"use client";

import { cloneElement, useEffect, useId, useLayoutEffect, useRef, useState, useSyncExternalStore, type PointerEvent, type ReactElement, type ReactNode } from "react";
import { createPortal } from "react-dom";
import { AnimatePresence, motion, useMotionValue, useReducedMotion, useSpring } from "motion/react";

type TooltipFloatProps = {
  /** Tooltip text. */
  content: ReactNode;
  /** One focusable element, like a button or link. */
  children: ReactElement<{ "aria-describedby"?: string }>;
  /** Preferred side. Flips by itself when there is no room. */
  side?: "top" | "bottom";
  /** Milliseconds of hover before it shows. Keyboard focus shows it at once. */
  delay?: number;
  /** Replaces the default look. */
  className?: string;
};

const GAP = 10;
const EDGE = 8;
const noop = () => () => {};

/* TooltipFloat: a label that hangs in the air above its target, bobbing a little and leaning toward the pointer. Works on keyboard focus too, Esc hides it, and the pointer can move onto it. */
export function TooltipFloat({
  content,
  children,
  side = "top",
  delay = 150,
  className = "bg-[#241e44] text-white shadow-lg shadow-black/40",
}: TooltipFloatProps) {
  const reduce = useReducedMotion();
  const id = useId();
  const anchor = useRef<HTMLSpanElement>(null);
  const tip = useRef<HTMLDivElement>(null);
  const timer = useRef<number>(undefined);
  const [open, setOpen] = useState(false);
  const browser = useSyncExternalStore(noop, () => true, () => false);
  const lean = useMotionValue(0);
  const x = useSpring(lean, { stiffness: 300, damping: 20 });

  const toggle = (next: boolean, wait: number) => {
    window.clearTimeout(timer.current);
    timer.current = window.setTimeout(() => setOpen(next), wait);
  };

  const onMove = (e: PointerEvent) => {
    const box = e.currentTarget.getBoundingClientRect();
    lean.set(Math.max(-10, Math.min(10, (e.clientX - box.left - box.width / 2) * 0.15)));
  };

  // Position is measured before paint: flip when the side has no room, slide to stay on screen.
  useLayoutEffect(() => {
    const el = tip.current;
    const box = anchor.current?.getBoundingClientRect();
    if (!open || !el || !box) return;
    const { offsetWidth: w, offsetHeight: h } = el;
    const { clientWidth, clientHeight } = document.documentElement;
    const fitsTop = box.top - h - GAP >= EDGE;
    const fitsBottom = box.bottom + h + GAP <= clientHeight - EDGE;
    const onTop = side === "top" ? fitsTop || !fitsBottom : fitsTop && !fitsBottom;
    const middle = box.left + box.width / 2;
    const left = Math.max(EDGE, Math.min(clientWidth - w - EDGE, middle - w / 2));
    el.dataset.side = onTop ? "top" : "bottom";
    el.style.top = `${onTop ? box.top - h - GAP : box.bottom + GAP}px`;
    el.style.left = `${left}px`;
    el.style.setProperty("--ax", `${middle - left}px`);
  }, [open, side]);

  // Esc or any scroll hides it.
  useEffect(() => {
    if (!open) return;
    const onKey = (e: globalThis.KeyboardEvent) => {
      if (e.key === "Escape") setOpen(false);
    };
    const onScroll = () => setOpen(false);
    window.addEventListener("keydown", onKey);
    window.addEventListener("scroll", onScroll, true);
    return () => {
      window.removeEventListener("keydown", onKey);
      window.removeEventListener("scroll", onScroll, true);
    };
  }, [open]);

  useEffect(() => () => window.clearTimeout(timer.current), []);

  return (
    <>
      <span
        ref={anchor}
        className="inline-flex"
        onPointerEnter={(e) => e.pointerType === "mouse" && toggle(true, delay)}
        onPointerLeave={() => toggle(false, 120)}
        onPointerMove={onMove}
        onFocus={() => toggle(true, 0)}
        onBlur={() => toggle(false, 0)}
      >
        {cloneElement(children, { "aria-describedby": id })}
      </span>
      <span id={id} role="tooltip" className="sr-only">
        {content}
      </span>
      {browser &&
        createPortal(
          <AnimatePresence>
            {open && (
              <div
                ref={tip}
                aria-hidden
                onPointerEnter={() => toggle(true, 0)}
                onPointerLeave={() => toggle(false, 120)}
                className="group fixed z-60 w-max max-w-[min(15rem,calc(100vw-1rem))]"
              >
                <motion.div
                  style={{ x: reduce ? 0 : x }}
                  initial={{ opacity: 0, scale: reduce ? 1 : 0.85 }}
                  animate={{ opacity: 1, scale: 1 }}
                  exit={{ opacity: 0, scale: reduce ? 1 : 0.9 }}
                  transition={reduce ? { duration: 0.1 } : { type: "spring", stiffness: 520, damping: 26 }}
                  className="group-data-[side=bottom]:origin-[var(--ax)_0%] group-data-[side=top]:origin-[var(--ax)_100%]"
                >
                  <motion.div
                    animate={reduce ? undefined : { y: [0, -2.5, 0] }}
                    transition={{ duration: 2.2, ease: "easeInOut", repeat: Infinity }}
                    className={`relative rounded-lg px-3 py-1.5 text-[13px] ${className}`}
                  >
                    {content}
                    <span
                      aria-hidden
                      style={{ left: "var(--ax)" }}
                      className="absolute h-2.5 w-2.5 -translate-x-1/2 rotate-45 bg-inherit group-data-[side=bottom]:-top-1 group-data-[side=top]:-bottom-1"
                    />
                  </motion.div>
                </motion.div>
              </div>
            )}
          </AnimatePresence>,
          document.body,
        )}
    </>
  );
}