<?php

/**
 * `ALTER` statement.
 *
 * @package    SqlParser
 * @subpackage Statements
 */
namespace SqlParser\Statements;

use SqlParser\Parser;
use SqlParser\Statement;
use SqlParser\Token;
use SqlParser\TokensList;
use SqlParser\Components\AlterOperation;
use SqlParser\Components\Expression;
use SqlParser\Components\OptionsArray;

/**
 * `ALTER` statement.
 *
 * @category   Statements
 * @package    SqlParser
 * @subpackage Statements
 * @author     Dan Ungureanu <udan1107@gmail.com>
 * @license    http://opensource.org/licenses/GPL-2.0 GNU Public License
 */
class AlterStatement extends Statement
{

    /**
     * Table affected.
     *
     * @var Expression
     */
    public $table;

    /**
     * Column affected by this statement.
     *
     * @var AlterOperation[]
     */
    public $altered = array();

    /**
     * Options of this statement.
     *
     * @var array
     */
    public static $OPTIONS = array(
        'ONLINE'                        => 1,
        'OFFLINE'                       => 1,
        'IGNORE'                        => 2,
    );

    /**
     * @param Parser     $parser The instance that requests parsing.
     * @param TokensList $list   The list of tokens to be parsed.
     *
     * @return void
     */
    public function parse(Parser $parser, TokensList $list)
    {
        ++$list->idx; // Skipping `ALTER`.
        $this->options = OptionsArray::parse(
            $parser,
            $list,
            static::$OPTIONS
        );

        // Skipping `TABLE`.
        $list->getNextOfTypeAndValue(Token::TYPE_KEYWORD, 'TABLE');

        // Parsing affected table.
        $this->table = Expression::parse(
            $parser,
            $list,
            array(
                'parseField' => 'column',
                'breakOnAlias' => true,
            )
        );
        ++$list->idx; // Skipping field.

        /**
         * The state of the parser.
         *
         * Below are the states of the parser.
         *
         *      0 -----------------[ alter operation ]-----------------> 1
         *
         *      1 -------------------------[ , ]-----------------------> 0
         *
         * @var int $state
         */
        $state = 0;

        for (; $list->idx < $list->count; ++$list->idx) {
            /**
             * Token parsed at this moment.
             *
             * @var Token $token
             */
            $token = $list->tokens[$list->idx];

            // End of statement.
            if ($token->type === Token::TYPE_DELIMITER) {
                break;
            }

            // Skipping whitespaces and comments.
            if (($token->type === Token::TYPE_WHITESPACE) || ($token->type === Token::TYPE_COMMENT)) {
                continue;
            }

            if ($state === 0) {
                $this->altered[] = AlterOperation::parse($parser, $list);
                $state = 1;
            } elseif ($state === 1) {
                if (($token->type === Token::TYPE_OPERATOR) && ($token->value === ',')) {
                    $state = 0;
                }
            }
        }
    }

    /**
     * @return string
     */
    public function build()
    {
        $tmp = array();
        foreach ($this->altered as $altered) {
            $tmp[] = $altered::build($altered);
        }

        return 'ALTER ' . OptionsArray::build($this->options)
            . ' TABLE ' . Expression::build($this->table)
            . ' ' . implode(', ', $tmp);
    }
}
