<?php

namespace App\Services;

class SelectionMapper
{
    /**
     * Map a pixel-based selection rectangle to cell-unit coordinates.
     *
     * @param  float  $x  Top-left x in pixels (canvas coords)
     * @param  float  $y  Top-left y in pixels (canvas coords)
     * @param  float  $w  Width in pixels
     * @param  float  $h  Height in pixels
     * @param  float  $offsetX  Canvas offset X (pan)
     * @param  float  $offsetY  Canvas offset Y (pan)
     * @param  int  $cellSize  Cell size in pixels
     * @return array{ x:int, y:int, w:int, h:int }
     */
    public function mapPixelsToCells(float $x, float $y, float $w, float $h, float $offsetX, float $offsetY, int $cellSize): array
    {
        $relX = $x - $offsetX;
        $relY = $y - $offsetY;

        $cellX = (int) max(0, floor($relX / $cellSize));
        $cellY = (int) max(0, floor($relY / $cellSize));

        $wCells = (int) max(1, ceil($w / $cellSize));
        $hCells = (int) max(1, ceil($h / $cellSize));

        return ['x' => $cellX, 'y' => $cellY, 'w' => $wCells, 'h' => $hCells];
    }
}