"use client";

import { AnimatePresence, motion, useReducedMotion } from "framer-motion";
import { LayoutRouterContext } from "next/dist/shared/lib/app-router-context.shared-runtime";
import { usePathname } from "next/navigation";
import { useContext, useState, type ReactNode } from "react";

/**
 * App Router swaps in the new page's content as soon as you navigate, so the
 * outgoing page would normally vanish before it can animate out. `FrozenRouter`
 * pins the layout-router context to the value it had when this instance
 * mounted, keeping the *old* subtree rendered while its exit animation plays.
 */
function FrozenRouter({ children }: { children: ReactNode }) {
  const context = useContext(LayoutRouterContext);
  // Freeze the context captured at mount so the outgoing subtree keeps
  // rendering (with its old route data) while its exit animation plays.
  const [frozen] = useState(context);

  if (!frozen) {
    return <>{children}</>;
  }

  return <LayoutRouterContext.Provider value={frozen}>{children}</LayoutRouterContext.Provider>;
}

/**
 * One unified page transition on every navigation: the old page animates out
 * (blur + rise up) before the new page animates in (blur + rise from below).
 */
export default function SiteTemplate({ children }: { children: ReactNode }) {
  const reducedMotion = useReducedMotion();
  const pathname = usePathname();

  return (
    <AnimatePresence mode="wait" initial={false}>
      <motion.div
        key={pathname}
        initial={reducedMotion ? false : { opacity: 0, y: 18, filter: "blur(10px)" }}
        animate={{ opacity: 1, y: 0, filter: "blur(0px)" }}
        exit={reducedMotion ? { opacity: 0 } : { opacity: 0, y: -18, filter: "blur(10px)" }}
        transition={reducedMotion ? { duration: 0 } : { duration: 0.4, ease: [0.22, 1, 0.36, 1] }}
      >
        <FrozenRouter>{children}</FrozenRouter>
      </motion.div>
    </AnimatePresence>
  );
}