"use client";

import { useEffect, useState } from "react";
import Link from "next/link";
import { useI18n } from "@/lib/i18n";
import { useAuth } from "@/lib/auth";
import { api } from "@/lib/api";
import type { DigitalCourse, DigitalLesson } from "@/lib/types";
import RingNext from "@/components/RingNext";
import { useRingSteps } from "@/lib/rings";

export default function DigitalLessonClient({
  moduleIndex,
  lessonIndex,
}: {
  moduleIndex: number;
  lessonIndex: number;
}) {
  const { t } = useI18n();
  const { token } = useAuth();
  const rings = useRingSteps();
  const [lesson, setLesson] = useState<DigitalLesson | null>(null);
  const [locked, setLocked] = useState(false);
  const [missing, setMissing] = useState(false);
  const [loading, setLoading] = useState(true);
  const [hasNext, setHasNext] = useState(false);
  const [nextHref, setNextHref] = useState<string | null>(null);
  const [prevHref, setPrevHref] = useState<string | null>(null);

  useEffect(() => {
    let cancelled = false;
    setLoading(true);
    (async () => {
      try {
        const course: DigitalCourse = await api.getDigitalCourse();
        const modules = course.modules || [];
        const mod = modules[moduleIndex];
        const meta = mod?.lessons?.[lessonIndex];
        if (!meta) {
          if (!cancelled) {
            setMissing(true);
            setLocked(false);
            setLesson(null);
            setHasNext(false);
            setNextHref(null);
            setPrevHref(null);
          }
          return;
        }
        let next: string | null = null;
        if (mod.lessons[lessonIndex + 1]) {
          next = `/digital/course/${moduleIndex}/${lessonIndex + 1}`;
        } else if (modules[moduleIndex + 1]?.lessons?.length) {
          next = `/digital/course/${moduleIndex + 1}/0`;
        }
        let prev: string | null = null;
        if (lessonIndex > 0) {
          prev = `/digital/course/${moduleIndex}/${lessonIndex - 1}`;
        } else if (moduleIndex > 0) {
          const prevMod = modules[moduleIndex - 1];
          const last = (prevMod?.lessons?.length || 1) - 1;
          if (prevMod?.lessons?.length) {
            prev = `/digital/course/${moduleIndex - 1}/${last}`;
          }
        }
        if (!cancelled) {
          setHasNext(Boolean(next));
          setNextHref(next);
          setPrevHref(prev);
        }
        try {
          const data = await api.getDigitalLesson(moduleIndex, lessonIndex, token || undefined);
          if (!cancelled) {
            setLesson(data);
            setLocked(false);
            setMissing(false);
          }
        } catch {
          if (!cancelled) {
            setLesson(null);
            setLocked(!meta.free);
            setMissing(meta.free);
          }
        }
      } catch {
        if (!cancelled) {
          setMissing(true);
          setLesson(null);
        }
      } finally {
        if (!cancelled) setLoading(false);
      }
    })();
    return () => {
      cancelled = true;
    };
  }, [moduleIndex, lessonIndex, token]);

  if (loading) {
    return (
      <div className="digital-page">
        <div className="container">
          <p className="dest-empty">{t.digital.loadingLesson}</p>
        </div>
      </div>
    );
  }

  if (missing) {
    return (
      <div className="digital-page">
        <div className="container">
          <div className="digital-gate reveal">
            <h2>{t.digital.missingLesson}</h2>
            <Link href="/digital/course" className="btn btn-primary">{t.digital.backCourse}</Link>
          </div>
        </div>
      </div>
    );
  }

  if (locked || !lesson) {
    return (
      <div className="digital-page">
        <div className="container">
          <div className="digital-gate reveal">
            <h2>{t.digital.locked}</h2>
            <p>{t.digital.lockedDesc}</p>
            <div className="dating-empty-actions">
              {!token && (
                <Link href={`/login?next=/digital/course/${moduleIndex}/${lessonIndex}`} className="btn">
                  {t.nav.login}
                </Link>
              )}
              <Link href="/join" className="btn btn-primary">{t.join.payBtn}</Link>
              <Link href="/digital/course" className="btn">{t.digital.backCourse}</Link>
            </div>
          </div>
          <RingNext steps={rings.afterGigs} />
        </div>
      </div>
    );
  }

  const prev = prevHref;
  const next = hasNext ? nextHref : null;

  return (
    <div className="digital-page">
      <div className="container">
        <nav className="detail-nav">
          <Link href="/digital/course">← {t.digital.backCourse}</Link>
        </nav>
        <article className="digital-lesson reveal">
          <span className="section-tag">{lesson.duration}</span>
          <h1>{lesson.title}</h1>
          <div className="digital-lesson-body">
            {lesson.content.split("\n").filter(Boolean).map((p, i) => (
              <p key={`${i}-${p.slice(0, 16)}`}>{p}</p>
            ))}
          </div>
          <footer className="digital-lesson-nav">
            {prev && (
              <Link href={prev} className="btn">
                ← {t.digital.prev}
              </Link>
            )}
            {next ? (
              <Link href={next} className="btn btn-primary">
                {t.digital.next} →
              </Link>
            ) : (
              <div className="dating-empty-actions">
                <Link href="/digital/course" className="btn btn-primary">
                  {t.digital.backCatalog}
                </Link>
                <Link href="/gigs" className="btn">
                  {t.nav.gigs}
                </Link>
                <Link href="/meetups" className="btn btn-ghost">
                  {t.nav.meetups}
                </Link>
              </div>
            )}
          </footer>
        </article>
        <RingNext steps={next ? rings.afterGigs : rings.afterDigital} />
      </div>
    </div>
  );
}