<?php

/**
 * Part of the Joomla Framework Database Package
 *
 * @copyright  Copyright (C) 2005 - 2021 Open Source Matters, Inc. All rights reserved.
 * @license    GNU General Public License version 2 or later; see LICENSE
 */

namespace Joomla\Database\Query;

/**
 * Trait for MySQL Query Building.
 *
 * @since  2.0.0
 */
trait MysqlQueryBuilder
{
    /**
     * Magic function to convert the query to a string.
     *
     * @return  string  The completed query.
     *
     * @since   2.0.0
     */
    public function __toString()
    {
        switch ($this->type) {
            case 'select':
                if ($this->selectRowNumber) {
                    $orderBy      = $this->selectRowNumber['orderBy'];
                    $tmpOffset    = $this->offset;
                    $tmpLimit     = $this->limit;
                    $this->offset = 0;
                    $this->limit  = 0;
                    $tmpOrder     = $this->order;
                    $this->order  = null;
                    $query        = parent::__toString();
                    $this->order  = $tmpOrder;
                    $this->offset = $tmpOffset;
                    $this->limit  = $tmpLimit;

                    // Add support for second order by, offset and limit
                    $query = PHP_EOL . 'SELECT * FROM (' . $query . PHP_EOL . "ORDER BY $orderBy" . PHP_EOL . ') w';

                    if ($this->order) {
                        $query .= (string) $this->order;
                    }

                    return $this->processLimit($query, $this->limit, $this->offset);
                }
        }

        return parent::__toString();
    }

    /**
     * Method to modify a query already in string format with the needed additions to make the query limited to a particular number of
     * results, or start at a particular offset.
     *
     * @param   string   $query   The query in string format
     * @param   integer  $limit   The limit for the result set
     * @param   integer  $offset  The offset for the result set
     *
     * @return  string
     *
     * @since   2.0.0
     */
    public function processLimit($query, $limit, $offset = 0)
    {
        if ($limit > 0 && $offset > 0) {
            $query .= ' LIMIT ' . $offset . ', ' . $limit;
        } elseif ($limit > 0) {
            $query .= ' LIMIT ' . $limit;
        }

        return $query;
    }

    /**
     * Concatenates an array of column names or values.
     *
     * @param   string[]     $values     An array of values to concatenate.
     * @param   string|null  $separator  As separator to place between each value.
     *
     * @return  string  The concatenated values.
     *
     * @since   2.0.0
     */
    public function concatenate($values, $separator = null)
    {
        if ($separator !== null) {
            $statement = 'CONCAT_WS(' . $this->quote($separator);

            foreach ($values as $value) {
                $statement .= ', ' . $value;
            }

            return $statement . ')';
        }

        return 'CONCAT(' . implode(',', $values) . ')';
    }

    /**
     * Aggregate function to get input values concatenated into a string, separated by delimiter
     *
     * Usage:
     * $query->groupConcat('id', ',');
     *
     * @param   string  $expression  The expression to apply concatenation to, this may be a column name or complex SQL statement.
     * @param   string  $separator   The delimiter of each concatenated value
     *
     * @return  string  Input values concatenated into a string, separated by delimiter
     *
     * @since   2.0.0
     */
    public function groupConcat($expression, $separator = ',')
    {
        return 'GROUP_CONCAT(' . $expression . ' SEPARATOR ' . $this->quote($separator) . ')';
    }

    /**
     * Method to quote and optionally escape a string to database requirements for insertion into the database.
     *
     * This method is provided for use where the query object is passed to a function for modification.
     * If you have direct access to the database object, it is recommended you use the quote method directly.
     *
     * Note that 'q' is an alias for this method as it is in DatabaseDriver.
     *
     * Usage:
     * $query->quote('fulltext');
     * $query->q('fulltext');
     * $query->q(array('option', 'fulltext'));
     *
     * @param   array|string  $text    A string or an array of strings to quote.
     * @param   boolean       $escape  True (default) to escape the string, false to leave it unchanged.
     *
     * @return  string  The quoted input string.
     *
     * @since   2.0.0
     * @throws  \RuntimeException if the internal db property is not a valid object.
     */
    abstract public function quote($text, $escape = true);

    /**
     * Get the regular expression operator
     *
     * Usage:
     * $query->where('field ' . $query->regexp($search));
     *
     * @param   string  $value  The regex pattern.
     *
     * @return  string
     *
     * @since   2.0.0
     */
    public function regexp($value)
    {
        return ' REGEXP ' . $value;
    }

    /**
     * Get the function to return a random floating-point value
     *
     * Usage:
     * $query->rand();
     *
     * @return  string
     *
     * @since   2.0.0
     */
    public function rand()
    {
        return ' RAND() ';
    }

    /**
     * Find a value in a varchar used like a set.
     *
     * Ensure that the value is an integer before passing to the method.
     *
     * Usage:
     * $query->findInSet((int) $parent->id, 'a.assigned_cat_ids')
     *
     * @param   string  $value  The value to search for.
     * @param   string  $set    The set of values.
     *
     * @return  string  A representation of the MySQL find_in_set() function for the driver.
     *
     * @since   2.0.0
     */
    public function findInSet($value, $set)
    {
        return ' find_in_set(' . $value . ', ' . $set . ')';
    }

    /**
     * Return the number of the current row.
     *
     * Usage:
     * $query->select('id');
     * $query->selectRowNumber('ordering,publish_up DESC', 'new_ordering');
     * $query->from('#__content');
     *
     * @param   string  $orderBy           An expression of ordering for window function.
     * @param   string  $orderColumnAlias  An alias for new ordering column.
     *
     * @return  $this
     *
     * @since   2.0.0
     * @throws  \RuntimeException
     */
    public function selectRowNumber($orderBy, $orderColumnAlias)
    {
        $this->validateRowNumber($orderBy, $orderColumnAlias);

        return $this->select("(SELECT @rownum := @rownum + 1 FROM (SELECT @rownum := 0) AS r) AS $orderColumnAlias");
    }

    /**
     * Casts a value to a char.
     *
     * Ensure that the value is properly quoted before passing to the method.
     *
     * Usage:
     * $query->select($query->castAs('CHAR', 'a'));
     *
     * @param   string  $type    The type of string to cast as.
     * @param   string  $value   The value to cast as a char.
     * @param   string  $length  The value to cast as a char.
     *
     * @return  string  SQL statement to cast the value as a char type.
     *
     * @since   1.0
     */
    public function castAs(string $type, string $value, ?string $length = null)
    {
        switch (strtoupper($type)) {
            case 'CHAR':
                if (!$length) {
                    return $value;
                } else {
                    return 'CAST(' . $value . ' AS CHAR(' . $length . '))';
                }

                // No break
            case 'INT':
                return '(' . $value . ' + 0)';
        }

        return parent::castAs($type, $value, $length);
    }
}
