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<?php

    namespace CzProject\SqlGenerator\Statements;

    use CzProject\SqlGenerator\OutOfRangeException;
    use CzProject\SqlGenerator\Helpers;
    use CzProject\SqlGenerator\IDriver;
    use CzProject\SqlGenerator\IStatement;


    class IndexColumnDefinition implements IStatement
    {
        const ASC = 'ASC';
        const DESC = 'DESC';

        /** @var string|NULL */
        private $name;

        /** @var string */
        private $order;

        /** @var int|NULL */
        private $length;


        /**
         * @param  string
         * @param  string
         * @param  int|NULL
         */
        public function __construct($name, $order = self::ASC, $length = NULL)
        {
            $this->name = $name;
            $this->setOrder($order);
            $this->length = $length;
        }


        /**
         * @param  string
         * @return self
         */
        private function setOrder($order)
        {
            $order = (string) $order;

            if ($order !== self::ASC && $order !== self::DESC) {
                throw new OutOfRangeException("Order type '$order' not found.");
            }

            $this->order = $order;
            return $this;
        }


        /**
         * @return string
         */
        public function toSql(IDriver $driver)
        {
            $output = $driver->escapeIdentifier($this->name);

            if ($this->length !== NULL) {
                $output .= ' (' . $this->length . ')';
            }

            if ($this->order !== self::ASC) {
                $output .= ' ' . $this->order;
            }

            return $output;
        }
    }