import * as maptalks from 'maptalks'

const options = {
  'maxClusterRadius': 160,
  'textSumProperty': null,
  'symbol': null,
  'drawClusterText': true,
  'textSymbol': null,
  'animation': true,
  'animationDuration': 450,
  'maxClusterZoom': null,
  'noClusterWithOneMarker': true,
  'forceRenderOnZooming': true
}

export class ClusterLayer extends maptalks.VectorLayer {
  /**
     * Reproduce a ClusterLayer from layer's profile JSON.
     * @param  {Object} json - layer's profile JSON
     * @return {maptalks.ClusterLayer}
     * @static
     * @private
     * @function
     */
  static fromJSON(json) {
    if (!json || json['type'] !== 'ClusterLayer') { return null }
    const layer = new ClusterLayer(json['id'], json['options'])
    const geoJSONs = json['geometries']
    const geometries = []
    for (let i = 0; i < geoJSONs.length; i++) {
      const geo = maptalks.Geometry.fromJSON(geoJSONs[i])
      if (geo) {
        geometries.push(geo)
      }
    }
    layer.addGeometry(geometries)
    return layer
  }

  addMarker(markers) {
    return this.addGeometry(markers)
  }

  addGeometry(markers) {
    for (let i = 0, len = markers.length; i < len; i++) {
      if (!(markers[i] instanceof maptalks.Marker)) {
        throw new Error('Only a point(Marker) can be added into a ClusterLayer')
      }
    }
    return super.addGeometry.apply(this, arguments)
  }

  onConfig(conf) {
    super.onConfig(conf)
    if (conf['maxClusterRadius'] ||
            conf['symbol'] ||
            conf['drawClusterText'] ||
            conf['textSymbol'] ||
            conf['maxClusterZoom']) {
      const renderer = this._getRenderer()
      if (renderer) {
        renderer.render()
      }
    }
    return this
  }

  /**
     * Identify the clusters on the given coordinate
     * @param  {maptalks.Coordinate} coordinate   - coordinate to identify
     * @return {Object|Geometry[]}  result: cluster { center : [cluster's center], children : [geometries in the cluster] } or markers
     */
  identify(coordinate, options) {
    const map = this.getMap()
    const maxZoom = this.options['maxClusterZoom']
    if (maxZoom && map && map.getZoom() > maxZoom) {
      return super.identify(coordinate, options)
    }
    if (this._getRenderer()) {
      return this._getRenderer().identify(coordinate, options)
    }
    return null
  }

  /**
     * Export the ClusterLayer's JSON.
     * @return {Object} layer's JSON
     */
  toJSON() {
    const json = super.toJSON.call(this)
    json['type'] = 'ClusterLayer'
    return json
  }
  /**
     * Get the ClusterLayer's current clusters
     * @return {Object} layer's clusters
     **/
  getClusters() {
    const renderer = this._getRenderer()
    if (renderer) {
      return renderer._currentClusters || []
    }
    return []
  }
}

// merge to define ClusterLayer's default options.
ClusterLayer.mergeOptions(options)

// register ClusterLayer's JSON type for JSON deserialization.
ClusterLayer.registerJSONType('ClusterLayer')

const defaultTextSymbol = {
  'textFaceName': '"microsoft yahei"',
  'textSize': 16,
  'textDx': 0,
  'textDy': 0
}

const defaultSymbol = {
  'markerType': 'ellipse',
  // 'markerFill': { property: 'count', type: 'interval', stops: [[0, 'rgb(135, 196, 240)'], [9, '#1bbc9b'], [99, 'rgb(216, 115, 149)']] },
  'markerFill': { property: 'count', type: 'interval', stops: [[0, '#1bbc9b'], [9, '#1bbc9b'], [99, '#1bbc9b']] },
  'markerFillOpacity': 0.7,
  'markerLineOpacity': 1,
  'markerLineWidth': 3,
  'markerLineColor': '#fff',
  'markerWidth': { property: 'count', type: 'interval', stops: [[0, 40], [9, 60], [99, 80]] },
  'markerHeight': { property: 'count', type: 'interval', stops: [[0, 40], [9, 60], [99, 80]] }
}

ClusterLayer.registerRenderer('canvas', class extends maptalks.renderer.VectorLayerCanvasRenderer {
  constructor(layer) {
    super(layer)
    this._animated = true
    this._refreshStyle()
    this._clusterNeedRedraw = true
  }

  checkResources() {
    const symbol = this.layer.options['symbol'] || defaultSymbol
    const resources = super.checkResources.apply(this, arguments)
    if (symbol !== this._symbolResourceChecked) {
      const res = maptalks.Util.getExternalResources(symbol, true)
      if (res) {
        resources.push.apply(resources, res)
      }
      this._symbolResourceChecked = symbol
    }
    return resources
  }

  draw() {
    if (!this.canvas) {
      this.prepareCanvas()
    }
    const map = this.getMap()
    const zoom = map.getZoom()
    const maxClusterZoom = this.layer.options['maxClusterZoom']
    if (maxClusterZoom &&  zoom > maxClusterZoom) {
      delete this._currentClusters
      this._markersToDraw = this.layer._geoList
      super.draw.apply(this, arguments)
      return
    }
    if (this._clusterNeedRedraw) {
      this._clearDataCache()
      this._computeGrid()
      this._clusterNeedRedraw = false
    }
    const zoomClusters = this._clusterCache[zoom] ? this._clusterCache[zoom]['clusters'] : null

    const clusters = this._getClustersToDraw(zoomClusters)
    clusters.zoom = zoom
    this._drawLayer(clusters)
  }

  _getClustersToDraw(zoomClusters) {
    this._markersToDraw = []
    const map = this.getMap()
    const font = maptalks.StringUtil.getFont(this._textSymbol)
    const digitLen = maptalks.StringUtil.stringLength('9', font).toPoint()
    const extent = map.getContainerExtent()
    const clusters = []
    let pt, pExt, sprite, width, height
    for (const p in zoomClusters) {
      this._currentGrid = zoomClusters[p]
      if (zoomClusters[p]['count'] === 1 && this.layer.options['noClusterWithOneMarker']) {
        const marker = zoomClusters[p]['children'][0]
        marker._cluster = zoomClusters[p]
        this._markersToDraw.push(marker)
        continue
      }
      sprite = this._getSprite()
      width = sprite.canvas.width
      height = sprite.canvas.height
      pt = map._prjToContainerPoint(zoomClusters[p]['center'])
      pExt = new maptalks.PointExtent(pt.sub(width, height), pt.add(width, height))
      if (!extent.intersects(pExt)) {
        continue
      }

      if (!zoomClusters[p]['textSize']) {
        const text = this._getClusterText(zoomClusters[p])
        zoomClusters[p]['textSize'] = new maptalks.Point(digitLen.x * text.length, digitLen.y)._multi(1 / 2)
      }
      clusters.push(zoomClusters[p])
    }
    return clusters
  }

  drawOnInteracting() {
    if (this._currentClusters) {
      this._drawClusters(this._currentClusters, 1)
    }
    super.drawOnInteracting.apply(this, arguments)
  }

  _getCurrentNeedRenderGeos() {
    if (this._markersToDraw) {
      return this._markersToDraw
    }
    return []
  }

  forEachGeo(fn, context) {
    if (this._markersToDraw) {
      this._markersToDraw.forEach((g) => {
        if (context) {
          fn.call(context, g)
        } else {
          fn(g)
        }
      })
    }
  }

  onGeometryShow() {
    this._clusterNeedRedraw = true
    super.onGeometryShow.apply(this, arguments)
  }

  onGeometryHide() {
    this._clusterNeedRedraw = true
    super.onGeometryHide.apply(this, arguments)
  }

  onGeometryAdd() {
    this._clusterNeedRedraw = true
    super.onGeometryAdd.apply(this, arguments)
  }

  onGeometryRemove() {
    this._clusterNeedRedraw = true
    super.onGeometryRemove.apply(this, arguments)
  }

  onGeometryPositionChange() {
    this._clusterNeedRedraw = true
    super.onGeometryPositionChange.apply(this, arguments)
  }

  onRemove() {
    this._clearDataCache()
  }

  identify(coordinate, options) {
    const map = this.getMap()
    const maxZoom = this.layer.options['maxClusterZoom']
    if (maxZoom && map.getZoom() > maxZoom) {
      return super.identify(coordinate, options)
    }
    if (this._currentClusters) {
      const point = map.coordinateToContainerPoint(coordinate)
      const old = this._currentGrid
      for (let i = 0; i < this._currentClusters.length; i++) {
        const c = this._currentClusters[i]
        const pt = map._prjToContainerPoint(c['center'])
        this._currentGrid = c
        const markerWidth = this._getSprite().canvas.width

        if (point.distanceTo(pt) <= markerWidth) {
          return {
            'center': map.getProjection().unproject(c.center.copy()),
            'children': c.children.slice(0)
          }
        }
      }
      this._currentGrid = old
    }

    // if no clusters is hit, identify markers
    if (this._markersToDraw && this._markersToDraw[0]) {
      const point = map.coordinateToContainerPoint(coordinate)
      return this.layer._hitGeos(this._markersToDraw, point, options)
    }
    return null
  }

  onSymbolChanged() {
    this._refreshStyle()
    this._computeGrid()
    this._stopAnim()
    this.setToRedraw()
  }

  _refreshStyle() {
    const symbol = this.layer.options['symbol'] || defaultSymbol
    const textSymbol = this.layer.options['textSymbol'] || defaultTextSymbol
    const argFn =  () => [this.getMap().getZoom(), this._currentGrid]
    this._symbol = maptalks.MapboxUtil.loadFunctionTypes(symbol, argFn)
    this._textSymbol = maptalks.MapboxUtil.loadFunctionTypes(textSymbol, argFn)
  }

  _drawLayer(clusters) {
    const parentClusters = this._currentClusters || clusters
    this._currentClusters = clusters
    delete this._clusterMaskExtent
    const layer = this.layer
    //if (layer.options['animation'] && this._animated && this._inout === 'out') {
    if (layer.options['animation'] && this._animated && this._inout) {
      let dr = [0, 1]
      if (this._inout === 'in') {
        dr = [1, 0]
      }
      this._player = maptalks.animation.Animation.animate(
        { 'd': dr },
        { 'speed': layer.options['animationDuration'], 'easing': 'inAndOut' },
        frame => {
          if (frame.state.playState === 'finished') {
            this._animated = false
            this._drawClusters(clusters, 1)
            this._drawMarkers()
            this.completeRender()
          } else {
            if (this._inout === 'in') {
              this._drawClustersFrame(clusters, parentClusters, frame.styles.d)
            } else {
              this._drawClustersFrame(parentClusters, clusters, frame.styles.d)
            }
            this.setCanvasUpdated()
          }
        }
      )
        .play()
    } else {
      this._animated = false
      this._drawClusters(clusters, 1)
      this._drawMarkers()
      this.completeRender()
    }
  }

  _drawMarkers() {
    super.drawGeos(this._clusterMaskExtent)
  }

  _drawClustersFrame(parentClusters, toClusters, ratio) {
    this._clusterMaskExtent = this.prepareCanvas()
    const map = this.getMap()
    const drawn = {}
    if (parentClusters) {
      parentClusters.forEach(c => {
        const p = map._prjToContainerPoint(c['center'])
        if (!drawn[c.key]) {
          drawn[c.key] = 1
          this._drawCluster(p, c, 1 - ratio)
        }
      })
    }
    if (ratio === 0 || !toClusters) {
      return
    }
    const z = parentClusters.zoom
    const r = map._getResolution(z) * this.layer.options['maxClusterRadius']
    const min = this._markerExtent.getMin()
    toClusters.forEach(c => {
      let pt = map._prjToContainerPoint(c['center'])
      const center = c.center
      const pgx = Math.floor((center.x - min.x) / r)
      const pgy = Math.floor((center.y - min.y) / r)
      const pkey = pgx + '_' + pgy
      const parent = this._clusterCache[z] ? this._clusterCache[z]['clusterMap'][pkey] : null
      if (parent) {
        const pp = map._prjToContainerPoint(parent['center'])
        pt = pp.add(pt.sub(pp)._multi(ratio))
      }
      this._drawCluster(pt, c, ratio > 0.5 ? 1 : ratio)
    })
  }

  _drawClusters(clusters, ratio) {
    if (!clusters) {
      return
    }
    this._clusterMaskExtent = this.prepareCanvas()
    const map = this.getMap()
    clusters.forEach(c => {
      const pt = map._prjToContainerPoint(c['center'])
      this._drawCluster(pt, c, ratio > 0.5 ? 1 : ratio)
    })
  }

  _drawCluster(pt, cluster, op) {
    this._currentGrid = cluster
    const ctx = this.context
    const sprite = this._getSprite()
    const opacity = ctx.globalAlpha
    if (opacity * op === 0) {
      return
    }
    ctx.globalAlpha = opacity * op
    if (sprite) {
      const pos = pt.add(sprite.offset)._sub(sprite.canvas.width / 2, sprite.canvas.height / 2)
      ctx.drawImage(sprite.canvas, pos.x, pos.y)
    }

    if (this.layer.options['drawClusterText'] && cluster['textSize']) {
      maptalks.Canvas.prepareCanvasFont(ctx, this._textSymbol)
      ctx.textBaseline = 'middle'
      const dx = this._textSymbol['textDx'] || 0
      const dy = this._textSymbol['textDy'] || 0
      const text = this._getClusterText(cluster)
      maptalks.Canvas.fillText(ctx, text, pt.sub(cluster['textSize'].x, 0)._add(dx, dy))
    }
    ctx.globalAlpha = opacity
  }

  _getClusterText(cluster) {
    const text = this.layer.options['textSumProperty'] ? cluster['textSumProperty'] : cluster['count']
    return text + ''
  }

  _getSprite() {
    if (!this._spriteCache) {
      this._spriteCache = {}
    }
    const key = maptalks.Util.getSymbolStamp(this._symbol)
    if (!this._spriteCache[key]) {
      this._spriteCache[key] = new maptalks.Marker([0, 0], { 'symbol': this._symbol })._getSprite(this.resources, this.getMap().CanvasClass)
    }
    return this._spriteCache[key]
  }

  _initGridSystem() {
    const points = []
    let extent, c
    this.layer.forEach(g => {
      if (!g.isVisible()) {
        return
      }
      c = g._getPrjCoordinates()
      if (!extent) {
        extent = g._getPrjExtent()
      } else {
        extent = extent._combine(g._getPrjExtent())
      }
      points.push({
        x: c.x,
        y: c.y,
        id: g._getInternalId(),
        geometry: g
      })
    })
    this._markerExtent = extent
    this._markerPoints = points
  }

  _computeGrid() {
    const map = this.getMap()
    const zoom = map.getZoom()
    if (!this._markerExtent) {
      this._initGridSystem()
    }
    if (!this._clusterCache) {
      this._clusterCache = {}
    }
    const pre = map._getResolution(map.getMinZoom()) > map._getResolution(map.getMaxZoom()) ? zoom - 1 : zoom + 1
    if (this._clusterCache[pre] && this._clusterCache[pre].length === this.layer.getCount()) {
      this._clusterCache[zoom] = this._clusterCache[pre]
    }
    if (!this._clusterCache[zoom]) {
      this._clusterCache[zoom] = this._computeZoomGrid(zoom)
    }

    map.fire('cluster-compute-grid')
  }

  _computeZoomGrid(zoom) {
    if (!this._markerExtent) {
      return null
    }
    const map = this.getMap()
    const r = map._getResolution(zoom) * this.layer.options['maxClusterRadius']
    const preT = map._getResolution(zoom - 1) ? map._getResolution(zoom - 1) * this.layer.options['maxClusterRadius'] : null
    let preCache = this._clusterCache[zoom - 1]
    if (!preCache && zoom - 1 >= map.getMinZoom()) {
      this._clusterCache[zoom - 1] = preCache = this._computeZoomGrid(zoom - 1)
    }
    // 1. format extent of markers to grids with raidus of r
    // 2. find point's grid in the grids
    // 3. sum up the point into the grid's collection
    const points = this._markerPoints
    const sumProperty = this.layer.options['textSumProperty']
    const grids = {}
    const min = this._markerExtent.getMin()
    let gx, gy, key, pgx, pgy, pkey
    for (let i = 0, len = points.length; i < len; i++) {
      const geo = points[i].geometry
      let sumProp = 0

      if (sumProperty && geo.getProperties() && geo.getProperties()[sumProperty]) {
        sumProp = geo.getProperties()[sumProperty]
      }

      gx = Math.floor((points[i].x - min.x) / r)
      gy = Math.floor((points[i].y - min.y) / r)
      key = gx + '_' + gy
      if (!grids[key]) {
        grids[key] = {
          'sum': new maptalks.Coordinate(points[i].x, points[i].y),
          'center': new maptalks.Coordinate(points[i].x, points[i].y),
          'count': 1,
          'textSumProperty': sumProp,
          'children': [geo],
          'key': key + ''
        }
        if (preT && preCache) {
          pgx = Math.floor((points[i].x - min.x) / preT)
          pgy = Math.floor((points[i].y - min.y) / preT)
          pkey = pgx + '_' + pgy
          grids[key]['parent'] = preCache['clusterMap'][pkey]
        }
      } else {
        grids[key]['sum']._add(new maptalks.Coordinate(points[i].x, points[i].y))
        grids[key]['count']++
        grids[key]['center'] = grids[key]['sum'].multi(1 / grids[key]['count'])
        grids[key]['children'].push(geo)
        grids[key]['textSumProperty'] += sumProp
      }
    }
    return this._mergeClusters(grids, r / 2)
  }

  _mergeClusters(grids, r) {
    const clusterMap = {}
    for (const p in grids) {
      clusterMap[p] = grids[p]
    }

    // merge adjacent clusters
    const merging = {}

    const visited = {}
    // find clusters need to merge
    let c1, c2
    for (const p in grids) {
      c1 = grids[p]
      if (visited[c1.key]) {
        continue
      }
      const gxgy = c1.key.split('_')
      const gx = +(gxgy[0])
      const gy = +(gxgy[1])
      //traverse adjacent grids
      for (let ii = -1; ii <= 1; ii++) {
        for (let iii = -1; iii <= 1; iii++) {
          if (ii === 0 && iii === 0) {
            continue
          }
          const key2 = (gx + ii) + '_' + (gy + iii)
          c2 = grids[key2]
          if (c2 && this._distanceTo(c1['center'], c2['center']) <= r) {
            if (!merging[c1.key]) {
              merging[c1.key] = []
            }
            merging[c1.key].push(c2)
            visited[c2.key] = 1
          }
        }
      }
    }

    //merge clusters
    for (const m in merging) {
      const grid = grids[m]
      if (!grid) {
        continue
      }
      const toMerge = merging[m]
      for (let i = 0; i < toMerge.length; i++) {
        if (grids[toMerge[i].key]) {
          grid['sum']._add(toMerge[i].sum)
          grid['count'] += toMerge[i].count
          grid['textSumProperty'] += toMerge[i].textSumProperty
          grid['children'] = grid['children'].concat(toMerge[i].children)
          clusterMap[toMerge[i].key] = grid
          delete grids[toMerge[i].key]
        }
      }
      grid['center'] = grid['sum'].multi(1 / grid['count'])
    }

    return {
      'clusters': grids,
      'clusterMap': clusterMap
    }
  }

  _distanceTo(c1, c2) {
    const x = c1.x - c2.x
    const y = c1.y - c2.y
    return Math.sqrt(x * x + y * y)
  }

  _stopAnim() {
    if (this._player && this._player.playState !== 'finished') {
      this._player.finish()
    }
  }

  onZoomStart(param) {
    this._stopAnim()
    super.onZoomStart(param)
  }

  onZoomEnd(param) {
    if (this.layer.isEmpty() || !this.layer.isVisible()) {
      super.onZoomEnd.apply(this, arguments)
      return
    }
    this._inout = param['from'] > param['to'] ? 'in' : 'out'
    this._animated = true
    this._computeGrid()
    super.onZoomEnd.apply(this, arguments)
  }

  _clearDataCache() {
    this._stopAnim()
    delete this._markerExtent
    delete this._markerPoints
    delete this._clusterCache
    delete this._zoomInClusters
  }
})