frontend/src/utils/element.ts

import tinycolor from 'tinycolor2'
import { nanoid } from 'nanoid'
import type { PPTElement, PPTLineElement, Slide } from '@/types/slides'

interface RotatedElementData {
  left: number
  top: number
  width: number
  height: number
  rotate: number
}

interface IdMap {
  [id: string]: string
}

/**
 * 计算元素在画布中的矩形范围旋转后的新位置范围
 * @param element 元素的位置大小和旋转角度信息
 */
export const getRectRotatedRange = (element: RotatedElementData) => {
  const { left, top, width, height, rotate = 0 } = element

  const radius = Math.sqrt( Math.pow(width, 2) + Math.pow(height, 2) ) / 2
  const auxiliaryAngle = Math.atan(height / width) * 180 / Math.PI

  const tlbraRadian = (180 - rotate - auxiliaryAngle) * Math.PI / 180
  const trblaRadian = (auxiliaryAngle - rotate) * Math.PI / 180

  const middleLeft = left + width / 2
  const middleTop = top + height / 2

  const xAxis = [
    middleLeft + radius * Math.cos(tlbraRadian),
    middleLeft + radius * Math.cos(trblaRadian),
    middleLeft - radius * Math.cos(tlbraRadian),
    middleLeft - radius * Math.cos(trblaRadian),
  ]
  const yAxis = [
    middleTop - radius * Math.sin(tlbraRadian),
    middleTop - radius * Math.sin(trblaRadian),
    middleTop + radius * Math.sin(tlbraRadian),
    middleTop + radius * Math.sin(trblaRadian),
  ]

  return {
    xRange: [Math.min(...xAxis), Math.max(...xAxis)],
    yRange: [Math.min(...yAxis), Math.max(...yAxis)],
  }
}

/**
 * 计算元素在画布中的矩形范围旋转后的新位置与旋转之前位置的偏离距离
 * @param element 元素的位置大小和旋转角度信息
 */
export const getRectRotatedOffset = (element: RotatedElementData) => {
  const { xRange: originXRange, yRange: originYRange } = getRectRotatedRange({
    left: element.left,
    top: element.top,
    width: element.width,
    height: element.height,
    rotate: 0,
  })
  const { xRange: rotatedXRange, yRange: rotatedYRange } = getRectRotatedRange({
    left: element.left,
    top: element.top,
    width: element.width,
    height: element.height,
    rotate: element.rotate,
  })
  return {
    offsetX: rotatedXRange[0] - originXRange[0],
    offsetY: rotatedYRange[0] - originYRange[0],
  }
}

/**
 * 计算元素在画布中的位置范围
 * @param element 元素信息
 */
export const getElementRange = (element: PPTElement) => {
  let minX, maxX, minY, maxY

  if (element.type === 'line') {
    minX = element.left
    maxX = element.left + Math.max(element.start[0], element.end[0])
    minY = element.top
    maxY = element.top + Math.max(element.start[1], element.end[1])
  }
  else if ('rotate' in element && element.rotate) {
    const { left, top, width, height, rotate } = element
    const { xRange, yRange } = getRectRotatedRange({ left, top, width, height, rotate })
    minX = xRange[0]
    maxX = xRange[1]
    minY = yRange[0]
    maxY = yRange[1]
  }
  else {
    minX = element.left
    maxX = element.left + element.width
    minY = element.top
    maxY = element.top + element.height
  }
  return { minX, maxX, minY, maxY }
}

/**
 * 计算一组元素在画布中的位置范围
 * @param elementList 一组元素信息
 */
export const getElementListRange = (elementList: PPTElement[]) => {
  const leftValues: number[] = []
  const topValues: number[] = []
  const rightValues: number[] = []
  const bottomValues: number[] = []

  elementList.forEach(element => {
    const { minX, maxX, minY, maxY } = getElementRange(element)
    leftValues.push(minX)
    topValues.push(minY)
    rightValues.push(maxX)
    bottomValues.push(maxY)
  })

  const minX = Math.min(...leftValues)
  const maxX = Math.max(...rightValues)
  const minY = Math.min(...topValues)
  const maxY = Math.max(...bottomValues)

  return { minX, maxX, minY, maxY }
}

/**
 * 计算线条元素的长度
 * @param element 线条元素
 */
export const getLineElementLength = (element: PPTLineElement) => {
  const deltaX = element.end[0] - element.start[0]
  const deltaY = element.end[1] - element.start[1]
  const len = Math.sqrt(deltaX * deltaX + deltaY * deltaY)
  return len
}

export interface AlignLine {
  value: number
  range: [number, number]
}

/**
 * 将一组对齐吸附线进行去重：同位置的的多条对齐吸附线仅留下一条，取该位置所有对齐吸附线的最大值和最小值为新的范围
 * @param lines 一组对齐吸附线信息
 */
export const uniqAlignLines = (lines: AlignLine[]) => {
  const uniqLines: AlignLine[] = []
  lines.forEach(line => {
    const index = uniqLines.findIndex(_line => _line.value === line.value)
    if (index === -1) uniqLines.push(line)
    else {
      const uniqLine = uniqLines[index]
      const rangeMin = Math.min(uniqLine.range[0], line.range[0])
      const rangeMax = Math.max(uniqLine.range[1], line.range[1])
      const range: [number, number] = [rangeMin, rangeMax]
      const _line = { value: line.value, range }
      uniqLines[index] = _line
    }
  })
  return uniqLines
}

/**
 * 以页面列表为基础，为每一个页面生成新的ID，并关联到旧ID形成一个字典
 * 主要用于页面元素时，维持数据中各处页面ID原有的关系
 * @param slides 页面列表
 */
export const createSlideIdMap = (slides: Slide[]) => {
  const slideIdMap: IdMap = {}
  for (const slide of slides) {
    slideIdMap[slide.id] = nanoid(10)
  }
  return slideIdMap
}

/**
   * 以元素列表为基础，为每一个元素生成新的ID，并关联到旧ID形成一个字典
   * 主要用于复制元素时，维持数据中各处元素ID原有的关系
   * 例如：原本两个组合的元素拥有相同的groupId，复制后依然会拥有另一个相同的groupId
   * @param elements 元素列表数据
   */
export const createElementIdMap = (elements: PPTElement[]) => {
  const groupIdMap: IdMap = {}
  const elIdMap: IdMap = {}
  for (const element of elements) {
    const groupId = element.groupId
    if (groupId && !groupIdMap[groupId]) {
      groupIdMap[groupId] = nanoid(10)
    }
    elIdMap[element.id] = nanoid(10)
  }
  return {
    groupIdMap,
    elIdMap,
  }
}

/**
 * 根据表格的主题色，获取对应用于配色的子颜色
 * @param themeColor 主题色
 */
export const getTableSubThemeColor = (themeColor: string) => {
  const rgba = tinycolor(themeColor)
  return [
    rgba.setAlpha(0.3).toRgbString(),
    rgba.setAlpha(0.1).toRgbString(),
  ]
}

/**
 * 获取线条元素路径字符串
 * @param element 线条元素
 */
export const getLineElementPath = (element: PPTLineElement) => {
  const start = element.start.join(',')
  const end = element.end.join(',')
  if (element.broken) {
    const mid = element.broken.join(',')
    return `M${start} L${mid} L${end}`
  }
  else if (element.broken2) {
    const { minX, maxX, minY, maxY } = getElementRange(element)
    if (maxX - minX >= maxY - minY) return `M${start} L${element.broken2[0]},${element.start[1]} L${element.broken2[0]},${element.end[1]} ${end}`
    return `M${start} L${element.start[0]},${element.broken2[1]} L${element.end[0]},${element.broken2[1]} ${end}`
  }
  else if (element.curve) {
    const mid = element.curve.join(',')
    return `M${start} Q${mid} ${end}`
  }
  else if (element.cubic) {
    const [c1, c2] = element.cubic
    const p1 = c1.join(',')
    const p2 = c2.join(',')
    return `M${start} C${p1} ${p2} ${end}`
  }
  return `M${start} L${end}`
}

/**
 * 判断一个元素是否在可视范围内
 * @param element 元素
 * @param parent 父元素
 */
export const isElementInViewport = (element: HTMLElement, parent: HTMLElement): boolean => {
  const elementRect = element.getBoundingClientRect()
  const parentRect = parent.getBoundingClientRect()

  return (
    elementRect.top >= parentRect.top &&
    elementRect.bottom <= parentRect.bottom
  )
}