/**
 * InitializerDisplay - Displays model initializers (constant tensors / weights)
 * Requirements: 7.1, 7.2, 7.3, 7.4, 7.5
 */

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

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

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

  /**
   * 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;
  }

  /**
   * Format a shape array to a readable string.
   * @param {Array<number>} shape
   * @returns {string}
   */
  _formatShape(shape) {
    if (!shape || shape.length === 0) return '[]';
    return `[${shape.join(', ')}]`;
  }

  /**
   * Resolve a numeric data type to its string name.
   * @param {number|string} dataType
   * @returns {string}
   */
  _resolveDataType(dataType) {
    if (typeof dataType === 'string') return dataType;
    if (CONFIG && CONFIG.DATA_TYPES && CONFIG.DATA_TYPES[dataType]) {
      return CONFIG.DATA_TYPES[dataType];
    }
    return String(dataType);
  }

  /**
   * Format a byte count to a human-readable string (e.g. "4.2 KB").
   * @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]}`;
  }

  /**
   * Compute the size label for an initializer.
   * Prefer size in bytes; fall back to element count.
   * @param {InitializerInfo} init
   * @returns {string}
   */
  _sizeLabel(init) {
    if (init.size && init.size > 0) {
      return this._formatBytes(init.size);
    }
    if (init.elementCount && init.elementCount > 0) {
      return `${init.elementCount.toLocaleString()} elements`;
    }
    // Compute element count from shape if available
    if (init.shape && init.shape.length > 0) {
      const count = init.shape.reduce((acc, d) => acc * (d || 1), 1);
      return `${count.toLocaleString()} elements`;
    }
    return 'Unknown size';
  }

  /**
   * Build the HTML for a single initializer item.
   * @param {InitializerInfo} init
   * @returns {string}
   */
  _buildItem(init) {
    const shape = this._formatShape(init.shape);
    const dtype = this._resolveDataType(init.dataType);
    const size = this._sizeLabel(init);

    return `
      <div class="initializer-item border rounded p-2 mb-2 cursor-pointer"
           role="button"
           tabindex="0"
           data-init-name="${this._escapeHtml(init.name)}"
           title="Click to highlight in graph"
           aria-label="Initializer ${this._escapeHtml(init.name)}">
        <div class="fw-medium text-truncate mb-1">${this._escapeHtml(init.name)}</div>
        <div class="small text-muted d-flex flex-wrap gap-2">
          <span><i class="fas fa-shapes me-1"></i>${this._escapeHtml(shape)}</span>
          <span><i class="fas fa-tag me-1"></i>${this._escapeHtml(dtype)}</span>
          <span><i class="fas fa-database me-1"></i>${this._escapeHtml(size)}</span>
        </div>
      </div>`;
  }

  /**
   * Attach click and keyboard handlers to initializer items.
   */
  _attachItemHandlers() {
    if (!this._container) return;
    const items = this._container.querySelectorAll('.initializer-item');
    items.forEach((item) => {
      const handler = () => {
        const name = item.dataset.initName;
        if (name && window.EventBus) {
          window.EventBus.emit(CONFIG.EVENTS.NODE_SELECTED, { nodeId: name, source: 'initializer' });
        }
        if (name && window.StateManager) {
          window.StateManager.setSelectedNodeId(name);
        }
      };
      item.addEventListener('click', handler);
      item.addEventListener('keydown', (e) => {
        if (e.key === 'Enter' || e.key === ' ') {
          e.preventDefault();
          handler();
        }
      });
    });
  }

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

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

    const initializers = (model && model.initializers)
      ? model.initializers
      : (model && model.graph && model.graph.initializers)
        ? model.graph.initializers
        : [];

    if (initializers.length === 0) {
      this._container.innerHTML = `
        <p class="text-muted">
          <i class="fas fa-info-circle me-1"></i>No initializers found in this model.
        </p>`;
      return;
    }

    const header = `<p class="text-secondary small mb-2">${initializers.length} initializer${initializers.length !== 1 ? 's' : ''}</p>`;
    const items = initializers.map((init) => this._buildItem(init)).join('');

    this._container.innerHTML = header + items;
    this._attachItemHandlers();
  }

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

window.InitializerDisplay = InitializerDisplay;