/**
 * A position is the fundamental geometry construct.
 *
 * The first two elements are longitude and latitude, or easting and northing,
 * precisely in that order and using decimal numbers.
 *
 * Altitude or elevation MAY be included as an optional third element.
 */
export type Position = [number, number, number] | [number, number];

/**
 * A GeoJSON object MAY have a member named "bbox" to include
 * information on the coordinate range for its Geometries, Features, or
 * FeatureCollections.
 *
 * The value of the bbox member MUST be an array of
 * length 2*n where n is the number of dimensions represented in the
 * contained geometries, with all axes of the most southwesterly point
 * followed by all axes of the more northeasterly point. The axes order
 * of a bbox follows the axes order of geometries.
 */
export type BoundingBox = [number, number, number, number] | [number, number, number, number, number, number];

export type AbstractBoundingBox = {
  west: number | null;
  south: number | null;
  low: number | null;
  east: number | null;
  north: number | null;
  high: number | null;
};

export type GeoJsonJson = {
  type: string;
  bbox?: BoundingBox;
};

/**
 * A GeoJSON object represents a Geometry, Feature, or collection of
 * Features.
 */
export class GeoJSON {
  /**
   *
   *
   * A GeoJSON object MAY have a member named "bbox" to include
   * information on the coordinate range for its Geometries, Features, or
   * FeatureCollections
   */
  boundingbox: AbstractBoundingBox = {
    west: null,
    south: null,
    low: null,
    east: null,
    north: null,
    high: null,
  };

  get bbox(): BoundingBox | null {
    if (
      this.boundingbox.west === null ||
      this.boundingbox.south === null ||
      this.boundingbox.east === null ||
      this.boundingbox.north === null
    ) {
      return null;
    }

    return this.boundingbox.low === null || this.boundingbox.high === null
      ? [this.boundingbox.west, this.boundingbox.south, this.boundingbox.east, this.boundingbox.north]
      : [
          this.boundingbox.west,
          this.boundingbox.south,
          this.boundingbox.low,
          this.boundingbox.east,
          this.boundingbox.north,
          this.boundingbox.high,
        ];
  }

  toJSON(): GeoJsonJson {
    const json: GeoJsonJson = {
      type: this.constructor.name,
    };

    const bbox = this.bbox;
    bbox !== null && (json.bbox = bbox);

    return json;
  }
}