<?php
/**
 * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
 * Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
 *
 * Licensed under The MIT License
 * For full copyright and license information, please see the LICENSE.txt
 * Redistributions of files must retain the above copyright notice.
 *
 * @copyright     Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
 * @link          http://cakephp.org CakePHP(tm) Project
 * @since         3.0.0
 * @license       http://www.opensource.org/licenses/mit-license.php MIT License
 */
namespace Cake\Database;

use Cake\Database\ExpressionInterface;
use Cake\Database\Expression\FieldInterface;
use Cake\Database\Expression\IdentifierExpression;
use Cake\Database\Expression\OrderByExpression;

/**
 * Contains all the logic related to quoting identifiers in a Query object
 *
 * @internal
 */
class IdentifierQuoter
{

    /**
     * The driver instance used to do the identifier quoting
     *
     * @var \Cake\Database\Driver
     */
    protected $_driver;

    /**
     * Constructor
     *
     * @param \Cake\Database\Driver $driver The driver instance used to do the identifier quoting
     */
    public function __construct(Driver $driver)
    {
        $this->_driver = $driver;
    }

    /**
     * Iterates over each of the clauses in a query looking for identifiers and
     * quotes them
     *
     * @param \Cake\Database\Query $query The query to have its identifiers quoted
     * @return \Cake\Database\Query
     */
    public function quote(Query $query)
    {
        $binder = $query->valueBinder();
        $query->valueBinder(false);

        if ($query->type() === 'insert') {
            $this->_quoteInsert($query);
        } elseif ($query->type() === 'update') {
            $this->_quoteUpdate($query);
        } else {
            $this->_quoteParts($query);
        }

        $query->traverseExpressions([$this, 'quoteExpression']);
        $query->valueBinder($binder);
        return $query;
    }

    /**
     * Quotes identifiers inside expression objects
     *
     * @param \Cake\Database\ExpressionInterface $expression The expression object to walk and quote.
     * @return void
     */
    public function quoteExpression($expression)
    {
        if ($expression instanceof FieldInterface) {
            $this->_quoteComparison($expression);
            return;
        }

        if ($expression instanceof OrderByExpression) {
            $this->_quoteOrderBy($expression);
            return;
        }

        if ($expression instanceof IdentifierExpression) {
            $this->_quoteIdentifierExpression($expression);
            return;
        }
    }

    /**
     * Quotes all identifiers in each of the clauses of a query
     *
     * @param \Cake\Database\Query $query The query to quote.
     * @return void
     */
    protected function _quoteParts($query)
    {
        foreach (['distinct', 'select', 'from', 'group'] as $part) {
            $contents = $query->clause($part);

            if (!is_array($contents)) {
                continue;
            }

            $result = $this->_basicQuoter($contents);
            if ($result) {
                $query->{$part}($result, true);
            }
        }

        $joins = $query->clause('join');
        if ($joins) {
            $joins = $this->_quoteJoins($joins);
            $query->join($joins, [], true);
        }
    }

    /**
     * A generic identifier quoting function used for various parts of the query
     *
     * @param array $part the part of the query to quote
     * @return array
     */
    protected function _basicQuoter($part)
    {
        $result = [];
        foreach ((array)$part as $alias => $value) {
            $value = !is_string($value) ? $value : $this->_driver->quoteIdentifier($value);
            $alias = is_numeric($alias) ? $alias : $this->_driver->quoteIdentifier($alias);
            $result[$alias] = $value;
        }
        return $result;
    }

    /**
     * Quotes both the table and alias for an array of joins as stored in a Query
     * object
     *
     * @param array $joins The joins to quote.
     * @return array
     */
    protected function _quoteJoins($joins)
    {
        $result = [];
        foreach ($joins as $value) {
            $alias = null;
            if (!empty($value['alias'])) {
                $alias = $this->_driver->quoteIdentifier($value['alias']);
                $value['alias'] = $alias;
            }

            if (is_string($value['table'])) {
                $value['table'] = $this->_driver->quoteIdentifier($value['table']);
            }

            $result[$alias] = $value;
        }

        return $result;
    }

    /**
     * Quotes the table name and columns for an insert query
     *
     * @param \Cake\Database\Query $query The insert query to quote.
     * @return void
     */
    protected function _quoteInsert($query)
    {
        list($table, $columns) = $query->clause('insert');
        $table = $this->_driver->quoteIdentifier($table);
        foreach ($columns as &$column) {
            if (is_string($column)) {
                $column = $this->_driver->quoteIdentifier($column);
            }
        }
        $query->insert($columns)->into($table);
    }

    /**
     * Quotes the table name for an update query
     *
     * @param \Cake\Database\Query $query The update query to quote.
     * @return void
     */
    protected function _quoteUpdate($query)
    {
        $table = $query->clause('update')[0];
        
        if (is_string($table)) {
            $query->update($this->_driver->quoteIdentifier($table));
        }
    }

    /**
     * Quotes identifiers in expression objects implementing the field interface
     *
     * @param \Cake\Database\Expression\FieldInterface $expression The expression to quote.
     * @return void
     */
    protected function _quoteComparison(FieldInterface $expression)
    {
        $field = $expression->getField();
        if (is_string($field)) {
            $expression->setField($this->_driver->quoteIdentifier($field));
        } elseif (is_array($field)) {
            $quoted = [];
            foreach ($field as $f) {
                $quoted[] = $this->_driver->quoteIdentifier($f);
            }
            $expression->setField($quoted);
        } elseif ($field instanceof ExpressionInterface) {
            $this->quoteExpression($field);
        }
    }

    /**
     * Quotes identifiers in "order by" expression objects
     *
     * Strings with spaces are treated as literal expressions
     * and will not have identifiers quoted.
     *
     * @param \Cake\Database\Expression\OrderByExpression $expression The expression to quote.
     * @return void
     */
    protected function _quoteOrderBy(OrderByExpression $expression)
    {
        $expression->iterateParts(function ($part, &$field) {
            if (is_string($field)) {
                $field = $this->_driver->quoteIdentifier($field);
                return $part;
            }
            if (is_string($part) && strpos($part, ' ') === false) {
                return $this->_driver->quoteIdentifier($part);
            }
            return $part;
        });
    }

    /**
     * Quotes identifiers in "order by" expression objects
     *
     * @param \Cake\Database\Expression\IdentifierExpression $expression The identifiers to quote.
     * @return void
     */
    protected function _quoteIdentifierExpression(IdentifierExpression $expression)
    {
        $expression->setIdentifier(
            $this->_driver->quoteIdentifier($expression->getIdentifier())
        );
    }
}