"use client";

/**
 * The roadmap's practice loop: a progressive quiz (question first, reveal,
 * honest self-mark, score at the end) and spaced-repetition flashcards
 * (flip, then "knew it / again" drives a 1d/3d/7d Leitner schedule with a
 * due-today queue). Replaces the old static lists that printed answers and
 * card backs in plain sight. All state persists through the roadmap the
 * same way topics do. Editorial ledger styling, no accent colour.
 */

import Link from "next/link";
import { useMemo, useState } from "react";
import {
  dueFlashcards,
  recordRoadmapQuizResult,
  reviewFlashcard,
  type LearnAnythingRoadmap,
  type RoadmapQuizResult,
} from "@/lib/phase3-learning";
import { buildStudyIntentUrl } from "@/lib/study-intents";

export function RoadmapPracticeSection({
  roadmap,
  onChange,
  onQuizSubmitted,
}: {
  roadmap: LearnAnythingRoadmap;
  onChange: (next: LearnAnythingRoadmap) => void;
  onQuizSubmitted?: (result: RoadmapQuizResult) => void;
}) {
  return (
    <section className="mt-12">
      <p className="text-[11px] font-semibold uppercase tracking-[0.18em] text-[#92949a]">Practice and revision</p>
      <p className="mt-4 max-w-[62ch] text-sm font-light leading-relaxed text-[#62635e]">{roadmap.practiceTask}</p>
      <FlashcardReview roadmap={roadmap} onChange={onChange} />
      <ProgressiveQuiz roadmap={roadmap} onChange={onChange} onQuizSubmitted={onQuizSubmitted} />
    </section>
  );
}

function FlashcardReview({
  roadmap,
  onChange,
}: {
  roadmap: LearnAnythingRoadmap;
  onChange: (next: LearnAnythingRoadmap) => void;
}) {
  const due = useMemo(() => dueFlashcards(roadmap), [roadmap]);
  const [reviewing, setReviewing] = useState(false);
  const [flipped, setFlipped] = useState(false);

  const card = due[0];
  const retired = roadmap.flashcards.filter((c) => roadmap.srState?.[c.front]?.retired).length;

  function handleMark(remembered: boolean) {
    if (!card) return;
    setFlipped(false);
    onChange(reviewFlashcard(roadmap, card.front, remembered));
  }

  return (
    <div className="mt-8">
      <div className="flex flex-wrap items-baseline justify-between gap-3">
        <p className="text-[11px] font-semibold uppercase tracking-wide text-[#a0a2a8]">Flashcards</p>
        <p className="font-mono text-xs text-[#7a7c84]">
          {due.length} due · {retired} retired
        </p>
      </div>

      {!reviewing ? (
        <div className="mt-3 flex flex-wrap items-center justify-between gap-4 rounded-2xl border border-[#e5e5e1] p-5">
          <p className="text-sm font-light leading-relaxed text-[#62635e]">
            {due.length > 0
              ? `${due.length} card${due.length === 1 ? "" : "s"} due for review. Remembered cards come back in 1, 3, then 7 days.`
              : "All caught up — nothing due right now. Cards return on their schedule."}
          </p>
          {due.length > 0 ? (
            <button
              type="button"
              onClick={() => setReviewing(true)}
              className="inline-flex h-10 items-center rounded-lg bg-white px-5 text-sm font-bold text-black transition hover:bg-[#303136]"
            >
              Review now
            </button>
          ) : null}
        </div>
      ) : card ? (
        <div className="mt-3 rounded-2xl border border-[#e5e5e1] bg-white p-6 shadow-[0_1px_2px_rgba(15,17,23,0.03)]">
          <p className="font-mono text-[11px] text-[#a0a2a8]">
            Card · {due.length} left
          </p>
          <p className="mt-4 text-lg font-semibold leading-snug text-[#17181b]">{card.front}</p>
          {flipped ? (
            <>
              <p className="mt-4 border-t border-[#e5e5e1] pt-4 text-sm font-light leading-relaxed text-[#45474d]">
                {card.back}
              </p>
              <div className="mt-6 flex flex-wrap items-center gap-3">
                <button
                  type="button"
                  onClick={() => handleMark(true)}
                  className="inline-flex h-10 items-center rounded-lg bg-white px-5 font-mono text-sm font-bold text-black transition hover:bg-[#303136]"
                >
                  Knew it
                </button>
                <button
                  type="button"
                  onClick={() => handleMark(false)}
                  className="inline-flex h-10 items-center rounded-lg border border-[#deded9] px-5 font-mono text-sm font-semibold text-[#45474d] transition hover:border-white/40 hover:text-[#17181b]"
                >
                  Again
                </button>
              </div>
            </>
          ) : (
            <button
              type="button"
              onClick={() => setFlipped(true)}
              className="mt-6 inline-flex h-10 items-center rounded-lg border border-[#deded9] px-5 text-sm font-semibold text-[#45474d] transition hover:border-white/40 hover:text-[#17181b]"
            >
              Show answer
            </button>
          )}
        </div>
      ) : (
        <div className="mt-3 rounded-2xl border border-[#e5e5e1] p-5">
          <p className="text-sm font-light text-[#62635e]">
            Session done — everything due is reviewed. Come back tomorrow.
          </p>
          <button
            type="button"
            onClick={() => setReviewing(false)}
            className="mt-3 text-sm font-semibold text-[#7a7c84] transition hover:text-[#17181b]"
          >
            Close
          </button>
        </div>
      )}
    </div>
  );
}

function ProgressiveQuiz({
  roadmap,
  onChange,
  onQuizSubmitted,
}: {
  roadmap: LearnAnythingRoadmap;
  onChange: (next: LearnAnythingRoadmap) => void;
  onQuizSubmitted?: (result: RoadmapQuizResult) => void;
}) {
  const questions = roadmap.quiz;
  const [state, setState] = useState<"idle" | "running" | "done">("idle");
  const [index, setIndex] = useState(0);
  const [revealed, setRevealed] = useState(false);
  const [gotIt, setGotIt] = useState<boolean[]>([]);

  const last = roadmap.quizResult;

  function start() {
    setState("running");
    setIndex(0);
    setRevealed(false);
    setGotIt([]);
  }

  function mark(correct: boolean) {
    const marks = [...gotIt, correct];
    if (index + 1 < questions.length) {
      setGotIt(marks);
      setIndex(index + 1);
      setRevealed(false);
      return;
    }
    const missed: string[] = [];
    questions.forEach((q, i) => {
      if (!marks[i]) missed.push(q.question);
    });
    const next = recordRoadmapQuizResult(roadmap, {
      correct: marks.filter(Boolean).length,
      total: questions.length,
      missedQuestions: missed,
    });
    onChange(next);
    if (next.quizResult) onQuizSubmitted?.(next.quizResult);
    setGotIt(marks);
    setState("done");
  }

  const question = questions[index];
  const correctCount = gotIt.filter(Boolean).length;
  const missed: string[] = [];
  questions.forEach((q, i) => {
    if (!gotIt[i]) missed.push(q.question);
  });

  return (
    <div className="mt-8">
      <div className="flex flex-wrap items-baseline justify-between gap-3">
        <p className="text-[11px] font-semibold uppercase tracking-wide text-[#a0a2a8]">Quiz</p>
        {last ? (
          <p className="font-mono text-xs text-[#7a7c84]">
            last run {last.correct}/{last.total}
          </p>
        ) : null}
      </div>

      {state === "idle" ? (
        <div className="mt-3 flex flex-wrap items-center justify-between gap-4 rounded-2xl border border-[#e5e5e1] p-5">
          <p className="text-sm font-light leading-relaxed text-[#62635e]">
            {questions.length} questions. See each answer only after committing, then mark yourself honestly.
          </p>
          <button
            type="button"
            onClick={start}
            className="inline-flex h-10 items-center rounded-lg bg-white px-5 text-sm font-bold text-black transition hover:bg-[#303136]"
          >
            {last ? "Retake quiz" : "Start quiz"}
          </button>
        </div>
      ) : null}

      {state === "running" && question ? (
        <div className="mt-3 rounded-2xl border border-[#e5e5e1] bg-white p-6 shadow-[0_1px_2px_rgba(15,17,23,0.03)]">
          <p className="font-mono text-[11px] text-[#a0a2a8]">
            Q {String(index + 1).padStart(2, "0")} / {String(questions.length).padStart(2, "0")}
          </p>
          <p className="mt-4 text-lg font-semibold leading-snug text-[#17181b]">{question.question}</p>
          {revealed ? (
            <>
              <p className="mt-4 border-t border-[#e5e5e1] pt-4 text-sm font-light leading-relaxed text-[#45474d]">
                {question.answer}
              </p>
              <p className="mt-5 text-[11px] font-semibold uppercase tracking-[0.18em] text-[#92949a]">Did you have it?</p>
              <div className="mt-2 flex flex-wrap items-center gap-3">
                <button
                  type="button"
                  onClick={() => mark(true)}
                  className="inline-flex h-10 items-center rounded-lg bg-white px-5 font-mono text-sm font-bold text-black transition hover:bg-[#303136]"
                >
                  Got it
                </button>
                <button
                  type="button"
                  onClick={() => mark(false)}
                  className="inline-flex h-10 items-center rounded-lg border border-[#deded9] px-5 font-mono text-sm font-semibold text-[#45474d] transition hover:border-white/40 hover:text-[#17181b]"
                >
                  Missed it
                </button>
              </div>
            </>
          ) : (
            <button
              type="button"
              onClick={() => setRevealed(true)}
              className="mt-6 inline-flex h-10 items-center rounded-lg border border-[#deded9] px-5 text-sm font-semibold text-[#45474d] transition hover:border-white/40 hover:text-[#17181b]"
            >
              Show answer
            </button>
          )}
        </div>
      ) : null}

      {state === "done" ? (
        <div className="mt-3 rounded-2xl border border-[#e5e5e1] p-6">
          <p className="font-mono text-2xl font-semibold text-[#17181b]">
            {correctCount}/{questions.length}
          </p>
          <p className="mt-1 text-sm font-light text-[#6a6b72]">
            {missed.length === 0 ? "Clean run — everything held." : "Missed questions to close out:"}
          </p>
          {missed.length > 0 ? (
            <>
              <ul className="mt-3">
                {missed.map((q) => (
                  <li key={q} className="border-b border-[#efefec] py-2 text-sm text-[#45474d]">
                    {q}
                  </li>
                ))}
              </ul>
              <Link
                href={buildStudyIntentUrl({
                  intent: "generate_quiz",
                  prompt: `I missed these questions on ${roadmap.topic}: ${missed.join(" | ")}. Reteach the ideas briefly, then quiz me again on them.`,
                  run: true,
                })}
                className="mt-4 inline-block text-xs font-semibold text-[#17181b]/65 underline decoration-white/25 underline-offset-4 transition hover:text-[#17181b]"
              >
                Practice the missed ones in Study Chat
              </Link>
            </>
          ) : null}
          <div className="mt-4">
            <button
              type="button"
              onClick={start}
              className="text-sm font-semibold text-[#7a7c84] transition hover:text-[#17181b]"
            >
              Retake
            </button>
          </div>
        </div>
      ) : null}
    </div>
  );
}