<?php

namespace Ulmus\Query;

class Select extends Fragment {

    const FIELD_AS = "%s as %s";
    
    public int $order = -100;

    public bool $distinct = false;

    public bool $union = false;

    public bool $isInternalSelect = false;

    public ? int $top = null;

    protected array $fields = [];

    const SQL_TOKEN = "SELECT";

    public function set($fields) : self
    {
        $this->fields = is_array($fields) ? $fields : [ $fields ];
        return $this;
    }

    public function add($fields) : self
    {
        if ( is_array($fields) ) {
            $this->fields = array_merge($this->fields, $fields);
        }
        else {
            $this->fields[] = $fields;
        }

        return $this;
    }

    public function render() : string
    {
        foreach($this->fields as $key => &$value) {
            if ( ! is_numeric($key) ) {
                $value = sprintf(static::FIELD_AS, $value, $key);
            }
        }
        
        return $this->renderSegments([
            ( $this->union ? 'UNION' : false ),
            static::SQL_TOKEN,
            ( $this->distinct ? 'DISTINCT' : false ),
            ( $this->top ? sprintf('TOP (%s)', $this->top) : false ),
            implode(', ', $this->fields)
        ]);
    }
}