class Point {
  constructor(x, y) {
    this.x = x;
    this.y = y;
  }

  toString() {
    return this.x + ',' + this.y;
  }

  equals(p) {
    if (this.x === p.x && this.y === p.y) {
      return true;
    }
    return false;
  }
}

class Node {
  constructor(prev, startHandle, endHandle, endPoint, next) {
    this.prev = prev;
    this.startHandle = startHandle;
    this.endHandle = endHandle;
    this.endPoint = endPoint;
    this.next = next;
  }

  get startPoint() {
    return this.prev.endPoint;
  }
  // endPoint remains
  partiallyReverse() {
    let tempPointer = this.prev;
    this.prev = this.next;
    this.next = tempPointer;
    tempPointer = this.startHandle;
    this.startHandle = this.endHandle;
    this.endHandle = tempPointer;
  }

  toString() {
    return `${this.startHandle} ${this.endHandle} ${this.endPoint}`;
  }
}

class Path {
  constructor(first, length) {
    this.first = first;
    this.length = length;
  }

  static fromString(s) {
    let first;
    let prev = null;
    let curr = null;
    let words = s.split(/\s|,/);
    let index = 0;
    let length = 0;
    while (index < words.length) {
      if (words[index].toUpperCase() === 'Z') {
        break;
      }
      if (words[index] === 'M') {
        index += 2;
      } else if (words[index] === 'C') {
      } else {
        let x1 = Number(words[index]);
        index += 1;
        let y1 = Number(words[index]);
        index += 1;
        let x2 = Number(words[index]);
        index += 1;
        let y2 = Number(words[index]);
        index += 1;
        let x = Number(words[index]);
        index += 1;
        let y = Number(words[index]);
        curr = new Node(prev, new Point(x1, y1), new Point(x2, y2), new Point(x, y), null);
        if (!first) {
          first = curr;
        }
        if (curr.prev) {
          curr.prev.next = curr;
        }
        prev = curr;
        length += 1;
      }

      index += 1;
    }
    first.prev = prev;
    prev.next = first;

    return new Path(first, length);
  }

  reverse() {
    let curr = this.first.prev;
    let endPoint = curr.endPoint;
    for (let i = 0; i < this.length - 1; i += 1) {
      curr.partiallyReverse();
      // fix endPoints
      curr.endPoint = curr.next.endPoint;
      curr = curr.next;
    }
    curr.partiallyReverse();
    curr.endPoint = endPoint;
  }

  reorder(startPoint, endPoint) {
    let curr = this.first;
    for (let i = 0; i < this.length; i += 1) {
      if (curr.startPoint.equals(startPoint) && curr.endPoint.equals(endPoint)) {
        this.first = curr;
        return this;
      }
      if (curr.startPoint.equals(endPoint) && curr.endPoint.equals(startPoint)) {
        this.first = curr;
        this.reverse();
        return this;
      }
      curr = curr.next;
    }
  }

  toString() {
    let curr = this.first;
    let s = `M ${curr.startPoint.x} ${curr.startPoint.y} C `;
    for (let i = 0; i < this.length; i += 1) {
      s += curr + ' ';
      curr = curr.next;
    }
    s += 'Z';
    return s;
  }
}