/**
 * 学习进度、继续学习、收藏、笔记 - localStorage（来自 nomadlms）
 */

const PREFIX = "lms-";
const KEY_LAST = `${PREFIX}last`;
const KEY_COMPLETED = `${PREFIX}completed`;
const KEY_BOOKMARKS = `${PREFIX}bookmarks`;
const KEY_NOTES = `${PREFIX}notes`;
const KEY_RATING = `${PREFIX}rating`;

export type LastWatched = { moduleIndex: number; lessonIndex: number; name: string };

export function getLastWatched(): LastWatched | null {
  if (typeof window === "undefined") return null;
  try {
    const raw = localStorage.getItem(KEY_LAST);
    if (!raw) return null;
    const d = JSON.parse(raw);
    if (typeof d?.moduleIndex !== "number" || typeof d?.lessonIndex !== "number") return null;
    return { moduleIndex: d.moduleIndex, lessonIndex: d.lessonIndex, name: d.name || "" };
  } catch {
    return null;
  }
}

export function setLastWatched(m: number, l: number, name: string): void {
  if (typeof window === "undefined") return;
  try {
    localStorage.setItem(KEY_LAST, JSON.stringify({ moduleIndex: m, lessonIndex: l, name }));
  } catch {
    /* ignore */
  }
}

export function getCompletedLessons(): Set<string> {
  if (typeof window === "undefined") return new Set();
  try {
    const raw = localStorage.getItem(KEY_COMPLETED);
    if (!raw) return new Set();
    const arr = JSON.parse(raw);
    return new Set(Array.isArray(arr) ? arr : []);
  } catch {
    return new Set();
  }
}

export function markCompleted(moduleIndex: number, lessonIndex: number): void {
  if (typeof window === "undefined") return;
  try {
    const set = getCompletedLessons();
    set.add(`${moduleIndex}-${lessonIndex}`);
    localStorage.setItem(KEY_COMPLETED, JSON.stringify([...set]));
    window.dispatchEvent(new CustomEvent("learning:progress"));
  } catch {
    /* ignore */
  }
}

export function getProgress(totalLessons: number): { completed: number; percent: number } {
  const set = getCompletedLessons();
  const completed = set.size;
  return { completed, percent: totalLessons > 0 ? Math.round((completed / totalLessons) * 100) : 0 };
}

export function getBookmarks(): Set<string> {
  if (typeof window === "undefined") return new Set();
  try {
    const raw = localStorage.getItem(KEY_BOOKMARKS);
    if (!raw) return new Set();
    const arr = JSON.parse(raw);
    return new Set(Array.isArray(arr) ? arr : []);
  } catch {
    return new Set();
  }
}

export function toggleBookmark(moduleIndex: number, lessonIndex: number): boolean {
  if (typeof window === "undefined") return false;
  try {
    const set = getBookmarks();
    const key = `${moduleIndex}-${lessonIndex}`;
    if (set.has(key)) set.delete(key);
    else set.add(key);
    localStorage.setItem(KEY_BOOKMARKS, JSON.stringify([...set]));
    window.dispatchEvent(new CustomEvent("learning:bookmarks"));
    return set.has(key);
  } catch {
    return false;
  }
}

export function isBookmarked(moduleIndex: number, lessonIndex: number): boolean {
  return getBookmarks().has(`${moduleIndex}-${lessonIndex}`);
}

export function getNote(moduleIndex: number, lessonIndex: number): string {
  if (typeof window === "undefined") return "";
  try {
    const raw = localStorage.getItem(KEY_NOTES);
    if (!raw) return "";
    const map = JSON.parse(raw);
    return map[`${moduleIndex}-${lessonIndex}`] ?? "";
  } catch {
    return "";
  }
}

export function setNote(moduleIndex: number, lessonIndex: number, text: string): void {
  if (typeof window === "undefined") return;
  try {
    const raw = localStorage.getItem(KEY_NOTES);
    const map = raw ? JSON.parse(raw) : {};
    map[`${moduleIndex}-${lessonIndex}`] = text;
    localStorage.setItem(KEY_NOTES, JSON.stringify(map));
  } catch {
    /* ignore */
  }
}

export function getRating(): { stars: number; comment: string } | null {
  if (typeof window === "undefined") return null;
  try {
    const raw = localStorage.getItem(KEY_RATING);
    if (!raw) return null;
    const d = JSON.parse(raw);
    return { stars: d?.stars ?? 0, comment: d?.comment ?? "" };
  } catch {
    return null;
  }
}

export function setRating(stars: number, comment: string): void {
  if (typeof window === "undefined") return;
  try {
    localStorage.setItem(KEY_RATING, JSON.stringify({ stars, comment }));
    window.dispatchEvent(new CustomEvent("learning:rating"));
  } catch {
    /* ignore */
  }
}