<?php
/**
 * Zend Framework (http://framework.zend.com/)
 *
 * @link      http://github.com/zendframework/zf2 for the canonical source repository
 * @copyright Copyright (c) 2005-2015 Zend Technologies USA Inc. (http://www.zend.com)
 * @license   http://framework.zend.com/license/new-bsd New BSD License
 */

namespace Zend\Db\Sql;

abstract class AbstractExpression implements ExpressionInterface
{
    /**
     * @var string[]
     */
    protected $allowedTypes = array(
        self::TYPE_IDENTIFIER,
        self::TYPE_LITERAL,
        self::TYPE_SELECT,
        self::TYPE_VALUE,
    );

    /**
     * Normalize Argument
     *
     * @param mixed $argument
     * @param string $defaultType
     *
     * @return array
     *
     * @throws Exception\InvalidArgumentException
     */
    protected function normalizeArgument($argument, $defaultType = self::TYPE_VALUE)
    {
        if ($argument instanceof ExpressionInterface || $argument instanceof SqlInterface) {
            return $this->buildNormalizedArgument($argument, self::TYPE_VALUE);
        }

        if (is_scalar($argument) || $argument === null) {
            return $this->buildNormalizedArgument($argument, $defaultType);
        }

        if (is_array($argument)) {
            $value = current($argument);

            if ($value instanceof ExpressionInterface || $value instanceof SqlInterface) {
                return $this->buildNormalizedArgument($value, self::TYPE_VALUE);
            }

            $key = key($argument);

            if (is_integer($key) && ! in_array($value, $this->allowedTypes)) {
                return $this->buildNormalizedArgument($value, $defaultType);
            }

            return $this->buildNormalizedArgument($key, $value);
        }

        throw new Exception\InvalidArgumentException(sprintf(
            '$argument should be %s or %s or %s or %s or %s, "%s" given',
            'null',
            'scalar',
            'array',
            'Zend\Db\Sql\ExpressionInterface',
            'Zend\Db\Sql\SqlInterface',
            is_object($argument) ? get_class($argument) : gettype($argument)
        ));
    }

    /**
     * @param mixed  $argument
     * @param string $argumentType
     *
     * @return array
     *
     * @throws Exception\InvalidArgumentException
     */
    private function buildNormalizedArgument($argument, $argumentType)
    {
        if (! in_array($argumentType, $this->allowedTypes)) {
            throw new Exception\InvalidArgumentException(sprintf(
                'Argument type should be in array(%s)',
                implode(',', $this->allowedTypes)
            ));
        }

        return array(
            $argument,
            $argumentType,
        );
    }
}
