<?php

/**
 * Simple query builder for MySQL and Sphinx Search (SphinxQL)
 * Has no dependencies on actual connection & query layer (mysqli or whatever)
 *
 * Use it freely under the terms of GNU GPLv2 or later license
 *
 * Version: 2018-09-12
 * (c) Vitaliy Filippov 2012-2018
 */
abstract class MysqlQueryBuilder
{
    public $tableNames = [];
    public $isSphinx = false;

    /**
     * Override this single method to use query builder
     */
    abstract function quote($value);

    function quoteId($name)
    {
        return "`".str_replace("`", "``", $name)."`";
    }

    /**
     * Replace ? placeholders in $str with quoted parameters from $params
     *
     * @param string $str query fragment
     * @param array $params bind parameters to interpolate into
     */
    function quoteInto($str, $params)
    {
        $i = 0;
        $r = '';
        while (($p = strpos($str, '?')) !== false)
        {
            $r .= substr($str, 0, $p) . $this->quote($params[$i++]);
            $str = substr($str, $p+1);
        }
        return $r.$str;
    }

    /**
     * Builds SQL SELECT query text.
     *
     * @param mixed $tables see $this->tablesBuilder()
     * @param mixed $fields Field definitions - either a string or an array.
     *   Strings are passed to resulting query text as-is.
     *   Arrays have the following format:
     *   [ 'field1', 'alias2' => 'expression2', ... ]
     * @param mixed $where see $this->whereBuilder()
     * @param array $options query options - array of:
     *   'CALC_FOUND_ROWS'
     *   'NO_CACHE' or 'CACHE'
     *   'FOR UPDATE' or 'LOCK IN SHARE MODE'
     *   'GROUP BY' => 'field ASC' or [ $groupby_field1 => 'ASC', $groupby_field2 => 'DESC' ]
     *   'ORDER BY' => 'field ASC' or [ $orderby_field1 => 'ASC', $orderby_field2 => 'DESC' ]
     *   'LIMIT' => [ $offset, $limit ] or [ $limit ] or just $limit
     *   'OFFSET' => $offset, for the case when 'LIMIT' is just $limit
     *
     *   Sphinx Search extensions:
     *   'WITHIN GROUP ORDER BY' => [ $orderby_field => 'ASC' ]
     *   'FIELD_WEIGHTS' => [ 'field' => <weight>, ... ]
     *   'RANKER' => bm25|sph04|...|expr('...ranker expression...')
     */
    function select_builder($tables, $fields, $where, $options = NULL)
    {
        if (!$options)
            $options = [];
        else
        {
            foreach ($options as $k => $v)
                if (ctype_digit("$k"))
                    $options[$v] = true;
        }
        if (is_array($fields))
        {
            foreach ($fields as $k => $v)
                if (!ctype_digit("$k"))
                    $fields[$k] = "$v AS ".$this->quoteId($k);
            $fields = join(',', $fields);
        }
        $more = NULL;
        $tables = $this->tables_builder($tables, $more);
        if ($more)
            $where = array_merge($where, (array)$more);
        $where = $this->where_builder($where);
        $sql = 'SELECT ';
        if (isset($options['CALC_FOUND_ROWS']) || isset($options['SQL_CALC_FOUND_ROWS']))
            $sql .= 'SQL_CALC_FOUND_ROWS ';
        if (isset($options['NO_CACHE']) || isset($options['SQL_NO_CACHE']))
            $sql .= 'SQL_NO_CACHE ';
        elseif (isset($options['CACHE']) || isset($options['SQL_CACHE']))
            $sql .= 'SQL_CACHE ';
        $sql .= "$fields FROM $tables";
        if ($where)
        {
            $sql .= " WHERE $where";
        }
        if (!empty($options['GROUP BY']) && $options['GROUP BY'] !== '0')
        {
            $sql .= " GROUP BY ".$this->order_option($options['GROUP BY']);
        }
        if (!empty($options['ORDER BY']) && $options['ORDER BY'] !== '0')
        {
            $sql .= " ORDER BY ".$this->order_option($options['ORDER BY']);
        }
        if ($this->isSphinx && !empty($options['WITHIN GROUP ORDER BY']) && $options['WITHIN GROUP GROUP BY'] !== '0')
        {
            // Sphinx Search extension
            $sql .= " WITHIN GROUP ORDER BY ".$this->order_option($options['WITHIN GROUP ORDER BY']);
        }
        $sql .= $this->limit_option($options);
        if ($this->isSphinx && !empty($options['FIELD_WEIGHTS']) || !empty($options['RANKER']))
        {
            // Sphinx Search extension
            $opt = [];
            if (!empty($options['FIELD_WEIGHTS']))
            {
                $weights = [];
                foreach ($options['FIELD_WEIGHTS'] as $f => $w)
                {
                    $weights[] = "`$f`=$w";
                }
                $opt[] = "field_weights=(".implode(', ', $weights).")";
            }
            if (!empty($options['RANKER']))
            {
                $opt[] = "ranker=".$options['RANKER'];
            }
            $sql .= " OPTION ".implode(', ', $opt);
        }
        if (isset($options['FOR UPDATE']))
            $sql .= ' FOR UPDATE';
        elseif (isset($options['LOCK IN SHARE MODE']))
            $sql .= ' LOCK IN SHARE MODE';
        return $sql;
    }

    /**
     * Builds WHERE-part of an SQL query.
     * $where can also be a string - then it's passed as-is.
     *
     * @param array $where Query conditions:
     *   [
     *     'conditional expression',
     *     'field_name' => 'value',
     *     'field_name' => [ 'one', 'of', 'values' ],
     *     'field_name < ?' => 'value',
     *     'field_name < DATE_SUB(?, ?)' => [ 'arg1', 'arg2' ],
     *     'field1,field2' => [ [ 1, 2 ], [ 3, 4 ] ],
     *   ]
     */
    function where_builder($where)
    {
        if (!is_array($where))
            return $where;
        $wh = [];
        foreach ($where as $k => $v)
        {
            if (ctype_digit("$k"))
            {
                if (is_array($v))
                {
                    $str = array_shift($v);
                    $wh[] = $this->quoteInto($str, $v);
                }
                else
                {
                    $wh[] = $v;
                }
            }
            elseif (($p = strrpos($k, '?')) !== false)
            {
                $wh[] = $this->quoteInto($k, (array)$v);
            }
            elseif (is_array($v))
            {
                if (!$v)
                {
                    throw new Exception("Error: empty array for '$k IN (...)', don't know what to do");
                }
                else
                {
                    if (is_array(reset($v)))
                    {
                        // (a,b) IN ((1,2), (3,4)) ...
                        foreach ($v as &$l)
                        {
                            $l = "(" . implode(",", array_map([ $this, 'quote' ], $l)) . ")";
                        }
                        $wh[] = "$k IN (" . implode(",", $v) . ")";
                    }
                    else
                    {
                        $r = '';
                        $null = false;
                        foreach ($v as $i => $l)
                        {
                            if ($l === NULL)
                            {
                                $null = true;
                            }
                            else
                            {
                                $r .= $this->quote($l).',';
                            }
                        }
                        $r = $r !== '' ? "$k IN (" . substr($r, 0, -1) . ")" : '';
                        if ($null)
                        {
                            $r = $r !== '' ? "($r OR $k IS NULL)" : "$k IS NULL";
                        }
                        $wh[] = $r;
                    }
                }
            }
            elseif (preg_match('/^-?\d+(\.\d+)?$/s', $v)) // int/float
                $wh[] = "$k=$v";
            elseif ($v !== NULL)
                $wh[] = "$k=".$this->quote($v);
            else
                $wh[] = "$k IS NULL";
        }
        if ($this->isSphinx)
        {
            // Sphinx supports neither brackets nor OR operator as of 2.0.6-release O_o
            $where = join(' AND ', $wh);
        }
        elseif ($where)
            $where = '(' . join(') AND (', $wh) . ')';
        else
            $where = '';
        return $where;
    }

    /**
     * Handles ORDER BY or GROUP BY options
     */
    protected function order_option($g)
    {
        if (is_array($g))
        {
            $g1 = [];
            foreach ($g as $k => $v)
            {
                if (ctype_digit("$k"))
                    $g1[] = $v;
                else
                    $g1[] = "$k $v";
            }
            $g = join(',', $g1);
        }
        return $g;
    }

    /**
     * Handles a single LIMIT or LIMIT and OFFSET options.
     */
    protected function limit_option($options)
    {
        if (isset($options['LIMIT']))
        {
            $g = $options['LIMIT'];
            if (is_array($g))
                $g = join(',', $g);
            elseif ($g && isset($options['OFFSET']))
                $g = "$options[OFFSET], $g";
            if ($g)
                return " LIMIT $g";
        }
        return '';
    }

    /**
     * Builds FROM-part of an SQL query.
     *
     * $tables = [
     *   'table',
     *   'alias' => 'table',
     *   'alias' => [ 'INNER', 'table_name', $where_for_on_clause ],
     *   'alias(ignored)' => [ 'INNER', $nested_tables, $on_for_join_group ],
     * ]
     * or just a string "`table1` INNER JOIN `table2` ON ..."
     * names taken into `backticks` will be transformed using $this->tableNames
     */
    function tables_builder($tables, &$where = NULL)
    {
        if (is_array($tables))
        {
            $t = '';
            foreach ($tables as $k => $v)
            {
                if (!is_array($v))
                    $v = [ 'INNER', $v, NULL ];
                $join = strtolower(substr($v[0], 0, 4));
                if ($join == 'righ')
                    $join = 'RIGHT';
                elseif ($join == 'left')
                    $join = 'LEFT';
                else /* if (!$join || $join == 'inne' || $join == 'join') */
                    $join = 'INNER';
                if (is_array($v[1])) // nested join (left join (A join B on ...) on ...)
                {
                    $more = NULL;
                    $table = $this->tables_builder($v[1], $more);
                    if ($more)
                        $v[2] = array_merge((array)$v[2], (array)$more);
                    if (count($v[1]) > 1)
                        $table = "($table)";
                }
                else
                {
                    $table = (isset($this->tableNames[$v[1]]) ? $this->quoteId($this->tableNames[$v[1]]) : $v[1]);
                    if (!ctype_digit("$k"))
                        $table .= ' ' . $k;
                }
                if ($t)
                    $t .= " $join JOIN $table ON ".($this->where_builder($v[2]) ?: '1=1');
                else
                {
                    $t = $table;
                    $where = $v[2]; // extract ON to WHERE if only a single join is specified
                }
            }
            $tables = $t;
        }
        else
            $tables = (isset($this->tableNames[$tables]) ? $this->quoteId($this->tableNames[$tables]) : $tables);
        return $tables;
    }

    /**
     * Delete a set of rows.
     *
     * @param mixed $tables see $this->tables_builder()
     * @param mixed $where see $this->where_builder()
     * @param array $options Options for query:
     *   'LIMIT' => [ $limit, $offset ] or [ $limit ] or just $limit
     *   'OFFSET' => $offset, for the case when 'LIMIT' is just $limit
     */
    function delete_builder($tables, $where, $options = NULL)
    {
        $tables = $this->tables_builder($tables);
        $where = $this->where_builder($where) ?: '1=1';
        $sql = "DELETE FROM $tables WHERE $where";
        $sql .= $this->limit_option($options);
        return $sql;
    }

    /**
     * Builds an INSERT / REPLACE / INSERT IGNORE / INSERT OR UPDATE query.
     *
     * @param string $table Table name to insert rows to.
     * @param array $rows Array of table rows to be inserted.
     * @param string $action Conflict action: NULL, 'REPLACE', 'IGNORE' or 'UPDATE'
     *   REPLACE: delete matching rows, then insert all rows (MySQL REPLACE)
     *   IGNORE: ignore matching rows, insert missing rows (MySQL INSERT IGNORE)
     *   UPDATE: update matching rows, insert missing rows (MySQL INSERT ... ON DUPLICATE KEY UPDATE)
     * @param array|string $uniqueKey Single unique key for conflict checking
     * @param array|NULL $updateCols Columns to update in case of a conflict
     */
    function insert_builder($table, $rows, $action = NULL, $uniqueKey = NULL, $updateCols = NULL)
    {
        if (!$rows || !is_array($rows))
            return false;
        $first = reset($rows);
        if (!is_array($first))
            $rows = [ $rows ];
        if (isset($this->tableNames[$table]))
            $table = $this->tableNames[$table];
        $key = array_keys($rows[0]);
        foreach ($rows as &$r)
        {
            $rs = [];
            foreach ($key as &$k)
                $rs[] = $this->quote($r[$k]);
            $r = "(".implode(",", $rs).")";
        }
        foreach ($key as &$k)
            if (strpos($k, '`') === false && (!$this->isSphinx || $k !== 'id'))
                $k = $this->quoteId($k);
        $sql = ($action == "REPLACE" ? "REPLACE" : "INSERT" . ($action == "IGNORE" ? " IGNORE" : "")).
            " INTO $table (".implode(",",$key).") VALUES ".implode(",",$rows);
        if ($action == "UPDATE")
        {
            if ($uniqueKey)
            {
                $uniqueKey = array_flip(is_array($uniqueKey) ? $uniqueKey : array_map('trim', explode(",", $uniqueKey)));
                $cond = $uniqueKey;
                foreach ($cond as $k => $v)
                    $v = "$k!=VALUES($k)";
                // Trigger ERROR 1242 (21000): Subquery returns more than 1 row if trying to update based on different key conflict
                $cond = "CASE WHEN ".implode(" OR ", $cond)." THEN (SELECT 1 UNION SELECT 2) ELSE ";
            }
            if ($updateCols)
            {
                $key = (array)$updateCols;
            }
            foreach ($key as &$k)
            {
                if ($uniqueKey && isset($uniqueKey[$k]))
                    $k = "$k=($cond $k END)";
                else
                    $k = "$k=VALUES($k)";
            }
            $sql .= " ON DUPLICATE KEY UPDATE ".implode(",",$key);
        }
        return $sql;
    }

    /**
     * Update row(s) in $table.
     *
     * @param string $table Table name to update.
     * @param array $set Assoc array with values for update query.
     * @param array $where Conditions for update query, see $this->where_builder().
     * @param array $options Options for update query:
     *   'LIMIT' => [ $limit, $offset ] or [ $limit ] or just $limit
     *   'OFFSET' => $offset, for the case when 'LIMIT' is just $limit
     */
    function update_builder($table, $set, $where = NULL, $options = NULL)
    {
        if (!$set)
            return false;
        if (count(func_get_args()) == 2)
            throw new Exception(__CLASS__."::update(table, rows) is the old syntax, use upsert()");
        $sql = [];
        foreach ((array)$set as $k => $v)
        {
            if (!ctype_digit("$k"))
                $sql[] = $k.'='.$this->quote($v);
            else
                $sql[] = $v;
        }
        $where = $this->where_builder($where) ?: '1=1';
        $sql = 'UPDATE ' . $this->tables_builder($table) . ' SET ' . implode(', ', $sql) . ' WHERE ' . $where;
        $sql .= $this->limit_option($options);
        return $sql;
    }
}