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<?php

    namespace CzProject\SqlGenerator\Statements;

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


    class ModifyColumn implements IStatement
    {
        const POSITION_FIRST = TRUE;
        const POSITION_LAST = FALSE;

        /** @var ColumnDefinition */
        private $definition;

        /** @var string|bool */
        private $position = self::POSITION_LAST;


        /**
         * @param  string
         * @param  string
         * @param  array
         * @param  array  [name => value]
         */
        public function __construct($name, $type, array $parameters = NULL, array $options = array())
        {
            $this->definition = new ColumnDefinition($name, $type, $parameters, $options);
        }


        /**
         * @return self
         */
        public function moveToFirstPosition()
        {
            $this->position = self::POSITION_FIRST;
            return $this;
        }


        /**
         * @param  string
         * @return self
         */
        public function moveAfterColumn($column)
        {
            $this->position = $column;
            return $this;
        }


        /**
         * @return self
         */
        public function moveToLastPosition()
        {
            $this->position = self::POSITION_LAST;
            return $this;
        }


        /**
         * @param  bool
         * @return self
         */
        public function setNullable($nullable = TRUE)
        {
            $this->definition->setNullable($nullable);
            return $this;
        }


        /**
         * @param  scalar|NULL
         * @return self
         */
        public function setDefaultValue($defaultValue)
        {
            $this->definition->setDefaultValue($defaultValue);
            return $this;
        }


        /**
         * @param  bool
         * @return self
         */
        public function setAutoIncrement($autoIncrement = TRUE)
        {
            $this->definition->setAutoIncrement($autoIncrement);
            return $this;
        }


        /**
         * @param  string|NULL
         * @return self
         */
        public function setComment($comment)
        {
            $this->definition->setComment($comment);
            return $this;
        }


        /**
         * @return string
         */
        public function toSql(IDriver $driver)
        {
            $output = 'MODIFY COLUMN ' . $this->definition->toSql($driver);

            if ($this->position === self::POSITION_FIRST) {
                $output .= ' FIRST';

            } elseif ($this->position !== self::POSITION_LAST) {
                $output .= ' AFTER ' . $driver->escapeIdentifier($this->position);
            }

            return $output;
        }
    }