'use strict';
/* board-clip.js — save a whiteboard page or a selected region into the
 * student's personal materials ("Мои материалы"). Shared by the live
 * classroom (classroom.html) and the past-session review (my-lessons.html).
 *
 * Requires window.LS (api.js: uploadFile, downloadFileUrl, saveMaterial, toast)
 * and a Whiteboard instance exposing exportBlob(cb) (whiteboard.js).
 *
 *   BoardClip.savePage(wb, meta, btn?)    // whole current page  -> kind 'board'
 *   BoardClip.saveRegion(wb, meta, btn?)  // crop a rectangle    -> kind 'image'
 *   meta: { sourceSessionId, sourceTitle, pageNum? }
 */
(function () {
  function titleFor(meta, suffix) {
    const base = (meta && meta.sourceTitle) || 'Доска';
    const pg = (meta && meta.pageNum) ? ' · стр. ' + meta.pageNum : '';
    return base + pg + (suffix || '');
  }

  async function uploadBlob(blob, name) {
    const fd = new FormData();
    fd.append('file', blob, name);
    const up = await LS.uploadFile(fd);
    return LS.downloadFileUrl(up.id);
  }

  async function persist(meta, kind, url) {
    await LS.saveMaterial({
      kind: kind,
      url: url,
      title: titleFor(meta, kind === 'image' ? ' · фрагмент' : ''),
      sourceSessionId: meta && meta.sourceSessionId,
      sourceTitle: meta && meta.sourceTitle,
    });
  }

  function savePage(wb, meta, btn) {
    if (!wb || typeof wb.exportBlob !== 'function') { LS.toast('Доска не готова', 'warn'); return; }
    if (btn) btn.disabled = true;
    wb.exportBlob(async function (blob) {
      try {
        if (!blob) throw new Error('Не удалось снять доску');
        const url = await uploadBlob(blob, 'board.png');
        await persist(meta, 'board', url);
        LS.toast('Страница сохранена в «Мои материалы»', 'success');
      } catch (e) {
        LS.toast(e.message || 'Ошибка сохранения', 'error');
      } finally { if (btn) btn.disabled = false; }
    });
  }

  function saveRegion(wb, meta, btn) {
    if (!wb || typeof wb.exportBlob !== 'function') { LS.toast('Доска не готова', 'warn'); return; }
    if (btn) btn.disabled = true;
    wb.exportBlob(function (blob) {
      if (btn) btn.disabled = false;
      if (!blob) { LS.toast('Не удалось снять доску', 'error'); return; }
      openCropOverlay(blob, meta);
    });
  }

  function ensureCropStyles() {
    if (document.getElementById('bclip-style')) return;
    const s = document.createElement('style');
    s.id = 'bclip-style';
    s.textContent = `
      .bclip-ov { position: fixed; inset: 0; z-index: 2147483600; background: rgba(15,12,30,.72); display: flex; align-items: center; justify-content: center; padding: 16px; }
      .bclip-box { background: #fff; border-radius: 14px; max-width: 92vw; max-height: 92vh; display: flex; flex-direction: column; overflow: hidden; box-shadow: 0 20px 60px rgba(0,0,0,.4); }
      .bclip-hint { padding: 12px 16px; font-weight: 700; font-size: .9rem; color: #1a1433; border-bottom: 1px solid #eee; font-family: 'Manrope', system-ui, sans-serif; }
      .bclip-stage { position: relative; background: #f1f5f9; line-height: 0; }
      .bclip-img { display: block; max-width: 84vw; max-height: 64vh; width: auto; height: auto; user-select: none; -webkit-user-drag: none; touch-action: none; cursor: crosshair; }
      .bclip-sel { position: absolute; border: 2px dashed #8b5cf6; background: rgba(139,92,246,.14); pointer-events: none; }
      .bclip-actions { display: flex; justify-content: flex-end; gap: 8px; padding: 12px 16px; border-top: 1px solid #eee; }
      .bclip-actions button { padding: 8px 16px; border-radius: 9px; border: 1px solid #e2e8f0; background: #fff; font-weight: 700; font-size: .85rem; cursor: pointer; color: #475569; font-family: 'Manrope', system-ui, sans-serif; }
      .bclip-actions button.primary { background: #8b5cf6; border-color: #8b5cf6; color: #fff; }
      .bclip-actions button:disabled { opacity: .5; cursor: default; }
    `;
    document.head.appendChild(s);
  }

  function openCropOverlay(blob, meta) {
    ensureCropStyles();
    const url = URL.createObjectURL(blob);
    const ov = document.createElement('div');
    ov.className = 'bclip-ov';
    ov.innerHTML = `
      <div class="bclip-box">
        <div class="bclip-hint">Выделите мышью нужную область (таблицу, рисунок и т.п.)</div>
        <div class="bclip-stage">
          <img class="bclip-img" alt="" draggable="false" />
          <div class="bclip-sel" style="display:none"></div>
        </div>
        <div class="bclip-actions">
          <button data-act="cancel">Отмена</button>
          <button data-act="save" class="primary" disabled>Сохранить область</button>
        </div>
      </div>`;
    document.body.appendChild(ov);
    const img = ov.querySelector('.bclip-img');
    const sel = ov.querySelector('.bclip-sel');
    const saveBtn = ov.querySelector('[data-act="save"]');
    img.src = url;

    let dragging = false, start = null, rect = null;
    function close() { ov.remove(); URL.revokeObjectURL(url); }
    ov.querySelector('[data-act="cancel"]').onclick = close;

    function rel(e) {
      const r = img.getBoundingClientRect();
      return {
        x: Math.max(0, Math.min(r.width,  e.clientX - r.left)),
        y: Math.max(0, Math.min(r.height, e.clientY - r.top)),
      };
    }
    function onMove(e) {
      if (!dragging) return;
      const p = rel(e);
      const x = Math.min(p.x, start.x), y = Math.min(p.y, start.y);
      const w = Math.abs(p.x - start.x), h = Math.abs(p.y - start.y);
      rect = { x, y, w, h };
      sel.style.display = 'block';
      sel.style.left = x + 'px'; sel.style.top = y + 'px';
      sel.style.width = w + 'px'; sel.style.height = h + 'px';
      saveBtn.disabled = (w < 6 || h < 6);
    }
    function onUp() {
      dragging = false;
      document.removeEventListener('pointermove', onMove);
      document.removeEventListener('pointerup', onUp);
    }
    img.addEventListener('pointerdown', function (e) {
      e.preventDefault();
      dragging = true; start = rel(e); rect = null; saveBtn.disabled = true;
      sel.style.display = 'none';
      document.addEventListener('pointermove', onMove);
      document.addEventListener('pointerup', onUp);
    });

    saveBtn.onclick = async function () {
      if (!rect || rect.w < 6 || rect.h < 6) return;
      saveBtn.disabled = true;
      try {
        const r = img.getBoundingClientRect();
        const sx = img.naturalWidth / r.width, sy = img.naturalHeight / r.height;
        const cw = Math.max(1, Math.round(rect.w * sx)), ch = Math.max(1, Math.round(rect.h * sy));
        const off = document.createElement('canvas'); off.width = cw; off.height = ch;
        off.getContext('2d').drawImage(img, Math.round(rect.x * sx), Math.round(rect.y * sy), cw, ch, 0, 0, cw, ch);
        const cblob = await new Promise(function (res) { off.toBlob(res, 'image/png'); });
        if (!cblob) throw new Error('Не удалось обрезать область');
        const cropUrl = await uploadBlob(cblob, 'board-region.png');
        await persist(meta, 'image', cropUrl);
        close();
        LS.toast('Фрагмент сохранён в «Мои материалы»', 'success');
      } catch (e) {
        LS.toast(e.message || 'Ошибка сохранения', 'error');
        saveBtn.disabled = false;
      }
    };
  }

  window.BoardClip = { savePage: savePage, saveRegion: saveRegion };
})();