import { TokenFlow } from "../flow";

export class GridFlow extends TokenFlow {
  rows: number;
  columns: number;

  constructor(rows: number, columns: number) {
    super();
    this.rows = rows;
    this.columns = columns;
  }

  get requiredLength(): number | null {
    return this.rows * this.columns;
  }

  isWithin(
    anchorIndex: number,
    headIndex: number,
    otherIndex: number
  ): boolean {
    const anchorRow = Math.floor(anchorIndex / this.columns);
    const anchorCol = anchorIndex % this.columns;
    const headRow = Math.floor(headIndex / this.columns);
    const headCol = headIndex % this.columns;
    const otherRow = Math.floor(otherIndex / this.columns);
    const otherCol = otherIndex % this.columns;

    const minRow = Math.min(anchorRow, headRow);
    const maxRow = Math.max(anchorRow, headRow);
    const minCol = Math.min(anchorCol, headCol);
    const maxCol = Math.max(anchorCol, headCol);

    return (
      otherRow >= minRow &&
      otherRow <= maxRow &&
      otherCol >= minCol &&
      otherCol <= maxCol
    );
  }

  verticalCandidates(
    direction: "up" | "down",
    fromIndex: number,
    length: number
  ): number[] {
    const row = Math.floor(fromIndex / this.columns);
    const col = fromIndex % this.columns;
    const candidates: number[] = [];

    if (direction === "up" && row > 0) {
      candidates.push((row - 1) * this.columns + col);
    } else if (direction === "down" && row < this.rows - 1) {
      candidates.push((row + 1) * this.columns + col);
    }

    return candidates.filter((index) => index < length);
  }
}