const Glib = require('./Glib');
const Vector = require('./Vector');

const ORIGIN = new Vector(0, 0);

const DIRECTIONS = {
  UP: new Vector(0, 1),
  DOWN: new Vector(0, -1),
  LEFT: new Vector(-1, 0),
  RIGHT: new Vector(1, 0),
};

class Rectangle {
  static fromPoints(one, two) {
    const [x1, x2] = [one.v[0], two.v[0]].sortInts();
    const [y1, y2] = [one.v[1], two.v[1]].sortInts();
    const bottomLeft = new Vector(x1, y1);
    const size = bottomLeft
      .multiply(-1)
      .add(new Vector(x2, y2))
      .add(1n);
    return new Rectangle(bottomLeft, size);
  }
  static fromXXYY(x1, x2, y1, y2) {
    return Rectangle.fromPoints(new Vector(x1, y1), new Vector(x2, y2));
  }
  constructor(offset, size) {
    // console.log(`${offset.string} ${offset.add(size).string}`);
    // todo: normalize?
    this.offset = offset;
    this.size = size;
  }
  allPoints() {
    return new Glib(
      (function*(_this) {
        const [startX, startY] = _this.offset.toArray();
        const [endX, endY] = _this.offset.add(_this.size).toArray();
        for (let x = startX; x < endX; x++) {
          for (let y = startY; y < endY; y++) {
            yield new Vector(x, y);
          }
        }
      })(this),
    );
  }
  get bottomLeft() {
    return this.offset;
  }
  get topRight() {
    return this.offset.add(this.size);
  }
}

class Instruction {
  static fromString(string, instructionSet) {
    const [char, ...num] = string.split('');

    if (!instructionSet.hasOwnProperty(char)) {
      throw new Error('invalid move');
    }

    const move = instructionSet[char];
    return num.length === 0
      ? new Instruction(move)
      : new Instruction(move, BigInt(num.join('')));
  }
  constructor(move, count = 1n) {
    this.move = move;
    this.count = count;
  }
  jump(source) {
    // console.log(this.count);
    return source.add(this.move.multiply(this.count));
  }
  walk(source) {
    return new Glib(
      (function*(_this) {
        for (let i = 0n; i < _this.count; i++) {
          // console.log(source.string);
          source = source.add(_this.move);
          yield source;
        }
        // console.log(source.string);
      })(this),
    );
  }
}

module.exports = {
  Instruction,
  Rectangle,
  DIRECTIONS,
  ORIGIN,
  '^v<>': {
    '^': DIRECTIONS.UP,
    v: DIRECTIONS.DOWN,
    '<': DIRECTIONS.LEFT,
    '>': DIRECTIONS.RIGHT,
  },
  udlr: {
    u: DIRECTIONS.UP,
    d: DIRECTIONS.DOWN,
    l: DIRECTIONS.LEFT,
    r: DIRECTIONS.RIGHT,
  },
  UDLR: {
    U: DIRECTIONS.UP,
    D: DIRECTIONS.DOWN,
    L: DIRECTIONS.LEFT,
    R: DIRECTIONS.RIGHT,
  },
  everyStep(instructions, source = ORIGIN) {
    return new Glib(
      (function*() {
        for (const instruction of instructions) {
          // console.log(instruction);
          yield* instruction.walk(source);
          source = instruction.jump(source);
        }
      })(),
    );
  },
};