/**
 * LayerStats - Displays operator type statistics for a loaded ONNX model
 * Computes counts, percentages, and summary totals; highlights nodes by type on click.
 * Requirements: 19.1, 19.2, 19.3, 19.4, 19.5
 */

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

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

    this._setupEventListeners();
  }

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

  /**
   * Listen for model:loaded events to auto-update stats.
   */
  _setupEventListeners() {
    if (window.EventBus && CONFIG && CONFIG.EVENTS) {
      window.EventBus.on(CONFIG.EVENTS.MODEL_LOADED, (data) => {
        if (data && data.model) {
          const stats = this.compute(data.model);
          this.render(stats);
        }
      });
    }
  }

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

  /**
   * Attach click and keyboard handlers to operator rows in the stats table.
   */
  _attachRowHandlers() {
    if (!this._container) return;
    const rows = this._container.querySelectorAll('.layer-stats-row');
    rows.forEach((row) => {
      const handler = () => {
        const opType = row.dataset.opType;
        if (opType && window.EventBus) {
          window.EventBus.emit('layerstats:highlight', { opType });
        }
      };
      row.addEventListener('click', handler);
      row.addEventListener('keydown', (e) => {
        if (e.key === 'Enter' || e.key === ' ') {
          e.preventDefault();
          handler();
        }
      });
    });
  }

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

  /**
   * Compute operator statistics from a parsed model.
   * @param {ParsedModel} parsedModel
   * @returns {LayerStatsData}
   */
  compute(parsedModel) {
    const nodes = (parsedModel && parsedModel.graph && parsedModel.graph.nodes) ? parsedModel.graph.nodes : [];
    const edges = (parsedModel && parsedModel.graph && parsedModel.graph.edges) ? parsedModel.graph.edges : [];
    const initializers = (parsedModel && parsedModel.initializers) ? parsedModel.initializers : [];

    const totalNodes = nodes.length;
    const totalEdges = edges.length;
    const totalInitializers = initializers.length;

    // Count each operator type
    const countMap = {};
    nodes.forEach((node) => {
      const op = node.opType || 'Unknown';
      countMap[op] = (countMap[op] || 0) + 1;
    });

    // Build sorted array with percentages
    const opTypeCounts = Object.entries(countMap)
      .map(([opType, count]) => ({
        opType,
        count,
        percentage: totalNodes > 0 ? parseFloat(((count / totalNodes) * 100).toFixed(1)) : 0,
      }))
      .sort((a, b) => b.count - a.count);

    this._stats = { opTypeCounts, totalNodes, totalEdges, totalInitializers };
    return this._stats;
  }

  /**
   * Render the statistics table into the container.
   * @param {LayerStatsData} stats
   */
  render(stats) {
    if (!this._container) return;

    if (!stats) {
      this._container.innerHTML = '<p class="text-muted">No statistics available.</p>';
      return;
    }

    const { opTypeCounts, totalNodes, totalEdges, totalInitializers } = stats;

    // Summary section
    let html = `
      <div class="mb-3">
        <div class="d-flex flex-wrap gap-3 small">
          <span><i class="fas fa-project-diagram me-1"></i><strong>${totalNodes}</strong> Nodes</span>
          <span><i class="fas fa-arrows-alt-h me-1"></i><strong>${totalEdges}</strong> Edges</span>
          <span><i class="fas fa-database me-1"></i><strong>${totalInitializers}</strong> Initializers</span>
        </div>
      </div>`;

    if (opTypeCounts.length === 0) {
      html += '<p class="text-muted">No operators found.</p>';
      this._container.innerHTML = html;
      return;
    }

    // Operator stats table
    html += `
      <table class="table table-sm table-hover mb-0" role="grid" aria-label="Operator statistics">
        <thead>
          <tr>
            <th scope="col">Operator</th>
            <th scope="col" class="text-end">Count</th>
            <th scope="col" class="text-end">%</th>
          </tr>
        </thead>
        <tbody>`;

    opTypeCounts.forEach((entry) => {
      html += `
          <tr class="layer-stats-row cursor-pointer"
              role="button"
              tabindex="0"
              data-op-type="${this._escapeHtml(entry.opType)}"
              title="Click to highlight all ${this._escapeHtml(entry.opType)} nodes"
              aria-label="${this._escapeHtml(entry.opType)}: ${entry.count} nodes, ${entry.percentage}%">
            <td>${this._escapeHtml(entry.opType)}</td>
            <td class="text-end">${entry.count}</td>
            <td class="text-end">${entry.percentage}%</td>
          </tr>`;
    });

    html += `
        </tbody>
      </table>`;

    this._container.innerHTML = html;
    this._attachRowHandlers();
  }

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

  /**
   * Get the last computed stats.
   * @returns {LayerStatsData|null}
   */
  getStats() {
    return this._stats;
  }
}

window.LayerStats = LayerStats;