// deck.gl-community
// SPDX-License-Identifier: MIT
// Copyright (c) vis.gl contributors

import turfCentroid from '@turf/centroid';
import turfDistance from '@turf/distance';
import turfTransformScale from '@turf/transform-scale';
import {SimpleFeatureCollection, Position, SimpleGeometry} from '../utils/geojson-types';
import {PointerMoveEvent, StartDraggingEvent, StopDraggingEvent} from '../edit-modes/types';
import {EditAction, ModeHandler} from './mode-handler';

// TODO edit-modes: delete handlers once EditMode fully implemented
export class ScaleHandler extends ModeHandler {
  _isScalable: boolean = undefined!;
  _geometryBeingScaled: SimpleFeatureCollection | null | undefined;

  handlePointerMove(event: PointerMoveEvent): {
    editAction: EditAction | null | undefined;
    cancelMapPan: boolean;
  } {
    let editAction: EditAction | null | undefined = null;

    this._isScalable = Boolean(this._geometryBeingScaled) || this.isSelectionPicked(event.picks);

    if (!this._isScalable || !event.pointerDownMapCoords) {
      // Nothing to do
      return {editAction: null, cancelMapPan: false};
    }

    if (event.isDragging && this._geometryBeingScaled) {
      // Scale the geometry
      editAction = this.getScaleAction(event.pointerDownMapCoords, event.mapCoords, 'scaling');
    }

    return {editAction, cancelMapPan: true};
  }

  handleStartDragging(event: StartDraggingEvent): EditAction | null | undefined {
    if (!this._isScalable) {
      return null;
    }

    this._geometryBeingScaled = this.getSelectedFeaturesAsFeatureCollection();
    return null;
  }

  handleStopDragging(event: StopDraggingEvent): EditAction | null | undefined {
    let editAction: EditAction | null | undefined = null;

    if (this._geometryBeingScaled) {
      // Scale the geometry
      editAction = this.getScaleAction(event.pointerDownMapCoords, event.mapCoords, 'scaled');
      this._geometryBeingScaled = null;
    }

    return editAction;
  }

  getCursor({isDragging}: {isDragging: boolean}): string {
    if (this._isScalable) {
      // TODO: look at doing SVG cursors to get a better "scale" cursor
      return 'move';
    }
    return isDragging ? 'grabbing' : 'grab';
  }

  getScaleAction(startDragPoint: Position, currentPoint: Position, editType: string): EditAction {
    const startPosition = startDragPoint;
    const centroid = turfCentroid(this._geometryBeingScaled);
    const factor = getScaleFactor(centroid.geometry.coordinates, startPosition, currentPoint);
    const scaledFeatures = turfTransformScale(this._geometryBeingScaled, factor, {
      origin: centroid
    });

    let updatedData = this.getImmutableFeatureCollection();

    const selectedIndexes = this.getSelectedFeatureIndexes();
    for (let i = 0; i < selectedIndexes.length; i++) {
      const selectedIndex = selectedIndexes[i];
      const movedFeature = scaledFeatures.features[i];
      updatedData = updatedData.replaceGeometry(selectedIndex, movedFeature.geometry);
    }

    return {
      updatedData: updatedData.getObject(),
      editType,
      featureIndexes: selectedIndexes,
      editContext: null
    };
  }
}

function getScaleFactor(centroid: Position, startDragPoint: Position, currentPoint: Position) {
  const startDistance = turfDistance(centroid, startDragPoint);
  const endDistance = turfDistance(centroid, currentPoint);
  return endDistance / startDistance;
}