(() => {
  "use strict";

  const STORAGE_KEY = "links_home_v1";
  const THEME_KEY = "links_home_theme_v1";

  const el = {
    subtitle: document.getElementById("subtitle"),
    q: document.getElementById("q"),
    sort: document.getElementById("sort"),
    onlyFav: document.getElementById("onlyFav"),
    meta: document.getElementById("meta"),
    grid: document.getElementById("grid"),
    empty: document.getElementById("empty"),
    btnAdd: document.getElementById("btnAdd"),
    btnImport: document.getElementById("btnImport"),
    btnExport: document.getElementById("btnExport"),
    btnTheme: document.getElementById("btnTheme"),
    modal: document.getElementById("modal"),
    btnClose: document.getElementById("btnClose"),
    btnCancel: document.getElementById("btnCancel"),
    form: document.getElementById("form"),
    id: document.getElementById("id"),
    title: document.getElementById("title"),
    url: document.getElementById("url"),
    description: document.getElementById("description"),
    tags: document.getElementById("tags"),
    favorite: document.getElementById("favorite"),
    file: document.getElementById("file"),
    toast: document.getElementById("toast"),
  };

  // NOTE:
  // 예전에는 links.json을 못 읽는 환경(file:// 등)에서 "내장 기본 목록"으로 조용히 대체했는데,
  // 그러면 links.json의 순서/내용 변경이 반영되지 않아 혼란이 생깁니다.
  // 이제는 links.json 로드를 우선하며, 실패 시 경고를 띄우고 빈 목록(또는 localStorage 커스텀)으로 동작합니다.
  const DEFAULT_LINKS_INLINE = [];

  const state = {
    baseLinks: [],
    baseOrder: new Map(),
    store: loadStore(),
    query: "",
    sortKey: "json",
    onlyFav: false,
  };

  function nowIso() {
    return new Date().toISOString();
  }

  function safeJsonParse(s, fallback) {
    try {
      return JSON.parse(s);
    } catch {
      return fallback;
    }
  }

  function loadStore() {
    const raw = localStorage.getItem(STORAGE_KEY);
    const data = raw ? safeJsonParse(raw, null) : null;
    const store = {
      overridesById: {},
      tombstones: [],
      custom: [],
    };
    if (!data || typeof data !== "object") return store;
    if (data.overridesById && typeof data.overridesById === "object") store.overridesById = data.overridesById;
    if (Array.isArray(data.tombstones)) store.tombstones = data.tombstones;
    if (Array.isArray(data.custom)) store.custom = data.custom;
    return store;
  }

  function saveStore() {
    localStorage.setItem(STORAGE_KEY, JSON.stringify(state.store));
  }

  function normalizeUrl(url) {
    const u = String(url || "").trim();
    if (!u) return "";
    if (/^https?:\/\//i.test(u)) return u;
    return "https://" + u;
  }

  function normalizeTags(tagsText) {
    if (!tagsText) return [];
    return String(tagsText)
      .split(",")
      .map((t) => t.trim())
      .filter(Boolean)
      .slice(0, 12);
  }

  function getDomain(url) {
    try {
      return new URL(url).host;
    } catch {
      return url.replace(/^https?:\/\//i, "").split("/")[0] || "";
    }
  }

  function faviconUrl(url) {
    const domainUrl = encodeURIComponent(url);
    return `https://www.google.com/s2/favicons?domain_url=${domainUrl}&sz=64`;
  }

  function escapeHtml(s) {
    return String(s)
      .replaceAll("&", "&")
      .replaceAll("<", "&lt;")
      .replaceAll(">", "&gt;")
      .replaceAll('"', "&quot;")
      .replaceAll("'", "&#039;");
  }

  function idFromUrl(url) {
    const d = getDomain(url).toLowerCase();
    const cleaned = d.replace(/[^a-z0-9]+/g, "-").replace(/^-+|-+$/g, "");
    return cleaned || "link";
  }

  function newId(prefix = "custom") {
    if (globalThis.crypto && crypto.randomUUID) return `${prefix}-${crypto.randomUUID()}`;
    return `${prefix}-${Date.now()}-${Math.random().toString(16).slice(2)}`;
  }

  function normalizeLink(link) {
    const url = normalizeUrl(link.url);
    const id = String(link.id || "").trim() || idFromUrl(url) || newId("link");
    const title = String(link.title || "").trim() || getDomain(url) || "Link";
    const description = String(link.description || "").trim();
    const tags = Array.isArray(link.tags) ? link.tags.map((t) => String(t).trim()).filter(Boolean) : [];
    const favorite = Boolean(link.favorite);
    const createdAt = String(link.createdAt || nowIso());
    const updatedAt = String(link.updatedAt || createdAt);
    return { id, title, url, description, tags, favorite, createdAt, updatedAt };
  }

  function getMergedLinks() {
    const tomb = new Set(state.store.tombstones || []);
    const overrides = state.store.overridesById || {};

    const byId = new Map();
    for (const base of state.baseLinks) {
      if (!base || !base.id) continue;
      if (tomb.has(base.id)) continue;
      const o = overrides[base.id];
      byId.set(base.id, { ...base, ...(o || {}) });
    }
    for (const c of state.store.custom || []) {
      const n = normalizeLink(c);
      byId.set(n.id, n);
    }
    return [...byId.values()];
  }

  function matchesQuery(link, q) {
    if (!q) return true;
    const hay = [
      link.title,
      link.url,
      getDomain(link.url),
      link.description || "",
      (link.tags || []).join(" "),
    ]
      .join(" ")
      .toLowerCase();
    return hay.includes(q);
  }

  function toTime(s) {
    const t = Date.parse(String(s || ""));
    return Number.isFinite(t) ? t : 0;
  }

  function orderKey(link) {
    const idx = state.baseOrder.get(link.id);
    if (typeof idx === "number") return idx;
    // custom/imported links go after base list, in creation order
    return 1_000_000 + toTime(link.createdAt);
  }

  function compareLinks(a, b) {
    const key = state.sortKey;
    if (key === "json") {
      const oa = orderKey(a);
      const ob = orderKey(b);
      if (oa !== ob) return oa - ob;
      return a.title.localeCompare(b.title, "ko");
    }
    if (key === "favorite") {
      if (a.favorite !== b.favorite) return a.favorite ? -1 : 1;
      // tie-breaker: keep json order
      const oa = orderKey(a);
      const ob = orderKey(b);
      if (oa !== ob) return oa - ob;
    }
    if (key === "name") return a.title.localeCompare(b.title, "ko");
    if (key === "domain") return getDomain(a.url).localeCompare(getDomain(b.url), "en");
    // recent (default)
    return String(b.updatedAt).localeCompare(String(a.updatedAt));
  }

  function render() {
    const q = state.query.trim().toLowerCase();
    const all = getMergedLinks();
    const filtered = all
      .filter((l) => (state.onlyFav ? l.favorite : true))
      .filter((l) => matchesQuery(l, q))
      .sort(compareLinks);

    el.grid.innerHTML = filtered.map(cardHtml).join("");
    el.empty.hidden = filtered.length !== 0;

    const favCount = all.filter((l) => l.favorite).length;
    el.meta.textContent = `표시 ${filtered.length}개 · 전체 ${all.length}개 · 즐겨찾기 ${favCount}개`;
    el.subtitle.textContent = all.length ? `링크 ${all.length}개` : "개인 링크 관리";
  }

  function cardHtml(link) {
    const domain = escapeHtml(getDomain(link.url));
    const title = escapeHtml(link.title);
    const desc = escapeHtml(link.description || "");
    const url = escapeHtml(link.url);
    const starClass = link.favorite ? "star on" : "star";
    const tags = (link.tags || []).slice(0, 8);
    const tagHtml = [
      link.favorite ? `<span class="tag fav">★ 즐겨찾기</span>` : "",
      ...tags.map((t) => `<span class="tag">#${escapeHtml(t)}</span>`),
    ]
      .filter(Boolean)
      .join("");

    const letter = escapeHtml((link.title || domain || "L").trim().slice(0, 1).toUpperCase());

    return `
      <article class="card" data-id="${escapeHtml(link.id)}">
        <div class="card-head">
          <div class="card-title">
            <div class="favicon" aria-hidden="true">
              <img src="${faviconUrl(link.url)}" alt="" onerror="this.remove(); this.parentNode.insertAdjacentHTML('beforeend','<div class=&quot;letter&quot;>${letter}</div>');" />
            </div>
            <div class="title-wrap">
              <div class="title" title="${title}">${title}</div>
              <div class="domain" title="${domain}">${domain}</div>
            </div>
          </div>
          <button class="icon-btn" type="button" data-act="fav" title="즐겨찾기">
            <span class="${starClass}" aria-hidden="true">★</span>
          </button>
        </div>

        <div class="card-desc">${desc || "&nbsp;"}</div>
        <div class="tags">${tagHtml || ""}</div>

        <div class="card-actions">
          <a class="btn mini" href="${url}" target="_blank" rel="noopener noreferrer" data-act="open">열기</a>
          <button class="btn mini" type="button" data-act="copy">URL 복사</button>
          <button class="btn mini" type="button" data-act="edit">편집</button>
          <button class="btn mini mini-danger" type="button" data-act="del">삭제</button>
        </div>
      </article>
    `;
  }

  function openModal(mode, link) {
    el.modal.hidden = false;
    document.body.style.overflow = "hidden";
    const isEdit = mode === "edit";

    document.getElementById("modalTitle").textContent = isEdit ? "링크 편집" : "링크 추가";
    el.id.value = isEdit ? link.id : "";
    el.title.value = isEdit ? link.title : "";
    el.url.value = isEdit ? link.url : "";
    el.description.value = isEdit ? link.description || "" : "";
    el.tags.value = isEdit ? (link.tags || []).join(", ") : "";
    el.favorite.checked = isEdit ? Boolean(link.favorite) : false;

    setTimeout(() => el.title.focus(), 0);
  }

  function closeModal() {
    el.modal.hidden = true;
    document.body.style.overflow = "";
    el.form.reset();
    el.id.value = "";
  }

  function getLinkById(id) {
    return getMergedLinks().find((l) => l.id === id) || null;
  }

  function isBaseId(id) {
    return state.baseLinks.some((l) => l.id === id);
  }

  function setOverride(id, patch) {
    state.store.overridesById[id] = { ...(state.store.overridesById[id] || {}), ...patch };
    saveStore();
  }

  function removeOverride(id) {
    if (state.store.overridesById && state.store.overridesById[id]) {
      delete state.store.overridesById[id];
    }
    saveStore();
  }

  function toast(msg) {
    el.toast.textContent = msg;
    el.toast.hidden = false;
    clearTimeout(toast._t);
    toast._t = setTimeout(() => {
      el.toast.hidden = true;
    }, 2400);
  }

  async function copyText(text) {
    try {
      await navigator.clipboard.writeText(text);
      toast("복사했습니다.");
    } catch {
      // fallback
      const ta = document.createElement("textarea");
      ta.value = text;
      ta.setAttribute("readonly", "readonly");
      ta.style.position = "fixed";
      ta.style.left = "-9999px";
      document.body.appendChild(ta);
      ta.select();
      document.execCommand("copy");
      ta.remove();
      toast("복사했습니다.");
    }
  }

  function upsertCustom(link) {
    const n = normalizeLink(link);
    const idx = state.store.custom.findIndex((c) => c && c.id === n.id);
    if (idx >= 0) state.store.custom[idx] = n;
    else state.store.custom.push(n);
    saveStore();
  }

  function deleteLink(id) {
    if (isBaseId(id)) {
      const s = new Set(state.store.tombstones || []);
      s.add(id);
      state.store.tombstones = [...s];
      removeOverride(id);
      saveStore();
      toast("기본 링크를 숨겼습니다.");
      return;
    }
    const before = state.store.custom.length;
    state.store.custom = (state.store.custom || []).filter((c) => c && c.id !== id);
    saveStore();
    if (state.store.custom.length !== before) toast("삭제했습니다.");
  }

  function toggleFavorite(id) {
    const link = getLinkById(id);
    if (!link) return;
    const next = !link.favorite;
    if (isBaseId(id)) {
      setOverride(id, { favorite: next, updatedAt: nowIso() });
    } else {
      upsertCustom({ ...link, favorite: next, updatedAt: nowIso() });
    }
    render();
  }

  function editLink(id) {
    const link = getLinkById(id);
    if (!link) return;
    openModal("edit", link);
  }

  async function loadBaseLinks() {
    // 1) index.html 내부 내장 데이터(서버 없이도 동작)
    const dataEl = document.getElementById("linksData");
    if (dataEl && dataEl.textContent) {
      const parsed = safeJsonParse(dataEl.textContent, null);
      if (Array.isArray(parsed)) return parsed.map(normalizeLink);
    }

    // 2) 동일 디렉토리의 links.json (서버 환경에서 권장)
    const candidates = [
      new URL("./links.json", document.baseURI).toString(),
      new URL("links.json", document.baseURI).toString(),
    ];

    for (const url of candidates) {
      try {
        const res = await fetch(url, { cache: "no-store" });
        if (!res.ok) continue;
        const data = await res.json();
        if (!Array.isArray(data)) continue;
        return data.map(normalizeLink);
      } catch {
        // try next
      }
    }

    const hint =
      location.protocol === "file:"
        ? "기본 링크 데이터가 없습니다. index.html의 linksData를 확인하세요."
        : "links.json을 불러오지 못했습니다. 배포 경로에 links.json이 있는지 확인하세요.";
    toast(hint);
    return DEFAULT_LINKS_INLINE.map(normalizeLink);
  }

  function applyTheme(theme) {
    const t = theme === "light" ? "light" : "dark";
    document.documentElement.setAttribute("data-theme", t);
    el.btnTheme.setAttribute("aria-pressed", t === "dark" ? "true" : "false");
    localStorage.setItem(THEME_KEY, t);
  }

  function initTheme() {
    const saved = localStorage.getItem(THEME_KEY);
    if (saved === "light" || saved === "dark") return applyTheme(saved);
    const prefersLight = window.matchMedia && window.matchMedia("(prefers-color-scheme: light)").matches;
    applyTheme(prefersLight ? "light" : "dark");
  }

  function exportJson() {
    const data = getMergedLinks().sort((a, b) => a.title.localeCompare(b.title, "ko"));
    const blob = new Blob([JSON.stringify(data, null, 2)], { type: "application/json;charset=utf-8" });
    const a = document.createElement("a");
    a.href = URL.createObjectURL(blob);
    a.download = `links-export-${new Date().toISOString().slice(0, 10)}.json`;
    document.body.appendChild(a);
    a.click();
    setTimeout(() => {
      URL.revokeObjectURL(a.href);
      a.remove();
    }, 0);
    toast("내보내기 파일을 생성했습니다.");
  }

  function importJsonText(text) {
    const parsed = safeJsonParse(text, null);
    if (!parsed) throw new Error("JSON 파싱 실패");

    const list = Array.isArray(parsed) ? parsed : Array.isArray(parsed.links) ? parsed.links : null;
    if (!list) throw new Error("JSON 형식이 올바르지 않습니다. (배열 또는 {links:[...]} )");

    const merged = getMergedLinks();
    const used = new Set(merged.map((l) => l.id));

    let added = 0;
    for (const item of list) {
      if (!item) continue;
      const n0 = normalizeLink(item);
      let n = n0;
      if (used.has(n.id)) {
        n = { ...n, id: newId("import"), createdAt: nowIso(), updatedAt: nowIso() };
      }
      used.add(n.id);
      // 가져오기는 custom로 추가(기본과 충돌 방지)
      state.store.custom.push(n);
      added++;
    }
    saveStore();
    toast(`가져오기 완료: ${added}개`);
  }

  function onGridClick(e) {
    const btn = e.target.closest("[data-act]");
    if (!btn) return;
    const card = e.target.closest(".card");
    if (!card) return;
    const id = card.getAttribute("data-id");
    if (!id) return;

    const act = btn.getAttribute("data-act");
    if (act === "fav") {
      toggleFavorite(id);
      return;
    }
    if (act === "copy") {
      const link = getLinkById(id);
      if (link) copyText(link.url);
      return;
    }
    if (act === "edit") {
      editLink(id);
      return;
    }
    if (act === "del") {
      const link = getLinkById(id);
      const name = link ? link.title : id;
      if (confirm(`삭제할까요?\n\n- ${name}`)) {
        deleteLink(id);
        render();
      }
      return;
    }
  }

  function onFormSubmit(e) {
    e.preventDefault();
    const isEdit = Boolean(el.id.value);

    const title = String(el.title.value || "").trim();
    const url = normalizeUrl(el.url.value);
    if (!title) return toast("제목을 입력하세요.");
    if (!url) return toast("URL을 입력하세요.");

    let parsed;
    try {
      parsed = new URL(url);
    } catch {
      return toast("URL 형식이 올바르지 않습니다.");
    }
    if (!/^https?:$/.test(parsed.protocol)) return toast("http/https URL만 지원합니다.");

    const description = String(el.description.value || "").trim();
    const tags = normalizeTags(el.tags.value);
    const favorite = Boolean(el.favorite.checked);

    if (isEdit) {
      const id = el.id.value;
      const current = getLinkById(id);
      if (!current) {
        closeModal();
        toast("편집 대상이 없습니다.");
        return;
      }
      const patch = {
        title,
        url,
        description,
        tags,
        favorite,
        updatedAt: nowIso(),
      };
      if (isBaseId(id)) setOverride(id, patch);
      else upsertCustom({ ...current, ...patch });
      closeModal();
      render();
      toast("저장했습니다.");
      return;
    }

    const id = newId("custom");
    upsertCustom({
      id,
      title,
      url,
      description,
      tags,
      favorite,
      createdAt: nowIso(),
      updatedAt: nowIso(),
    });
    closeModal();
    render();
    toast("추가했습니다.");
  }

  function wire() {
    el.q.addEventListener("input", () => {
      state.query = el.q.value || "";
      render();
    });

    el.sort.addEventListener("change", () => {
      state.sortKey = el.sort.value || "json";
      render();
    });

    el.onlyFav.addEventListener("change", () => {
      state.onlyFav = Boolean(el.onlyFav.checked);
      render();
    });

    el.grid.addEventListener("click", onGridClick);

    el.btnAdd.addEventListener("click", () => openModal("add", null));
    el.btnClose.addEventListener("click", closeModal);
    el.btnCancel.addEventListener("click", closeModal);
    el.modal.addEventListener("click", (e) => {
      const close = e.target && e.target.getAttribute && e.target.getAttribute("data-close");
      if (close) closeModal();
    });
    document.addEventListener("keydown", (e) => {
      if (e.key === "Escape" && !el.modal.hidden) closeModal();
    });

    el.form.addEventListener("submit", onFormSubmit);

    el.btnExport.addEventListener("click", exportJson);
    el.btnImport.addEventListener("click", () => el.file.click());
    el.file.addEventListener("change", async () => {
      const f = el.file.files && el.file.files[0];
      el.file.value = "";
      if (!f) return;
      try {
        const text = await f.text();
        importJsonText(text);
        render();
      } catch (err) {
        toast(String(err && err.message ? err.message : "가져오기 실패"));
      }
    });

    el.btnTheme.addEventListener("click", () => {
      const cur = document.documentElement.getAttribute("data-theme") || "dark";
      applyTheme(cur === "dark" ? "light" : "dark");
    });
  }

  async function main() {
    initTheme();
    wire();
    state.baseLinks = await loadBaseLinks();
    state.baseOrder = new Map(state.baseLinks.map((l, i) => [l.id, i]));
    el.sort.value = state.sortKey;
    render();
  }

  main().catch(() => {
    toast("초기화에 실패했습니다.");
  });
})();