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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 ForeignKeyDefinition implements IStatement
    {
        const ACTION_RESTRICT = 'RESTRICT';
        const ACTION_NO_ACTION = 'NO ACTION';
        const ACTION_CASCADE = 'CASCADE';
        const ACTION_SET_NULL = 'SET NULL';

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

        /** @var string[] */
        private $columns;

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

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

        /** @var string */
        private $onUpdateAction = self::ACTION_RESTRICT;

        /** @var string */
        private $onDeleteAction = self::ACTION_RESTRICT;


        /**
         * @param  string
         * @param  string[]|string
         * @param  string
         * @param  string[]|string
         */
        public function __construct($name, $columns = array(), $targetTable, $targetColumns = array())
        {
            $this->name = $name;
            $this->targetTable = $targetTable;

            if (!is_array($columns)) {
                $columns = array($columns);
            }

            foreach ($columns as $column) {
                $this->columns[] = $column;
            }

            if (!is_array($targetColumns)) {
                $targetColumns = array($targetColumns);
            }

            foreach ($targetColumns as $targetColumn) {
                $this->targetColumns[] = $targetColumn;
            }
        }


        /**
         * @param  string
         * @return static
         */
        public function setOnUpdateAction($onUpdateAction)
        {
            if (!$this->validateAction($onUpdateAction)) {
                throw new OutOfRangeException("Action '$onUpdateAction' is invalid.");
            }

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


        /**
         * @param  string
         * @return static
         */
        public function setOnDeleteAction($onDeleteAction)
        {
            if (!$this->validateAction($onDeleteAction)) {
                throw new OutOfRangeException("Action '$onDeleteAction' is invalid.");
            }

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


        /**
         * @return string
         */
        public function toSql(IDriver $driver)
        {
            $output = 'CONSTRAINT ' . $driver->escapeIdentifier($this->name);
            $output .= ' FOREIGN KEY (';
            $output .= implode(', ', array_map(array($driver, 'escapeIdentifier'), $this->columns));
            $output .= ') REFERENCES ' . $driver->escapeIdentifier($this->targetTable) . ' (';
            $output .= implode(', ', array_map(array($driver, 'escapeIdentifier'), $this->targetColumns));
            $output .= ')';
            $output .= ' ON DELETE ' . $this->onDeleteAction;
            $output .= ' ON UPDATE ' . $this->onUpdateAction;
            return $output;
        }


        /**
         * @param  string
         * @return bool
         */
        private function validateAction($action)
        {
            return $action === self::ACTION_RESTRICT
                || $action === self::ACTION_NO_ACTION
                || $action === self::ACTION_CASCADE
                || $action === self::ACTION_SET_NULL;
        }
    }