// ──────────────────────────────────────────────────────────
// ErpAttachViewer — 첨부 모달
//   - 이미지: 마우스 드래그로 패닝 (이미지 크면 스크롤). 확대/축소/맞춤.
//   - 엑셀 (xlsx/xls/csv): SheetJS 로 시트 표시 (CDN lazy load).
//   - 기타: 다운로드 링크 표시.
// API: ErpAttachViewer.openFor(itemId, { title })
// ──────────────────────────────────────────────────────────

(function () {
  if (window.ErpAttachViewer) return;

  const IMG_EXTS = new Set(["png", "jpg", "jpeg", "gif", "webp", "bmp"]);
  const SHEET_EXTS = new Set(["xlsx", "xls", "xlsm", "csv", "ods"]);
  const XLSX_CDN = "https://cdn.jsdelivr.net/npm/xlsx@0.18.5/dist/xlsx.full.min.js";

  let overlay = null;
  let state = {
    items: [],
    currentIdx: -1,
    title: "",
    zoom: 1,           // 이미지 줌 (1 = 100%)
    // 패닝
    panning: false,
    panStartX: 0, panStartY: 0,
    scrollStartLeft: 0, scrollStartTop: 0,
  };
  let xlsxLoading = null;

  function ensureOverlay() {
    if (overlay) return overlay;
    overlay = document.createElement("div");
    overlay.className = "eav-overlay";
    overlay.innerHTML = `
      <div class="eav-modal" role="dialog" aria-modal="true">
        <div class="eav-head">
          <div class="eav-title" data-role="title">첨부 보기</div>
          <div class="eav-toolbar" data-role="toolbar"></div>
          <button class="eav-close" data-role="close" aria-label="닫기">✕</button>
        </div>
        <div class="eav-body">
          <div class="eav-list" data-role="list"></div>
          <div class="eav-canvas-wrap" data-role="stage"></div>
        </div>
      </div>
    `;
    document.body.appendChild(overlay);

    overlay.addEventListener("click", (e) => { if (e.target === overlay) close(); });
    overlay.querySelector('[data-role="close"]').addEventListener("click", close);
    document.addEventListener("keydown", (e) => {
      if (overlay.dataset.open === "true" && e.key === "Escape") close();
    });
    return overlay;
  }

  function loadXlsxLib() {
    if (window.XLSX) return Promise.resolve(window.XLSX);
    if (xlsxLoading) return xlsxLoading;
    xlsxLoading = new Promise((resolve, reject) => {
      const s = document.createElement("script");
      s.src = XLSX_CDN;
      s.onload = () => resolve(window.XLSX);
      s.onerror = () => reject(new Error("XLSX 라이브러리 로드 실패"));
      document.head.appendChild(s);
    });
    return xlsxLoading;
  }

  function buildToolbar() {
    const tb = overlay.querySelector('[data-role="toolbar"]');
    tb.innerHTML = "";
    const cur = state.items[state.currentIdx];
    if (!cur) return;
    const ext = (cur.filename.split(".").pop() || "").toLowerCase();

    if (IMG_EXTS.has(ext)) {
      [
        { label: "－", title: "축소", fn: () => setZoom(state.zoom / 1.25) },
        { label: "100%", title: "원본", fn: () => setZoom(1) },
        { label: "＋", title: "확대", fn: () => setZoom(state.zoom * 1.25) },
        { label: "맞춤", title: "화면에 맞춤", fn: () => setZoom("fit") },
      ].forEach((b) => {
        const btn = document.createElement("button");
        btn.className = "eav-btn";
        btn.textContent = b.label;
        btn.title = b.title;
        btn.onclick = b.fn;
        tb.appendChild(btn);
      });
    }

    const dl = document.createElement("a");
    dl.className = "eav-btn";
    dl.textContent = "다운로드";
    dl.href = `/expense/api/attachments/${cur.id}`;
    dl.setAttribute("download", cur.filename);
    tb.appendChild(dl);

    const open = document.createElement("a");
    open.className = "eav-btn";
    open.textContent = "새 창";
    open.href = `/expense/api/attachments/${cur.id}`;
    open.target = "_blank";
    tb.appendChild(open);
  }

  function buildList() {
    const list = overlay.querySelector('[data-role="list"]');
    list.innerHTML = "";
    state.items.forEach((a, i) => {
      const item = document.createElement("button");
      item.className = "eav-item" + (i === state.currentIdx ? " is-active" : "");
      const ext = (a.filename.split(".").pop() || "").toLowerCase();
      const isImg = IMG_EXTS.has(ext);
      const isSheet = SHEET_EXTS.has(ext);
      const icon = isImg ? `<img src="/expense/api/attachments/${a.id}" alt="" />`
                          : isSheet ? "📊" : "📄";
      item.innerHTML = `
        <span class="eav-item-thumb">${icon}</span>
        <span class="eav-item-meta">
          <span class="eav-item-name">${escapeHtml(a.filename)}</span>
          <span class="eav-item-sub">${a.kind === "receipt" ? "영수증" : "기타파일"} · ${fmtSize(a.size_bytes)}</span>
        </span>
      `;
      item.onclick = () => { state.currentIdx = i; state.zoom = 1; renderCurrent(); buildList(); buildToolbar(); };
      list.appendChild(item);
    });
  }

  function renderCurrent() {
    const stage = overlay.querySelector('[data-role="stage"]');
    stage.innerHTML = "";
    stage.className = "eav-canvas-wrap";
    const cur = state.items[state.currentIdx];
    if (!cur) {
      stage.innerHTML = `<div class="eav-fallback">첨부가 없습니다.</div>`;
      return;
    }
    const ext = (cur.filename.split(".").pop() || "").toLowerCase();

    if (IMG_EXTS.has(ext)) return renderImage(stage, cur);
    if (SHEET_EXTS.has(ext)) return renderSheet(stage, cur, ext);
    return renderFallback(stage, cur);
  }

  function renderImage(stage, cur) {
    stage.classList.add("eav-pan");
    const img = document.createElement("img");
    img.className = "eav-img";
    img.alt = cur.filename;
    img.src = `/expense/api/attachments/${cur.id}`;
    img.draggable = false;
    img.onload = () => { applyZoom(); };
    img.onerror = () => { stage.innerHTML = `<div class="eav-fallback">이미지 로드 실패</div>`; };
    stage.appendChild(img);
    state.image = img;

    // 마우스 드래그 패닝
    stage.addEventListener("pointerdown", (e) => {
      if (e.button !== 0) return;
      state.panning = true;
      state.panStartX = e.clientX;
      state.panStartY = e.clientY;
      state.scrollStartLeft = stage.scrollLeft;
      state.scrollStartTop = stage.scrollTop;
      stage.setPointerCapture(e.pointerId);
      stage.classList.add("is-panning");
    });
    stage.addEventListener("pointermove", (e) => {
      if (!state.panning) return;
      stage.scrollLeft = state.scrollStartLeft - (e.clientX - state.panStartX);
      stage.scrollTop  = state.scrollStartTop  - (e.clientY - state.panStartY);
    });
    const endPan = (e) => {
      if (!state.panning) return;
      state.panning = false;
      try { stage.releasePointerCapture(e.pointerId); } catch (_) {}
      stage.classList.remove("is-panning");
    };
    stage.addEventListener("pointerup", endPan);
    stage.addEventListener("pointercancel", endPan);
    stage.addEventListener("pointerleave", endPan);
  }

  function applyZoom() {
    if (!state.image) return;
    const stage = overlay.querySelector('[data-role="stage"]');
    const img = state.image;
    if (state.zoom === "fit") {
      img.style.maxWidth = "100%";
      img.style.maxHeight = "calc(100vh - 200px)";
      img.style.width = "";
      img.style.height = "";
    } else {
      img.style.maxWidth = "none";
      img.style.maxHeight = "none";
      img.style.width = (img.naturalWidth * state.zoom) + "px";
      img.style.height = "auto";
    }
  }

  function setZoom(z) {
    state.zoom = z;
    applyZoom();
  }

  async function renderSheet(stage, cur, ext) {
    stage.classList.remove("eav-pan");
    stage.innerHTML = `<div class="eav-sheet-loading">시트 로드 중…</div>`;
    try {
      const XLSX = await loadXlsxLib();
      const res = await fetch(`/expense/api/attachments/${cur.id}`);
      if (!res.ok) throw new Error(`HTTP ${res.status}`);
      const buf = await res.arrayBuffer();
      const wb = XLSX.read(buf, { type: "array" });
      stage.innerHTML = "";

      const sheetWrap = document.createElement("div");
      sheetWrap.className = "eav-sheet-wrap";

      const tabs = document.createElement("div");
      tabs.className = "eav-sheet-tabs";
      const body = document.createElement("div");
      body.className = "eav-sheet-body";

      function showSheet(name) {
        const ws = wb.Sheets[name];
        const html = XLSX.utils.sheet_to_html(ws, { editable: false });
        body.innerHTML = html;
        tabs.querySelectorAll("button").forEach((b) => {
          b.classList.toggle("is-active", b.dataset.sheet === name);
        });
      }
      wb.SheetNames.forEach((name) => {
        const b = document.createElement("button");
        b.className = "eav-btn";
        b.dataset.sheet = name;
        b.textContent = name;
        b.onclick = () => showSheet(name);
        tabs.appendChild(b);
      });
      sheetWrap.appendChild(tabs);
      sheetWrap.appendChild(body);
      stage.appendChild(sheetWrap);
      showSheet(wb.SheetNames[0]);
    } catch (err) {
      stage.innerHTML = `<div class="eav-fallback">시트 로드 실패: ${escapeHtml(err.message || String(err))}
        <br/><a href="/expense/api/attachments/${cur.id}" target="_blank">원본 다운로드</a></div>`;
    }
  }

  function renderFallback(stage, cur) {
    stage.classList.remove("eav-pan");
    stage.innerHTML = `
      <div class="eav-fallback">
        미리보기를 지원하지 않는 파일입니다.<br/>
        <a href="/expense/api/attachments/${cur.id}" target="_blank">다운로드 / 새 창 열기</a>
      </div>
    `;
  }

  function fmtSize(b) {
    b = Number(b || 0);
    if (b < 1024) return `${b} B`;
    if (b < 1024 * 1024) return `${(b / 1024).toFixed(1)} KB`;
    return `${(b / 1024 / 1024).toFixed(2)} MB`;
  }
  function escapeHtml(s) {
    return String(s || "").replace(/[&<>"']/g, (c) =>
      ({ "&": "&amp;", "<": "&lt;", ">": "&gt;", '"': "&quot;", "'": "&#39;" }[c])
    );
  }

  function open(items, opts) {
    ensureOverlay();
    state.items = items || [];
    state.currentIdx = state.items.length ? 0 : -1;
    state.zoom = 1;
    state.title = (opts && opts.title) || "첨부 보기";
    overlay.querySelector('[data-role="title"]').textContent = state.title;
    overlay.dataset.open = "true";
    buildList();
    buildToolbar();
    renderCurrent();
  }

  function close() {
    if (!overlay) return;
    overlay.dataset.open = "false";
    state.items = [];
    state.currentIdx = -1;
    state.image = null;
  }

  async function openFor(itemId, opts) {
    try {
      const res = await fetch(`/expense/api/items/${itemId}/attachments`);
      if (!res.ok) throw new Error((await res.json()).detail || res.status);
      const { attachments } = await res.json();
      if (!attachments || !attachments.length) {
        alert("첨부 파일이 없습니다.");
        return;
      }
      open(attachments, opts);
    } catch (err) {
      alert(`첨부 로드 실패: ${err.message || err}`);
    }
  }

  window.ErpAttachViewer = { open, openFor, close };
})();