<?php

declare(strict_types=1);

namespace GraphQL\Language;

/**
 * Represents a range of characters represented by a lexical token
 * within a Source.
 */
class Token
{
    // Each kind of token.
    const SOF          = '<SOF>';
    const EOF          = '<EOF>';
    const BANG         = '!';
    const DOLLAR       = '$';
    const AMP          = '&';
    const PAREN_L      = '(';
    const PAREN_R      = ')';
    const SPREAD       = '...';
    const COLON        = ':';
    const EQUALS       = '=';
    const AT           = '@';
    const BRACKET_L    = '[';
    const BRACKET_R    = ']';
    const BRACE_L      = '{';
    const PIPE         = '|';
    const BRACE_R      = '}';
    const NAME         = 'Name';
    const INT          = 'Int';
    const FLOAT        = 'Float';
    const STRING       = 'String';
    const BLOCK_STRING = 'BlockString';
    const COMMENT      = 'Comment';

    /**
     * The kind of Token (see one of constants above).
     *
     * @var string
     */
    public $kind;

    /**
     * The character offset at which this Node begins.
     *
     * @var int
     */
    public $start;

    /**
     * The character offset at which this Node ends.
     *
     * @var int
     */
    public $end;

    /**
     * The 1-indexed line number on which this Token appears.
     *
     * @var int
     */
    public $line;

    /**
     * The 1-indexed column number at which this Token begins.
     *
     * @var int
     */
    public $column;

    /** @var string|null */
    public $value;

    /**
     * Tokens exist as nodes in a double-linked-list amongst all tokens
     * including ignored tokens. <SOF> is always the first node and <EOF>
     * the last.
     *
     * @var Token
     */
    public $prev;

    /** @var Token */
    public $next;

    /**
     * @param string     $kind
     * @param int        $start
     * @param int        $end
     * @param int        $line
     * @param int        $column
     * @param mixed|null $value
     */
    public function __construct($kind, $start, $end, $line, $column, ?Token $previous = null, $value = null)
    {
        $this->kind   = $kind;
        $this->start  = $start;
        $this->end    = $end;
        $this->line   = $line;
        $this->column = $column;
        $this->prev   = $previous;
        $this->next   = null;
        $this->value  = $value;
    }

    /**
     * @return string
     */
    public function getDescription()
    {
        return $this->kind . ($this->value ? ' "' . $this->value . '"' : '');
    }

    /**
     * @return (string|int|null)[]
     */
    public function toArray()
    {
        return [
            'kind'   => $this->kind,
            'value'  => $this->value,
            'line'   => $this->line,
            'column' => $this->column,
        ];
    }
}