"use client";

import { useRef, useState } from "react";
import { AnimatePresence, motion, useMotionValue, useTransform, type PanInfo, type Variants } from "framer-motion";
import ObjectFace from "./ObjectFace";
import { useOpenWindow } from "../fenster/WindowProvider";
import { labelFor, windowFor } from "./windowFor";
import type { TischLabels, TischObject } from "./types";

interface DeckProps {
  objects: TischObject[];
  labels: TischLabels;
}

const VISIBLE = 4;
// Ab dieser Strecke oder Geschwindigkeit fliegt die Karte weg (Emil: ein kurzer Wisch reicht)
const DISTANCE = 110;
const VELOCITY = 500;
const EASE_OUT: [number, number, number, number] = [0.23, 1, 0.32, 1];

const pad = (n: number) => String(n).padStart(2, "0");

type Exit = { kind: "fly"; dir: 1 | -1 } | { kind: "fade" };

// Bekommt den aktuellen Exit-Modus über `custom` von AnimatePresence
const exitVariants: Variants = {
  leave: (e: Exit) =>
    e.kind === "fly"
      ? { x: e.dir * 460, rotate: e.dir * 18, opacity: 0, transition: { duration: 0.3, ease: EASE_OUT } }
      : { scale: 0.85, opacity: 0, transition: { duration: 0.2, ease: EASE_OUT } },
};

/** Handy: Kartenstapel. Oberste Karte zur Seite wischen, antippen zum Umdrehen. */
export default function Deck({ objects, labels }: DeckProps) {
  const [order, setOrder] = useState(() => objects.map((_, i) => i));
  // Wie die Karte geht, die den sichtbaren Stapel verlässt: oben weggeworfen oder hinten ausgeblendet
  const [exit, setExit] = useState<Exit>({ kind: "fly", dir: 1 });

  const next = (d: 1 | -1 = 1) => {
    setExit({ kind: "fly", dir: d });
    setOrder((o) => [...o.slice(1), o[0]]);
  };
  const prev = () => {
    setExit({ kind: "fade" });
    setOrder((o) => [o[o.length - 1], ...o.slice(0, -1)]);
  };

  const visible = order.slice(0, VISIBLE);

  return (
    <div>
      <p className="mb-2 px-4 font-mono text-[13px] sm:px-6">{labels.hintDeck}</p>
      <div className="relative h-[440px] overflow-hidden">
        <AnimatePresence initial={false} custom={exit}>
          {visible
            .map((idx, depth) => (
              <DeckCard
                key={objects[idx].id}
                obj={objects[idx]}
                labels={labels}
                depth={depth}
                enteringFromLeft={depth === 0 && exit.kind === "fade"}
                onDismiss={next}
              />
            ))
            .reverse()}
        </AnimatePresence>
      </div>
      <div className="flex items-center justify-between px-4 pb-10 pt-1 sm:px-6">
        <RoundButton label={labels.prev} onClick={prev}>
          ←
        </RoundButton>
        <span className="font-mono text-[13px] [font-variant-numeric:tabular-nums]" aria-live="polite">
          {pad(order[0] + 1)} / {pad(objects.length)}
        </span>
        <RoundButton label={labels.next} onClick={() => next(1)}>
          →
        </RoundButton>
      </div>
    </div>
  );
}

function RoundButton({ label, onClick, children }: { label: string; onClick: () => void; children: React.ReactNode }) {
  return (
    <button
      type="button"
      aria-label={label}
      onClick={onClick}
      className="grid h-[52px] w-[52px] place-items-center rounded-full border-2 border-ink bg-paper text-xl font-semibold transition-[background-color,transform] duration-150 ease-out active:scale-95 active:bg-paper-2"
    >
      <span aria-hidden="true">{children}</span>
    </button>
  );
}

interface DeckCardProps {
  obj: TischObject;
  labels: TischLabels;
  depth: number;
  enteringFromLeft: boolean;
  onDismiss: (dir: 1 | -1) => void;
}

function DeckCard({ obj, labels, depth, enteringFromLeft, onDismiss }: DeckCardProps) {
  const dragged = useRef(false);
  const cardRef = useRef<HTMLDivElement>(null);
  const openWindow = useOpenWindow();
  const openIt = () => openWindow?.(windowFor(obj), cardRef.current);
  const x = useMotionValue(0);
  const dragRotate = useTransform(x, [-220, 0, 220], [-14, 0, 14]);
  const isTop = depth === 0;
  const restRotate = depth === 0 ? 0 : depth % 2 ? 3 : -3;

  const handleDragEnd = (_: unknown, info: PanInfo) => {
    if (Math.abs(info.offset.x) > DISTANCE || Math.abs(info.velocity.x) > VELOCITY) {
      onDismiss(info.offset.x > 0 ? 1 : -1);
    }
  };

  return (
    <motion.div
      className="absolute inset-x-0 top-4 mx-auto h-[390px] w-[min(300px,82vw)]"
      style={{ zIndex: 10 - depth }}
      initial={enteringFromLeft ? { x: -420, rotate: -14, opacity: 0 } : { scale: 0.85, y: 3 * 14, opacity: 0 }}
      animate={{ x: 0, scale: 1 - Math.min(depth, 3) * 0.05, y: Math.min(depth, 3) * 14, rotate: restRotate, opacity: 1 }}
      variants={exitVariants}
      exit="leave"
      transition={{ type: "spring", bounce: 0, duration: 0.45 }}
    >
      <motion.div
        ref={cardRef}
        className={`h-full w-full ${obj.kind === "sticker" ? "rounded-full" : "rounded-2xl"} shadow-[6px_6px_0_rgb(var(--plakat-ink))] ${isTop ? "cursor-grab" : "pointer-events-none"}`}
        style={{ x, rotate: dragRotate, touchAction: "pan-y" }}
        drag={isTop ? "x" : false}
        dragSnapToOrigin
        dragElastic={0.9}
        onPointerDown={() => {
          dragged.current = false;
        }}
        onDragStart={() => {
          dragged.current = true;
        }}
        onDragEnd={handleDragEnd}
        onTap={isTop ? () => !dragged.current && openIt() : undefined}
        onKeyDown={(e) => {
          if (isTop && e.key === " ") {
            e.preventDefault();
            openIt();
          }
        }}
        tabIndex={isTop ? 0 : -1}
        role="button"
        aria-haspopup="dialog"
        aria-label={labelFor(obj, labels)}
        aria-hidden={!isTop}
      >
        <ObjectFace obj={obj} labels={labels} />
      </motion.div>
    </motion.div>
  );
}