<?php
/**
 * CSV output.
 *
 * @package HostKhata
 */

namespace HostKhata\Support;

defined( 'ABSPATH' ) || exit;

/**
 * Writes CSV lines that are safe to open in a spreadsheet.
 *
 * A cell that starts with `=`, `+`, `-`, `@`, a tab or a carriage return can be
 * run as a formula by Excel and LibreOffice (CSV injection), so text like that
 * gets a leading apostrophe. Real numbers, such as a negative amount, are left
 * as they are.
 *
 * @since 0.1.0
 */
final class CsvWriter {

	/**
	 * One CSV line, ending in a newline.
	 *
	 * @since 0.1.0
	 *
	 * @param array<int, scalar|null> $cells Cells.
	 * @return string
	 */
	public static function line( array $cells ): string {
		return implode( ',', array_map( array( self::class, 'cell' ), $cells ) ) . "\r\n";
	}

	/**
	 * One cell: made safe, then quoted when it needs it.
	 *
	 * @since 0.1.0
	 *
	 * @param scalar|null $value Cell value.
	 * @return string
	 */
	public static function cell( $value ): string {
		$text = null === $value ? '' : (string) ( is_bool( $value ) ? (int) $value : $value );

		if ( '' !== $text && ! is_numeric( $text ) && 1 === preg_match( '/^[=+\-@\t\r]/', $text ) ) {
			$text = "'" . $text;
		}

		if ( preg_match( '/[",\r\n]/', $text ) ) {
			$text = '"' . str_replace( '"', '""', $text ) . '"';
		}

		return $text;
	}
}