<?php
/**
 * @package    Proxim
 * @author     Davison Pro <davis@davisonpro.dev | https://davisonpro.dev>
 * @copyright  2019 Proxim
 * @version    1.5.0
 * @since      File available since Release 1.0.0
 */

namespace Proxim\Database;

use Exception;

/**
 * SQL query builder
 *
 * @since 1.0.0
 */
class DbQuery
{
    /**
     * List of data to build the query.
     *
     * @var array
     */
    protected $query = array(
        'type' => 'SELECT',
        'select' => array(),
        'from' => array(),
        'join' => array(),
        'where' => array(),
        'group' => array(),
        'having' => array(),
        'order' => array(),
        'limit' => array('offset' => 0, 'limit' => 0),
    );

    /**
     * Sets type of the query.
     *
     * @param string $type SELECT|DELETE
     *
     * @return DbQuery
     */
    public function type($type)
    {
        $types = array('SELECT', 'DELETE');

        if (!empty($type) && in_array($type, $types)) {
            $this->query['type'] = $type;
        }

        return $this;
    }

    /**
     * Adds fields to SELECT clause.
     *
     * @param string $fields List of fields to concat to other fields
     *
     * @return DbQuery
     */
    public function select($fields)
    {
        if (!empty($fields)) {
            $this->query['select'][] = $fields;
        }

        return $this;
    }

    /**
     * Sets table for FROM clause.
     *
     * @param string $table Table name
     * @param string|null $alias Table alias
     *
     * @return DbQuery
     */
    public function from($table, $alias = null)
    {
        if (!empty($table)) {
            $this->query['from'][] = '`' . PROX_DB_PREFIX . $table . '`' . ($alias ? ' ' . $alias : '');
        }

        return $this;
    }

    /**
     * Adds JOIN clause
     * E.g. $this->join('RIGHT JOIN '.PROX_DB_PREFIX.'product p ON ...');.
     *
     * @param string $join Complete string
     *
     * @return DbQuery
     */
    public function join($join)
    {
        if (!empty($join)) {
            $this->query['join'][] = $join;
        }

        return $this;
    }

    /**
     * Adds a LEFT JOIN clause.
     *
     * @param string $table Table name (without prefix)
     * @param string|null $alias Table alias
     * @param string|null $on ON clause
     *
     * @return DbQuery
     */
    public function leftJoin($table, $alias = null, $on = null)
    {
        return $this->join('LEFT JOIN `' . PROX_DB_PREFIX . bqSQL($table) . '`' . ($alias ? ' `' . pSQL($alias) . '`' : '') . ($on ? ' ON ' . $on : ''));
    }

    /**
     * Adds an INNER JOIN clause
     * E.g. $this->innerJoin('product p ON ...').
     *
     * @param string $table Table name (without prefix)
     * @param string|null $alias Table alias
     * @param string|null $on ON clause
     *
     * @return DbQuery
     */
    public function innerJoin($table, $alias = null, $on = null)
    {
        return $this->join('INNER JOIN `' . PROX_DB_PREFIX . bqSQL($table) . '`' . ($alias ? ' `' . pSQL($alias) . '`' : '') . ($on ? ' ON ' . $on : ''));
    }

    /**
     * Adds a LEFT OUTER JOIN clause.
     *
     * @param string $table Table name (without prefix)
     * @param string|null $alias Table alias
     * @param string|null $on ON clause
     *
     * @return DbQuery
     */
    public function leftOuterJoin($table, $alias = null, $on = null)
    {
        return $this->join('LEFT OUTER JOIN `' . PROX_DB_PREFIX . bqSQL($table) . '`' . ($alias ? ' `' . pSQL($alias) . '`' : '') . ($on ? ' ON ' . $on : ''));
    }

    /**
     * Adds a NATURAL JOIN clause.
     *
     * @param string $table Table name (without prefix)
     * @param string|null $alias Table alias
     *
     * @return DbQuery
     */
    public function naturalJoin($table, $alias = null)
    {
        return $this->join('NATURAL JOIN `' . PROX_DB_PREFIX . bqSQL($table) . '`' . ($alias ? ' `' . pSQL($alias) . '`' : ''));
    }

    /**
     * Adds a RIGHT JOIN clause.
     *
     * @param string $table Table name (without prefix)
     * @param string|null $alias Table alias
     * @param string|null $on ON clause
     *
     * @return DbQuery
     */
    public function rightJoin($table, $alias = null, $on = null)
    {
        return $this->join('RIGHT JOIN `' . PROX_DB_PREFIX . bqSQL($table) . '`' . ($alias ? ' `' . pSQL($alias) . '`' : '') . ($on ? ' ON ' . $on : ''));
    }

    /**
     * Adds a restriction in WHERE clause (each restriction will be separated by AND statement).
     *
     * @param string $restriction
     *
     * @return DbQuery
     */
    public function where($restriction)
    {
        if (!empty($restriction)) {
            $this->query['where'][] = $restriction;
        }

        return $this;
    }

    /**
     * Adds a restriction in HAVING clause (each restriction will be separated by AND statement).
     *
     * @param string $restriction
     *
     * @return DbQuery
     */
    public function having($restriction)
    {
        if (!empty($restriction)) {
            $this->query['having'][] = $restriction;
        }

        return $this;
    }

    /**
     * Adds an ORDER BY restriction.
     *
     * @param string $fields List of fields to sort. E.g. $this->order('myField, b.mySecondField DESC')
     *
     * @return DbQuery
     */
    public function orderBy($fields)
    {
        if (!empty($fields)) {
            $this->query['order'][] = $fields;
        }

        return $this;
    }

    /**
     * Adds a GROUP BY restriction.
     *
     * @param string $fields List of fields to group. E.g. $this->group('myField1, myField2')
     *
     * @return DbQuery
     */
    public function groupBy($fields)
    {
        if (!empty($fields)) {
            $this->query['group'][] = $fields;
        }

        return $this;
    }

    /**
     * Sets query offset and limit.
     *
     * @param int $limit
     * @param int $offset
     *
     * @return DbQuery
     */
    public function limit($limit, $offset = 0)
    {
        $offset = (int) $offset;
        if ($offset < 0) {
            $offset = 0;
        }

        $this->query['limit'] = array(
            'offset' => $offset,
            'limit' => (int) $limit,
        );

        return $this;
    }

    /**
     * Generates query and return SQL string.
     *
     * @return string
     *
     * @throws Exception
     */
    public function build()
    {
        if ($this->query['type'] == 'SELECT') {
            $sql = 'SELECT ' . ((($this->query['select'])) ? implode(",\n", $this->query['select']) : '*') . "\n";
        } else {
            $sql = $this->query['type'] . ' ';
        }

        if (!$this->query['from']) {
            throw new Exception('Table name not set in DbQuery object. Cannot build a valid SQL query.');
        }

        $sql .= 'FROM ' . implode(', ', $this->query['from']) . "\n";

        if ($this->query['join']) {
            $sql .= implode("\n", $this->query['join']) . "\n";
        }

        if ($this->query['where']) {
            $sql .= 'WHERE (' . implode(') AND (', $this->query['where']) . ")\n";
        }

        if ($this->query['group']) {
            $sql .= 'GROUP BY ' . implode(', ', $this->query['group']) . "\n";
        }

        if ($this->query['having']) {
            $sql .= 'HAVING (' . implode(') AND (', $this->query['having']) . ")\n";
        }

        if ($this->query['order']) {
            $sql .= 'ORDER BY ' . implode(', ', $this->query['order']) . "\n";
        }

        if ($this->query['limit']['limit']) {
            $limit = $this->query['limit'];
            $sql .= 'LIMIT ' . ($limit['offset'] ? $limit['offset'] . ', ' : '') . $limit['limit'];
        }

        return $sql;
    }

    /**
     * Converts object to string.
     *
     * @return string
     */
    public function __toString()
    {
        return $this->build();
    }
}