/**
 * Annotation Editor - Fabric.js-based editor for image annotations
 *
 * Alpine.js component for the Maker role to place measurement markers,
 * arrows, and area rectangles on technical drawings.
 *
 * Dependencies:
 *   - Fabric.js v5.3.1 (loaded via CDN before this file)
 *   - Alpine.js (loaded with defer)
 *
 * Annotation JSON Format (output):
 * {
 *   "version": 1,
 *   "width": 800,
 *   "height": 480,
 *   "objects": [
 *     { "type": "marker", "left": 150, "top": 200, "markerNumber": 1, ... },
 *     { "type": "arrow",  "left": 100, "top": 80, "x1": 100, "y1": 80, "x2": 300, "y2": 200, ... },
 *     { "type": "area",   "left": 50,  "top": 60, "width": 150, "height": 100, ... }
 *   ]
 * }
 *
 * Usage:
 * <div x-data="annotationEditor()"
 *      x-init="loadBackgroundImage('/path/to/image.jpg')">
 *   <canvas x-ref="fabricCanvas"></canvas>
 * </div>
 */

function annotationEditor() {
  'use strict';

  // ---- Debounce utility ----

  function debounce(fn, delay) {
    var timer = null;
    return function () {
      var context = this;
      var args = arguments;
      if (timer) clearTimeout(timer);
      timer = setTimeout(function () {
        fn.apply(context, args);
      }, delay);
    };
  }

  return {
    // ---- State ----

    /** @type {fabric.Canvas|null} */
    canvas: null,
    /** @type {HTMLCanvasElement|null} */
    canvasEl: null,

    /** Current interaction mode: 'select' | 'marker' | 'arrow' | 'rect' | 'pan' */
    activeMode: 'select',

    /** Next auto-assigned marker number */
    nextMarkerNumber: 1,

    /** Current zoom level (1 = 100%) */
    zoomLevel: 1,

    /** Whether a background image has been loaded */
    imageLoaded: false,

    /** Whether the canvas has unsaved changes */
    isDirty: false,

    // ----------------------------------------------------------------
    // Initialization
    // ----------------------------------------------------------------

    /**
     * Alpine init hook.
     * Creates the Fabric.js canvas instance and wires up all event listeners.
     */
    init() {
      this.canvasEl = this.$refs.fabricCanvas;
      if (!this.canvasEl) {
        console.error('AnnotationEditor: canvas ref "fabricCanvas" not found');
        return;
      }

      this.canvas = new fabric.Canvas(this.canvasEl, {
        selection: true,
        preserveObjectStacking: true,
        backgroundColor: '#f1f5f9',
      });

      this.setupEvents();
      this.setupKeyboard();
      this.resizeCanvas();

      this._debouncedResize = debounce(this.resizeCanvas.bind(this), 200);
      window.addEventListener('resize', this._debouncedResize);

      // ---- Bridge: listen for commands from recipeEditor ----
      var self = this;

      this._onToolChange = function (e) {
        if (e.detail && e.detail.tool) {
          self.setMode(e.detail.tool);
        }
      };
      window.addEventListener('anno-tool-change', this._onToolChange);

      this._onDeleteSelected = function () {
        self.deleteSelected();
      };
      window.addEventListener('anno-delete-selected', this._onDeleteSelected);

      this._onZoom = function (e) {
        if (e.detail && e.detail.delta > 0) {
          self.zoomIn();
        } else {
          self.zoomOut();
        }
      };
      window.addEventListener('anno-zoom', this._onZoom);

      this._onZoomReset = function () {
        self.resetZoom();
      };
      window.addEventListener('anno-zoom-reset', this._onZoomReset);

      this._onImageLoaded = function (e) {
        if (e.detail && e.detail.path) {
          // Wait for x-show transition to reveal the canvas
          setTimeout(function () {
            self.resizeCanvas();
            self.loadBackgroundImage('/api/files/' + e.detail.path);
            if (e.detail.annotations) {
              self.loadAnnotationsJson(e.detail.annotations);
            }
          }, 150);
        }
      };
      window.addEventListener('image-loaded', this._onImageLoaded);

      // ---- Initial load: check parent scope for existing file ----
      var filePath = this.currentFilePath; // from parent recipeEditor scope
      if (filePath) {
        var annoJson = this.annotationsJson; // from parent recipeEditor scope
        this.loadBackgroundImage('/api/files/' + filePath);
        if (annoJson) {
          this.loadAnnotationsJson(annoJson);
        }
      }
    },

    // ----------------------------------------------------------------
    // Background image
    // ----------------------------------------------------------------

    /**
     * Load an image as the canvas background.
     * Scales the image to fit within the canvas while maintaining aspect ratio
     * and never exceeding the original size (scale <= 1).
     *
     * @param {string} imageUrl - URL of the image to load
     */
    loadBackgroundImage(imageUrl) {
      if (!this.canvas) return;

      fabric.Image.fromURL(
        imageUrl,
        function (img) {
          if (!img || !img.width || !img.height) {
            console.error('AnnotationEditor: failed to load background image');
            return;
          }

          var scale = Math.min(
            this.canvas.width / img.width,
            this.canvas.height / img.height,
            1 // never upscale
          );

          this.canvas.setBackgroundImage(
            img,
            this.canvas.renderAll.bind(this.canvas),
            {
              scaleX: scale,
              scaleY: scale,
              originX: 'left',
              originY: 'top',
            }
          );

          this.imageLoaded = true;
        }.bind(this),
        { crossOrigin: 'anonymous' }
      );
    },

    // ----------------------------------------------------------------
    // Object creation - Markers
    // ----------------------------------------------------------------

    /**
     * Add a numbered circle marker at the given position.
     *
     * @param {number} x - left position on canvas
     * @param {number} y - top position on canvas
     * @param {number} [number] - explicit marker number (auto-increments if omitted)
     * @returns {fabric.Group} the created marker group
     */
    addMarker(x, y, number) {
      var markerNumber = number || this.nextMarkerNumber++;

      var circle = new fabric.Circle({
        radius: 16,
        fill: '#2563EB',
        originX: 'center',
        originY: 'center',
        stroke: '#ffffff',
        strokeWidth: 2,
      });

      var text = new fabric.Text(markerNumber.toString(), {
        fontSize: 14,
        fill: '#ffffff',
        fontFamily: 'Inter, sans-serif',
        fontWeight: 'bold',
        originX: 'center',
        originY: 'center',
      });

      var marker = new fabric.Group([circle, text], {
        left: x,
        top: y,
        selectable: true,
        hasControls: false,
        hasBorders: true,
        lockScalingX: true,
        lockScalingY: true,
        // Custom properties
        objectType: 'marker',
        markerNumber: markerNumber,
      });

      this.canvas.add(marker);
      this.canvas.setActiveObject(marker);
      this.isDirty = true;
      window.dispatchEvent(new CustomEvent('annotations-changed', { detail: { json: this.getAnnotationsJson() } }));
      return marker;
    },

    // ----------------------------------------------------------------
    // Object creation - Arrows
    // ----------------------------------------------------------------

    /**
     * Add an arrow (line + triangular arrowhead) between two points.
     *
     * @param {number} x1 - start x
     * @param {number} y1 - start y
     * @param {number} x2 - end x
     * @param {number} y2 - end y
     * @returns {fabric.Group} the created arrow group
     */
    addArrow(x1, y1, x2, y2) {
      var line = new fabric.Line([x1, y1, x2, y2], {
        stroke: '#DC2626',
        strokeWidth: 2,
        originX: 'center',
        originY: 'center',
      });

      var angle = (Math.atan2(y2 - y1, x2 - x1) * 180) / Math.PI;

      var arrowHead = new fabric.Triangle({
        left: x2,
        top: y2,
        originX: 'center',
        originY: 'center',
        width: 12,
        height: 12,
        fill: '#DC2626',
        angle: angle + 90,
      });

      var arrow = new fabric.Group([line, arrowHead], {
        selectable: true,
        objectType: 'arrow',
        // Store original endpoints for serialization
        arrowX1: x1,
        arrowY1: y1,
        arrowX2: x2,
        arrowY2: y2,
      });

      this.canvas.add(arrow);
      this.isDirty = true;
      window.dispatchEvent(new CustomEvent('annotations-changed', { detail: { json: this.getAnnotationsJson() } }));
      return arrow;
    },

    // ----------------------------------------------------------------
    // Object creation - Rectangles
    // ----------------------------------------------------------------

    /**
     * Add a dashed-outline area rectangle.
     *
     * @param {number} x      - left position
     * @param {number} y      - top position
     * @param {number} [width=150]  - rectangle width
     * @param {number} [height=100] - rectangle height
     * @returns {fabric.Rect} the created rectangle
     */
    addRect(x, y, width, height) {
      var rect = new fabric.Rect({
        left: x,
        top: y,
        width: width || 150,
        height: height || 100,
        fill: 'rgba(37, 99, 235, 0.1)',
        stroke: '#2563EB',
        strokeWidth: 2,
        strokeDashArray: [5, 3],
        selectable: true,
        objectType: 'area',
      });

      this.canvas.add(rect);
      this.isDirty = true;
      window.dispatchEvent(new CustomEvent('annotations-changed', { detail: { json: this.getAnnotationsJson() } }));
      return rect;
    },

    // ----------------------------------------------------------------
    // Toolbar / mode switching
    // ----------------------------------------------------------------

    /**
     * Set the current interaction mode.
     *
     * @param {'select'|'marker'|'arrow'|'rect'|'pan'} mode
     */
    setMode(mode) {
      this.activeMode = mode;

      if (mode === 'select') {
        this.canvas.selection = true;
        this.canvas.defaultCursor = 'default';
        this.canvas.forEachObject(function (o) {
          o.selectable = true;
        });
      } else if (mode === 'pan') {
        this.canvas.selection = false;
        this.canvas.defaultCursor = 'grab';
        this.canvas.forEachObject(function (o) {
          o.selectable = false;
        });
      } else {
        // marker, arrow, rect
        this.canvas.selection = false;
        this.canvas.defaultCursor = 'crosshair';
        this.canvas.discardActiveObject();
      }

      this.canvas.renderAll();
    },

    // ----------------------------------------------------------------
    // Mouse events
    // ----------------------------------------------------------------

    /**
     * Wire up all Fabric.js mouse events for drawing, panning, selection,
     * and zoom.
     */
    setupEvents() {
      var self = this;
      var isDrawing = false;
      var drawStartX = 0;
      var drawStartY = 0;
      var tempRect = null;
      var tempLine = null;
      var isPanning = false;
      var lastPanX = 0;
      var lastPanY = 0;

      // ---- mouse:down ----

      this.canvas.on('mouse:down', function (opt) {
        var pointer = self.canvas.getPointer(opt.e);

        if (self.activeMode === 'marker') {
          self.addMarker(pointer.x, pointer.y);
          self.setMode('select');
        } else if (self.activeMode === 'arrow') {
          isDrawing = true;
          drawStartX = pointer.x;
          drawStartY = pointer.y;
          // Preview line
          tempLine = new fabric.Line(
            [drawStartX, drawStartY, drawStartX, drawStartY],
            {
              stroke: '#DC2626',
              strokeWidth: 2,
              strokeDashArray: [4, 4],
              selectable: false,
              evented: false,
              objectType: '_temp',
            }
          );
          self.canvas.add(tempLine);
        } else if (self.activeMode === 'rect') {
          isDrawing = true;
          drawStartX = pointer.x;
          drawStartY = pointer.y;
          // Preview rect
          tempRect = new fabric.Rect({
            left: drawStartX,
            top: drawStartY,
            width: 0,
            height: 0,
            fill: 'rgba(37, 99, 235, 0.05)',
            stroke: '#2563EB',
            strokeWidth: 1,
            strokeDashArray: [4, 4],
            selectable: false,
            evented: false,
            objectType: '_temp',
          });
          self.canvas.add(tempRect);
        } else if (self.activeMode === 'pan') {
          isPanning = true;
          lastPanX = opt.e.clientX;
          lastPanY = opt.e.clientY;
          self.canvas.defaultCursor = 'grabbing';
        }
      });

      // ---- mouse:move ----

      this.canvas.on('mouse:move', function (opt) {
        if (isPanning) {
          var vpt = self.canvas.viewportTransform;
          vpt[4] += opt.e.clientX - lastPanX;
          vpt[5] += opt.e.clientY - lastPanY;
          lastPanX = opt.e.clientX;
          lastPanY = opt.e.clientY;
          self.canvas.requestRenderAll();
          return;
        }

        if (!isDrawing) return;
        var pointer = self.canvas.getPointer(opt.e);

        if (self.activeMode === 'arrow' && tempLine) {
          tempLine.set({ x2: pointer.x, y2: pointer.y });
          self.canvas.requestRenderAll();
        } else if (self.activeMode === 'rect' && tempRect) {
          var x = Math.min(drawStartX, pointer.x);
          var y = Math.min(drawStartY, pointer.y);
          var w = Math.abs(pointer.x - drawStartX);
          var h = Math.abs(pointer.y - drawStartY);
          tempRect.set({ left: x, top: y, width: w, height: h });
          self.canvas.requestRenderAll();
        }
      });

      // ---- mouse:up ----

      this.canvas.on('mouse:up', function (opt) {
        // Clean up temp preview objects
        if (tempLine) {
          self.canvas.remove(tempLine);
          tempLine = null;
        }
        if (tempRect) {
          self.canvas.remove(tempRect);
          tempRect = null;
        }

        if (isDrawing) {
          var pointer = self.canvas.getPointer(opt.e);

          if (self.activeMode === 'arrow') {
            var dx = pointer.x - drawStartX;
            var dy = pointer.y - drawStartY;
            var dist = Math.sqrt(dx * dx + dy * dy);
            if (dist > 10) {
              self.addArrow(drawStartX, drawStartY, pointer.x, pointer.y);
            }
          } else if (self.activeMode === 'rect') {
            var w = Math.abs(pointer.x - drawStartX);
            var h = Math.abs(pointer.y - drawStartY);
            var x = Math.min(drawStartX, pointer.x);
            var y = Math.min(drawStartY, pointer.y);
            if (w > 5 && h > 5) {
              self.addRect(x, y, w, h);
            }
          }

          isDrawing = false;
          self.setMode('select');
        }

        if (isPanning) {
          isPanning = false;
          self.canvas.defaultCursor = 'grab';
        }
      });

      // ---- Selection events ----

      this.canvas.on('selection:created', function (e) {
        window.dispatchEvent(new CustomEvent('annotation-selected', { detail: { selected: true } }));
        var selected = e.selected;
        if (selected && selected.length === 1 && selected[0].objectType === 'marker') {
          window.dispatchEvent(new CustomEvent('marker-selected', {
            detail: { markerNumber: selected[0].markerNumber }
          }));
        }
      });

      this.canvas.on('selection:updated', function (e) {
        window.dispatchEvent(new CustomEvent('annotation-selected', { detail: { selected: true } }));
        var selected = e.selected;
        if (selected && selected.length === 1 && selected[0].objectType === 'marker') {
          window.dispatchEvent(new CustomEvent('marker-selected', {
            detail: { markerNumber: selected[0].markerNumber }
          }));
        }
      });

      this.canvas.on('selection:cleared', function () {
        window.dispatchEvent(new CustomEvent('annotation-selected', { detail: { selected: false } }));
        window.dispatchEvent(new CustomEvent('marker-selected', { detail: { markerNumber: null } }));
      });

      // ---- Object modification ----

      this.canvas.on('object:modified', function () {
        self.isDirty = true;
        window.dispatchEvent(new CustomEvent('annotations-changed', { detail: { json: self.getAnnotationsJson() } }));
      });

      this.canvas.on('object:moved', function () {
        self.isDirty = true;
        window.dispatchEvent(new CustomEvent('annotations-changed', { detail: { json: self.getAnnotationsJson() } }));
      });

      // ---- Zoom with mouse wheel ----

      this.canvas.on('mouse:wheel', function (opt) {
        var delta = opt.e.deltaY;
        var zoom = self.canvas.getZoom();
        zoom *= Math.pow(0.999, delta);
        zoom = Math.max(0.25, Math.min(5, zoom));
        self.canvas.zoomToPoint(
          { x: opt.e.offsetX, y: opt.e.offsetY },
          zoom
        );
        self.zoomLevel = zoom;
        opt.e.preventDefault();
        opt.e.stopPropagation();
      });
    },

    // ----------------------------------------------------------------
    // Keyboard shortcuts
    // ----------------------------------------------------------------

    /**
     * Register global keyboard shortcuts.
     * Ignored when focus is inside input / textarea elements.
     */
    setupKeyboard() {
      var self = this;

      document.addEventListener('keydown', function (e) {
        // Skip when typing in form fields
        var tag = e.target.tagName;
        if (tag === 'INPUT' || tag === 'TEXTAREA' || tag === 'SELECT') return;
        if (e.target.isContentEditable) return;

        if (e.key === 'Delete' || e.key === 'Backspace') {
          e.preventDefault();
          self.deleteSelected();
        } else if (e.key === 'Escape') {
          self.setMode('select');
          self.canvas.discardActiveObject();
          self.canvas.renderAll();
        }
      });
    },

    // ----------------------------------------------------------------
    // Object manipulation
    // ----------------------------------------------------------------

    /**
     * Delete the currently selected object(s) from the canvas.
     */
    deleteSelected() {
      var active = this.canvas.getActiveObject();
      if (!active) return;

      if (active.type === 'activeSelection') {
        var self = this;
        active.forEachObject(function (obj) {
          self.canvas.remove(obj);
        });
        this.canvas.discardActiveObject();
      } else {
        this.canvas.remove(active);
      }

      this.isDirty = true;
      window.dispatchEvent(new CustomEvent('annotations-changed', { detail: { json: this.getAnnotationsJson() } }));
      this.canvas.renderAll();
    },

    /**
     * Clear all annotation objects from the canvas (keeps background image).
     */
    clearAll() {
      this.canvas.getObjects().slice().forEach(
        function (obj) {
          this.canvas.remove(obj);
        }.bind(this)
      );
      this.nextMarkerNumber = 1;
      this.isDirty = true;
      window.dispatchEvent(new CustomEvent('annotations-changed', { detail: { json: this.getAnnotationsJson() } }));
      this.canvas.renderAll();
    },

    // ----------------------------------------------------------------
    // Zoom controls
    // ----------------------------------------------------------------

    /**
     * Zoom in by 20%.
     */
    zoomIn() {
      var zoom = Math.min(this.canvas.getZoom() * 1.2, 5);
      this.canvas.setZoom(zoom);
      this.zoomLevel = zoom;
    },

    /**
     * Zoom out by 20%.
     */
    zoomOut() {
      var zoom = Math.max(this.canvas.getZoom() / 1.2, 0.25);
      this.canvas.setZoom(zoom);
      this.zoomLevel = zoom;
    },

    /**
     * Reset zoom and pan to default (1:1, origin at top-left).
     */
    resetZoom() {
      this.canvas.setViewportTransform([1, 0, 0, 1, 0, 0]);
      this.canvas.setZoom(1);
      this.zoomLevel = 1;
    },

    // ----------------------------------------------------------------
    // Canvas sizing
    // ----------------------------------------------------------------

    /**
     * Resize the Fabric.js canvas to fill its parent container.
     * Maintains a minimum 5:3 aspect ratio (height = width * 0.6).
     */
    resizeCanvas() {
      var container = this.canvasEl ? this.canvasEl.parentElement : null;
      if (!container || !this.canvas) return;

      var width = container.clientWidth;
      var height = Math.max(400, Math.round(width * 0.6));

      this.canvas.setWidth(width);
      this.canvas.setHeight(height);
      this.canvas.renderAll();
    },

    // ----------------------------------------------------------------
    // Serialization - Export
    // ----------------------------------------------------------------

    /**
     * Serialize all canvas annotation objects to a JSON string.
     *
     * @returns {string} JSON representation of all annotations
     */
    getAnnotationsJson() {
      var objects = this.canvas.getObjects().map(function (obj) {
        var data = {
          type: obj.objectType || obj.type,
          left: Math.round(obj.left * 100) / 100,
          top: Math.round(obj.top * 100) / 100,
          width: Math.round((obj.width || 0) * 100) / 100,
          height: Math.round((obj.height || 0) * 100) / 100,
          scaleX: Math.round((obj.scaleX || 1) * 1000) / 1000,
          scaleY: Math.round((obj.scaleY || 1) * 1000) / 1000,
          angle: Math.round((obj.angle || 0) * 100) / 100,
          markerNumber: obj.markerNumber || null,
        };

        // Arrow-specific: store original endpoints
        if (obj.objectType === 'arrow') {
          data.x1 = obj.arrowX1 != null ? Math.round(obj.arrowX1 * 100) / 100 : null;
          data.y1 = obj.arrowY1 != null ? Math.round(obj.arrowY1 * 100) / 100 : null;
          data.x2 = obj.arrowX2 != null ? Math.round(obj.arrowX2 * 100) / 100 : null;
          data.y2 = obj.arrowY2 != null ? Math.round(obj.arrowY2 * 100) / 100 : null;
        }

        return data;
      });

      return JSON.stringify({
        version: 1,
        width: this.canvas.width,
        height: this.canvas.height,
        objects: objects,
      });
    },

    // ----------------------------------------------------------------
    // Serialization - Import
    // ----------------------------------------------------------------

    /**
     * Load annotations from a JSON string and recreate all objects on the canvas.
     * Clears any existing annotation objects first (keeps background image).
     *
     * @param {string|Object} jsonString - JSON string or parsed object
     */
    loadAnnotationsJson(jsonString) {
      if (!jsonString) return;

      try {
        var data =
          typeof jsonString === 'string' ? JSON.parse(jsonString) : jsonString;

        // Remove existing objects
        this.canvas.getObjects().slice().forEach(
          function (obj) {
            this.canvas.remove(obj);
          }.bind(this)
        );

        var objects = data.objects || [];

        for (var i = 0; i < objects.length; i++) {
          var obj = objects[i];

          if (obj.type === 'marker') {
            this.addMarker(obj.left, obj.top, obj.markerNumber);
          } else if (obj.type === 'arrow') {
            // Reconstruct arrow from stored endpoints or from position/size
            var x1 = obj.x1 != null ? obj.x1 : obj.left;
            var y1 = obj.y1 != null ? obj.y1 : obj.top;
            var x2 = obj.x2 != null ? obj.x2 : obj.left + (obj.width || 100);
            var y2 = obj.y2 != null ? obj.y2 : obj.top + (obj.height || 50);
            this.addArrow(x1, y1, x2, y2);
          } else if (obj.type === 'area') {
            var w = (obj.width || 150) * (obj.scaleX || 1);
            var h = (obj.height || 100) * (obj.scaleY || 1);
            this.addRect(obj.left, obj.top, w, h);
          }
        }

        // Recalculate nextMarkerNumber
        var markerNumbers = objects
          .filter(function (o) {
            return o.type === 'marker' && o.markerNumber;
          })
          .map(function (o) {
            return o.markerNumber;
          });

        this.nextMarkerNumber =
          markerNumbers.length > 0 ? Math.max.apply(null, markerNumbers) + 1 : 1;

        this.isDirty = false;
        this.canvas.renderAll();
      } catch (e) {
        console.error('AnnotationEditor: failed to load annotations:', e);
      }
    },

    // ----------------------------------------------------------------
    // Marker query helpers
    // ----------------------------------------------------------------

    /**
     * Get a sorted list of all markers currently on the canvas.
     *
     * @returns {Array<{number: number, left: number, top: number}>}
     */
    getMarkers() {
      return this.canvas
        .getObjects()
        .filter(function (obj) {
          return obj.objectType === 'marker';
        })
        .map(function (obj) {
          return {
            number: obj.markerNumber,
            left: Math.round(obj.left * 100) / 100,
            top: Math.round(obj.top * 100) / 100,
          };
        })
        .sort(function (a, b) {
          return a.number - b.number;
        });
    },

    /**
     * Highlight a specific marker by its number.
     * Selects it on the canvas so the user sees the Fabric selection border.
     *
     * @param {number} markerNumber
     */
    selectMarkerByNumber(markerNumber) {
      var target = null;
      this.canvas.forEachObject(function (obj) {
        if (obj.objectType === 'marker' && obj.markerNumber === markerNumber) {
          target = obj;
        }
      });

      if (target) {
        this.canvas.setActiveObject(target);
        this.canvas.renderAll();
      }
    },

    // ----------------------------------------------------------------
    // Cleanup
    // ----------------------------------------------------------------

    /**
     * Destroy the Fabric.js canvas and remove event listeners.
     * Call this when the Alpine component is removed from the DOM.
     */
    destroy() {
      if (this._debouncedResize) {
        window.removeEventListener('resize', this._debouncedResize);
      }
      if (this._onToolChange) {
        window.removeEventListener('anno-tool-change', this._onToolChange);
      }
      if (this._onDeleteSelected) {
        window.removeEventListener('anno-delete-selected', this._onDeleteSelected);
      }
      if (this._onZoom) {
        window.removeEventListener('anno-zoom', this._onZoom);
      }
      if (this._onZoomReset) {
        window.removeEventListener('anno-zoom-reset', this._onZoomReset);
      }
      if (this._onImageLoaded) {
        window.removeEventListener('image-loaded', this._onImageLoaded);
      }
      if (this.canvas) {
        this.canvas.dispose();
        this.canvas = null;
      }
    },
  };
}