/**
 * Copyright © 2023-2026 Blockchain Commons, LLC
 * Copyright © 2025-2026 Parity Technologies
 *
 */

import { Grid } from "./grid";
import type { Data } from "./data";
import { BitAggregator, BitEnumerator } from "./bit-enumerator";
import type { ChangeGrid } from "./change-grid";

/**
 * A class that holds an array of boolean cells and that is
 * capable of running Conway's Game of Life to produce the next generation.
 */
export class CellGrid {
  public readonly grid: Grid<boolean>;

  constructor(width: number, height: number) {
    this.grid = new Grid<boolean>(width, height, false);
  }

  private static isAliveInNextGeneration(currentAlive: boolean, neighborsCount: number): boolean {
    if (currentAlive) {
      return neighborsCount === 2 || neighborsCount === 3;
    } else {
      return neighborsCount === 3;
    }
  }

  private countNeighbors(px: number, py: number): number {
    let total = 0;
    this.grid.forNeighborhood(px, py, (ox, oy, nx, ny) => {
      if (ox === 0 && oy === 0) {
        return;
      }
      if (this.grid.getValue(nx, ny)) {
        total++;
      }
    });
    return total;
  }

  data(): Data {
    const a = new BitAggregator();
    this.grid.forAll((x, y) => {
      a.append(this.grid.getValue(x, y));
    });
    return a.data();
  }

  setData(data: Data): void {
    const e = new BitEnumerator(data);
    let i = 0;
    e.forAll((b) => {
      this.grid.storage[i] = b;
      i++;
    });
  }

  nextGeneration(
    currentChangeGrid: ChangeGrid,
    nextCellGrid: CellGrid,
    nextChangeGrid: ChangeGrid,
  ): void {
    nextCellGrid.grid.setAll(false);
    nextChangeGrid.grid.setAll(false);

    const width = this.grid.width;
    const height = this.grid.height;
    for (let y = 0; y < height; y++) {
      for (let x = 0; x < width; x++) {
        const currentAlive = this.grid.getValue(x, y);
        if (currentChangeGrid.grid.getValue(x, y)) {
          const neighborsCount = this.countNeighbors(x, y);
          const nextAlive = CellGrid.isAliveInNextGeneration(currentAlive, neighborsCount);
          if (nextAlive) {
            nextCellGrid.grid.setValue(true, x, y);
          }
          if (currentAlive !== nextAlive) {
            nextChangeGrid.setChanged(x, y);
          }
        } else {
          nextCellGrid.grid.setValue(currentAlive, x, y);
        }
      }
    }
  }
}