"use client";

import { useEffect, useState } from "react";
import { useRouter } from "next/navigation";
import { Question, QuizAnswer, QuizAttempt } from "@/types/quiz";

interface ResultItem {
  question: Question;
  selectedAnswers: string[];
  correct: boolean;
}

export default function UserResultsPage() {
  const router = useRouter();
  const [results, setResults] = useState<ResultItem[]>([]);
  const [attempt, setAttempt] = useState<QuizAttempt | null>(null);
  const [pastAttempts, setPastAttempts] = useState<QuizAttempt[]>([]);
  const [loading, setLoading] = useState(true);
  const [userName, setUserName] = useState("");

  useEffect(() => {
    const attemptStr = sessionStorage.getItem("userAttempt");
    const answersStr = sessionStorage.getItem("userQuizAnswers");
    const questionsStr = sessionStorage.getItem("userQuizQuestions");
    const userStr = sessionStorage.getItem("quizUser");

    if (!attemptStr || !answersStr || !questionsStr) {
      router.push("/");
      return;
    }

    const att: QuizAttempt = JSON.parse(attemptStr);
    const answers: QuizAnswer[] = JSON.parse(answersStr);
    const questions: Question[] = JSON.parse(questionsStr);

    setAttempt(att);

    if (userStr) {
      const user = JSON.parse(userStr);
      setUserName(user.name);

      // Fetch past attempts
      fetch(`/api/user/attempts?userId=${user.id}`)
        .then((r) => r.json())
        .then((data) => setPastAttempts(data))
        .catch(() => {});
    }

    const items: ResultItem[] = questions.map((q) => {
      const answer = answers.find((a) => a.questionId === q.id);
      const selected = answer?.selectedAnswers || [];

      let correct: boolean;
      if (q.type === "multiple-dropdown") {
        correct = (q.subQuestions || []).every((sq) => {
          const entry = selected.find((a) => a.startsWith(sq.id + ":"));
          return entry ? entry.split(":")[1] === sq.correctOptionId : false;
        });
      } else {
        correct =
          selected.length === q.correctAnswers.length &&
          selected.every((s) => q.correctAnswers.includes(s));
      }

      return { question: q, selectedAnswers: selected, correct };
    });

    setResults(items);
    setLoading(false);
  }, [router]);

  if (loading || !attempt) {
    return (
      <div className="min-h-screen bg-gray-50 flex items-center justify-center">
        <p className="text-gray-500">Loading results...</p>
      </div>
    );
  }

  function formatDuration(startedAt: string, completedAt: string | null) {
    if (!completedAt) return null;
    const ms = new Date(completedAt).getTime() - new Date(startedAt).getTime();
    const totalSeconds = Math.floor(ms / 1000);
    const hours = Math.floor(totalSeconds / 3600);
    const minutes = Math.floor((totalSeconds % 3600) / 60);
    const seconds = totalSeconds % 60;
    if (hours > 0) return `${hours}h ${minutes}m ${seconds}s`;
    if (minutes > 0) return `${minutes}m ${seconds}s`;
    return `${seconds}s`;
  }

  const correctCount = results.filter((r) => r.correct).length;
  const percentage = results.length > 0 ? Math.round((correctCount / results.length) * 100) : 0;

  // Past attempts excluding the current one
  const otherAttempts = pastAttempts.filter((a) => a.id !== attempt.id);

  return (
    <div className="min-h-screen bg-gray-50">
      <header className="border-b bg-white px-6 py-4">
        <div className="max-w-3xl mx-auto flex items-center justify-between">
          <h1 className="text-xl font-bold text-gray-900">Quiz Results</h1>
          <span className="text-sm text-gray-500">{userName}</span>
        </div>
      </header>

      <main className="max-w-3xl mx-auto p-6 space-y-6">
        {/* Score */}
        <div className="bg-white rounded-xl p-8 text-center shadow-sm">
          <div
            className={`text-6xl font-bold mb-2 ${
              percentage >= 70
                ? "text-green-600"
                : percentage >= 50
                ? "text-yellow-600"
                : "text-red-600"
            }`}
          >
            {percentage}%
          </div>
          <p className="text-gray-600">
            You got {correctCount} out of {results.length} questions correct
          </p>
          <p className="text-sm text-gray-400 mt-1">
            Mode: {attempt.quizMode === "learning" ? "Learning" : "Testing"}
            {attempt.completedAt && (
              <> &middot; Time: {formatDuration(attempt.startedAt, attempt.completedAt)}</>
            )}
          </p>
        </div>

        {/* Review */}
        <div className="space-y-4">
          <h2 className="text-lg font-semibold text-gray-900">Review</h2>
          {results.map((item, i) => (
            <div
              key={item.question.id}
              className={`p-4 rounded-lg border ${
                item.correct
                  ? "bg-green-50 border-green-200"
                  : "bg-red-50 border-red-200"
              }`}
            >
              <div className="flex items-start gap-3">
                <span
                  className={`mt-0.5 text-lg ${
                    item.correct ? "text-green-600" : "text-red-600"
                  }`}
                >
                  {item.correct ? "✓" : "✗"}
                </span>
                <div className="flex-1">
                  <p className="font-medium text-gray-900">
                    {i + 1}. {item.question.text}
                  </p>
                  <div className="mt-2 space-y-1">
                    {item.question.type === "multiple-dropdown" ? (
                      (item.question.subQuestions || []).map((sq) => {
                        const entry = item.selectedAnswers.find((a) =>
                          a.startsWith(sq.id + ":")
                        );
                        const selectedOptId = entry ? entry.split(":")[1] : "";
                        const selectedOpt = (sq.options || []).find(
                          (o) => o.id === selectedOptId
                        );
                        const correctOpt = (sq.options || []).find(
                          (o) => o.id === sq.correctOptionId
                        );
                        const isCorrect = selectedOptId === sq.correctOptionId;

                        return (
                          <div
                            key={sq.id}
                            className="text-sm flex items-start gap-2"
                          >
                            {isCorrect ? (
                              <span className="text-green-600">✓</span>
                            ) : (
                              <span className="text-red-600">✗</span>
                            )}
                            <div>
                              <span className="text-gray-700">{sq.text}</span>
                              <span
                                className={`ml-2 ${
                                  isCorrect
                                    ? "text-green-700 font-medium"
                                    : "text-red-600"
                                }`}
                              >
                                → {selectedOpt?.label || "(no answer)"}
                              </span>
                              {!isCorrect && correctOpt && (
                                <span className="ml-2 text-green-700 font-medium">
                                  (correct: {correctOpt.label})
                                </span>
                              )}
                            </div>
                          </div>
                        );
                      })
                    ) : (
                      item.question.options.map((opt) => {
                        const isCorrect =
                          item.question.correctAnswers.includes(opt.id);
                        const wasSelected =
                          item.selectedAnswers.includes(opt.id);

                        return (
                          <div
                            key={opt.id}
                            className={`text-sm flex items-center gap-2 ${
                              isCorrect
                                ? "text-green-700 font-medium"
                                : wasSelected
                                ? "text-red-600 line-through"
                                : "text-gray-500"
                            }`}
                          >
                            {isCorrect && <span>✓</span>}
                            {wasSelected && !isCorrect && <span>✗</span>}
                            {!isCorrect && !wasSelected && (
                              <span className="w-3" />
                            )}
                            <span>{opt.label}</span>
                          </div>
                        );
                      })
                    )}
                  </div>
                </div>
              </div>
            </div>
          ))}
        </div>

        {/* Past Attempts */}
        {otherAttempts.length > 0 && (
          <div className="space-y-3">
            <h2 className="text-lg font-semibold text-gray-900">
              Past Attempts
            </h2>
            {otherAttempts.map((a) => (
              <div
                key={a.id}
                className="bg-white rounded-lg border border-gray-200 p-4 flex items-center justify-between"
              >
                <div>
                  <div className="flex items-center gap-2">
                    <span
                      className={`text-xs px-2 py-0.5 rounded-full font-medium ${
                        a.status === "completed"
                          ? "bg-green-100 text-green-700"
                          : "bg-yellow-100 text-yellow-700"
                      }`}
                    >
                      {a.status === "completed" ? "Completed" : "In Progress"}
                    </span>
                    <span className="text-sm text-gray-500">
                      {a.quizMode === "learning" ? "Learning" : "Testing"}
                    </span>
                  </div>
                  <p className="text-sm text-gray-600 mt-1">
                    {new Date(a.startedAt).toLocaleDateString()} &middot;{" "}
                    {a.status === "completed"
                      ? `${a.score}% (${a.correctCount}/${a.totalQuestions})`
                      : `${a.answeredCount}/${a.totalQuestions} answered`}
                    {a.status === "completed" && a.completedAt
                      ? ` · ${formatDuration(a.startedAt, a.completedAt)}`
                      : ` · Started ${new Date(a.startedAt).toLocaleString()}`}
                  </p>
                </div>
              </div>
            ))}
          </div>
        )}

        {/* Actions */}
        <div className="flex gap-3">
          <button
            onClick={() => router.push("/user/setup")}
            className="flex-1 py-3 bg-[#2b579a] text-white rounded-lg hover:bg-[#1e3f70] font-medium"
          >
            Take Another Quiz
          </button>
          <button
            onClick={() => {
              sessionStorage.removeItem("userAttempt");
              sessionStorage.removeItem("userQuizAnswers");
              sessionStorage.removeItem("userQuizQuestions");
              router.push("/");
            }}
            className="flex-1 py-3 bg-gray-200 text-gray-700 rounded-lg hover:bg-gray-300 font-medium"
          >
            Change User
          </button>
        </div>
      </main>
    </div>
  );
}