/**
 * MetadataDisplay - Displays ONNX model metadata
 * Requirements: 6.1, 6.2, 6.3, 6.4, 6.5, 6.6
 */

class MetadataDisplay {
  /**
   * @param {string} containerId - ID of the container element
   */
  constructor(containerId) {
    this._containerId = containerId;
    this._container = document.getElementById(containerId);

    if (!this._container) {
      console.warn(`[MetadataDisplay] Container #${containerId} not found`);
    }
  }

  // ─── Private ──────────────────────────────────────────────────────────────

  /**
   * Return a display value, falling back to "Not available".
   * @param {*} value
   * @returns {string}
   */
  _displayValue(value) {
    if (value === null || value === undefined || value === '') {
      return '<span class="text-muted fst-italic">Not available</span>';
    }
    return this._escapeHtml(String(value));
  }

  /**
   * Escape HTML special characters.
   * @param {string} str
   * @returns {string}
   */
  _escapeHtml(str) {
    const div = document.createElement('div');
    div.appendChild(document.createTextNode(str));
    return div.innerHTML;
  }

  /**
   * Build a metadata row.
   * @param {string} label
   * @param {string} valueHtml - Already-escaped HTML string
   * @returns {string}
   */
  _row(label, valueHtml) {
    return `
      <tr>
        <th scope="row" class="text-nowrap pe-3" style="width:40%">${this._escapeHtml(label)}</th>
        <td>${valueHtml}</td>
      </tr>`;
  }

  /**
   * Render custom metadata attributes.
   * @param {Record<string, any>} attrs
   * @returns {string} HTML string
   */
  _renderCustomAttributes(attrs) {
    if (!attrs || Object.keys(attrs).length === 0) {
      return '';
    }

    const rows = Object.entries(attrs)
      .map(([key, val]) => this._row(key, this._displayValue(val)))
      .join('');

    return `
      <tr>
        <td colspan="2" class="pt-3 pb-1">
          <strong class="text-secondary small text-uppercase">Custom Attributes</strong>
        </td>
      </tr>
      ${rows}`;
  }

  // ─── Public API ───────────────────────────────────────────────────────────

  /**
   * Render metadata for a parsed model.
   * @param {ParsedModel} model
   */
  render(model) {
    if (!this._container) return;

    const meta = (model && model.metadata) ? model.metadata : {};

    const html = `
      <table class="table table-sm table-borderless mb-0">
        <tbody>
          ${this._row('Producer Name', this._displayValue(meta.producerName))}
          ${this._row('Producer Version', this._displayValue(meta.producerVersion))}
          ${this._row('Opset Version', this._displayValue(meta.opsetVersion))}
          ${this._row('IR Version', this._displayValue(meta.irVersion))}
          ${this._row('File Name', this._displayValue(meta.fileName))}
          ${this._row('File Size', meta.fileSize ? this._displayValue(this._formatBytes(meta.fileSize)) : '<span class="text-muted fst-italic">Not available</span>')}
          ${this._renderCustomAttributes(meta.customAttributes)}
        </tbody>
      </table>`;

    this._container.innerHTML = html;
  }

  /**
   * Format bytes to a human-readable string.
   * @param {number} bytes
   * @returns {string}
   */
  _formatBytes(bytes) {
    if (bytes === 0) return '0 B';
    const k = 1024;
    const sizes = ['B', 'KB', 'MB', 'GB'];
    const i = Math.floor(Math.log(bytes) / Math.log(k));
    return `${parseFloat((bytes / Math.pow(k, i)).toFixed(2))} ${sizes[i]}`;
  }

  /**
   * Clear the metadata display.
   */
  clear() {
    if (!this._container) return;
    this._container.innerHTML = '<p class="text-muted">Select a model to view metadata</p>';
  }
}

window.MetadataDisplay = MetadataDisplay;