/**
 * {数学相关}
 * @author yutent<yutent.io@gmail.com>
 * @date 2024/03/06 13:05:25
 */

/* -------------------------------------------------------- */
/* ---------------------   数学方法    ---------------------- */
/* -------------------------------------------------------- */

/**
 * Returns an angle between two or three points
 - x1 (number) x coord of first point
 - y1 (number) y coord of first point
 - x2 (number) x coord of second point
 - y2 (number) y coord of second point
 - x3 (number) #optional x coord of third point
 - y3 (number) #optional y coord of third point
 = (number) angle in degrees
 */
export function angle(x1, y1, x2, y2, x3, y3) {
  if (x3 == null) {
    let x = x1 - x2,
      y = y1 - y2
    if (!x && !y) {
      return 0
    }
    return (180 + (Math.atan2(-y, -x) * 180) / Math.PI + 360) % 360
  } else {
    return angle(x1, y1, x3, y3) - angle(x2, y2, x3, y3)
  }
}

export function rad(deg) {
  return ((deg % 360) * Math.PI) / 180
}

export function deg(radius) {
  return ((radius * 180) / Math.PI) % 360
}

export function sin(angle) {
  return Math.sin(rad(angle))
}

export function tan(angle) {
  return Math.tan(rad(angle))
}

export function cos(angle) {
  return Math.cos(rad(angle))
}

export function asin(num) {
  return deg(Math.asin(num))
}

export function acos(num) {
  return deg(Math.acos(num))
}

export function atan(num) {
  return deg(Math.atan(num))
}

export function atan2(x, y) {
  return deg(Math.atan2(x, y))
}

/*\
 **
 * Returns distance between two points
 - x1 (number) x coord of first point
 - y1 (number) y coord of first point
 - x2 (number) x coord of second point
 - y2 (number) y coord of second point
\*/
export function len(x1, y1, x2, y2) {
  return Math.sqrt(len2(x1, y1, x2, y2))
}
/*\
 **
 * Returns squared distance between two points
 - x1 (number) x coord of first point
 - y1 (number) y coord of first point
 - x2 (number) x coord of second point
 - y2 (number) y coord of second point
\*/
export function len2(x1, y1, x2, y2) {
  return (x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2)
}