/**
 * NodeDetailPanel - Displays detailed information for a selected graph node
 * Shows node name, opType, domain, attributes, and input/output tensors.
 * Listens for 'node:selected' events via EventBus and hides when no node is selected.
 * Requirements: 16.1, 16.2, 16.3, 16.4, 16.5
 */

class NodeDetailPanel {
  /**
   * @param {string} containerId - ID of the container element
   */
  constructor(containerId) {
    this._containerId = containerId;
    this._container = document.getElementById(containerId);
    this._currentNodeData = null;
    /** @type {Function|null} */
    this._unsubscribeEvent = null;
    /** @type {Function|null} */
    this._unsubscribeState = null;

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

    this._bindEvents();
    this._renderGuidance();
  }

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

  /**
   * Subscribe to EventBus and StateManager for node selection changes.
   * @private
   */
  _bindEvents() {
    // Listen for node:selected via EventBus
    if (typeof EventBus !== 'undefined' && typeof CONFIG !== 'undefined') {
      this._unsubscribeEvent = EventBus.on(CONFIG.EVENTS.NODE_SELECTED, (data) => {
        if (data && data.nodeData) {
          this._onNodeSelected(data.nodeData);
        } else if (data && data.nodeId) {
          // Minimal data — show what we have
          this._onNodeSelected({ id: data.nodeId });
        }
      });
    }

    // Listen for selectedNodeId becoming null (background click)
    if (typeof StateManager !== 'undefined') {
      this._unsubscribeState = StateManager.subscribe('selectedNodeId', (newId) => {
        if (!newId) {
          this._onNodeDeselected();
        }
      });
    }
  }

  /**
   * Handle node selection.
   * @param {Object} nodeData
   * @private
   */
  _onNodeSelected(nodeData) {
    this._currentNodeData = nodeData;
    this._render(nodeData);
  }

  /**
   * Handle node deselection (background click).
   * @private
   */
  _onNodeDeselected() {
    this._currentNodeData = null;
    this._renderGuidance();
  }

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

  /**
   * Format an attribute value for display.
   * @param {*} val
   * @returns {string} Escaped HTML string
   * @private
   */
  _formatAttrValue(val) {
    if (val === null || val === undefined) {
      return '<span class="text-muted fst-italic">null</span>';
    }
    if (Array.isArray(val)) {
      const preview = val.slice(0, 8).map((v) => String(v)).join(', ');
      const suffix = val.length > 8 ? `, … (+${val.length - 8})` : '';
      return this._escapeHtml(`[${preview}${suffix}]`);
    }
    if (typeof val === 'object') {
      try {
        const json = JSON.stringify(val, null, 2);
        return `<pre class="mb-0 small">${this._escapeHtml(json)}</pre>`;
      } catch (_) {
        return this._escapeHtml(String(val));
      }
    }
    return this._escapeHtml(String(val));
  }

  /**
   * Build the header section (name, opType, domain).
   * @param {Object} nodeData
   * @returns {string}
   * @private
   */
  _buildHeader(nodeData) {
    const name = nodeData.name || nodeData.label || nodeData.id || 'Unnamed';
    const opType = nodeData.opType || 'N/A';
    const domain = nodeData.domain || 'ai.onnx';

    return `
      <div class="node-detail-header mb-3">
        <h6 class="mb-1 text-truncate" title="${this._escapeHtml(name)}">
          <i class="fas fa-circle-nodes me-1 text-primary"></i>${this._escapeHtml(name)}
        </h6>
        <div class="small">
          <span class="badge bg-info me-1">${this._escapeHtml(opType)}</span>
          <span class="badge bg-secondary">${this._escapeHtml(domain)}</span>
        </div>
      </div>`;
  }

  /**
   * Build the attributes section.
   * @param {Record<string, any>} attributes
   * @returns {string}
   * @private
   */
  _buildAttributes(attributes) {
    if (!attributes || Object.keys(attributes).length === 0) {
      return `
        <div class="node-detail-section mb-3">
          <h6 class="small text-uppercase text-secondary mb-2">
            <i class="fas fa-sliders me-1"></i>Attributes
          </h6>
          <p class="text-muted small mb-0">No attributes</p>
        </div>`;
    }

    const rows = Object.entries(attributes).map(([key, val]) => `
      <tr>
        <td class="text-nowrap pe-2 small fw-medium">${this._escapeHtml(key)}</td>
        <td class="small">${this._formatAttrValue(val)}</td>
      </tr>`).join('');

    return `
      <div class="node-detail-section mb-3">
        <h6 class="small text-uppercase text-secondary mb-2">
          <i class="fas fa-sliders me-1"></i>Attributes (${Object.keys(attributes).length})
        </h6>
        <table class="table table-sm table-borderless mb-0">
          <tbody>${rows}</tbody>
        </table>
      </div>`;
  }

  /**
   * Build the input/output tensors section.
   * @param {Array<string>} inputs
   * @param {Array<string>} outputs
   * @returns {string}
   * @private
   */
  _buildTensors(inputs, outputs) {
    const buildList = (items, label, icon, colorClass) => {
      if (!items || items.length === 0) {
        return `<p class="text-muted small mb-0">No ${label.toLowerCase()}</p>`;
      }
      const listItems = items.map((name) =>
        `<li class="list-group-item py-1 px-2 small">${this._escapeHtml(String(name))}</li>`
      ).join('');
      return `
        <h6 class="small text-uppercase ${colorClass} mb-1">
          <i class="fas ${icon} me-1"></i>${label} (${items.length})
        </h6>
        <ul class="list-group list-group-flush mb-2">${listItems}</ul>`;
    };

    return `
      <div class="node-detail-section mb-3">
        ${buildList(inputs, 'Inputs', 'fa-arrow-right', 'text-primary')}
        ${buildList(outputs, 'Outputs', 'fa-arrow-left', 'text-success')}
      </div>`;
  }

  /**
   * Render the full node detail panel.
   * @param {Object} nodeData
   * @private
   */
  _render(nodeData) {
    if (!this._container) return;

    const nodeId = nodeData.id || '';

    const html = `
      <div class="node-detail-panel-content">
        ${this._buildHeader(nodeData)}
        <div class="d-flex gap-2 mb-2">
          <button class="btn btn-sm btn-outline-primary flex-fill trace-path-btn" data-node-id="${this._escapeHtml(nodeId)}" title="Highlight data flow path through this node">
            <i class="fas fa-route me-1"></i>Trace Path
          </button>
          <button class="btn btn-sm btn-outline-warning flex-fill annotate-node-btn" data-node-id="${this._escapeHtml(nodeId)}" title="Add or edit annotation for this node">
            <i class="fas fa-sticky-note me-1"></i>Annotate
          </button>
        </div>
        <hr class="my-2">
        ${this._buildAttributes(nodeData.attributes)}
        <hr class="my-2">
        ${this._buildTensors(nodeData.inputs, nodeData.outputs)}
      </div>`;

    this._container.innerHTML = html;

    // Bind Trace Path button
    var traceBtn = this._container.querySelector('.trace-path-btn');
    if (traceBtn) {
      traceBtn.addEventListener('click', function () {
        var nid = traceBtn.dataset.nodeId;
        if (nid && window.EventBus) {
          window.EventBus.emit('path:highlight-requested', { nodeId: nid });
        }
      });
    }

    // Bind Annotate button
    var annotateBtn = this._container.querySelector('.annotate-node-btn');
    if (annotateBtn) {
      annotateBtn.addEventListener('click', function () {
        var nid = annotateBtn.dataset.nodeId;
        if (nid && window._onnxApp && window._onnxApp.getGraphAnnotation) {
          var ga = window._onnxApp.getGraphAnnotation();
          if (ga) {
            ga.showAnnotationPopup(nid);
          }
        }
      });
    }
  }

  /**
   * Render guidance message when no node is selected.
   * @private
   */
  _renderGuidance() {
    if (!this._container) return;

    this._container.innerHTML = `
      <div class="text-center text-muted py-4">
        <i class="fas fa-hand-pointer fa-2x mb-2 d-block"></i>
        <p class="mb-0 small">Click a node in the graph to view its details</p>
      </div>`;
  }

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

  /**
   * Programmatically show details for a node.
   * @param {Object} nodeData
   */
  showNode(nodeData) {
    if (nodeData) {
      this._onNodeSelected(nodeData);
    }
  }

  /**
   * Clear the panel and show guidance.
   */
  clear() {
    this._currentNodeData = null;
    this._renderGuidance();
  }

  /**
   * Get the currently displayed node data.
   * @returns {Object|null}
   */
  getCurrentNode() {
    return this._currentNodeData;
  }

  /**
   * Destroy and clean up event subscriptions.
   */
  destroy() {
    if (this._unsubscribeEvent) {
      this._unsubscribeEvent();
      this._unsubscribeEvent = null;
    }
    if (this._unsubscribeState) {
      this._unsubscribeState();
      this._unsubscribeState = null;
    }
    this._currentNodeData = null;
    if (this._container) {
      this._container.innerHTML = '';
    }
  }
}

window.NodeDetailPanel = NodeDetailPanel;