<?php

namespace TablePress\Matrix\Operators;

use TablePress\Matrix\Matrix;
use TablePress\Matrix\Exception;

class Subtraction extends Operator
{
	/**
	 * Execute the subtraction
	 *
	 * @param mixed $value The matrix or numeric value to subtract from the current base value
	 * @throws Exception If the provided argument is not appropriate for the operation
	 * @return $this The operation object, allowing multiple subtractions to be chained
	 **/
	public function execute($value): Operator
	{
		if (is_array($value)) {
			$value = new Matrix($value);
		}

		if (is_object($value) && ($value instanceof Matrix)) {
			return $this->subtractMatrix($value);
		} elseif (is_numeric($value)) {
			return $this->subtractScalar($value);
		}

		throw new Exception('Invalid argument for subtraction');
	}

	/**
	 * Execute the subtraction for a scalar
	 *
	 * @param mixed $value The numeric value to subtracted from the current base value
	 * @return $this The operation object, allowing multiple additions to be chained
	 **/
	protected function subtractScalar($value): Operator
	{
		for ($row = 0; $row < $this->rows; ++$row) {
			for ($column = 0; $column < $this->columns; ++$column) {
				$this->matrix[$row][$column] -= $value;
			}
		}

		return $this;
	}

	/**
	 * Execute the subtraction for a matrix
	 *
	 * @param TablePress\Matrix $value The numeric value to subtract from the current base value
	 * @return $this The operation object, allowing multiple subtractions to be chained
	 * @throws Exception If the provided argument is not appropriate for the operation
	 **/
	protected function subtractMatrix(TablePress\Matrix $value): Operator
	{
		$this->validateMatchingDimensions($value);

		for ($row = 0; $row < $this->rows; ++$row) {
			for ($column = 0; $column < $this->columns; ++$column) {
				$this->matrix[$row][$column] -= $value->getValue($row + 1, $column + 1);
			}
		}

		return $this;
	}
}