import { throttle, getElementCorners, getBoundingRect } from './utils'
import Rectangle from './elements/Rectangle'
import Canvas from './Canvas'
import Coordinate from './Coordinate'
import MultiSelectElement from './elements/MultiSelectElement'
import { DRAG_ELEMENT_PARTS } from './constants'

// 多选类
export default class Selection {
  constructor(app) {
    this.app = app
    this.canvas = null
    this.ctx = null
    // 当前是否正在创建选区中
    this.creatingSelection = false
    // 当前是否存在多选元素
    this.hasSelection = false
    // 当前是否正在调整被选中的元素
    this.isResizing = false
    this.state = this.app.state
    this.width = this.app.width
    this.height = this.app.height
    this.coordinate = new Coordinate(this)
    // 选区矩形
    this.rectangle = new Rectangle(
      {
        type: 'rectangle',
        style: {
          strokeStyle: 'rgba(9,132,227,0.3)',
          fillStyle: 'rgba(9,132,227,0.3)'
        }
      },
      this
    )
    // 被选中的元素的虚拟元素，用于显示拖拽框
    this.multiSelectElement = new MultiSelectElement(
      {
        type: 'multiSelectElement'
      },
      this
    )
    this.checkInNodes = throttle(this.checkInNodes, this, 500)
    // 稍微缓解一下卡顿
    this.handleResize = throttle(this.handleResize, this, 16)
    this.init()
    this.bindEvent()
  }

  // 初始化
  init() {
    if (this.canvas) {
      this.app.container.removeChild(this.canvas.el)
    }
    this.width = this.app.width
    this.height = this.app.height
    // 创建canvas元素
    this.canvas = new Canvas(this.width, this.height, {
      className: 'selection'
    })
    this.ctx = this.canvas.ctx
    this.app.container.appendChild(this.canvas.el)
  }

  // 监听事件
  bindEvent() {
    this.app.on('change', () => {
      this.state = this.app.state
      this.multiSelectElement.updateElements(this.app.elements.elementList)
      this.renderSelection()
    })
    this.app.on('scrollChange', () => {
      this.renderSelection()
    })
    this.app.on('zoomChange', () => {
      this.renderSelection()
    })
  }

  // 鼠标按下
  onMousedown(e, event) {
    if (e.originEvent.which !== 1) {
      return
    }
    this.creatingSelection = true
    this.rectangle.updatePos(event.mousedownPos.x, event.mousedownPos.y)
  }

  // 鼠标移动
  onMousemove(e, event) {
    if (
      Math.abs(event.mouseOffset.x) <= 10 &&
      Math.abs(event.mouseOffset.y) <= 10
    ) {
      return
    }
    this.onMove(e, event)
  }

  // 鼠标松开
  onMouseup() {
    this.creatingSelection = false
    this.rectangle.updateRect(0, 0, 0, 0)
    // 判断是否有元素被选中
    this.hasSelection = this.hasSelectionElements()
    this.multiSelectElement.updateRect()
    this.renderSelection()
    this.emitChange()
  }

  // 复位
  reset() {
    this.setMultiSelectElements([])
    this.hasSelection = false
    this.renderSelection()
    this.emitChange()
  }

  // 渲染
  renderSelection() {
    this.canvas.clearCanvas()
    this.ctx.save()
    this.ctx.scale(this.app.state.scale, this.app.state.scale)
    this.rectangle.render()
    this.multiSelectElement.render()
    this.ctx.restore()
  }

  // 鼠标移动事件
  onMove(e, event) {
    this.rectangle.updateSize(event.mouseOffset.x, event.mouseOffset.y)
    this.renderSelection()
    this.checkInElements(e, event)
  }

  // 检测在选区里的节点
  checkInElements(e, event) {
    let minx = Math.min(event.mousedownPos.x, e.clientX)
    let miny = Math.min(event.mousedownPos.y, e.clientY)
    let maxx = Math.max(event.mousedownPos.x, e.clientX)
    let maxy = Math.max(event.mousedownPos.y, e.clientY)
    let selectedElementList = []
    this.app.elements.elementList.forEach(element => {
      let _minx = Infinity
      let _maxx = -Infinity
      let _miny = Infinity
      let _maxy = -Infinity
      let endPointList = element.getEndpointList()
      let rect = getBoundingRect(
        endPointList.map(point => {
          return [point.x, point.y]
        }),
        true
      )
      rect.forEach(({ x, y }) => {
        if (x < _minx) {
          _minx = x
        }
        if (x > _maxx) {
          _maxx = x
        }
        if (y < _miny) {
          _miny = y
        }
        if (y > _maxy) {
          _maxy = y
        }
      })
      if (_minx >= minx && _maxx <= maxx && _miny >= miny && _maxy <= maxy) {
        selectedElementList.push(element)
      }
    })
    let finalList = [...selectedElementList]
    selectedElementList.forEach(item => {
      if (item.hasGroup()) {
        finalList.push(...this.app.group.getGroupElements(item))
      }
    })
    finalList = new Set(finalList)
    finalList = Array.from(finalList)
    this.setMultiSelectElements(finalList, true)
    this.app.render.render()
  }

  // 检测指定位置是否在元素调整手柄上
  checkInResizeHand(x, y) {
    return this.multiSelectElement.dragElement.checkPointInDragElementWhere(
      x,
      y
    )
  }

  // 检查是否需要进行元素调整操作
  checkIsResize(x, y, e) {
    if (!this.hasSelection) {
      return false
    }
    let hand = this.multiSelectElement.dragElement.checkPointInDragElementWhere(
      x,
      y
    )
    if (hand) {
      this.isResizing = true
      this.multiSelectElement.startResize(hand, e)
      this.app.cursor.setResize(hand)
      return true
    }
    return false
  }

  // 进行元素调整操作
  handleResize(...args) {
    if (!this.isResizing) {
      return
    }
    this.multiSelectElement.resize(...args)
    this.app.render.render()
    this.multiSelectElement.updateRect()
    this.renderSelection()
  }

  // 结束元素调整操作
  endResize() {
    this.isResizing = false
    this.multiSelectElement.endResize()
  }

  // 为多选元素设置样式
  setSelectedElementStyle(style = {}) {
    if (!this.hasSelectionElements()) {
      return
    }
    Object.keys(style).forEach(key => {
      this.getSelectionElements().forEach(element => {
        element.style[key] = style[key]
        if (key === 'fontSize' && element.type === 'text') {
          element.updateTextSize()
          this.multiSelectElement.updateRect()
        }
      })
    })
    this.app.render.render()
    this.app.emitChange()
  }

  // 删除当前选中的元素
  deleteSelectedElements() {
    this.getSelectionElements().forEach(element => {
      this.app.elements.deleteElement(element)
    })
    this.selectElements([])
    this.app.emitChange()
  }

  // 当前是否存在被选中元素
  hasSelectionElements() {
    return this.getSelectionElements().length > 0
  }

  // 获取当前被选中的元素
  getSelectionElements() {
    return this.multiSelectElement.selectedElementList
  }

  // 复制当前选中的元素
  async copySelectionElements(pos) {
    let task = this.getSelectionElements().map(element => {
      return this.app.elements.copyElement(element, true)
    })
    this.app.group.clearCopyMap()
    let elements = await Promise.all(task)
    this.setMultiSelectElements(elements)
    // 粘贴到指定位置
    if (pos) {
      this.multiSelectElement.startResize(DRAG_ELEMENT_PARTS.BODY)
      let ox =
        pos.x - this.multiSelectElement.x - this.multiSelectElement.width / 2
      let oy =
        pos.y - this.multiSelectElement.y - this.multiSelectElement.height / 2
      // 如果开启了网格，那么要坐标要吸附到网格
      let gridAdsorbentPos = this.app.coordinate.gridAdsorbent(ox, oy)
      this.multiSelectElement.resize(
        null,
        null,
        null,
        gridAdsorbentPos.x,
        gridAdsorbentPos.y
      )
      this.multiSelectElement.endResize()
      this.multiSelectElement.updateRect()
    }
    this.app.render.render()
    this.renderSelection()
    this.app.emitChange()
  }

  // 选中指定元素
  selectElements(elements = []) {
    this.hasSelection = elements.length > 0
    this.setMultiSelectElements(elements)
    this.app.render.render()
    this.renderSelection()
    this.emitChange()
  }

  // 设置选中的元素
  setMultiSelectElements(elements = [], notUpdateRect) {
    this.multiSelectElement.setSelectedElementList(elements)
    if (!notUpdateRect) {
      this.multiSelectElement.updateRect()
    }
  }

  // 触发多选元素变化事件
  emitChange() {
    this.app.emit('multiSelectChange', this.getSelectionElements())
  }
}