<?php

declare(strict_types=1);

namespace Doctrine\SqlFormatter;

final class Cursor
{
    /** @var int */
    private $position = -1;

    /** @var Token[] */
    private $tokens;

    /**
     * @param Token[] $tokens
     */
    public function __construct(array $tokens)
    {
        $this->tokens = $tokens;
    }

    public function next(?int $exceptTokenType = null) : ?Token
    {
        while ($token = $this->tokens[++$this->position] ?? null) {
            if ($exceptTokenType !== null && $token->isOfType($exceptTokenType)) {
                continue;
            }

            return $token;
        }

        return null;
    }

    public function previous(?int $exceptTokenType = null) : ?Token
    {
        while ($token = $this->tokens[--$this->position] ?? null) {
            if ($exceptTokenType !== null && $token->isOfType($exceptTokenType)) {
                continue;
            }

            return $token;
        }

        return null;
    }

    public function subCursor() : self
    {
        $cursor           = new self($this->tokens);
        $cursor->position = $this->position;

        return $cursor;
    }
}