"use client";

import { useMemo, useState } from "react";

import type { Activity } from "@/lib/schemas";
import { cn, shuffle } from "@/lib/utils";

import {
  ActivityHeader,
  FeedbackPanel,
  Hint,
  PromptCard,
  type ActivityComponentProps,
} from "./shared";

type MatchingActivity = Extract<Activity, { type: "matching" }>;

export function Matching({ activity, onAnswered, onNext, isLast }: ActivityComponentProps<MatchingActivity>) {
  const terms = useMemo(
    () => shuffle(activity.pairs.map((pair, index) => ({ index, text: pair.term }))),
    [activity],
  );
  const definitions = useMemo(
    () => shuffle(activity.pairs.map((pair, index) => ({ index, text: pair.definition }))),
    [activity],
  );

  const [selectedTerm, setSelectedTerm] = useState<number | null>(null);
  const [matched, setMatched] = useState<number[]>([]);
  const [misses, setMisses] = useState(0);
  const [flash, setFlash] = useState<{ term: number; definition: number } | null>(null);
  const [done, setDone] = useState(false);

  const total = activity.pairs.length;
  const complete = matched.length === total;

  const onDefinitionTap = (definitionIndex: number) => {
    if (done || selectedTerm === null || matched.includes(definitionIndex)) return;
    if (selectedTerm === definitionIndex) {
      const next = [...matched, definitionIndex];
      setMatched(next);
      setSelectedTerm(null);
      if (next.length === total) {
        const correct = misses === 0;
        setDone(true);
        onAnswered(correct);
      }
    } else {
      setMisses((value) => value + 1);
      setFlash({ term: selectedTerm, definition: definitionIndex });
      window.setTimeout(() => setFlash(null), 500);
      setSelectedTerm(null);
    }
  };

  return (
    <>
      <ActivityHeader
        type="matching"
        topic={activity.topic}
        extra={
          <span className="rounded-full bg-[var(--surface-strong)] px-3 py-1 text-xs font-bold text-frost-600 dark:text-frost-200">
            {matched.length}/{total} matched
          </span>
        }
      />
      <PromptCard className="py-4">
        <p className="text-lg font-bold text-frost-950 dark:text-frost-50">{activity.instruction}</p>
        <Hint>
          {done
            ? "All matched!"
            : selectedTerm === null
              ? "Tap a term on the left, then its match on the right."
              : "Now tap the matching definition →"}
        </Hint>
      </PromptCard>

      <div className="grid grid-cols-2 gap-2.5">
        <div className="flex flex-col gap-2.5">
          {terms.map((term) => {
            const isMatched = matched.includes(term.index);
            const isSelected = selectedTerm === term.index;
            const isFlashing = flash?.term === term.index;
            return (
              <button
                key={`term-${term.index}`}
                type="button"
                disabled={isMatched || done}
                onClick={() => setSelectedTerm(isSelected ? null : term.index)}
                className={cn(
                  "min-h-16 rounded-2xl border px-3 py-2 text-left text-sm font-semibold backdrop-blur-xl transition-all",
                  isMatched
                    ? "border-emerald-200/80 bg-emerald-50/85 text-emerald-800 dark:border-emerald-400/40 dark:bg-emerald-400/15 dark:text-emerald-100"
                    : isSelected
                      ? "border-accent-400 bg-accent-50/80 text-frost-900 dark:bg-accent-500/20 dark:text-white"
                      : "border-white/60 bg-white/55 text-frost-950 hover:bg-white/80 dark:border-white/12 dark:bg-white/[0.07] dark:text-frost-50",
                  isFlashing && "animate-wiggle border-rose-400 bg-rose-50 dark:bg-rose-400/15",
                )}
              >
                <span className="mr-1">{isMatched ? "✓" : "•"}</span>
                {term.text}
              </button>
            );
          })}
        </div>

        <div className="flex flex-col gap-2.5">
          {definitions.map((definition) => {
            const isMatched = matched.includes(definition.index);
            const isFlashing = flash?.definition === definition.index;
            return (
              <button
                key={`def-${definition.index}`}
                type="button"
                disabled={isMatched || done || selectedTerm === null}
                onClick={() => onDefinitionTap(definition.index)}
                className={cn(
                  "min-h-16 rounded-2xl border-2 px-3 py-2 text-left text-sm transition-all",
                  isMatched
                    ? "border-emerald-200/80 bg-emerald-50/85 text-emerald-800 dark:border-emerald-400/40 dark:bg-emerald-400/15 dark:text-emerald-100"
                    : "border-white/60 bg-white/55 text-frost-700 hover:bg-white/80 disabled:opacity-60 dark:border-white/12 dark:bg-white/[0.07] dark:text-frost-200",
                  isFlashing && "animate-wiggle border-rose-400 bg-rose-50 dark:bg-rose-400/15",
                )}
              >
                {definition.text}
              </button>
            );
          })}
        </div>
      </div>

      {complete ? (
        <FeedbackPanel
          correct={misses === 0}
          explanation={activity.explanation}
          xp={activity.xp}
          isLast={isLast}
          onNext={onNext}
          headline={misses === 0 ? "Perfect match!" : "Matched — with a few slips"}
          detail={
            <span>
              {misses === 0
                ? "You matched everything first try."
                : `You made ${misses} wrong ${misses === 1 ? "attempt" : "attempts"}.`}
            </span>
          }
        />
      ) : null}
    </>
  );
}