# All files / utils annotationData.ts

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     import {AnnotationMark, LineHoverDimension, Scale} from '../types'
    import {ANNOTATION_DEFAULT_OVERLAP_HOVER_MARGIN} from '../constants/index'

    export const getAnnotationsPositions = (
      annotationData: AnnotationMark[],
      xScale: Scale,
      yScale: Scale
    ): AnnotationMark[] => {
      const annotationMarks: AnnotationMark[] = []

      annotationData.forEach(annotation => {
        annotationMarks.push({
          ...annotation,
          pin: annotation.pin || 'none',
          startValue:
            annotation.dimension === 'y'
              ? yScale(annotation.startValue)
              : xScale(annotation.startValue),
          stopValue:
            annotation.dimension === 'y'
              ? yScale(annotation.stopValue)
              : xScale(annotation.stopValue),
        })
      })
      return annotationMarks
    }

    // is the mouse within the start/stop area ? (using the margin)
    const isWithinHoverableArea = (
      startValue: number,
      stopValue: number,
      margin: number,
      hoverPosition: number
    ): boolean => {
      return (
        startValue - margin <= hoverPosition && stopValue + margin >= hoverPosition
      )
    }

    const distanceToMousePointer = (
      annotationMark: AnnotationMark,
      hoverPosition: number
    ) => {
      // check if the Annotation is a range type
      if (annotationMark.startValue !== annotationMark.stopValue) {
        if (
          annotationMark.startValue <= hoverPosition &&
          hoverPosition <= annotationMark.stopValue
        ) {
          // hover position is in the range, effective distance is 0
          return 0
        }
        // distance is the shortest of:
        // the distance between hoverPosition and annotation.startValue,
        // and the distance between hoverPosition and annotation.stopValue
        const distanceToStartLine = Math.abs(
          hoverPosition - annotationMark.startValue
        )
        const distanceToStopLine = Math.abs(
          hoverPosition - annotationMark.stopValue
        )
        return Math.min(distanceToStartLine, distanceToStopLine)
      }
      return Math.abs(hoverPosition - annotationMark.startValue)
    }

    /**
     * Summary: do a weighted comparison between the distance of the mouse to range and point
     * annotations.
     *
     * Details:
     * While a mouse is hovering within a range annotation, the 'distance' is zero.
     *
     * But there might be a point annotation overlapping the range,
     * and then when the mouse is directly over that point, it should show the tooltip for
     * the point and not the range
     *
     * Without weighting it, the point annotation hovered tooltip will never show.
     * (very hard to get it *exactly*; and even if so, 0 === 0)
     *
     * If the types of the annotations are different, 'weighting' the range annotation by a small factor
     * (ANNOTATION_DEFAULT_OVERLAP_HOVER_MARGIN, which is equal to 8)
     * so that when you are *very* close to the point;  then the point, and not the range annotation
     * will show up in the tooltip popup.
     *
     * If the two types of annotations being compared are the same, then they will be weighed the same
     * and the weights will cancel each other out and it will be a simple comparison.
     *
     * NOTE:  the overlap hover margin is currently less than the default hover margin (which is 20)
     * If the default hover margin gets below the the overlap hover margin (or the user sets a lower one),
     * then the overlap margin should be reduced.
     */
    const getWeightedDistance = distance => {
      if (distance.annoType === 'range') {
        return distance.dist + ANNOTATION_DEFAULT_OVERLAP_HOVER_MARGIN
      }
      return distance.dist
    }

    export const sortDistances = (dist1, dist2) => {
      return getWeightedDistance(dist1) - getWeightedDistance(dist2)
    }

    /***********************************************************************************
     * ANNOTATIONS HOVERING
     *
     * This returns the index of the annotation in the cell that should have its
     *  tooltip popup appear.
     *
     * hover dimension 'xy' means find annotations only near the mouse position
     * hover dimension 'x' means find annotations along the x-axis at mouse position
     * hover dimension 'y' means find annotations along the y-axis at mouse position
     * hover dimension 'auto' means 'xy' see above
     *
     * Check to see if mouse position is within annotation's hoverable area only when
     *   hover dimension is 'xy' or hover dimension is same as annotation dimension
     *
     * Cross dimensions means the annotation is always hovered, occurs when:
     *   hover dimension is 'x' && annotation dimension is 'y'
     *   hover dimension is 'y' && annotation dimension is 'x'
     *
     *  This method accounts for overlapping annotations; if a point annotation is within a range
     *  annotation, the point annotation tooltip *will* show up when the mouse is within
     *  the ANNOTATION_DEFAULT_OVERLAP_HOVER_MARGIN, which is equal to 10;
     *  which is essentially only when the mouse is right on top of the line.
     *
     *  (see previous method to sort distances for details)
     *
     */
    export const getAnnotationHoverIndices = (
      hoverDimension: LineHoverDimension,
      hoverMargin: number,
      annotationData: AnnotationMark[],
      hoverX: number,
      hoverY: number
    ): number[] => {
      return Array.isArray(annotationData)
        ? annotationData.reduce((result, annotation, i) => {
            if (hoverX === null || hoverY === null) {
              return result
            }
            const {dimension, startValue, stopValue} = annotation
            if (
              (hoverDimension !== 'xy' && hoverDimension !== dimension) ||
              ((hoverDimension === 'xy' || hoverDimension === dimension) &&
                isWithinHoverableArea(
                  startValue,
                  stopValue,
                  hoverMargin,
                  dimension === 'x' ? hoverX : hoverY
                ))
            ) {
              result.push(i)

              if (result.length > 1) {
                const distances = []
                result.forEach(i => {
                  const dist = distanceToMousePointer(
                    annotationData[i],
                    dimension === 'x' ? hoverX : hoverY
                  )
                  const annoType =
                    annotationData[i].startValue === annotationData[i].stopValue
                      ? 'point'
                      : 'range'
                  distances.push({index: i, dist, annoType})
                })

                const closestAnnotation = distances.sort(sortDistances)[0].index
                result = [closestAnnotation]
              }
            }
            return result
          }, [])
        : []
    }