iwmlib/lib/interaction.js

/* eslint-disable no-unused-vars */
/* globals Hammer, propagating */
/*eslint no-console: ["error", { allow: ["log", "warn", "info", "error"] }]*/

import Interface from './interface.js'
import { Points, MapProxy } from './utils.js'
import Events from './events.js'
import Logging from './logging.js'

/** Interaction patterns

    See interaction.html for explanation
*/

export class IInteractionTarget extends Interface {
    capture(event) {
        return typeof true
    }

    onStart(event, interaction) {}
    onMove(event, interaction) {}
    onEnd(event, interaction) {}

    onMouseWheel(event) {}
}

export class IInteractionMapperTarget extends Interface {
    capture(event) {
        return typeof true
    }

    findTarget(event, local, global) {
        return IInteractionTarget
    }
}

export class PointMap extends MapProxy {
    // Collects touch points, mouse coordinates, etc. as key value pairs.
    // Keys are pointer and touch ids, the special "mouse" key.
    // Values are points, i.e. all objects with numeric x and y properties.
    constructor(points = {}) {
        super()
        for (let key in points) {
            this.set(key, points[key])
        }
    }

    toString() {
        let points = []
        for (let key of this.keys()) {
            let value = this.get(key)
            points.push(`${key}:{x:${value.x}, y:${value.y}}`)
        }
        let attrs = points.join(', ')
        return `[PointMap ${attrs}]`
    }

    clone() {
        let result = new PointMap()
        for (let key of this.keys()) {
            let value = this.get(key)
            result.set(key, { x: value.x, y: value.y })
        }
        return result
    }

    keyOf(value) {
        for (let key of this.keys()) {
            let p = this.get(key)
            if (p.x == value.x && p.y == value.y) {
                return key
            }
        }
        return null
    }

    firstKey() {
        for (let key of this.keys()) {
            return key
        }
        return null
    }

    first() {
        for (let key of this.keys()) {
            return this.get(key)
        }
        return null
    }

    farthests() {
        if (this.size == 0) {
            return null
        }
        let pairs = []
        for (let key of this.keys()) {
            let p = this.get(key)
            p.key = key
            for (let k of this.keys()) {
                let q = this.get(k)
                q.key = k
                pairs.push([p, q])
            }
        }
        let sorted = pairs.sort((a, b) => {
            return Points.distance(b[0], b[1]) - Points.distance(a[0], a[1])
        })
        return sorted[0]
    }

    mean() {
        if (this.size == 0) {
            return null
        }
        let x = 0.0,
            y = 0.0
        for (let p of this.values()) {
            x += p.x
            y += p.y
        }
        return { x: x / this.size, y: y / this.size }
    }
}

export class InteractionDelta {
    /**
     *Creates an instance of InteractionDelta.
     * @param {*} x
     * @param {*} y
     * @param {*} zoom
     * @param {*} rotate
     * @param {*} about
     * @param {*} number - number of involved pointer
     * @param {*} distance - distance of farthests touch points
     * @memberof InteractionDelta
     */
    constructor(x, y, zoom, rotate, about, number, distance) {
        this.x = x
        this.y = y
        this.zoom = zoom
        this.rotate = rotate
        this.about = about
        this.number = number
        this.distance = distance
    }

    toString() {
        let values = []
        for (let key of Object.keys(this)) {
            let value = this[key]
            if (key == 'about') {
                values.push(`${key}:{x:${value.x}, y:${value.y}}`)
            } else {
                values.push(`${key}:${value}`)
            }
        }
        let attrs = values.join(', ')
        return `[InteractionDelta ${attrs}]`
    }
}

export class InteractionPoints {
    constructor(parent = null) {
        this.parent = parent
        this.current = new PointMap()
        this.previous = new PointMap()
        this.start = new PointMap()
        this.ended = new PointMap()
        this.timestamps = new Map()
    }

    moved(key) {
        let current = this.current.get(key)
        let previous = this.previous.get(key)
        return Points.subtract(current, previous)
    }

    move() {
        let current = this.current.mean()
        let previous = this.previous.mean()
        return Points.subtract(current, previous)
    }

    /**
     * Computes the delta between previous and current angles. Corrects
     * value that are larger than 45°
     * @param {*} a
     * @param {*} b
     * @returns delta
     */
    diffAngle(a, b) {
        let alpha = Math.atan2(Math.sin(a - b), Math.cos(a - b))
        if (Math.abs(alpha) > Math.PI / 4) {
            alpha -= Math.PI
        }
        return alpha
    }

    /**
     * Computes the delta between interaction points at t and t+1.
     *
     * @returns InteractionDelta
     * @memberof InteractionPoints
     */
    delta() {
        let prev = []
        let curr = []
        let cm = { x: 0, y: 0}
        let pm = { x: 0, y: 0}
        let count = 0
        for(let key of this.current.keys()) {
            if (this.previous.has(key)) {
                let p = this.previous.get(key)
                let c = this.current.get(key)
                pm = Points.add(pm, p)
                cm = Points.add(cm, c)
                prev.push(p)
                curr.push(c)
                count += 1
            }
        }
        if (count > 0) {
            pm = Points.multiplyScalar(pm, 1 / count)
            cm = Points.multiplyScalar(cm, 1 / count)
            let delta = Points.subtract(cm, pm)
            let scale = 0
            let scaled = 0
            let alpha = 0
            let zoom = 1
            for(let i=0; i<count; i++) {
                let p = prev[i]
                let c = curr[i]
                let previousAngle = Points.angle(p, pm)
                let currentAngle = Points.angle(c, cm)
                let diff = this.diffAngle(currentAngle, previousAngle)
                alpha += diff

                let distance1 = Points.distance(p, pm)
                let distance2 = Points.distance(c, cm)
                if (distance1 != 0 && distance2 != 0) {
                    scale += distance2 / distance1
                    scaled += 1
                }
            }
            if (scaled > 0) {
                zoom = scale / scaled
            }
            alpha /= count

            let current = this.current.farthests()

            let c1 = current[0]
            let c2 = current[1]
            let distance2 = Points.distance(c1, c2)

            return new InteractionDelta(
                delta.x,
                delta.y,
                zoom,
                alpha,
                cm,
                count,
                distance2
            )
        }
        else {
            return null
        }
    }

    /**
     * Computes the delta between interaction points at t and t+1.
     *
     * @returns InteractionDelta
     * @memberof InteractionPoints
     */
    deltaByTwoFarthestsPoints() {
        let csize = this.current.size
        let psize = this.previous.size
        if (csize >= 2 && csize == psize) {
            // Reduce to the two farthests points
            let current = this.current.farthests()

            let c1 = current[0]
            let c2 = current[1]

            let p1 = this.previous.get(c1.key)
            let p2 = this.previous.get(c2.key)

            let d1 = Points.subtract(c1, p1)
            let d2 = Points.subtract(c2, p2)
            let cm = Points.mean(c1, c2)

            // Using the mean leads to jumps between time slices with 3 and 2 fingers
            // We use the mean of deltas instead
            let delta = Points.mean(d1, d2)
            let zoom = 1.0
            let distance1 = Points.distance(p1, p2)
            let distance2 = Points.distance(c1, c2)
            if (distance1 != 0 && distance2 != 0) {
                zoom = distance2 / distance1
            }
            let currentAngle = Points.angle(c1, c2)
            let previousAngle = Points.angle(p1, p2)
            let alpha = this.diffAngle(currentAngle, previousAngle)
            return new InteractionDelta(
                delta.x,
                delta.y,
                zoom,
                alpha,
                cm,
                csize,
                distance2
            )
        } else if (
            csize == 1 &&
            psize == 1 &&
            this.current.firstKey() == this.previous.firstKey()
        ) {
            // We need to ensure that the keys are the same, since single points with different keys
            // can jump
            let current = this.current.first()
            let previous = this.previous.first()
            let delta = Points.subtract(current, previous)
            return new InteractionDelta(
                delta.x,
                delta.y,
                1.0,
                0.0,
                current,
                csize
            )
        }
        return null
    }

    started(key, point) {
        this.current.set(key, point)
        this.start.set(key, point)
        this.previous.set(key, point)
        this.timestamps.set(key, performance.now())
    }

    update(key, point) {
        // Returns true iff the key is new
        this.current.set(key, point)
        if (!this.start.has(key)) {
            this.start.set(key, point)
            this.previous.set(key, point)
            this.timestamps.set(key, performance.now())
            return true
        }
        return false
    }

    updatePrevious() {
        for (let key of this.current.keys()) {
            this.previous.set(key, this.current.get(key))
        }
    }

    stop(key, point) {
        if (this.current.has(key)) {
            this.current.delete(key)
            this.previous.delete(key)
            this.ended.set(key, point)
        }
    }

    finish(key, point) {
        this.current.delete(key)
        this.previous.delete(key)
        this.start.delete(key)
        this.timestamps.delete(key)
        this.ended.delete(key)
    }

    isFinished() {
        return this.current.size == 0
    }

    isNoLongerTwoFinger() {
        return this.previous.size > 1 && this.current.size < 2
    }

    isTap(key) {
        return this.parent.isTap(key)
    }

    isDoubleTap(key) {
        return this.parent.isDoubleTap(key)
    }

    isLongPress(key) {
        return this.parent.isLongPress(key)
    }
}

export class Interaction extends InteractionPoints {
    constructor(tapDistance = 10, tapDuration = 250.0, longPressTime = 500.0) {
        super()
        this.tapDistance = tapDistance
        this.tapCounts = new Map()
        this.tapPositions = new Map()
        this.tapTimestamps = new Map()
        this.tapDuration = tapDuration
        this.longPressTime = longPressTime
        this.targets = new Map()
        this.subInteractions = new Map() // target:Object : InteractionPoints
    }

    stop(key, point) {
        super.stop(key, point)
        for (let points of this.subInteractions.values()) {
            points.stop(key, point)
        }
    }

    addTarget(key, target) {
        this.targets.set(key, target)
        this.subInteractions.set(target, new InteractionPoints(this))
    }

    removeTarget(key) {
        let target = this.targets.get(key)
        this.targets.delete(key)
        // Only remove target if no keys are refering to the target
        let remove = true
        for (let t of this.targets.values()) {
            if (target === t) {
                remove = false
            }
        }
        if (remove) {
            this.subInteractions.delete(target)
        }
    }

    finish(key, point) {
        super.finish(key, point)
        this.removeTarget(key)
    }

    mapInteraction(points, aspects, mappingFunc) {
        // Map centrally registered points to target interactions
        // Returns an array of [target, updated subInteraction] pairs
        let result = new Map()
        for (let key in points) {
            if (this.targets.has(key)) {
                let target = this.targets.get(key)
                if (this.subInteractions.has(target)) {
                    let interaction = this.subInteractions.get(target)
                    for (let aspect of aspects) {
                        let pointMap = this[aspect]
                        let point = pointMap.get(key)
                        let mapped = mappingFunc(point, target)
                        interaction[aspect].set(key, mapped)
                    }
                    result.set(target, interaction)
                }
            }
        }
        return result
    }

    registerTap(key, point) {
        if (this.tapCounts.has(key)) {
            let count = this.tapCounts.get(key)
            this.tapCounts.set(key, count + 1)
        } else {
            this.tapCounts.set(key, 1)
        }
        this.tapPositions.set(key, point)
        this.tapTimestamps.set(key, performance.now())
    }

    unregisterTap(key) {
        this.tapCounts.delete(key)
        this.tapPositions.delete(key)
        this.tapTimestamps.delete(key)
    }

    isTap(key) {
        let ended = this.ended.get(key)
        let start = this.start.get(key)
        if (
            start &&
            ended &&
            Points.distance(ended, start) < this.tapDistance
        ) {
            let t1 = this.timestamps.get(key)
            let tookLong = performance.now() > t1 + this.longPressTime
            if (tookLong) {
                return false
            }
            return true
        }
        return false
    }

    isDoubleTap(key) {
        let ended = this.ended.get(key)
        if (this.tapCounts.has(key) && this.tapCounts.get(key) > 2) {
            this.unregisterTap(key)
        }
        if (this.tapPositions.has(key)) {
            let pos = this.tapPositions.get(key)
            if (Points.distance(ended, pos) > this.tapDistance) {
                this.unregisterTap(key)
            }
        }
        if (
            this.tapTimestamps.has(key) &&
            performance.now() > this.tapTimestamps.get(key) + this.tapDuration
        ) {
            //console.log("tap too long")
            this.unregisterTap(key)
        }
        let result = false
        if (this.isTap(key)) {
            this.registerTap(key, ended)
            result = this.tapCounts.get(key) == 2
        } else {
            this.unregisterTap(key)
        }
        //console.log("isDoubleTap", this.tapCounts.get(key), result)
        return result
    }

    isAnyTap() {
        for (let key of this.ended.keys()) {
            if (this.isTap(key)) return true
        }
        return false
    }

    isLongPress(key) {
        let ended = this.ended.get(key)
        let start = this.start.get(key)
        if (
            start &&
            ended &&
            Points.distance(ended, start) < this.tapDistance
        ) {
            let t1 = this.timestamps.get(key)
            let tookLong = performance.now() > t1 + this.longPressTime
            if (tookLong) {
                return true
            }
            return false
        }
        return false
    }

    isAnyLongPress() {
        for (let key of this.ended.keys()) {
            if (this.isLongPress(key)) return true
        }
        return false
    }

    isStylus(key) {
        return key === 'stylus'
    }
}

/**
 * This class implements the main delegate functionality: All necessary event handlers are registered for the
 * given element. Uses PointerEvents if available or TouchEvents on iOS. The fallback is on mouse events.
 * Collects the events if the interaction target captures the start event (i.e. declares that
 * the target wants the start event as well as all following move and end evcents.)
 *
 * @export
 * @class InteractionDelegate
 */
export class InteractionDelegate {
    // Long press: http://stackoverflow.com/questions/1930895/how-long-is-the-event-onlongpress-in-the-android
    // Stylus support: https://w3c.github.io/touch-events/

    /**
     * Creates an instance of InteractionDelegate.
     * @param {any} element
     * @param {any} target
     * @param {any} [{ mouseWheelElement = null, useCapture = true, capturePointerEvents = true, debug = false }={}]
     * @memberof InteractionDelegate
     */
    constructor(
        element,
        target,
        {
            mouseWheelElement = null,
            useCapture = true,
            capturePointerEvents = true,
            cancelOnWindowOut = true,
            debug = false
        } = {}
    ) {
        this.debug = debug
        this.interaction = new Interaction()
        this.element = element
        this.mouseWheelElement = mouseWheelElement || element
        this.target = target
        this.useCapture = useCapture
        this.capturePointerEvents = capturePointerEvents
        this.cancelOnWindowOut = cancelOnWindowOut
        this.setupInteraction()
    }

    setupInteraction() {
        if (this.debug) {
            let error = this.targetInterface.implementationError(
                this.target.constructor
            )
            if (error != null) {
                throw new Error('Expected IInteractionTarget: ' + error)
            }
        }
        this.setupTouchInteraction()
        this.setupMouseWheelInteraction()
    }

    get targetInterface() {
        return IInteractionTarget
    }

    setupTouchInteraction() {
        let element = this.element
        let useCapture = this.useCapture
        if (window.PointerEvent) {
            if (this.debug) console.log('Pointer API' + window.PointerEvent)
            element.addEventListener(
                'pointerdown',
                e => {
                    if (this.debug) console.log('pointerdown', e.pointerId)
                    if (this.capture(e)) {
                        if (this.capturePointerEvents) {
                            try {
                                element.setPointerCapture(e.pointerId)
                            } catch (e) {
                                console.warn('Cannot setPointerCapture')
                            }
                        }
                        this.onStart(e)
                    }
                },
                useCapture
            )
            element.addEventListener(
                'pointermove',
                e => {
                    if (this.debug)
                        console.log('pointermove', e.pointerId, e.pointerType)

                    if (
                        e.pointerType == 'touch' ||
                        (e.pointerType == 'mouse' && Events.isPointerDown(e))
                    ) {
                        // this.capture(e) &&
                        if (this.debug)
                            console.log('pointermove captured', e.pointerId)
                        this.onMove(e)
                    }
                },
                useCapture
            )
            element.addEventListener(
                'pointerup',
                e => {
                    if (this.debug)
                        console.log('pointerup', e.pointerId, e.pointerType)
                    this.onEnd(e)
                    if (this.capturePointerEvents) {
                        try {
                            element.releasePointerCapture(e.pointerId)
                        } catch (e) {
                            console.warn('Cannot release pointer')
                        }
                    }
                },
                useCapture
            )
            element.addEventListener(
                'pointercancel',
                e => {
                    if (this.debug)
                        console.log('pointercancel', e.pointerId, e.pointerType)
                    this.onEnd(e)
                    if (this.capturePointerEvents)
                        element.releasePointerCapture(e.pointerId)
                },
                useCapture
            )

            if (!this.capturePointerEvents) {
                element.addEventListener(
                    'pointerleave',
                    e => {
                        if (this.debug)
                            console.log(
                                'pointerleave',
                                e.pointerId,
                                e.pointerType
                            )
                        if (e.target == element) this.onEnd(e)
                    },
                    useCapture
                )
            }

            if (!this.capturePointerEvents) {
                element.addEventListener(
                    'pointerout',
                    e => {
                        if (this.debug)
                            console.log(
                                'pointerout',
                                e.pointerId,
                                e.pointerType
                            )
                        if (e.target == element) this.onEnd(e)
                    },
                    useCapture
                )
            }

            if (this.cancelOnWindowOut) {
                window.addEventListener(
                    'pointerout',
                    e => {
                        if (this.debug)
                            console.log(
                                'pointerout',
                                e.pointerId,
                                e.pointerType,
                                e.target
                            )
                        if (e.target == element) {
                            this.onEnd(e)
                        }
                    },
                    useCapture
                )
            }
        } else if (window.TouchEvent) {
            if (this.debug) console.log('Touch API')
            element.addEventListener(
                'touchstart',
                e => {
                    if (this.debug)
                        console.log('touchstart', this.touchPoints(e))
                    if (this.capture(e)) {
                        for (let touch of e.changedTouches) {
                            this.onStart(touch)
                        }
                    }
                },
                useCapture
            )
            element.addEventListener(
                'touchmove',
                e => {
                    if (this.debug)
                        console.log('touchmove', this.touchPoints(e), e)
                    for (let touch of e.changedTouches) {
                        this.onMove(touch)
                    }
                    for (let touch of e.targetTouches) {
                        this.onMove(touch)
                    }
                },
                useCapture
            )
            element.addEventListener(
                'touchend',
                e => {
                    if (this.debug) console.log('touchend', this.touchPoints(e))
                    for (let touch of e.changedTouches) {
                        this.onEnd(touch)
                    }
                },
                useCapture
            )
            element.addEventListener(
                'touchcancel',
                e => {
                    if (this.debug)
                        console.log(
                            'touchcancel',
                            e.targetTouches.length,
                            e.changedTouches.length
                        )
                    for (let touch of e.changedTouches) {
                        this.onEnd(touch)
                    }
                },
                useCapture
            )
        } else {
            if (this.debug) console.log('Mouse API')

            element.addEventListener(
                'mousedown',
                e => {
                    if (this.debug) console.log('mousedown', e)
                    if (this.capture(e)) {
                        this.onStart(e)
                    }
                },
                useCapture
            )
            element.addEventListener(
                'mousemove',
                e => {
                    // Dow we only use move events if the mouse is down?
                    // HOver effects have to be implemented by other means
                    // && Events.isMouseDown(e))

                    if (Events.isMouseDown(e)) {
                        if (this.debug) console.log('mousemove', e)
                        this.onMove(e)
                    }
                },
                useCapture
            )
            element.addEventListener(
                'mouseup',
                e => {
                    if (this.debug) console.log('mouseup', e)
                    this.onEnd(e)
                },
                true
            )

            if (!this.capturePointerEvents) {
                element.addEventListener(
                    'mouseout',
                    e => {
                        if (e.target == element) {
                            this.onEnd(e)
                            console.warn(
                                "Shouldn't happen: mouseout ends interaction"
                            )
                        }
                    },
                    useCapture
                )
            }
            if (this.cancelOnWindowOut) {
                window.addEventListener(
                    'mouseout',
                    e => {
                        if (e.target == element) {
                            this.onEnd(e)
                        }
                    },
                    useCapture
                )
            }
        }
    }

    isDescendant(parent, child) {
        if (parent == child) return true
        let node = child.parentNode
        while (node != null) {
            if (node == parent) {
                return true
            }
            node = node.parentNode
        }
        return false
    }

    touchPoints(event) {
        let result = []
        for (let touch of event.changedTouches) {
            result.push(this.extractPoint(touch))
        }
        return result
    }

    setupMouseWheelInteraction() {
        this.mouseWheelElement.addEventListener(
            'mousewheel',
            this.onMouseWheel.bind(this),
            true
        )
        this.mouseWheelElement.addEventListener(
            'DOMMouseScroll',
            this.onMouseWheel.bind(this),
            true
        )
    }

    onMouseWheel(event) {
        if (this.capture(event) && this.target.onMouseWheel) {
            this.target.onMouseWheel(event)
        } else {
            //console.warn('Target has no onMouseWheel callback')
        }
    }

    onStart(event) {
        let extracted = this.extractPoint(event)
        this.startInteraction(event, extracted)
        this.target.onStart(event, this.interaction)
    }

    onMove(event) {
        let extracted = this.extractPoint(event, 'all')
        this.updateInteraction(event, extracted)
        this.target.onMove(event, this.interaction)
        this.interaction.updatePrevious()
    }

    onEnd(event) {
        let extracted = this.extractPoint(event, 'changedTouches')
        this.endInteraction(event, extracted)
        this.target.onEnd(event, this.interaction)
        this.finishInteraction(event, extracted)
    }

    /**
     * Asks the target whether the event should be captured
     *
     * @param {any} event
     * @returns {bool}
     * @memberof InteractionDelegate
     */
    capture(event) {
        if (Events.isCaptured(event)) {
            return false
        }
        let captured = this.target.capture(event)
        return captured
    }

    getPosition(event) {
        return { x: event.clientX, y: event.clientY }
    }

    extractPoint(event, touchEventKey = 'all') {
        // 'targetTouches'
        let result = {}
        switch (event.constructor.name) {
            case 'MouseEvent': {
                let buttons = event.buttons || event.which
                if (buttons) result['mouse'] = this.getPosition(event)
                break
            }
            case 'PointerEvent': {
                result[event.pointerId.toString()] = this.getPosition(event)
                break
            }
            case 'Touch': {
                let id =
                    event.touchType === 'stylus'
                        ? 'stylus'
                        : event.identifier.toString()
                result[id] = this.getPosition(event)
                break
            }
            //             case 'TouchEvent':
            //                 // Needs to be observed: Perhaps changedTouches are all we need. If so
            //                 // we can remove the touchEventKey default parameter
            //                 if (touchEventKey == 'all') {
            //                     for(let t of event.targetTouches) {
            //                         result[t.identifier.toString()] = this.getPosition(t)
            //                     }
            //                     for(let t of event.changedTouches) {
            //                         result[t.identifier.toString()] = this.getPosition(t)
            //                     }
            //                 }
            //                 else {
            //                     for(let t of event.changedTouches) {
            //                         result[t.identifier.toString()] = this.getPosition(t)
            //                     }
            //                 }
            //                 break
            default:
                break
        }
        return result
    }

    interactionStarted(event, key, point) {
        // Callback: can be overwritten
    }

    interactionEnded(event, key, point) {
        // Callback: can be overwritten
    }

    interactionFinished(event, key, point) {}

    startInteraction(event, extracted) {
        for (let key in extracted) {
            let point = extracted[key]
            this.interaction.started(key, point)
            this.interactionStarted(event, key, point)
        }
    }

    updateInteraction(event, extracted) {
        for (let key in extracted) {
            let point = extracted[key]
            let updated = this.interaction.update(key, point)
            if (updated) {
                console.warn(
                    "new pointer in updateInteraction shouldn't happen",
                    key
                )
                this.interactionStarted(event, key, point)
            }
        }
    }

    endInteraction(event, ended) {
        for (let key in ended) {
            let point = ended[key]
            this.interaction.stop(key, point)
            this.interactionEnded(event, key, point)
        }
    }

    finishInteraction(event, ended) {
        for (let key in ended) {
            let point = ended[key]
            this.interaction.finish(key, point)
            this.interactionFinished(event, key, point)
        }
    }
}
/**
 * A special InteractionDelegate that maps events to specific parts of
 * the interaction target. The InteractionTarget must implement a findTarget
 * method that returns an object implementing the IInteractionTarget interface.
 *
 * If the InteractionTarget also implements a mapPositionToPoint method this
 * is used to map the points to the local coordinate space of the the target.
 *
 * This makes it easier to lookup elements and relate events to local
 * positions.
 *
 * @export
 * @class InteractionMapper
 * @extends {InteractionDelegate}
 */
export class InteractionMapper extends InteractionDelegate {
    constructor(
        element,
        target,
        {
            tapDistance = 10,
            longPressTime = 500.0,
            useCapture = true,
            mouseWheelElement = null,
            logInteractionsAbove = 12
        } = {}
    ) {
        super(element, target, {
            tapDistance,
            useCapture,
            longPressTime,
            mouseWheelElement
        })
        this.logInteractionsAbove = logInteractionsAbove
    }

    get targetInterface() {
        return IInteractionMapperTarget
    }

    mapPositionToPoint(point, element = null) {
        if (this.target.mapPositionToPoint) {
            return this.target.mapPositionToPoint(point, element)
        }
        return point
    }

    interactionStarted(event, key, point) {
        if (this.target.findTarget) {
            let local = this.mapPositionToPoint(point)
            let found = this.target.findTarget(event, local, point)
            if (found != null) {
                this.interaction.addTarget(key, found)
            }
        }
        let size = this.interaction.current.size
        let limit = this.logInteractionsAbove
        if (size > limit) {
            Logging.log(`Number of interactions ${size} exceeds ${limit}`)
        }
    }

    onMouseWheel(event) {
        if (this.capture(event)) {
            if (this.target.findTarget) {
                let point = this.getPosition(event)
                let local = this.mapPositionToPoint(point)
                let found = this.target.findTarget(event, local, point)
                if (found != null && found.onMouseWheel) {
                    found.onMouseWheel(event)
                    return
                }
            }
            if (this.target.onMouseWheel) {
                this.target.onMouseWheel(event)
            } else {
                //console.warn('Target has no onMouseWheel callback', this.target)
            }
        }
    }

    onStart(event) {
        let extracted = this.extractPoint(event)
        this.startInteraction(event, extracted)
        let mapped = this.interaction.mapInteraction(
            extracted,
            ['current', 'start'],
            this.mapPositionToPoint.bind(this)
        )
        for (let [target, interaction] of mapped.entries()) {
            target.onStart(event, interaction)
        }
    }

    onMove(event) {
        let extracted = this.extractPoint(event, 'all')
        this.updateInteraction(event, extracted)
        let mapped = this.interaction.mapInteraction(
            extracted,
            ['current', 'previous'],
            this.mapPositionToPoint.bind(this)
        )
        for (let [target, interaction] of mapped.entries()) {
            target.onMove(event, interaction)
            interaction.updatePrevious()
        }
        this.interaction.updatePrevious()
    }

    onEnd(event) {
        let extracted = this.extractPoint(event, 'changedTouches')
        this.endInteraction(event, extracted)
        let mapped = this.interaction.mapInteraction(
            extracted,
            ['ended'],
            this.mapPositionToPoint.bind(this)
        )
        for (let [target, interaction] of mapped.entries()) {
            target.onEnd(event, interaction)
        }
        this.finishInteraction(event, extracted)
    }

    /**
     *
     *
     * @static
     * @param {string|array} types - An event type, an array of event types or event types seperated by a space sign. The following
     *     events are possible:
     *         pan, panstart, panmove, panend, pancancel, panleft, panright, panup, pandown
     *         pinch, pinchstart, pinchmove, pinchend, pinchcancel, pinchin, pinchout
     *         press, pressup
     *         rotate, rotatestart, rotatemove, rotateend, rotatecancel
     *         swipe, swipeleft, swiperight, swipeup, swipedown
     *         tap
     * @param {HTMLElement|HTMLElement[]} elements - An HTML element or an array of HTML elements.
     * @param {function} [cb] - The callback. A function which is executed after the event occurs. Receives the event object as the
     *     first paramter
     * @param {object} [opts] - An options object. See the hammer documentation for more details.
     */
    static on(types, elements, cb, opts = {}) {
        opts = Object.assign({}, {}, opts)

        if (typeof Hammer === 'undefined') {
            console.error('Hammer.js not found!')
            return this
        }

        // convert to array
        types = Array.isArray(types) ? types : types.split(/\s/)
        if (
            elements instanceof NodeList ||
            elements instanceof HTMLCollection
        ) {
            elements = Array.from(elements)
        }
        elements = Array.isArray(elements) ? elements : [elements]

        for (let i = 0; i < types.length; i++) {
            const type = types[i].toLowerCase()

            // list of hammer events
            const useHammer = /^(tap|doubletap|press|pan|swipe|pinch|rotate).*$/.test(
                type
            )

            // if it is a hammer event
            if (useHammer) {
                for (let j = 0; j < elements.length; j++) {
                    // if(elements[j].tagName == "svg") return false;

                    let hammer = new Hammer(elements[j], opts)

                    if (window.propagating !== 'undefined') {
                        hammer = propagating(hammer)
                    }

                    // recognizers
                    if (type.startsWith('pan')) {
                        hammer
                            .get('pan')
                            .set(
                                Object.assign(
                                    { direction: Hammer.DIRECTION_ALL },
                                    opts
                                )
                            )
                    } else if (type.startsWith('pinch')) {
                        hammer
                            .get('pinch')
                            .set(Object.assign({ enable: true }, opts))
                    } else if (type.startsWith('press')) {
                        hammer.get('press').set(opts)
                    } else if (type.startsWith('rotate')) {
                        hammer
                            .get('rotate')
                            .set(Object.assign({ enable: true }, opts))
                    } else if (type.startsWith('swipe')) {
                        hammer
                            .get('swipe')
                            .set(
                                Object.assign(
                                    { direction: Hammer.DIRECTION_ALL },
                                    opts
                                )
                            )
                    } else if (type.startsWith('tap')) {
                        hammer.get('tap').set(opts)
                    }

                    hammer.on(type, event => {
                        cb(event)
                    })
                }
            } else {
                for (let j = 0; j < elements.length; j++) {
                    Hammer.on(elements[j], type, event => {
                        cb(event)
                    })
                }
            }
        }

        return this
    }
}

window.InteractionMapper = InteractionMapper