<?php

class Schema {
    public $name;
    public $engine;
    public $charset = 'utf8';
    public $collation;

    protected $fields = [];
    protected $current_field;

    function __construct($name){
        $this->name = $name;
    }

    // type

    function integer($name){
        $this->current_field = $name;
        $this->fields[$this->current_field] = [];
        $this->fields[$this->current_field]['type'] = 'integer';
        return $this;
    }

    function varchar($name){
        $this->current_field = $name;
        $this->fields[$this->current_field] = [];
        $this->fields[$this->current_field]['type'] = 'varchar';
        return $this;
    }

    // modifiers

    function auto(){
        // chequear si es un entero
        $this->fields[$this->current_field]['auto'] =  true;
        return $this;
    }

    function unsigned(){
        // chequear si es un entero
        $this->fields[$this->current_field]['unsigned'] =  true;
        return $this;
    }

    function nullable(){
        // chequear si es un entero
        $this->fields[$this->current_field]['nullable'] =  true;
        return $this;
    }


    // reflexion

    function getSchema(){
        return $this->fields;
    }
}


$table = new Schema('test');

$table->name      = 'users';
$table->engine    = 'InnoDB';
$table->charset   = 'utf8';
$table->collation = 'utf8_general_ci';

$table->integer('id')->auto()->unsigned();
$table->varchar('firstname');
$table->varchar('lastname')->nullable();
// ..

echo '<pre>';
var_dump($table->getSchema());
echo '</pre>';