const Math = require('./bnmath');
const Glib = require('./Glib');

module.exports = class Vector {
  static fromString(string) {
    if (!string.startsWith('(') || !string.endsWith(')')) {
      throw new Error('invalid format');
    }
    return new Vector(
      ...Glib.fromSplit(string.slice(1, -1), ',').map((i) => BigInt(i.trim())),
    );
  }
  constructor(...v) {
    this.v = v.map((i) => {
      switch (typeof i) {
        case 'number':
          return BigInt(i);
        case 'bigint':
          return i;
        default:
          throw new Error('invalid input');
      }
    });
  }
  _check(v) {
    if (typeof v !== 'object' || !(v instanceof Vector)) {
      throw new Error('nope');
    }
    if (this.len !== v.len) {
      throw new Error('mismatched length');
    }
  }
  _resolve(v) {
    if (typeof v === 'number' || typeof v === 'bigint') {
      return new Vector(...this.v.map((e) => v));
    }

    if (typeof v !== 'object' || !(v instanceof Vector)) {
      throw new Error('nope');
    }
    if (this.len !== v.len) {
      throw new Error('mismatched length');
    }

    return v;
  }
  multiply(v) {
    v = this._resolve(v);
    return new Vector(...this.v.map((e, i) => e * v.v[i]));
  }
  add(v) {
    v = this._resolve(v);
    return new Vector(...this.v.map((e, i) => e + v.v[i]));
  }
  subtract(v) {
    v = this._resolve(v);
    return this.add(v.multiply(-1));
  }
  remainder(v) {
    v = this._resolve(v);
    return new Vector(...this.v.map((e, i) => e % v.v[i]));
  }
  modulo(v) {
    v = this._resolve(v);
    return new Vector(
      ...this.v.map((e, i) => ((e % v.v[i]) + v.v[i]) % v.v[i]),
    );
  }
  distance(v) {
    this._check(v);
    return this.v
      .map((e, i) => {
        return Math.abs(e + v.v[i]);
      })
      .reduce((a, b) => a + b);
  }
  neighbors() {
    return new Glib(
      (function*(_this) {
        let permutations = 3n ** _this.length;
        const skipped = Math.parseInt('1'.repeat(_this.v.length), 3);
        for (let i = 0n; i < permutations; i++) {
          if (i === skipped) {
            continue;
          }
          yield _this.add(
            new Vector(
              ...Glib.fromIterable(
                i.toString(3).padStart(_this.v.length, '0'),
              ).map((i) => BigInt(i) - 1n),
            ),
          );
        }
      })(this),
    );
  }
  toArray() {
    return this.v.slice();
  }
  get length() {
    return BigInt(this.v.length);
  }
  get string() {
    return '(' + this.v.join(', ') + ')';
  }
};