/**
 * scan.js
 * -------
 * Directory scan and file selection table.
 *
 * Handles the "Scan for Files" button, the /api/scan fetch, rendering the
 * results table, and the select-all / deselect-all controls.
 *
 * Exports
 * -------
 *   initScan()  — attach all event listeners; call once at startup
 */

import { state, els, announce } from './state.js';
import { esc } from './utils.js';

// ─── Status helper ────────────────────────────────────────────────────────────

function setScanStatus(msg, type) {
  els.scanStatus.textContent = msg;
  els.scanStatus.style.color =
    type === 'error'   ? 'var(--text-danger)'
    : type === 'success' ? 'var(--text-success)'
    : type === 'warn'    ? 'var(--accent)'
    : 'var(--text-muted)';
}

// ─── File table ───────────────────────────────────────────────────────────────

function updateSelectionUI() {
  els.selectionSummary.textContent =
    `${state.selectedPaths.size} of ${state.scannedFiles.length} selected`;
  els.compressBtn.disabled = state.selectedPaths.size === 0;
}

/**
 * Build and inject the file selection table from the scan results.
 * Attaches checkbox change handlers for each row.
 * @param {Array} files  — enriched file objects from /api/scan
 */
export function renderFileTable(files) {
  let html = '';

  files.forEach((f, idx) => {
    const codec      = (f.codec || 'unknown').toLowerCase();
    const isHevc     = ['hevc', 'h265', 'x265'].includes(codec);
    const isH264     = ['h264', 'avc', 'x264'].includes(codec);
    const codecLabel = isHevc ? 'H.265 / HEVC'
                     : isH264 ? 'H.264 / AVC'
                     : codec.toUpperCase();
    const codecMod   = isHevc ? 'hevc' : isH264 ? 'h264' : '';
    const pathDir    = f.path.replace(f.name, '');

    html += `
      <tr id="row-${idx}" data-path="${esc(f.path)}">
        <td class="col-check">
          <input type="checkbox" class="file-checkbox" id="chk-${idx}"
            data-path="${esc(f.path)}"
            aria-label="Select ${esc(f.name)} for compression" />
        </td>
        <td class="col-name">
          <label for="chk-${idx}" class="file-name-cell" style="cursor:pointer">
            <span class="file-name">${esc(f.name)}</span>
            <span class="file-path" title="${esc(f.path)}">${esc(pathDir)}</span>
          </label>
        </td>
        <td class="col-size"><strong>${f.size_gb.toFixed(3)}</strong> GB</td>
        <td class="col-bitrate">
          <span class="bitrate-badge">
            ${esc(f.bit_rate_mbps ? f.bit_rate_mbps + ' Mbps' : 'Unknown')}
          </span>
        </td>
        <td class="col-target">
          <span class="bitrate-badge target">
            ${esc(f.target_bit_rate_mbps ? f.target_bit_rate_mbps + ' Mbps' : '—')}
          </span>
        </td>
        <td class="col-codec">
          <span class="codec-tag ${codecMod}"
                title="Encoder: ${isHevc ? 'libx265' : 'libx264'}">
            ${esc(codecLabel)}
          </span>
        </td>
      </tr>`;
  });

  els.fileTbody.innerHTML = html;

  els.fileTbody.querySelectorAll('.file-checkbox').forEach(chk => {
    chk.addEventListener('change', () => {
      const row = chk.closest('tr');
      if (chk.checked) {
        state.selectedPaths.add(chk.dataset.path);
        row.classList.add('selected');
      } else {
        state.selectedPaths.delete(chk.dataset.path);
        row.classList.remove('selected');
      }
      updateSelectionUI();
    });
  });

  updateSelectionUI();
}

// ─── Public init ─────────────────────────────────────────────────────────────

/**
 * Attach event listeners for the scan button and file selection controls.
 * Call once during app initialisation.
 */
export function initScan() {
  // ── Scan button ──────────────────────────────────────────────────────────
  els.scanBtn.addEventListener('click', async () => {
    const directory = els.dirInput.value.trim();
    const minSize   = parseFloat(els.minSizeInput.value);

    if (!directory) {
      setScanStatus('Please enter a directory path.', 'error');
      els.dirInput.focus();
      return;
    }
    if (isNaN(minSize) || minSize <= 0) {
      setScanStatus('Please enter a valid minimum size > 0.', 'error');
      els.minSizeInput.focus();
      return;
    }

    els.scanBtn.disabled    = true;
    els.scanBtn.textContent = '⟳ Scanning…';
    setScanStatus('Scanning directory, please wait…', 'info');
    announce('Scanning directory for video files.');
    els.sectionFiles.hidden = true;

    try {
      const resp = await fetch('/api/scan', {
        method:  'POST',
        headers: { 'Content-Type': 'application/json' },
        body:    JSON.stringify({ directory, min_size_gb: minSize }),
      });
      const data = await resp.json();

      if (!resp.ok) {
        setScanStatus(`Error: ${data.error}`, 'error');
        announce(`Scan failed: ${data.error}`);
        return;
      }

      state.scannedFiles = data.files;
      state.selectedPaths.clear();

      if (!data.files.length) {
        setScanStatus(`No video files larger than ${minSize} GB found.`, 'warn');
        announce('No video files found matching your criteria.');
        return;
      }

      setScanStatus(`Found ${data.files.length} file(s).`, 'success');
      announce(`Scan complete. Found ${data.files.length} video files.`);
      renderFileTable(data.files);
      els.sectionFiles.hidden = false;
      els.sectionFiles.scrollIntoView({ behavior: 'smooth', block: 'start' });

    } catch (err) {
      setScanStatus(`Network error: ${err.message}`, 'error');
    } finally {
      els.scanBtn.disabled  = false;
      els.scanBtn.innerHTML =
        '<span class="btn-icon-prefix" aria-hidden="true">⊙</span> Scan for Files';
    }
  });

  // ── Select all ───────────────────────────────────────────────────────────
  els.selectAllBtn.addEventListener('click', () => {
    els.fileTbody.querySelectorAll('.file-checkbox').forEach(chk => {
      chk.checked = true;
      state.selectedPaths.add(chk.dataset.path);
      chk.closest('tr').classList.add('selected');
    });
    updateSelectionUI();
    announce(`All ${state.scannedFiles.length} files selected.`);
  });

  // ── Deselect all ─────────────────────────────────────────────────────────
  els.deselectAllBtn.addEventListener('click', () => {
    els.fileTbody.querySelectorAll('.file-checkbox').forEach(chk => {
      chk.checked = false;
      state.selectedPaths.delete(chk.dataset.path);
      chk.closest('tr').classList.remove('selected');
    });
    updateSelectionUI();
    announce('All files deselected.');
  });
}