import { CellRef, cellRefEquals } from "./types";

export abstract class Selection {
  readonly gridId: string;
  readonly activeCellRef: CellRef;

  constructor(gridId: string, activeCellRef: CellRef) {
    this.gridId = gridId;
    this.activeCellRef = activeCellRef;
  }

  abstract extend(cellRef: CellRef): Selection;
}

export class ActiveCellSelection extends Selection {
  extend(cellRef: CellRef): Selection {
    if (cellRefEquals(cellRef, this.activeCellRef)) {
      return this;
    }

    return new RangeSelection(this.gridId, this.activeCellRef, [
      this.activeCellRef,
      cellRef,
    ]);
  }
}

export type CellRange = [CellRef, CellRef];

export class RangeSelection extends Selection {
  #range: CellRange;

  get range() {
    return this.#range;
  }

  constructor(gridId: string, activeCellRef: CellRef, range: CellRange) {
    super(gridId, activeCellRef);
    this.#range = range;
  }

  extend(cellRef: CellRef): Selection {
    if (cellRefEquals(cellRef, this.activeCellRef)) {
      return new ActiveCellSelection(this.gridId, cellRef);
    }

    return new RangeSelection(this.gridId, this.activeCellRef, [
      this.#range[0],
      cellRef,
    ]);
  }
}