={track}
        className="group/cta relative isolate mx-auto max-w-5xl overflow-hidden rounded-3xl px-6 py-14 text-center text-white @2xl:py-20"
        style={{ backgroundImage: `linear-gradient(120deg, ${from}, ${to})`, "--cr-x": "50%", "--cr-y": "50%" } as CSSProperties}
        initial={false}
        animate={state}
        variants={{
          shut: { clipPath: reduce ? "inset(0% 0% 0% 0% round 24px)" : "inset(47% 8% 47% 8% round 24px)" },
          open: { clipPath: "inset(0% 0% 0% 0% round 24px)", transition: { duration: reduce ? 0 : 1, ease: EASE } },
        }}
      >
        <span
          aria-hidden
          className="absolute inset-0 -z-10 opacity-0 transition-opacity duration-500 group-hover/cta:opacity-45 motion-reduce:transition-none"
          style={{ backgroundImage: `radial-gradient(20rem at var(--cr-x) var(--cr-y), ${glow}, transparent)` }}
        />
        <motion.span
          aria-hidden
          className="pointer-events-none absolute inset-0"
          style={{ backgroundColor: glow }}
          initial={false}
          animate={state}
          variants={{
            shut: { opacity: reduce ? 0 : 1 },
            open: { opacity: 0, transition: { duration: reduce ? 0 : 0.8, delay: reduce ? 0 : 0.1, ease: "easeOut" } },
          }}
        />

        {eyebrow && (
          <motion.p initial={false} animate={state} variants={rise(0.2)} className="mb-3 text-xs font-medium tracking-[0.2em] uppercase opacity-80">
            {eyebrow}
          </motion.p>
        )}
        <Heading className="text-[clamp(1.6rem,6cqw,3rem)] leading-tight font-semibold tracking-tight text-balance">
          <span className="sr-only">{title}</span>
          <span aria-hidden>
            {words.map((word, i) => (
              <span key={i}>
                <span className="inline-block overflow-hidden pb-[0.1em] align-bottom">
                  <motion.span initial={false} animate={state} variants={rise(0.3 + i * 0.05)} className="inline-block">
                    {word}
                  </motion.span>
                </span>
                {i < words.length - 1 && " "}
              </span>
            ))}
          </span>
        </Heading>
        {text && (
          <motion.p initial={false} animate={state} variants={rise(0.45 + words.length * 0.05)} className="mx-auto mt-4 max-w-xl text-pretty opacity-85">
            {text}
          </motion.p>
        )}
        {children && (
          <motion.div initial={false} animate={state} variants={rise(0.55 + words.length * 0.05)} className="mt-8 flex flex-wrap items-center justify-center gap-3">
            {children}
          </motion.div>
        )}
      </motion.div>
    </section>
  );
}