/** 相等, 相差小于diff */
export function equal(a: number, b: number, diff = 0.001): boolean
{
  return Math.abs(a - b) < diff
}

/** ab相差dis */
export function isDiffer(a: number, b: number, dis: number, diff = 0.001): boolean
{
  let rdis = Math.abs(a - b)
  return rdis > dis - diff && rdis < dis + diff
}

/** 两点间距离 */
export function getDis2(p1, p2): number
{
  let x1 = p1.pointX || p1.X || p1.x || 0
  let y1 = p1.pointY || p1.Y || p1.y || 0
  let x2 = p2.pointX || p2.X || p2.x || 0
  let y2 = p2.pointY || p2.Y || p2.y || 0
  return getDis(x1, y1, x2, y2)
}

/** 两点间距离 */
export function getDis(x1: number, y1: number, x2: number, y2: number): number
{
  let xt = x1 - x2
  let yt = y1 - y2
  return Math.sqrt(xt * xt + yt * yt)
}

/** 两点间弧度半径 */
export function getR(x1: number, y1: number, x2: number, y2: number, bul: number): number
{
  if (bul == 0)
    return 0
  let d = Math.sqrt((x1 - x2) ** 2 + (y1 - y2) ** 2) / 2
  return 0.5 * d * (1 + bul ** 2) / bul
}

/** 获取两点间的半径 */
export function getR2(p1, p2): number
{
  let bul = p1.Curve || p1.bul || 0
  if (bul == 0)
    return 0

  let x1 = p1.pointX || p1.X || p1.x
  let y1 = p1.pointY || p1.Y || p1.y
  let x2 = p2.pointX || p2.X || p2.x
  let y2 = p2.pointY || p2.Y || p2.y

  return getR(x1, y1, x2, y2, bul)
}

/** 截取小数点 */
export function round(n: number, bit = 3): number
{
  if (bit < 1)
    return n
  let tt = 10 ** bit
  return Math.round(n * tt) / tt
}

/**
 * 获得四点p{x,y}形成的矩形{x,y,w,l};
 *  不是矩形 返回null
 */
export function getRect(p0, p1, p2, p3): any
{
  if (equal(p0.x, p1.x) == false && equal(p0.y, p1.y) == false)
    return null

  // 中心点
  let xc = (p0.x + p1.x + p2.x + p3.x) / 4
  let yc = (p0.y + p1.y + p2.y + p3.y) / 4

  let dis0 = getDis(p0.x, p0.y, xc, yc)
  let dis1 = getDis(p1.x, p1.y, xc, yc)
  let dis2 = getDis(p2.x, p2.y, xc, yc)
  let dis3 = getDis(p3.x, p3.y, xc, yc)

  if (equal(dis0, dis1) && equal(dis0, dis2) && equal(dis0, dis3))
  {
    let x = Math.min(p0.x, p1.x, p2.x, p3.x)
    let y = Math.min(p0.y, p1.y, p2.y, p3.y)

    let w = Math.max(p0.x, p1.x, p2.x, p3.x) - x
    let l = Math.max(p0.y, p1.y, p2.y, p3.y) - y
    if (w < 0.01 || l < 0.01)
      return null
    return { x, y, w, l }
  }
  return null
}

/** 获取两点的直线的一般式方程AX+BY+C=0  ABC */
export function getLineABC(x1: number, y1: number, x2: number, y2: number)
{
  let A = y2 - y1
  let B = x1 - x2
  let C = x2 * y1 - x1 * y2
  return { A, B, C }
}

/** 获取点 p(x,y) 到两点的线的距离 */
export function getDis_PointLine(x1: number, y1: number, x2: number, y2: number, x: number, y: number)
{
  let abc = getLineABC(x1, y1, x2, y2)
  let aabb = Math.sqrt(abc.A * abc.A + abc.B * abc.B)
  if (aabb == 0)
    return 0

  return Math.abs(abc.A * x + abc.B * y + abc.C) / aabb
}

/** 删除重复点 */
export function removeRepeatPoint(pts, fuzz = 0.01)
{
  for (let n = pts.length - 1; n >= 0; n--) {
    let p = n - 1
    if (p < 0)
      p = pts.length - 1

    if (getDis2(pts[p], pts[n]) < fuzz)
      pts.splice(n, 1)
  }
}